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Restoring a Criterion Dynascope Deluxe Mount

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#51 Geo31

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Posted 19 December 2018 - 03:02 PM

Good eye Rolo. I noticed that too and I am unsure what the deal is. In all of the other pictures and advertisements for the Dynascope Deluxe 8 I have not seen another mount with an RA assembly box on the DEC. It has all same holes too. I think it came like this from the factory. The RA is on the left and DEC on the right. 

 

I also noticed something else while looking at pictures and advertisements for Dynascope Deluxe 8 mounts. For the 6" and 8" deluxe the equatorial heads are made of cast aluminium and like the one in your picture is one sided. Where as mine is made of cast iron and is double sided (see picture below). Here is a Criterion catalog featuring the Dynascope Deluxe: https://wiki.telesco..._Literature.pdf

 

My DEC assembly is also missing its setting circles pointer and it does not look like one was ever installed. I am a bit miffed about that. I will have to figure something out to replace it and possibly the RA pointer as well so they are matching.

 

I am starting to think that the maybe Criterion ran out of some of the normal parts when this scope was ordered and they just threw on some stuff that they had.

 

I hope some other Dynascope Deluxe owners would chime in with how their mounts are assembled.

With a small company in a cottage industry like Criterion, it's quite possible they used what they had on-hand.  I'm sure Cave did that as well.  If I ran one of those businesses, I would to.

 

That said, if there is a motor in the declination housing, my first thought would be someone wanted a motorized Dec drive.  But then, there is no control box.


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#52 mfoose

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Posted 19 December 2018 - 03:04 PM

I've been able to find self-etching primer in black.  Eastman I think.

I didn't find Eastman, but I did find Eastwood: https://www.eastwood...imer-black.html I already have a can of Rustoleum self etching primer in grey: https://www.amazon.com/Rust-Oleum-249322-Automotive-12-Ounce-Etching/dp/B003CT498A

 

Before I paint everything I like to do a test on a single part. I decided on the mount head which I just put on 3 light coats of the Rustoleum self etching primer. I have a half used can of Rustoleum camouflage flat black: https://www.amazon.c...e/dp/B0009XB3NQ that I plan on putting a single coat on before using VHT wrinkle black to finish: https://www.amazon.c...g/dp/B000CPIMXK


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#53 mfoose

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Posted 19 December 2018 - 03:08 PM

With a small company in a cottage industry like Criterion, it's quite possible they used what they had on-hand.  I'm sure Cave did that as well.  If I ran one of those businesses, I would to.

 

That said, if there is a motor in the declination housing, my first thought would be someone wanted a motorized Dec drive.  But then, there is no control box.

My thoughts as well. Maybe one day I will make it a dual motor drive. It would be easy to do.



#54 mfoose

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Posted 19 December 2018 - 04:28 PM

Dropped off the RA housing at the welders. He said that he will be able to take care of them. He also thought that the mount was most likely dropped and that's what caused the the cracks. Because of Christmas and New Years he is not sure when he can get to it. Probably in at least a week, maybe two. 


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#55 mfoose

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Posted 21 December 2018 - 09:49 AM

Well, I have some good news and some bad news. I will get to the good news first. 

 

I was able to strip and prime the mount head and it turned out pretty good. With the terrible weather we are experiencing in the Mid-Atlantic and family coming into town for Christmas I won't paint anymore until next week. 

 

Last night I was able to take the RA and DEC shaft to my buddies house and we polished them up on his lathe. Some light pitting on the exposed DEC shaft, but nothing to cry about. 

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#56 mfoose

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Posted 21 December 2018 - 09:58 AM

Now for the bad. I found more cracks, but this time on the DEC shaft housing. 

 

The first one isn't bad, just a small one by a set bolt. Unfortunately, the second one is much worse. It goes straight down the middle of the housing, around 2" long and it starts in a machine area. 

 

As I see it, I have two options moving forward:

 

1. The welder I am using charges $65/hr. For the RA housing alone he figured around two hours of work. With these cracks I could see it going to 3 or 4 hours of work and that is more than I would like to pay. I could just suck it up and hope it doesn't take as long, or...

 

2. Part everything out, count my losses, and look for another 1.5" shaft mount in the area. 

 

I hate to part it out, but I really don't want to be stuck with a high welding bill. I do have some time to think about it, but in the mean time I am going to go ahead and strip the paint off the DEC housing to see more of whats going on.

