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DIY SCT Cooler ?

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#1 Live_Steam_Mad

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Posted 25 September 2014 - 12:00 AM

There are a couple of DIY / home made SCT coolers on the web, but the pages are no longer available and I have to use archive.org to get them, and the contact details are sometimes no longer valid or don't work.

 

For example ;-

 

https://web.archive..../sctcooler.html

 

...I have contacted ade (AT) cotswoldobservatory (DOT) com about it but got no reply.

 

and ;-

 

https://web.archive.....com/cooler.htm

 

and;-

 

https://web.archive....cope_cooler.htm

 

The two problems that I have for each of these 3 coolers is 1) understanding what the parts are and how they fit together, 2) where I buy the parts from in England, UK.

 

For example in that 1st cooler, it is unclear to me by "32mm waste pipe" whether Ade is referring to the larger of the two white pipes or to the grey tube with holes and 2 flanges on either side? Or whether the "screw connector from 42mm larger type waste pipe" is the grey part or the white spacer or both? I tried to find such an item and it doesn't appear to actually exist. The standard waste pipes in this country seem to be 32mm and 40mm, not 42mm ?

 

later EDIT: Oh hang on, I just noticed that near the bottom it mentions "Exhaust : Water tank connector with holes drilled to allow outflow air to escape. None of this grey piece enters the 'scope.", ahh that's the part I was missing. Doah. I need to find that part online.

 

However it is also unclear to me how the parts manage to mount into each other co-axially and how the correct spacing is done axially etc.

 

In the 3rd cooler, I tried to locate the "  3" - 2"  PVC coupler  "  and came up with ;-

 

http://kscdirect.com...PVC-40+COUP+SXS

 

...which mentions that the 2" part is actually a socket and the outside diameter of the 2" part is 73.03mm, so how the heck does that fit into my C11's SCT's 2" internal baffle diameter?

 

Does anyone have any proper dimensioned plans for a home made DIY SCT cooler with parts that are fully described or where they can give me the item codes and manufacturers for the parts and where you can buy each part from?

 

Or anything that anyone can add to help me with understanding what parts are actually used and what sizes they are and how they fit together (and how they fit into the focusser / baffle tube)?

 

Regards,

 

Alistair G.



#2 Live_Steam_Mad

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Posted 27 September 2014 - 03:30 PM

I found another DIY SCT cooler, here are the pictures ;-

 

https://www.flickr.c...in/photostream/

 

https://www.flickr.c...in/photostream/

 

https://www.flickr.c...in/photostream/

 

https://www.flickr.c...in/photostream/

 

https://www.flickr.c...in/photostream/

 

https://www.flickr.c...in/photostream/

 

https://www.flickr.c...in/photostream/

 

It's by Jared Wellman and someone already asked the guy for info but all he says is that it is an "SCT cooler, made from PVC", and says "the pictures of it on this site [his Flickr photostream] are probably the best info on the construction of it. I no longer have the cooler (or any SCTs for that matter). I can't recall the sizes of the tubing or the pieces that were used."

 

I would think that the end cap is an End Cap for a 4" to 2" PVC Coupler, and the conical part is the 4" to 2" PVC Coupler, but the other parts are a mystery to me. However it looks like a really simple thing to make, I just wish someone could help me with the remaining parts (i.e. what the heck are they and what brand / item code and where do I buy them?).

 

Later EDIT: I think that the 2nd smallest white part (the plain sleeve) is a "  1 1/4" PVC Coupler "  such as item code CTX-6141626 from this page ;-

 

http://www.cableorga...ntex/couplings/

 

...since it is meant (in it's normal intended use) to accept a 1.25" Inside Diameter PVC pipe (external diameter 1 11/16", caused by the Schedule 40 wall thickness) and thus has a socket of 1 11/16" and an external diameter of 2" where it could be put into the baffle tube of a C11 or C14 (but NOT a C8 with only 38mm internal baffle tube diameter). This however is just a guess.

 

Best Regards,

 

Alistair G.


Edited by Live_Steam_Mad, 27 September 2014 - 05:47 PM.


#3 ur7x

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Posted 28 September 2014 - 12:24 PM

I made one basically for free.  Though you need a lathe. 

First I turned down a left over chunk of 4x4 fence post to a 2" diameter after horizontally drilling four 3/8" holes to provide for relieve vents.

Once that was done I bored a center hole for a left over chunk of 3/4" PCV electrical conduit.

 

The hardest part was whittling the "funnel" to increase the air path from the fan. 

 

For a fan I snagged a 12V fan from PC power supply from a 1980's vintage 386 that I hadn't thrown out yet. 

 

Other than turning the chunk of wood on the lathe, this was dead simple and easy.

 

I wired mine to take power from a 12v ac adapter, Though i like the idea of taking power from the mounts AUX ports...



#4 bumm

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Posted 28 September 2014 - 01:34 PM

One of the advantages of an SCT is the sealed optics.  I've been using my C8 for 37 years with no visible degradation of the mirror.  Do these coolers negate that advantage?

                                                                                                      Marty



#5 ur7x

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Posted 28 September 2014 - 07:24 PM

One of the advantages of an SCT is the sealed optics.  I've been using my C8 for 37 years with no visible degradation of the mirror.  Do these coolers negate that advantage?

                                                                                                      Marty

 

Sealed Optics?  How so?  All SCT's (other than Edge's) are open on the back side where the diagonal/eyepiece goes...  

 

These "ventilators" use that opening to push ambient (hopefully micro-filtered ) air into the tube near the corrector/secondary to force the warmer (or cooler) air inside the tube out.  This helps eliminate convection currents within the tube which give "mirage" like images .



#6 Live_Steam_Mad

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Posted 07 October 2014 - 03:36 PM

I am adding the JPEG's here as an attachment for the 1st DIY cooler made by someone in USA, since the pages are archived and the pictures can go missing.

 

EDIT: had to remove them all. Against TOS.

