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Restoring a Criterion Dynascope Deluxe Mount

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#1 mfoose

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Posted 09 December 2018 - 08:10 PM

I recently acquired a Criterion Dynascope Deluxe mount and I just started the disassembly process so I can clean and restore it. The mount looks like it has been customized over the years. A slow mo hand knob was added on the RA housing and a fine tune adjuster was added to the base. My plan is to completely disassemble, clean up the 1.5" shafts, have the parts powder coated back to an original black wrinkled finish, and have the legs replaced (they are 60 years old and a few cracks are present). 

 

I started disassembly a few hours ago and all was going well until a noticed some paint flaking on the RA shaft housing. The paint easily fell of an revealed a sizable crack on the top side of the RA shaft housing. As I continued to disassemble I noticed a smaller crack on the lower lower side as well. Both are directly over top off the needle bearings. Is this an issue that I could have fixed by having someone weld it or is it too much of a problem to repair?

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#2 mfoose

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Posted 09 December 2018 - 08:12 PM

More pictures.

 

 

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#3 Garyth64

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Posted 09 December 2018 - 08:34 PM

If you can find a good TIG welder, he might be able to mend the crack.   And/or make a couple of clamps out of aluminum that will fit over where the cracks are.


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#4 G-Tower

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Posted 09 December 2018 - 09:17 PM

I would definitely address the cracks.


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#5 clamchip

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Posted 09 December 2018 - 09:34 PM

Oh No! such a cool mount too.

I think someone miss measured the bore-to-bearing clearance and press'ed em on home with a

ten ton press or maybe in the last half century someone removed the plain bearings and hammered in

the needle bearings.

No sense crying over spilt milk, I'd stick with the needle bearings and have the cracks welded. Paint it

and you will never know the difference.

 

Robert


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#6 mfoose

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Posted 09 December 2018 - 09:50 PM

Oh No! such a cool mount too.
I think someone miss measured the bore-to-bearing clearance and press'ed em on home with a
ten ton press or maybe in the last half century someone removed the plain bearings and hammered in
the needle bearings.
No sense crying over spilt milk, I'd stick with the needle bearings and have the cracks welded. Paint it
and you will never know the difference.

Robert


Robert,

I believe that the needle bearings were standard. Good to know that welding and painting over them should do it.

Now to start searching for someone who can do it.

Michael
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#7 terraclarke

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Posted 10 December 2018 - 12:57 PM

Cool! Did you get the bell-pier?
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#8 mfoose

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Posted 10 December 2018 - 01:33 PM

Cool! Did you get the bell-pier?

Unfortunately, no. Hoping that I could find a replacement, but I will probably end up having to come up with something else. 



#9 mfoose

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Posted 10 December 2018 - 01:34 PM

Any idea where I could come up with spare needle bearings?



#10 DAVIDG

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Posted 10 December 2018 - 01:53 PM

 Being made in the 60's or 70's in the USA, the bearing is most likely a Timken. Look on the race cover for any numbers. Here is one on Ebay that might work but you'll need to measure the OD. https://www.ebay.com...Xkkbm:rk:2:pf:0

 

           - Dave 


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#11 Geo31

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Posted 10 December 2018 - 02:26 PM

Any idea where I could come up with spare needle bearings?

https://www.mcmaster...roller-bearings

 

While you could certainly weld up the crack, you could probably get away with JB Weld also (if you're careful).


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#12 mfoose

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Posted 10 December 2018 - 03:56 PM

 Being made in the 60's or 70's in the USA, the bearing is most likely a Timken. Look on the race cover for any numbers. Here is one on Ebay that might work but you'll need to measure the OD. https://www.ebay.com...Xkkbm:rk:2:pf:0

 

           - Dave 

Thanks Dave!