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#57 apfever

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Posted 21 December 2018 - 10:24 AM

Well this can be debated and already has, but I'd say this mount took a whollop of a fall and the cracks are NOT due to bad alignment boring.  

I would imagine that properly welding the parts would entail additional machining to rebore the housings.  Was this included in the price?

If you are set on only the two options presented of weld or part out, then you have a tuffy to decide.

I'd go with the third option of clamping the ends with double split stop collars, whether I was going to keep the scope OR plan on selling it after restoration. 

 

I will expedite two things, watch for it.  First I will examine my 10" Dynascope observatory model (yes I have this mount) and see if these cracks exist as a possible common issue. 

If mine is clear, then I'd say you have damage from accident or abuse and not an alignment issue. You could check alignment or have it checked for you. I'd check mine myself.

Second, I'll jump on stripping, cleaning, etching, and painting my stop collars to match my Edmund 8" so that you can get an idea of how a matched finish fit might look.  I'm not going with a wrinkle finish since there will be a mix of smooth and wrinkle from other parts anyway, and I'm willing to bet the double split collars will look SHARP with a matched color finish.  I'll be doing my shaft collars anyway so no harm in posting results even if you are dead set against the idea. I'm quite curious how my mount condition is for cracks.


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#58 mfoose

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Posted 21 December 2018 - 10:35 AM

Well this can be debated and already has, but I'd say this mount took a whollop of a fall and the cracks are NOT due to bad alignment boring.  

I would imagine that properly welding the parts would entail additional machining to rebore the housings.  Was this included in the price?

If you are set on only the two options presented of weld or part out, then you have a tuffy to decide.

I'd go with the third option of clamping the ends with double split stop collars, whether I was going to keep the scope OR plan on selling it after restoration. 

 

I will expedite two things, watch for it.  First I will examine my 10" Dynascope observatory model (yes I have this mount) and see if these cracks exist as a possible common issue. 

If mine is clear, then I'd say you have damage from accident or abuse and not an alignment issue. You could check alignment or have it checked for you. I'd check mine myself.

Second, I'll jump on stripping, cleaning, etching, and painting my stop collars to match my Edmund 8" so that you can get an idea of how a matched finish fit might look.  I'm not going with a wrinkle finish since there will be a mix of smooth and wrinkle from other parts anyway, and I'm willing to bet the double split collars will look SHARP with a matched color finish.  I'll be doing my shaft collars anyway so no harm in posting results even if you are dead set against the idea. I'm quite curious how my mount condition is for cracks.

The more I think about it, I think you're right and that the bores are not in bad alignment, but the damage is due to a fall.

 

The welder was not going to touch the crack from the inside, but make a v channel and then weld it from the outside. He said he wouldn't have to touch up the inside and re-bore it. He did give me the option of doing that, but he said it would have been around 5 hours of work. 

 

You may be in the clear for cracks. Look under equatorial heads it says, "Heads of the 6" and 8" models are of aluminum; 10" models are of cast iron." https://wiki.telesco...ture.pdf&page=2

 

I know that my equatorial head is cast iron, a magnet confirmed that, but my shaft housing is cast aluminum. My mount seems to be unique in a few areas. I would check and see if you shaft housing is cast aluminum or cast iron as well as looking for cracks. I will keep an eye out for your posts. Thanks!


Edited by mfoose, 21 December 2018 - 10:49 AM.

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#59 Geo31

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Posted 21 December 2018 - 10:49 AM

Have a frank discussion with the welder.  Tell him that the cost is going to exceed budget and ask what you can do to prep the parts and finish the parts.  If all he has to do is clean the cracks and lay the bead, the time could be much less.  You'd just have to grind/file down the welds to flush with the casting.  I'll bet there is a lot you can do to save time & money on this.  Doesn't hurt to see what he says.  Or perhaps get a second opinion/estimate.


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#60 apfever

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Posted 21 December 2018 - 10:52 AM

Here's the DEC housing from top and bottom as well as the lower part of the RA housing from the bottom.

 

I didn't find any cracks on anything from close examination in person as well as scrutinizing the photos.