 

So you'll have to take your chances on this archive link ;-

 

https://web.archive.....com/cooler.htm

 

The contact e-mail for the guy was ;-

 

scott@starcrwzr.com

 

...but that domain name no longer works.

 

BTW I finally figured out what all the parts are and how they go together and I'll be adding an explanation here shortly.

 

Regards,

 

Alistair G.


Edited by Live_Steam_Mad, 07 October 2014 - 09:36 PM.

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#7 Live_Steam_Mad

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Posted 07 October 2014 - 04:41 PM

When the Scott mentions a 2" computer fan, I believe he actually means a 60mm fan. The reason for this is that the 2" PVC coupler (which is the large diameter tube in the picture) itself has an Inside Diameter (ID) to take a 2" PVC pipe (since couplers are designed to join two sections of pipe), BUT by 2" pipe I mean that it adheres to a standard called "Nominal Pipe Size", used in the USA ;-

 

http://en.wikipedia....minal_Pipe_Size

 

...which defines only the OUTSIDE diameter (OD) of the pipe. So the "2 inch pipe" actually has a fixed OD of 2.375" / 60.33mm, and the "2 inch" bit of the name actually refers to the INSIDE diameter of the pipe. With the usual "Schedule 40" standard that these plumbing parts tend to be, Schedule 40 defines the wall thickness of the pipe, so if we have a 2" Sch.40 pipe it therefore has a 0.154" / 3.912mm wall thickness (according to the data table in the above link) and therefore has an ID of 2.375 - (2 * 0.154) = 2.067" / 52.502mm, or about 2".

 

So if the "2 inch" PVC pipe (that goes in such a "2 inch coupler") has an OD of 2.375" / 60.33mm, then the 2" coupler must have an ID of 2.375" i.e. 60.33mm, so it can accept a 60mm computer case fan if you, as is mentioned, cut off the corners to make it round, then the fan with the now round surround / fan shroud will fit into the "2 inch" PVC coupler.

 

Also as confirmation of this, I believe that the fan that Scott has used is an IMC Micro Boxer fan. Since his pictures show such. I Googled and found this fan on Amazon ;-

 

http://www.amazon.co...micro boxer fan

 

...which appears to be an exact match. Item code is 2410PL-04W-B20. It is a 60mm x 60mm x 25mm thick cooling fan for a PC case or CPU etc. heatsink, it draws 0.08A, has a 5-blade plastic impeller, and Ball bearing. IMC Magnetics Corporation who made it where taken over by Curtiss-Wright, and it appears you can no longer buy this fan from IMC. So those on Amazon etc. appear to be New Old Stock. The fan isn't particularly highly specified for a 60mm 12V fan, at a mere 18 CFM ;-

 

http://www.parts-exp...n-008a--259-147

 

The "2 inch to 1 1/4 inch PVC bushing" referred to in Scott's parts list is designed to be inserted as a push fit into FITTINGS that take pipes (in order to adapt a smaller diameter pipe to a fitting outlet), not into pipes themselves, so the "2 inch bushing" has the same OD as a "2 inch pipe" i.e. 2.375" / 60.33mm, and thus fits as a push fit into the "2 inch coupler". The other two reducing bushings are based on the same standards and principles and thus the two reducer bushings fit inside the large bushing with a push fit, the two smaller bushings fit into each other.

 

In the same way, ID of his "1 1/4 inch to 3/4 inch PVC bushing"  has the same ID as the OD of a "3/4 inch pipe", i.e. 1.050" / 26.67mm, and the "3/4 inch pipe" actually has an OD of 1.050" / 26.67mm, and an ID of 1.050 - (2 * 0.113) = 0.824" / 20.93mm, which is close to 3/4 inch, and the pipes are named by their internal size not their external size.

 

Scott is using a thin walled pipe called Class 200, the only PVC part mentioned that is not Schedule 40. This is to allow greater air flow due to smaller wall thickness. A "3/4 inch PVC plug" would NOT go into the pipe, even if the pipe was Schedule 40 wall thickness. This is because a plug is designed to plug up an unused FITTING, not to plug up the end of a pipe. So the plug is the SAME OD and ID as the pipe of the same Schedule wall thickness. Hence a "3/4 inch plug" does NOT fit a "3/4 inch pipe". Scott seems to have made a mistake in his description when he refers to the 3/4 PVC plug. I believe he meant a "1/2 inch PVC plug MPT", see below.

 

I know this since my contact from New Mexico, Paul G. was immensely helpful in showing me how all these parts fit together, as he actually had bought some of these parts for his own SCT cooler. He also used a thin walled Silverline brand 3/4" PVC pipe also called Class 200. Class 200 refers to the pressure it will withstand, in PSI, so that pipe will withstand 200 PSI. That PVC pipe of Paul's is also refered to as SDR21 (Standard Dimension Ratio), which is a ratio based on the diameter versus the wall thickness ;-

 

http://en.wikipedia....dimension_ratio

 

...where, at least nominally, the OD of the pipe divided by it's wall thickness is 21.

 

The part that Paul bought to plug up the end of the pipe was called "1/2 inch PVC plug MPT", where MPT means Male Pipe Thread, which is defined by a standard called National Pipe Thread, a standard used in USA ;-

 

http://en.wikipedia....nal_pipe_thread

 

...which defines a pipe having a 1/2 tapered male NPT thread on it as having a maximum OD (measured just before the threads meet the continuous pipe, not at the very end of the threaded section at the end of the pipe) of 0.840" / 21.336mm.

 

A "3/4 inch PVC Schedule 40 pipe" has an OD of 1.050" / 26.67mm, and an ID of 1.050 - (2 * 0.113) = 0.824" / 20.93mm, and so the "1/2 inch NPT / MPT PVC  plug" (0.840" / 21.336mm OD) should be a tight press fit into such a pipe since the plug's thread would be 16 thou / 0.406mm (or 8 thou either all around / either side) larger than the pipe (the "3/4 inch" pipe that we would use here has no internal matching thread of course) and would screw in tight simply because of the tapered thread gripping the plain internals of the pipe.