 

I went to measure the OD of the bearings and noticed that the rear bearing has the serial number facing outwards. The bearings are made by Torrington model #GB-2416. There are a few on ebay including a guy selling them NOS with boxes: https://www.ebay.com...p2047675.l2644 

 

The OD is 1.875" like you said.

 

If I need new ones I will buy those Timken ones because they are cheaper.

 

Michael



#13 mfoose

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Posted 10 December 2018 - 03:59 PM

https://www.mcmaster...roller-bearings

 

While you could certainly weld up the crack, you could probably get away with JB Weld also (if you're careful).

I thought about it, but since I am going to get it powder coated I'd like to have the piece of mind that it is welded. 


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#14 DAVIDG

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Posted 10 December 2018 - 04:16 PM

  Since the casting is aluminum you can repair it yourself with low melting welding rod made of a special alloy that works with aluminum. https://www.youtube....h?v=jtvOkI_pvMI  The secret is that the surface needs to be cleaned just before you do the repair since Aluminium oxidizes quick. I use a new steel wire brush and bush the surface until it is completely clean and shiny bright. 

   If your going to powder coat the mount then you can't use any type of epoxy or plastic filler since as you know they bake the finish on at a fairly high temperatures so "plastic" like materials would deteriorate under the heat.  

 

                      - Dave 


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#15 mfoose

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Posted 11 December 2018 - 10:15 AM

  Since the casting is aluminum you can repair it yourself with low melting welding rod made of a special alloy that works with aluminum. https://www.youtube....h?v=jtvOkI_pvMI  The secret is that the surface needs to be cleaned just before you do the repair since Aluminium oxidizes quick. I use a new steel wire brush and bush the surface until it is completely clean and shiny bright. 

   If your going to powder coat the mount then you can't use any type of epoxy or plastic filler since as you know they bake the finish on at a fairly high temperatures so "plastic" like materials would deteriorate under the heat.  

 

                      - Dave 

Thanks Dave, I may repair it myself using your suggested method. I'm no expert, but I did some brazing in high school so I have some experience. I may buy an aluminum tube like in the video to do some practice on before attempting it on the mount. I'd probably buy some hose clamp and lightly tighten it up around the crack to bridge the gap before brazing. Seems pretty straight forward. My only fear is the inside. I just removed the bearings and found that the cracks are worse than I initially thought (see post below for that).

 

I also may not have it powder coated and just try to do it myself. I have no problem spray painting, but with wrinkle finish, as I am sure you know, you have to bake it and I'm not sure how well using the oven will go over. May just ask for forgiveness later lol. Still going back on forth on that. 


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#16 mfoose

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Posted 11 December 2018 - 10:29 AM

So I just removed the needle bearings. The rear one was somewhat loose and came out with just using my finger to pull it out. The front one, where the larger crack is, was more difficult. I ended up using the 1.5" shaft to lightly tap it out from the back side. Came out with issue, but I was sure not to use too much force. Unfortunately, both cracks are worse than I thought. The rear one is a straight shot going back slightly more than an inch and it is not that wide. The top one splits into two directions and where it splits it is slightly raised on the inside. The split occurs about .8" in so the bearing would be right over it. Each split is about .75" long. Not impossible to fix, just more work. 

 

When I removed the top bearing it had a very thin metal sleeve wrapped around it. I'm guessing it was installed that way by Criterion to make it tighter. It is not the culprit for the crack, because the rear one is cracked as well and there is no sleeve, but I don't think it helped the situation at all. The rear bearing looks like it could be cleaned up and reused if necessary, while the top bearing has a few small cracks in it (12 o'clock in the picture). Now that I am writing this out it dawned on me that I may have caused those small cracks in the bearing when tapping on it with the 1.5" shaft. Oh well, new bearings were on the menu anyways.