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#61 apfever

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Posted 21 December 2018 - 10:59 AM

Here's the RA housing from the top, and the motor end from the bottom.  No cracks of any kind. Yes, there are some collars and brackets but the cracks presented in the OP scope all extend beyond the attached units. It is doubtful there are cracks just in the covered areas.  I'd say the problem scope had an accident and bore alignment is not an issue, making a clamp situation more practical.  

The unmachined outer circumferences are fairly round and could be clamped securely with minimal 'fill' by shim or other non permanent spacing if needed.  The web on the lower motor end of the RA housing might need a little buff off at the seam for a clamp, but minimal if anything.

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#62 apfever

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Posted 21 December 2018 - 11:16 AM

The more I think about it, I think you're right and that the bores are not in bad alignment, but the damage is due to a fall.

 

The welder was not going to touch the crack from the inside, but make a v channel and then weld it from the outside. He said he wouldn't have to touch up the inside and re-bore it. He did give me the option of doing that, but he said it would have been around 5 hours of work. 

 

You may be in the clear for cracks. Look under equatorial heads it says, "Heads of the 6" and 8" models are of aluminum; 10" models are of cast iron." https://wiki.telesco...ture.pdf&page=2

 

I know that my equatorial head is cast iron, a magnet confirmed that, but my shaft housing is cast aluminum. My mount seems to be unique in a few areas. I would check and see if you shaft housing is cast aluminum or cast iron as well as looking for cracks. I will keep an eye out for your posts. Thanks!

 

Interesting!  My DEC housing is aluminum, my RA housing is iron. 

My pier cap is iron, full fork as opposed to a single tang, and only a center bolt without holes for additional perimeter bolts. I don't know if the RA tang has slots for perimeter bolts since I've never had it apart. 

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Edited by apfever, 21 December 2018 - 11:45 AM.

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#63 mfoose

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Posted 21 December 2018 - 12:30 PM

Well I stripped the paint off of the DEC housing and cleaned up around the cracks a bit. They are worse then I hoped. 

 

The biggest crack clearly forks into two. The bigger one continues down for about 2" inside and out. The other part of the fork follows the lip around the outside for about 180 degrees around, it is only outside.

 

The other crack around the set screw doesn't stop at the set screw, but goes through it. and is both inside and outside and it continues to the inside lip. 

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#64 mfoose

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Posted 21 December 2018 - 12:32 PM

Forgot one. This is the inside look at the larger crack. You can see it continue inside.

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Edited by mfoose, 21 December 2018 - 12:32 PM.


#65 tim53

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Posted 21 December 2018 - 01:11 PM

I didn't find Eastman, but I did find Eastwood: https://www.eastwood...imer-black.html I already have a can of Rustoleum self etching primer in grey: https://www.amazon.com/Rust-Oleum-249322-Automotive-12-Ounce-Etching/dp/B003CT498A

 

Before I paint everything I like to do a test on a single part. I decided on the mount head which I just put on 3 light coats of the Rustoleum self etching primer. I have a half used can of Rustoleum camouflage flat black: https://www.amazon.c...e/dp/B0009XB3NQ that I plan on putting a single coat on before using VHT wrinkle black to finish: https://www.amazon.c...g/dp/B000CPIMXK

Ooops.  Eastwood it is!  



#66 DAVIDG

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Posted 21 December 2018 - 01:24 PM

 That is  a perfect job to stick weld the cracks with a propane torch and the low melting welding rods. The low melting alloy will flow right into those cracks. If you have the torch or can borrow one your talking $15 for the rods. Like I said before the secret is  that  the metal needs to  be really clean so you scrub it with a new steel wire brush so you have a fresh, non oxidized surface just before you heat it and the metal with  flow and bond perfectly. 

  Heat the part from the inside and stroke the welding rod  over the crack on the outside of the part so the metal will flow toward the heat and fill in the crack.

                    - Dave 


Edited by DAVIDG, 21 December 2018 - 01:27 PM.

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#67 apfever

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Posted 21 December 2018 - 01:49 PM

How do you clean the faces inside the crack?  I was wondering about working something like this through the crack with a brush, then rinse and braze with the aluminum rod. This is what I use on smaller aluminum parts like the Edmund clock housing parts I painted. 