 

Paul and Scott have both used a thinner wall "3/4 inch" pipe where the threaded plug was actually a sloppy fit in the pipe, so Paul tells me. Paul showed me a receipt of the parts he bought to confirm all of this (had item codes, descriptions etc).

 

The Silverline "3/4 inch" PVC class 200 / SDR21 pipe actually has a slightly thicker wall thickness in reality. It should have a wall thickness of 1.050 / 21 = 0.050" i.e. 50 thou, but they actually manufacture it to 0.060" minimum wall thickness in reality;-

 

http://www.slpipe.co.../SDR21Chart.pdf

 

So the plug should be a slightly less sloppy fit than it otherwise would be.

 

Paul simply used the flange on the end of the plug to glue onto the "3/4 inch" pipe, and did not rely on the thread etc which as he said was a sloppy push fit.

 

What we are actually supposed to use on the end of a pipe is a CAP, not a plug, so the ideal part should be a "3/4 inch PVC cap" which has an ID of the pipe's OD.

 

So you can't just buy a "3/4 inch PVC plug with a plain Male Spigot end", and expect it to plug up the end of the "3/4 inch" pipe, since plugs are supposed to go into pipe fittings, not pipes, as aforementioned.

 

So all you do is push the 3/4" pipe into the 1 1/4" to 3/4" reducing bushing, then push those into the 1 1/2" to 1 1/4" reducing bushing, then push those into the 2" to 1 1/2" reducing bushing, then push those into the 2" coupling, then push the fan into the end of the coupling, then push the 1/2" MPT plug into the end of the 3/4" pipe (which is a sloppy fit, you need to glue the flange onto the end of the pipe to hold it in).

 

I hope that helps explain how the first items (mentioned on this picture shown above) go together, and what the actual real dimensions are of each of the parts.

 

Regards,

 

Alistair G.


Edited by Live_Steam_Mad, 07 October 2014 - 05:14 PM.


#8 Live_Steam_Mad

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Posted 07 October 2014 - 06:14 PM

Here are the JPEG's showing Tom's DIY CAT cooler, in case the pictures in the article are no longer available from the archived web page ;-

 

EDIT: had to remove them all. Against TOS.

 

So you'll have to take your chances again on this archive link ;-

 

https://web.archive....cope_cooler.htm

 

Regards,

 

Alistair G.


Edited by Live_Steam_Mad, 07 October 2014 - 09:36 PM.


#9 Live_Steam_Mad

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Posted 07 October 2014 - 07:05 PM

There were a couple of errors and things that I found confusing in Tom's article. To clarify ;-

 

He mentions about three "couplers" (i.e. " 1" - 3/4" PVC coupler", " 1 1/2" - 1" PVC coupler", and " 2" - 1 1/2" PVC coupler"),  but they are usally referred to as "reducer bushings". The " 3" - 2" PVC coupler" is the large conical part on the outside, in the pictures, known as a "reducer coupling".

 

Note the use of the Schedule 40 wall thickness "3/4 inch" PVC pipe. This means less air flow than a 3/4" Class 200 / SDR21 pipe due to having the same OD but thicker walls (since pipes are defined by their fixed OD, but named after their approximate Internal Diameter).

 

The "offset" that he mentions was particularly confusing but I have figured that out. See later for explanation and pictures.

 

Note the use of the 1/2" MPT PVC plug in Tom's article. This, as aforementioned, is a apparently a tight-ish push fit in a "3/4 inch Schedule 40 PVC pipe" as explained above, from the dimensions listed. Tom has used this relatively thickwalled pipe (Sch.40). When you use relatively thin wall pipe like Scott and Paul did, you have to glue the plug's flange onto the pipe to get it to stay on at all (as Scott also mentioned).

 

Unfortunately Tom names this part wrong and calls it a "cap" instead of a "plug". A Cap is for going over (covering) the end of a pipe, and a plain end (male spigot) 1/2" PVC plug would not fit the 3/4" pipe, as the plug would be only of the same dimensions as a 1/2" pipe, and a 3/4" PVC plug with Spigot would be the same dimensions as a 3/4" pipe and not fit into it. It is only the fact that the plug has a thread that makes it conform to a different standard (National Pipe Thread, not Nominal Pipe Size), that allows the 1/2" threaded plug to fit the 3/4" pipe. A 1/2" plain cap would not work since it is designed to fit a 1/2" pipe, and a 1/2" threaded cap would not work since that would have a female 1/2" NPT thread to fit a threaded 1/2" pipe (so the cap would have a 0.840" ID hole but the 3/4" pipe has an OD of 1.050" and would not fit. However, a 3/4" PVC cap (socket fitting) would work just fine.

 

I cannot find the Radio Shack #TA-9002510 fan referred to anywhere online with a Google search, which was frustrating since Tom doesn't specify a size for the fan, which is unfortunate.

 

Finally, I don't understand the use of the " 3" PVC cap" that Tom mentions. A cap is to go on the end of a pipe, not to go into a reducer coupling. Unless I am very much mistaken? And since a 3" pipe is 3.5" OD, a 3" cap is 3.5" ID, and fits over the end of the pipe, and is the same ID and OD as a coupling. So I don't see how a cap fits into a 3" to 2" coupling. However, a 3" plug with male spigot end would fit into the "3 inch" end of a 3" to 2" reducing coupling, so perhaps Tom means this instead? Odd though that his photo does not show the flange on the end of the plug? So I don't understand that one yet. Can someone explain this part to me? But then again, the convention is that the larger caps have rounded ends, which Tom's does not have, his is flat, so it does look like he is using a plug, not a cap.

