28 replies to this topic

[mclerran82]

Hi all. I am looking for ideas on how I might repair this telescope. The scope is an old Tasco 76.2mm x 1200mm. You all may have to forgive me, I know very little about telescopes and astronomy at this point but I’ve been interested lately partially due to the upcoming conjunction of Jupiter and Saturn etc as well as a general long standing interest. If I am misusing any component terminology please let me know.

 

This telescope belonged to grandfather. Although I don’t remember ever using this one I have fond memories of going to neighborhood star parties with him as a teenager. In more recent years the telescope sat in its original wooden case in my dad’s home office where one day he unintentionally discharged a pump shotgun towards the floor where the telescope box sat!

 

Besides the box the main damage to the scope is to the drawtube which to my understanding is for a coarse focusing. I am able to extend it about 2.6 inches before the damaged portion interferes. I’m wondering if I cut off the damaged section of tube will this be enough adjustment left to be able to use the scope? I guess this is my only option anyway unless I can replace the tube. The scope appears to be otherwise complete as far as I can tell.

I found this site through some searching which led me to a post on here where someone made a new tube from a chrome drain pipe although this was to be able to install a custom visual back in order to use larger eyepieces. I may attempt to go this route at some point if I have to but in order to use the eyepieces I have I will have to internally thread the pipe for the stock visual back or have a pressfit section of tube made either of which will probably require a lathe.

If anyone has any other ideas for available parts that might work I would appreciate it. Thank you.

Attached Thumbnails

• 
• 

[Russell Smith]

Looks like a 10TE. Very nice telescope. 

I do hope someone here has a drawtube. 

Russ

[Couder]

Some people might be able to straighten the drawtube out, myself I think it is too far gone to repair. If you cut the end off, be sure to put the stop on the end so it cannot come out too far out of the focuser and drop your eyepiece. Planets and stars require infocus - that is, the focuser needs to be racked in towards the scope. Looking at trees, wildlife, etc. the focuser needs to be racked out. Difficult to tell if you have enough drawtube left to focus on the planets or not, might be close. Cutting the tube off will allow you to rack out a little further than you can now, as it looks like the bend will keep it from going in very far. Depending on the exact size - some plumbing shops have chrome pipe that might be a fit. It would take some machine work to accomplish it, but it can be done. You do realize probably the only reason you would attempt these repairs is the scope has sentimental value to you? You might place a wanted ad in the classifieds here on Cloudy Nights providing the manufacturer, dimensions, etc. and someone might have one.

[Augustus]

Should be enough travel left if you chop it, worst case is you need to add an extension tube.

[marsbase]

I'm not an expert but the tube seems to be too long for astro viewing anyway. Seems like it would cut into your astro images. Wouldn't hurt to cut it down and try it out. Seems that damaged part is beyond repair anyway. 

[ccwemyss]

Until now, I have never considered the way that the 10TE is stored with the focuser removed to be an advantage. But in this case it clearly saved the rest of the scope. 

 

The 10TE is generally seen as one of the optically best classics made. It is well worth saving. There are several older threads here about converting it to modern 1.25" eyepieces that involves replacing the drawtube, such as this one:

 

https://www.cloudyni...d-their-clones/

 

Although the Royal Astro eyepieces are quite good, you will get even more from this scope with modern designs.

 

If you want to try repairing it, you can unscrew the tailpiece ring at the far end, then you should be able to pull the old tube out toward the front. It's possible that someone with body shop skills would be able to work the dent out. Or you could use some steel rod, up the center, to start rolling it back out. Some gentle squeezing with a clamp or vice can also help. Then push some dowel through to further straighten it. 

 

Others who have done more of this kind of work will be along to offer more advice. Keep us posted. 

 

Chip W.

Edited by ccwemyss, 13 December 2020 - 03:04 PM.

[Bowlerhat]

try putting 1.25" diagonal and see whether it works.

[Garyth64]

Just replace the draw tube.  It is designed to be long.  There isn't enough to cut it off and still work as intended.

 

I have done this a few times, and it is very easy.  And while you have it apart you may need to do a little shimming to have it move nice and smooth.

 

Here you can see how far out the draw tube might have to go if you don't want to use a diagonal:

 

 

The picture is a Sears 6339a.  It is almost identical to a Tasco 10TE, and the drawtubes are identical.

Edited by Garyth64, 13 December 2020 - 04:54 PM.

[Bomber Bob]

I'd remove the pull-tube, put it in my smaller (plumbing) pipe cutter, and cut it off where the dent starts.  Bit of sanding, blackening the interior of the now shorter tube, and the scope would be fine.

[apfever]

No one is going to ask, but everyone is itching to see. 

I'm not proud.

Can we see some pictures of the shotgun damage, the case, interior, etc.?

cool.