 

I'd try that aluminum brazing, partly because I never have. I'd also practice on some scrap and also intentionally melt the scrap with the torch or test for that possibility. The bore would have to be filed back out. A reamer may not center depending on how much brazing rod flow goes into the bearing bore. Aluminum is pretty easy to work so I'd go after any 'slag' in the bore with a drill and....some kind of bits that I'd just play around with. I'll back off on the idea of the split collars being sufficient considering the extent and location of some cracks. I would be tempted to still consider them after any home brazing job I would do on something like this, since I have no real experience brazing aluminum. It seems more like brazing than welding but no expert here on terminology either.

 

This product list iron, steel, zinc, aluminum, and galvanized surfaces. It goes a long way, is a concentrate to 3 parts water.

spiffy in a jiffy

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Edited by apfever, 21 December 2018 - 02:06 PM.

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#68 Geo31

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Posted 21 December 2018 - 02:17 PM

The crack that scares me is the one inside the shoulder (or appears to me to extend around the shoulder).

 

I like Dave's idea.


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#69 mfoose

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Posted 21 December 2018 - 04:19 PM

 That is  a perfect job to stick weld the cracks with a propane torch and the low melting welding rods. The low melting alloy will flow right into those cracks. If you have the torch or can borrow one your talking $15 for the rods. Like I said before the secret is  that  the metal needs to  be really clean so you scrub it with a new steel wire brush so you have a fresh, non oxidized surface just before you heat it and the metal with  flow and bond perfectly. 

  Heat the part from the inside and stroke the welding rod  over the crack on the outside of the part so the metal will flow toward the heat and fill in the crack.

                    - Dave 

I am going to try this tomorrow morning. I will post results when I am done. Will definitely be a learning experience.


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#70 mfoose

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Posted 21 December 2018 - 04:21 PM

The crack that scares me is the one inside the shoulder (or appears to me to extend around the shoulder).

 

I like Dave's idea.

I have the same feeling. I'll have to braze and then clean it up. 


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#71 mfoose

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Posted 22 December 2018 - 10:56 AM

Well, I wanted to work on it this morning, but I don't have the time now. I will have to braze after the holidays. 

 

I did find another helpful video: https://www.youtube....h?v=aj0NjwBqsSg and I feel that I will be able to the job with some practice. I also found some cast aluminum that I can practice on. 


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#72 DAVIDG

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Posted 22 December 2018 - 11:19 AM

 Great video. Like I have said I have used these rods before with excellent results. I repaired a bracket on the local high school observatory dome that is part of the assembly used to open the shutters with this material and so far after 5 years it is still holding strong.

   In  the video they make a pretty deep V groove in the part that is cracked. I would not be so aggressive on your mount. Just open up the crack with maybe a  groove that is 1/8" wide.  If you have multiple cracks in the same part I would repair them all at once. You don't want to keep heating the part up a number of time because that can weaken it. Good Luck and Happy Holidays !

 

                       - Dave 


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#73 tim53

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Posted 22 December 2018 - 12:22 PM

 That is  a perfect job to stick weld the cracks with a propane torch and the low melting welding rods. The low melting alloy will flow right into those cracks. If you have the torch or can borrow one your talking $15 for the rods. Like I said before the secret is  that  the metal needs to  be really clean so you scrub it with a new steel wire brush so you have a fresh, non oxidized surface just before you heat it and the metal with  flow and bond perfectly. 

  Heat the part from the inside and stroke the welding rod  over the crack on the outside of the part so the metal will flow toward the heat and fill in the crack.

                    - Dave 

Many years ago I made a set of tripod legs out of 1 1/4" aluminum angle that I brazed with these rods.  I used an oxy-acetylene torch with a carburizing flame to heat the angle, which was necessary since aluminum dissipates heat so quickly with large parts.  It held my Super Polaris mount with the C-80 refractor on it for many years.


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#74 mfoose

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Posted 26 December 2018 - 11:41 AM

So with the uniqueness of my DEC housing box being an RA box that was retrofitted for it, the slo-mo hand control looks different as well. Most Dynascope Deluxe mounts that I have seen pictures of have a much nicer set up. For those Dynascope Deluxe owners, how is your DEC slo-mo hand control constructed? I don't like the looks of mine how it just emerges out of the hole with no adapter. 

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#75 Geo31

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Posted 26 December 2018 - 02:29 PM

I'd take advantage of that and look for an RV-6 RA drive.  Add a reversible motor and a control box and you'd have something really cool.


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