 

The dimensions of PVC parts (Schedule 40) are shown here ;-

 

http://parts.spearsm...ils.aspx?pid=27

 

...scroll down on the right (of the diagram of the PVC part shown) to see the table with the selections of sizes to choose from. If you choose "Schedule 40" and "Cap / Plug" and "Socket" type (which is a cap, therefore), it shows that a "3 inch" pipe which has an OD of 3.5", uses a "3 inch" cap which has an OD of 4 inches!

 

I finally now understand about the "After gluing the remaining couplers in place, I cut the ends off so that they were flush with the 2" - 1 1/2" coupler" he means inside the item, to make the air flow smooth for going down from 3" to 3/4", and he Dremeled it out to make it more of a funnel shape.

 

Unfortunately there were no details for Tom (full name Tom Shaull) on his archived web page at all.

 

Regards,

 

Alistair G.


Edited by Live_Steam_Mad, 08 October 2014 - 01:13 AM.


#10 Live_Steam_Mad

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Posted 09 October 2014 - 03:25 PM

OK I will attempt to explain that "offset" thing in Tom's Cooler... 

 

My C11 has a 50mm approx opening for the ID of the inner primary baffle tube (the part the primary mirror plus outer baffle tube that the primary is fastened to, slides up and down on), so does a C14. But it would be rather inconvenient to have to keep unscrewing the 3.25" to 2" SCT adapter collar (which comes as standard on all C11's) every time I wanted to insert a cooler in there, if such a cooler was made to fit a 2" / 50mm hole.

 

Also, if the cooler was made for a 38mm ID opening (for example the C8's internal diameter for it's inner primary baffle tube), then it would fit a C8 but you would have to keep unscrewing the Visual Back every time you used the cooler, in order to insert the cooler (many people use Visual Back's), and when such a cooler is in the 38mm opening of the adapter collar on the C11, it would not stay in place and would probably droop down internally since the inside of a C11 is 50mm ID approx.

 

So for maximum convenience, whilst still providing practical and adequate amounts of cooling, we use the 1.25" opening of the Visual Back to put the cooler into, and design the cooler to be fitted into that. Obviously the diagonal still has to be removed, but that's unavoidable.

 

In order that the cool air can get in, and the warm air can get out, we use a "3/4 inch" PVC pipe (which actually has an OD of 1.050" / 26.67mm, because it conforms to "Nominal Pipe Size" as explained in the above posts). This has holes in the very end, and the end with the holes is inserted far into the OTA, but the pipe is made short enough so that it does not ever contact the secondary mirror.

 

All we have to do now is get some extra scrap "3/4 inch" PVC pipe, about 3 inches long, and slit it in a straight line down one side, so that it can then slide on and fit over the existing "3/4 inch" PVC pipe. However the short 3" section will be a "C" shape and there will be a gap now between the two sides that were slit (because it is being forced so fit over the same size pipe). We can then make a bigger gap, if we want to allow more air flow, by cutting more off one of the sides that was slit. This placing of scrap section of pipe over the existing pipe, enlarges the diameter of the total pipe at that point, making it now 1.050" + (0.113" * 2) = 1.276" / 32.41mm, if a Schedule 40 wall thickness "3/4 inch" pipe was used and some scrap pipe of the same type.

 

The ID of my own Celestron 1.25" SCT Visual Back is 31.87mm, so the cooler would then be a rather tight fit in the Visual Back. Tom seems to have only used a rather shorter (by circumference) section of scrap pipe, as he has used Schedule 40 pipe, and then since there is effectively only 1 wall thickness to add, instead of 2, then the total OD of the cooler at the point at which it enters the Visual Back will be 1.050 + 0.113 = 1.163" / 29.54mm, which would then be a loose fit in the Visual Back, but can be made a tighter fit simply by making sure that the circumference of the scrap pipe used is sufficient to effectively close this gap between the Visual Back and the total diameter of the cooler at that point. Tom seems to call this the "Offset" part, since it effectively makes the inner 3/4" pipe slightly off centre with respect to the opening in the VB, and the scrap piece of pipe causes this offsetting of the inner pipe, as it were.

 

If a thin walled "3/4 inch" pipe is used, and a C shaped piece of scrap pipe for the "offset" or "air gap" or "air channel" then the total diameter at the point at which the cooler enters the 1.25" Visual Back would be 1.050" + (2 *0.060) = 1.170" / 29.718mm, which would be a sloppy fit in the VB. However if we use another strip (not C shaped piece, we need a piece with much shorter circumference) bonded to the outside of the existing C shaped piece, then we bring the OD to 1.050 + (3 * 0.060) = 1.230" / 31.242mm, which would be a pretty fair fit inside the Visual Back. Again the scrap piece could be extended in circumference to make the cooler a nice sliding fit into the VB.

 

Basically we are just padding the existing inner PVC pipe with scrap / shim material (glued on when happy with it) until it fits the 1.25" visual back, AS LONG AS it also provides a CHANNEL for the warm air to flow OUT of the inside of the OTA back through the air channel in the Visual Back and to then exhaust to atmosphere.

 

Maybe the picture attached will help explain. Here I am showing my Celestron SCT 1.25" Visual Back, and any old piece of PVC pipe that I found lying around, plus a C shaped piece of white paper that I roughly cut to size wrapped around the pipe (but not overlapping itself, and with a gap between the 2 sides of the C shape, to allow an "air channel" to be automatically created simply by making it C shaped). Please ignore the cellophane sticky tape holding the paper onto the tube to hold it in place whilst I take the photo. Also please excuse the undersized pipe and the thin paper to simulate a scrap section of pipe, I had nothing else handy at the time. I have lightened the picture on the right in one place to make the arrangement of C shape easier to see. I hope that helps explain how this "Air Channel" idea works?

 

My contact in NM, Paul G. has a great picture of this which explains it a little better but I am not allowed to show it here, unfortunately (TOS).

 

Best Regards,

 

Alistair G.

Attached Thumbnails

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Edited by Live_Steam_Mad, 09 October 2014 - 03:43 PM.