[Defenderslideguitar]

Welcome aboard   you have come to the right place. That is a very nice telescope    I have an old 1958 version. Mine has a very long pull out draw tube. I am not the nest technician here but I know when something works and fails to work. It may be that you have nothing to lose by trying all ideas... Got a body guy or want to try fixing it.. get to it....failing that cut the tube    try it out         then work on any adapter extensions   what have you.....you will benefit from converting it to 1.25 eyepieces     you should look into getting a couple of used eyepieces here in the classifieds            and  yes   we would really like to see the pics of the mishap

 

Good luck

 

 

Attached Thumbnails

• 

[JoeVanGeaux]

I'd carefully chop it to remove the damaged section at the points just before its looses its "roundness", then (with a bit of luck, perhaps) slide a sleeve between the two parts, maybe, with a dab of JB Weld if it doesn't give enough resistance to separating.  Then, polish the outside to remove burrs and the what-nots if your cut wasn't up to par.

A sleeve can be made with a slightly oversized tube then carefully cut a slit longitudinally until it matches the I.D. of your remaining tube pieces.  I believe the tube is plated brass so it it should be easy to work with.  The trickiest part is to get the cuts square.  (Note: You may have to insert a plastic pipe section or wood dowel before cutting to preserve its round.  Also, you may have to make some initial cuts near or in the deformed pieces to make it easier to work with.)

There's not much to loose for trying since its damaged anyway and you'd gain some experience by the attempt.

Best of luck!

Joe

[mclerran82]

Thank you to everyone for all of the feedback and advice. I believe several of you are right that there is nothing to lose at this point and I now have a few things to try. I attempted to push the dent out with a steel dowel as well as pushing various sockets through the tight spot with a little heat applied but it just started to crack at the dent and there was already a hole anyways.

Next I will just cut off the offending section, I might as well try it. I’ll see if I can get it to focus with the amount of tube left. If it doesn’t work I’ll look at rejoining the other good section with a sleeve. I have a saw guide intended for cutting bicycle steer tubes that should help me get fairly straight cuts. In the meantime I may put up a wanted ad on here, a search on ebay has found pretty much nothing. The more I get into this it doesn’t sound too bad to try building a replacement as linked above. If this scope truly is good enough to be worth the trouble I could see maybe buying a few eyepieces for it. For me it will be better than no telescope. As much as I love new hobbies I’m not ready to go too far down this rabbit hole just yet! I do remember my grandfather saying however very matter-of-factly that Astronomy is the best hobby there is!

 

 Since you all asked I’ll be happy to share some more pictures. At least I can say it wasn’t me! I think my dad was fairly embarrassed about it at the time, I still can’t believe it! 

[mclerran82]

The biggest hassle might be doing something with the box.

Attached Thumbnails

• 
• 
• 
• 

[Kasmos]

The box looks very repairable. It's not nearly as bad as I thought it would be. It also looks like the solar screen might have save things from being worse.

 

When I cut tubes I wrap a sheet of paper around them and line up the edges to make a nice square cut. I then usually carefully wrap the edge of the squared up paper with a few windings of masking tape to have a good guide to cut to. For precision I slowly use X-acto knife saws on brass and aluminum and then file the small burrs.

[mclerran82]

The rest of the components look serviceable as far as I can tell. The base seems like it will work ok although I have some learning to do on how to operate it and set it up. The objective lense(s) do look kinda dirty so I might want to look into how to clean them at some point.

Attached Thumbnails

• 

[ccwemyss]

The rest of the components look serviceable as far as I can tell. The base seems like it will work ok although I have some learning to do on how to operate it and set it up. The objective lense(s) do look kinda dirty so I might want to look into how to clean them at some point.

Some terminology, for help in searching other threads. The objective is the large lens in front. The ones you look through (eyepieces) are also called oculars.

 

The objective for this scope is called a doublet, because it has two lenses, made from different types of glass, to cause two different parts of the light spectrum to come to focus at the same point. It's a feature of better quality scopes, versus toys that have just one lens. The front glass of the pair is called the crown and the rear is the flint. 

 

Unless the objective is really dirty or fogged, so that you can't see through it clearly, it doesn't need cleaning. Some dust, dirt, or a few smudges won't affect the view.

 

If the objective needs cleaning, take some time to research helpful tips. It's not hard, but if you do it without knowing the process, it's easy to put chips in the edge of the glass, damage the coatings/surfaces, lose/damage the very important foil spacers between the lenses, or put the lenses back together in the wrong orientation.

 

This type of telescope has a holder for the objective (the "lens cell") that uses six screws, in three push-pull pairs, to align or collimate the objective so that it points perfectly down the center of the tube. If the lens gets out of collimation, the images will be soft and hard to focus. Again, collimation isn't hard to do, but you need to understand the process. You might be able to avoid it while cleaning the lenses by only removing the "pull" screws and being sure to put it back in the same orientation. The "push" screws set the alignment. 

 

It's not rocket science. I've taught high school students to do it in about 30 minutes. But preparation is key.

 

Chip W.

[Paul Sweeney]

That is a nice scope and well worth repairing. If there is a body shop in the area, ask them if they can fix it. You can also look for a pipe expander that fits on a drill, but you have to be very careful not to split the tube. Better let the body shop people do it. Same if you want to chop the tube. It is very easy to crush the tube, so let the specialists do it. If you want to use 1.25 eyepieces, you can get an adapter for about 5 bucks on ebay. Good luck and keep us posted.