#11 Live_Steam_Mad

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Posted 09 October 2014 - 04:20 PM

Well a few days ago, I ordered the following 4 parts in order to make my own DIY SCT cooler. I wanted grey parts like the Lymax cooler. Also, and unfortunately, these are a LOT more expensive than buying them in Home Depot or Lowes or other large American hardware store. But I could not find any other company except Amazon USA that was willing to accept international orders, plus it's most convenient doing it on Amazon's site, and I cannot visit USA just to buy some plumbing parts! ;-

 

http://smile.amazon....0?ie=UTF8&psc=1

 

...this was 3.95 USD and is a Spears brand, item code 437-248G PVC Pipe Fitting, [Reducer] Bushing, Schedule 40, Grey color, 2" Spigot x 3/4" Socket. The plain 2" end on this is the same size as a 2" pipe, and can fit straight into a 2" coupler. The 3/4" end fits the 3/4" pipe, since it has the same ID (1.050") as a 3/4" pipe of "Nominal Pipe Size" standard.

 

My contact Paul G. used a 1 1/2" to 3/4" bushing and a 1 1/2" coupler and a 2" female adapter with internal Female Pipe Thread, all from The Home Depot. His 3/4" pipe fits his reducer bushing great and this assembly then fit nicely into his 1 1/2" coupler, but the 1 1/2" coupler was a very loose fit into the 2" socket of his 2" female adapter, and I didn't understand why Paul had used a 2" adapter with a Female internal thread. Paul said the thread was irrelevant, they just happened to be the only parts he could find in the shop at the time.

 

So, since I was going to use at least a 60mm fan, which fits into a 2" coupler (because of the way the Nominal Pipe Size standard works), thus I decided to use a 2" bushing and 2" coupler instead of Paul's 1 1/2" bushing and 1 1/2" coupler and 2" adapter.

 

http://smile.amazon....0?ie=UTF8&psc=1

 

...this was 3.24 USD and is a Spears brand, item code 429-020G PVC Pipe Fitting, Coupling, Schedule 40, Grey, 2" Socket at both ends. This accepts the 2" plain male spigot end of the 2" to 3/4" reducer bushing that I ordered above.

 

http://smile.amazon....0?ie=UTF8&psc=1

 

...this was 4.44 USD and is a Spears brand 450-005G Series PVC Pipe Fitting, Plug, Schedule 40, Grey, 1/2" NPT Male. This part I explained in the above posts, and fits the 3/4" Schedule 40 pipe with a push fit (I hope), going on the dimensions listed, as remember it uses a 1/2" National Pipe Thread which is 0.840" OD, and the 3/4" pipe has OD of 1.050", and ID of 0.824. I can remove some of the threaded section with abrasive sheet if the fit is to tight. If I were to use a thin wall 3/4" PVC pipe then it would be a sloppy fit, and I would glue the flange at the end of the plug, onto the end of the 3/4" pipe, just to hold the plug onto the end of the pipe, which would be perfectly adequate.

 

http://smile.amazon....0?ie=UTF8&psc=1

 

...this was 5.06 USD and is a Spears brand, item code 449-020G PVC Pipe Fitting, Plug, Schedule 40, Gray, 2" Spigot. This part is a push fit into the 2" coupler that I ordered, and provides a flat end surface so that I can cut a suitable sized hole in it and mount my 60mm fan on it, hopefully.

 

I hope I ordered the correct parts and that my understanding of all of the above is correct. I'll find out when they arrive. Total was 16.69 USD / 10.86 GBP, postage was 5.28 GBP, total was 16.14 GBP with no VAT or anything else to pay. Rather expensive for 4 PVC parts that only cost a few pence each in volume, but that's life. 

 

I would of course have ordered British sourced parts, but I don't yet understand the standards and sizes for UK plumbing parts, and the DIY CAT Coolers that found on the web were mostly of USA origin using USA sized parts.

 

Regards,

 

Alistair G.


Edited by Live_Steam_Mad, 09 October 2014 - 04:24 PM.


#12 Live_Steam_Mad

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Posted 09 October 2014 - 04:36 PM

Next part that I ordered was the 3/4" pipe. This is actually 1.050" OD, as explained ;-

 

http://www.formufit....vc-pipe-2-feet/

 

I couldn't find anyone else but Formufit to do International Mail Orders. Except Amazon USA, but the cost for a 2 feet length of 3/4" Sch. 40 PVC pipe was rather expensive (20 GBP approx including postage). Cost was 2.30 USD for the pipe (about 1.50 GBP) plus 12 GBP (!) for the postage. But I had little choice at the time.

 

I really wanted thin walled pipe (grade 200 / SDR21) but I couldn't find any place that offered International postage on it. So the thick walled Schedule 40 wall thickness stuff will have to do.

 

I also wanted it to be a dark color like the Lymax one and this was the only dark color I could find (I chose Gloss Black, there was no Grey available). My motive is that I don't want anyone to be able to notice my 'scope setup in the dark since white parts are highly reflective of any slight ambient light, and white parts are easy to see on the outside of the OTA, and white parts also makes the inside of the OTA more noticeable when it's pointed towards certain positions (neighbours might think you are spying on them!).

 

I know the cost was excessive (since this stuff is worth about 10 pence per foot in reality). I have since found out that I could have used 25mm PVC circular rigid conduit, which is a UK standard size, of 25mm OD (approx, I don't know the exact OD) which would have fit the "3/4 inch" bushing of 1.050" ID (with a slightly sloppy fit but I could have fixed that with some scrap Plasticard of the required thickness). Oh well.

 

I don't appear to be able to obtain any of these parts from a UK source, not suprising really as we use UK / EU standards and sizes instead for plumbing parts.

 

Regards,

 

Alistair G.


Edited by Live_Steam_Mad, 09 October 2014 - 04:40 PM.


#13 Live_Steam_Mad

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Posted 09 October 2014 - 04:56 PM

The other parts that I ordered were an ABS plastic 60mm fan guard plus filter ;-

 

http://www.ebay.co.u...=STRK:MEBIDX:IT

 

...which arrived today and looks OK, the description was ;- "A good quality Fan Filter Assembly made from ABS Material featuring a guard, filter and snap-fit retainer. The guard has 4 Countersunk Mounting Holes. Assemblies have been specially designed for minimal air resistance, low noise and ease of filter changing. The Polyurethane Foam filter can simply be vacuumed or cleaned with detergent or cleaning solvents as needed.

Height: 9mm
Length: 66mm
Material: ABS
Type: Fan Filter Assembly
Width: 66mm"

 

...and I also ordered a Xilence brand 60mm fan with fairly good CFM and (hopefully) silent operation (or near silent) ;-

 

http://www.ebay.co.u...=STRK:MEBIDX:IT

 

...the description reads "Xilence] 60mm Super Silent Case Fan →Quiet 6cm Computer PC CPU Cooler Heatsink,

Xilence Slim 60mm Case Fan - Low Noise - Black
Excellence in Silent Technology.

60mm Case Fan made by Xilence - known for its quiet PC-components and excellent price performance ratio - the fans high air flow rate ensures efficient cooling and the Hydro bearing reduces vibrations and thereby results in a low level of noise (22dB).

Specifications:

    Size: 60 x 60 x 12mm
    Hole-Distance(Diagonal): approx. 66mm
    Voltage: 12V(7V-13.2V)

    Fan-Performance: 2100 RPM / 29.7 CFM
    Bearing Type: Xilence Hydro/Fluid Bearing
    Noise Level: 22dB
    Plug: 3-Pin Molex Connector(Mainboard)

Application/Installation:

Can be used as a case fan or also for heat sinks up to a size of 60mm.
The fan has got a 3-Pin Molex Connector which you will find on every mainboard, the installation is simple, plug in the cable, find a suitable place for the fan, fix it to the case and that's it, done.

Included:

1x Xilence 60mm Fan Black
1x Original packaging"

 

I have had a very good 80mm (IIRC) Xilence brand fan in the past, a "red wing" version, and it really was an inaudible addition to my existing PC and provided quite a bit of cooling. So I again bought the same brand, but 60mm sized, so that it can fit the end of my cooler (I hope).

 

In a couple of weeks I will have the parts in my hands and will assemble the push fit parts and see if they fit. I am admittedly rather poor with practical skills so I hope I can manage to make the cooler. I can however solder very well, if anyone needs help on that part.

 

The fan has 3 wires, but only 2 are needed so I believe, and takes 12V. The current required is rather small. I will be cutting and soldering into the fan's wiring and adding a 2m long cable onto the fan and then I will add a phono / RCA / cinch plug on the end, so that I can plug it into my combined 4 output Dew Heater (0-12V PWM), plus Single output 0-10.3V variable speed fan output, plus 2 Aux (12V) sockets unit (I will be plugging it into the Aux output) to give the fan the full 12V, and then we will see how silent the fan really is.

 

I already had to turn my CG-5 mount down to 1.00 degrees / sec in RA and Dec due to noise complaints at night from the neighbour, so I hope the fan is quiet. I can always plug it into less volts to make it run slower and less noisy if I have to, I hope.

 

Regards,

 

Alistair G.



#14 bilgebay

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Posted 10 October 2014 - 06:47 AM

Here is my take on this.

 

post-58269-14073679503322_thumb.jpg



#15 Live_Steam_Mad

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Posted 18 October 2014 - 10:49 PM

Well all the parts arrived. The "3/4 inch PVC pipe" was exactly as expected. Thick walled rigid glossy black PVC, 2 feet long. Rather heavier than I thought also. The fit of the 3/4" PVC pipe in my Celestron 1.25" Visual Back can be seen here ;-

 

https://plus.google....8897?banner=pwa

 

...as can be seen (pic's #2 and 3) there is plenty of clearance and it's a sloppy sliding fit, as expected. I measured and the pipe OD is 1.049" / 26.64mm. Picture #4 shows how thick the wall of the pipe is!

 

The 4 PVC plumbing parts arrived from Amazon USA, and I assembled them just to see if they all fit together as I expected, and indeed they did. See picture #5 in the above link. The 3/4" pvc pipe was a tight sliding fit into the reducing bushing but went in all the way, the bushing was a tight sliding fit into the coupler and only went as far as to leave 1cm of the male spigot plus flange (of the bushing) sticking out of the coupler, so nearly all the way on but not quite. The 2" PVC Plug was a tight sliding fit in the coupler in very much the same way. So it seems that I was correct about the fit and the dimensions and the standards involved, and my understanding is correct.

 

The 1/2" MPT plug was a VERY tight fit into the "3/4 inch PVC pipe". As expected, this is because (as explained above) the plug was 20.74mm OD, and the pipe ID was 20.44mm. At first I tried to sand / abrade the plug's threads with P400 Silicon Carbide abrasive sheet, but it was taking too long a time to be practical, so I ended up filing the PVC plug's threads and trying it in the pipe for fit, then filing some more, until it fit with a tight sliding fit and it ended up with a 1mm gap between the flange / head of the end of the plug and the pipe's end. This seemed to provide a more or less air tight seal (tested by blowing down the pipe), plus I didn't have to glue it in. The 1mm gap allows me to be able to lever the plug off the pipe with a flat blade screwdriver if I want to. The next 5 pictures in the photo album show the "1/2 inch MPT" pipe plug, and the bar code sticker that came on it.

 

I tried to remove the sticker's adhesive off the plug with Tamiya brand Acrylic Thinner (basically the same as IsoPropyl Alcohol) but oddly it didn't seem like a solvent for the sticky mess (but usually it gets sticky stuff off easily). So I tried some Tamiya brand Lacquer Thinner (for the Tamiya Synthetic Lacquer Spray paints) - the one with the yellow top - and with it the sticky residue dissolved almost instantly. Fortunately it did not affect the PVC plastic at all.