[photiost]

Have you tested if the scope comes to focus ?

 

You may only need to cut off the damaged area .

 

If it needs more back focus then a tube extender will do the trick.

 

Good luck  !!

[Jaz5833]

You might investigate plumbing hardware from RV systems. Otherwise, I'd keep an eye on the Goodwill online auction site. You might find a partially complete kit to cannibalize for super cheap.

[LukaszLu]

Hi! What if you just make a new drawtube and have it chrome plated? All you need to do is blacken the inside, thread one end and a hole on the other ...

[mclerran82]

I want to thank everyone for the advice and input on getting this scope going. I cut the drawtube just after the major dent and then painted the inside of the tube. I was able to get a little peak at Jupiter and Saturn but it took more finesse than I realized! I have identified some issues to work on and have decided I would like to get this scope back in fully serviceable condition.

 

To start I think I still need to work on the eyepiece and focuser end. I looked at the linked post and it doesn't look too hard to put together a new drawtube for 1.25" eyepieces. Did these scopes come with a diagonal because I sure don't have one? I did manage to use the straight through prism although it was awkward to use at best. I'm really not even sure if these items are normally required or not but I could not get the scope to focus without the prism device.

 

I thought I had a nice selection with half a dozen eyepieces or so but some of them are other brands or designs and don't really fit the drawtube or prism correctly. They are even smaller diameter and it appears my grandpa wrapped a bunch of electrical tape around these to get them to work maybe somehow!? They didn't seem to work for me as they don't fit the prism. The potentially useful 20mm eyepiece that I presume is one of the originals is also unfortunately very dirty inside so I didn't even bother trying it. I unscrewed the outer and inner barrels and blew out what I could with compressed air but it looks like even further disassembly is required to clean it. This plus the bunged up drawtube along with the fact that I probably want a diagonal makes me think I should just go the 1.25 route. I am hoping I can find a few decent eyepieces without spending a bunch.  

 

Another item to sort out is one of the fine adjust knobs on the mount. Fortunately it is the one that doesn't need to be used as much but the knob itself on the end of the cable had a bunch of play in it. I need to see if I can get it apart or do something without destroying it. I need to check again but I may have had play in the mount as well on this axis. I haven't read up on it yet but I understand I may need to adjust the bearings or gear mesh somehow?

 

My other biggest problem was vibration. I have read a couple threads on these scopes on here now and that seems to be a common issue. I had a pretty hard time between trying to focus and tracking the planet and then getting the vibration to slow down enough to get a good view. This was with the 12.5mm eyepiece so I'm sure the 20mm would have been a little easier. 

 

Thanks again and I'll post another picture or two when I get a chance.

[Tenacious]

Welcome to Cloudy Nights!

 

I love my 10TE-5, but had to struggle with many of the issues you mention, especially the inherent instability of the mount, primarily the tripod.  Discussed here.  In hind-sight, and if one has the time and resources, building a new tripod using thicker wood would improve things a lot.  I think Garyth64 may have done this.

 

Preston Smith's excellent tear-down tutorial is here.  I often recommend trying to renew the RA lubrication (try a light machine oil) before disturbing the factory alignment of the eccentric bushings of the RA worm drive.  They are difficult to re-install without introducing lost motion (backlash).

 

+1 for a new drawtube and 1.25" VB, EPs and accessories as mentioned above in post #6 and others.  I think it greatly improves the perfprmance and use of the scope.  Celestron makes a good 1.25" prism star diagonal (94115-A). 

Edited by Tenacious, 23 December 2020 - 11:29 AM.

[Beeham]

Hi! What if you just make a new drawtube and have it chrome plated? All you need to do is blacken the inside, thread one end and a hole on the other ...

That's exactly where I was going.

 

Look for a Metal Mart, Alro Metals Outlet, or similar shop near you - you can probably find a scrap of nice stainless tubing in the right size, and with minimal machining it could me made into a replacement part.  Blacken the inside and you're ready to go.

[Bomber Bob]

About the Mount...  Two Words:  Motor Drive

 

Motorized tracking doesn't make the mount more stable, but it does make the observing experience enjoyable.  Especially if you leave the long springy slow-motion cables installed.   I found that out first with my 1978 Tasco (Towa), which came with the drive installed.  Same thing with my 1964 Sears 6336.

 

The Eccentric Polar Axis Gear:  If your mount is undamaged, you can tweak out almost all the backlash.  In fact, I found it no more difficult than finding that perfect mesh point on my 1971 Criterion RV-6 EQ.  

 

TBH, it's amazing to me that these simple mechanical drives can track as well as they do.  Keep In Mind:  They were designed & made for visual use rather than long-exposure photography / imaging.  Both my Mayflower 815 (Yamamoto) and my Sears 6336 (Astro Optical) motorized EQs tracked good enough to keep a planet on the CCD chip for up to 5 minute video captures.