 

Next few pictures in the album show the assembly being trial fitted into my C11 SCT. I wrapped a couple of pieces of card around the pipe and put it into the visual back. You can see how far I pushed the pipe in, in the reflection of the end of the pipe in the primary / secondary, I found that with the end of the pipe in as far as the front of the secondary baffle, I had about 60mm too much pipe.

 

Then there is a series of pictures showing the "2 inch to 3/4 inch" reducing bushing. This item was just as expected, and has a nice conical entrance on the coupler side to make the air flow better. Again you can see the item's barcode in the pix.

 

I cut 60mm off the pipe with a Tamiya brand Thin Blade Craft Saw, basically a rather large razor saw, it cut through the pipe very fast and easy. The next 2 pictures show the plug in the pipe and then 2 more showing the fit of the pipe into the bushing.

 

More to come.

 

Regards,

 

Alistair G.


Edited by Live_Steam_Mad, 18 October 2014 - 11:14 PM.


#16 Starhawk

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Posted 19 October 2014 - 12:21 AM

Has anyone just put a stirring fan inside a C11?  It would seem the real problem is the poor thermal linkage from the central baffle to the outside.  Getting a gentle breeze going inside could be a clean solution.

 

-Rich



#17 junomike

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Posted 19 October 2014 - 05:59 AM

Has anyone just put a stirring fan inside a C11?  It would seem the real problem is the poor thermal linkage from the central baffle to the outside.  Getting a gentle breeze going inside could be a clean solution.

 

-Rich

Rick, ATM57 did just this, but on the outside of his C925. Here is the Mod on Pg2, but you may want to read the whole thread. I wish this was an easy modification offered loacally as I'd have it done ina heartbeat!

 

Mike



#18 Live_Steam_Mad

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Posted 19 October 2014 - 07:11 PM

OK so next up I decided to cut another 16mm or so off the 3/4" pipe as I wasn't happy with it being so close to the front of the secondary baffle. After doing that, my overall total length of the 3/4" pipe is now dead on 21 inches for my C11. BTW don't try this on a C11 Edge HD as there are lenses in the primary baffle tube!

 

I then had to make a decision as to whether to fasten / epoxy a thick plasticard plate to the end of the 2" PVC plug's flat top surface, so that I could attach the fan to the plastic plate via 4 bolts screwed through the plate with nuts on the underside of the plate, and put the fan guard / filter on top of the fan, OR cut away the outer parts of the fan making it a direct fit into the 2" PVC pipe coupler and then I would not need the 2" PVC plug at all, or a plastic plate, the second option would make it simpler and more elegant but more work.

 

I decided on the option for fitting the fan into the coupler. I used a Tamiya brand Modeler's Side Cutter (Straight Edge jaws) to cut through the plastic on the fan. Unfortunately the fan's square plastic shroud is quite brittle, but is tough enough to be able to withstand this and not shatter. The pieces flew in all directions at high speed as I cut at it - so USE EYE PROTECTION (goggles), I would imagine they are very cheap on Ebay. I am a spectacles wearer so I was just about protected. After I had cut off all 4 corners, I proceeded to use a file that was about 1/2 inch wide and 1/8 inch thick and about 12 inches long and quite sharp and rough (not a rasp though), and I started to file the shroud so that enough material was removed to be enable the fan to enter the coupling.

 

I kept placing the fan against the coupling to eye it up and see if it was possible and see how much I had to remove. It turns out that the answer was to file the shroud flush all round. This means that there was very little material left to hold the 4 "arms" on to the shroud (that 4 parts that keep the fan itself attached to the shroud) but just enough. It is not at all advisable to hold the shroud in a vice, and instead I held it by hand by the outside of it, with a cloth between the shroud and my fingers to protect my fingers from the sharp edges digging into me as I held the shroud with enough force to enable me to file it down. Also unfortunately the fan shroud's plastic material smelled like TCP (Tri Chloro Phenol) as I was filing it, and it's probably not healthy to breath it in, so maybe open a window or vacuum the stuff up every few minutes or so. Of course, I did neither but I come from a background of chemistry (Advanced level at school) and plastic model kit making (well OK, radio controlled models with hard PolyStyrene bodies that I have had to use aggressive chemicals to strip the paint off etc.) and I am well used to industrial chemical smells.

 

The next 3 pix in the album ;-

 

https://plus.google....857959160138897

 

...show the fan that arrived, before I cut it down. Then there are are 8 pictures showing the fan after I had finished cutting and filing it to size. To my amazement it did not fall apart, and it fits in the top of the coupler very nicely with a smooth sliding fit, very slightly loose. However if I push it in fully so the top of the fan shroud is about 3mm below the lip of the coupler then it stays put even if you turn it up side down and shake it. However it would be nice to stick it permanently in place with epoxy I suppose, but I haven't yet. The next 2 pix show the fan being tried in the cooler and being powered up and run in the C11. The fan didn't rub on the shroud after the surgery on it, and it runs very quiet at 12V, most of the noise being generated is "pipe" noises due to the air flow through the hollow pipe, plus the noise of a large amount of back pressure since the fan is working against the resistance of the air having to go down the small pipe.

 

The fan can be run off 12V DC by having the red as positive and the black as negative / ground. It runs the correct way when I did this (air flows into the cooler). I cut the connector off the fan, bared the ends of the wires, and hooked them up to a 12V Sealed Lead Acid battery. I haven't bothered to try reversing the polarity yet. I suggest that you don't either. You can safely cut the blue wire off, it isn't required. Make sure to push the fan into the cooler the correct way around, as shown in the pix. It's probably best to always handle the fan by it's shroud, and never by the fan itself. I have ordered "twin hook up wire/cable 2m red/black 2 x 0.35mm" from Ebay (1.65 GBP) in order to extend the wires from the fan so that they reach my variable speed fan unit. I tried the variable speed unit and also the 12V output (which gives a 12.3V output from one of my two 12V 7A PSU's). The fan was able to be controlled down to a rather low speed, and could run at full speed, I tested it by pushing the leads from the fan into the variable speed unit, using centre positive on the RCA / cinch / phono connectors. I will be soldering the extension wire onto the fan wire and also soldering a male phono  plug onto the end of the extension wire, so that I can plug it into my variable speed fan control unit.

 

Then I had a brain wave... To filter the air, I could cut the edges off the fan guard / filter (which is in 2 halves with the filter between the 2 sides of plastic) i.e. take the 4 corners off, and in the same way as I did with the fan, the fan guard / filter would be able to be push fit into the coupler! So I set to it, first I took a Tamiya Fine Craft Knife and cut off the 4 retaining plastic "clips" inside the fan guard that then enabled me to separate the filter into it's 3 parts, then with the same Tamiya "side cutters" as before, I started snipping off the edges and corners off the plastic of the 2 sides of the guard, one at a time, until they nearly fit inside the coupler, then I filed the edges down until it was a reasonably tight sliding fit. Then I took scissors and cut the square filter into a circle to fit the inside of the coupler.

 

The next 2 photos show the front and rear of one piece of the guard, the 2 photos after that show the front and rear of the second piece. The next photo shows the filter after I had cut it into a circle. Then I put the 3 pieces (2 guards, 1 filter) in to the coupler with the filter inbetween the 2 guards, it was all a tight fit and needs no glue. I made sure as I was doing this to align the 2 guards so that their "veins" overlapped above each other so as to provide maximum air flow. It was almost just blind luck that I managed to get them both centred when I cut and filed them so that the veins overlapped properly!

 

The next 3 photos show the 1mm flange at the middle of the length of the coupler, inside the coupler. This is the flange that allows me to press fit the filter and 2 guards up against this flange in order to retain these parts inside the coupler without them falling out or getting loose. The filter does add to the back pressure and slow the air flow but that's life. It can easily be removed for cleaning. The next 4 photos show me putting the filter and 2 guards into the coupler, adding one part at a time.  Then a photo showing a bright light shining into the other end of the coupler to show the filter and guards and how the veins overlap to keep the air resistance as low as possible.

 

Then there are 2 photos that show the fan lightly press fitted into the coupler. As can be seen, I used the razor saw then the edge of my file to create a slot deep and wide enough to accomodate the fan wires.

 

Finally I measured 16mm back from the end of the 3/4" pipe by digging one end of my sharp digital caliper legs into the relatively soft plastic pipe and I marked a line by dragging the caliper in a line across the pipe. Then with my razor saw I cut a very slight slot right on the line. Then I pressed in a marking out scribe to make a hole / centre pop, then I drilled a 2mm hole in the pipe using a Tamiya small blue self assembly kit "Electric Handy Drill" (the blue one, very cheap, powered by 2 AA cells), item 74041, and then repeated this for another 3 holes to make a total of 4, one every 90 degrees around the circumference of the pipe. Then I enlarged all 4 holes to about 3mm, then I used a larger hand drill to enlarge the holes to about 6mm, then I angled the drill to make the hole point backwards towards the primary mirror to make the air flow go away from the secondary. Later on I will enlarge the holes to 8 or 10mm for more air flow and less back pressure.

 

So it seems I have now got myself a working SCT cooler, and it wasn't all that difficult to make, and if you are in USA the parts cost about 20 dollars or so in total. I am in England, UK so I had to import everything. Hope that helps someone make one for their Cat. / Cass.

 

At present I have no idea what parts I would have to order if I wanted to make one of these out of UK sourced parts!

 

The only thing that I need to do now (as well as enlarging the 4 air delivery holes when I get around to it) is to epoxy 3 x 60mm long, C shaped pieces of plasticard onto the tube to create a channel for the warm air to escape through, and then epoxy a single short length C shaped ring ring of plasticard over those to act as a stop and create space for the air to escape the air channel via the visual back. I have in place at the moment a few pieces of plain card to do this job but I'll go hunting for my plasticard (I have some in a spares box) and do this in the next few days hopefully, and show pictures here of it.

 

Regards,

 

Alistair G.


Edited by Live_Steam_Mad, 20 October 2014 - 01:26 AM.


#19 evan9162

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Posted 05 November 2014 - 10:56 PM

Here's my cooler.  I made it entirely from materials lying around

 

I built this for my newly inherited 80's era Meade 10" SCT.  

 

The body is built from poplar and 1/4" hard board.  The tube is 3/4" PCV pipe.  Needs paint (which I intend to do soon).

 

My solution for securing within the scope is seen in the second picture - I fashioned a "baffle hook", which hooks over the edge of the end of the baffle tube.

Attached Thumbnails

  • IMG_7120.JPG
  • IMG_7122.JPG


#20 evan9162

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Posted 05 November 2014 - 10:58 PM

Here are the insides - I used a 12V, 60mm blower.  The blower can move air much more effectively against high resistance than an axial fan.  The green is felt fabric serving as an air filter.  Then, of course, the retainer cap.

Attached Thumbnails

  • IMG_7123.JPG

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#21 evan9162

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Posted 05 November 2014 - 10:59 PM

Here is the cooler in place in the scope.

 

And a close up of the baffle hook in place.

Attached Thumbnails

  • IMG_7124.JPG
  • IMG_7126.JPG

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#22 Asbytec

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Posted 06 November 2014 - 09:23 AM

Try one or two of these. I use them (one, smaller version), they work great for initial prep to modest ambient temps and maybe even to catch up with falling temps. I've used them to touch up equilibrium in the field. Ever see cold plumes? I have. It's amazing how quickly they dissipate and battle the opposing heat plume. The entire scope is very cool to the touch in short order.

 

http://www.walmart.c...ack-Pad/6537505




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