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#17 mfoose

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Posted 11 December 2018 - 10:31 AM

Inside look at the crack on the rear side (try not to laugh reading that)

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#18 mfoose

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Posted 11 December 2018 - 10:32 AM

Top side crack. Notice the split :/

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#19 mfoose

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Posted 11 December 2018 - 11:12 AM

While looking at the cracks I also noticed that RA setting circle indicator was not mounted in the proper place, but was instead glued on elsewhere. I had to dig at the glue a bit because I wasn't sure if one of the previous owners drilled and tapped the base to mount it and then put glue over the mounting screws. Turned out that they just widened the mounting holes on the indicator bracket and glued it straight to the base. Once I realized that I just used a bit of force and popped it off. Now sure how to mount it back on the base since they widened the holes pretty good. Oh well, not as big of an issue as the cracks. 

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#20 Geo31

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Posted 11 December 2018 - 11:43 AM

I have no problem spray painting, but with wrinkle finish, as I am sure you know, you have to bake it and I'm not sure how well using the oven will go over. May just ask for forgiveness later lol. Still going back on forth on that. 

You do not have to bake it.  I've used it extensively on my RVC-6N restomod scope.  See photo below:

 

dpp71kM.jpg

 

Every single black part you see is painted with wrinkle paint and not baked.  I've found it helps to do a couple of light coats and a heavier final coat.  It may even be a good idea to spray a base flat black coat first as when the paint pulls up to wrinkle, I could sometimes see the primer in the troughs.


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#21 mfoose

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Posted 11 December 2018 - 11:45 AM

You do not have to bake it.  I've used it extensively on my RVC-6N restomod scope.  See photo below:

 

dpp71kM.jpg

 

Every single black part you see is painted with wrinkle paint and not baked.  I've found it helps to do a couple of light coats and a heavier final coat.  It may even be a good idea to spray a base flat black coat first as when the paint pulls up to wrinkle, I could sometimes see the primer in the troughs.

What brand paint did you use?



#22 DAVIDG

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Posted 11 December 2018 - 12:10 PM

 I have used VHT wrinkled black paint many times. It works great, you just apply three coats within about 15 minutes of each one and doing it around 70°F. You'll  get a nice uniform wrinkling. It takes about a week or so for the finish to get real hard so before that you need to be a bit careful in handling the parts so as not the distort the finish. Baking them will also cure it much faster https://www.amazon.c...208289102&psc=1

    As for the cracks I won't try to close them up. They formed because the bore was either too small for the OD of the bearing, the bores aren't aligned so when the shaft is installed there is pressure on the casting, the casting wasn't cast correctly or the mount got dropped.

    I would just braze/weld them up. If you clamp the housing so the cracks close up then you going to need to boring the housing out so there is enough clearance for the bearing and to be sure they are aligned  To bore them your going to need to do on a mill. 

 

                          - Dave 


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#23 apfever

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Posted 11 December 2018 - 12:54 PM

If you want a quick fix to keep going on the rest, find a double split shaft collar like these.  They can go off and on without having to remove anything from the shaft.  They will give you all the confidence in clamping you'll need. These are 1.5" for a typical shaft but they can be found in practically any size. Your cast housing may not be machined perfectly round but it wouldn't take much to get one to work. They come in regular, stainless, aluminum, polymer, etc., so if you like the looks you can just leave it (or easy take off anytime).  NO marring, No set screw, and plenty of crush power. 

 

After using one on an 1.5" shaft, I ordered this set of 10 for $34 shipped.  The first one at Grainger cost a typical going rate of about $13 tax and all. Pretty quick love affair. I have a bunch of 1.5" setups so this purchase was a no brainer.  There are very cheap sets of 2 and sets of 4 on the web,  "double split shaft collars", "double split stop collars".   These just came in a few days ago, now I can go hog wild on setting circles. 

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#24 Geo31

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Posted 11 December 2018 - 02:44 PM

What brand paint did you use?

It was a VHT paint from an auto parts store.

 

0027426_vht-wrinkle-finish-paint-black-a

 

You should be able to find it an Autozone, Advance Auto, O'Reilly, NAPA, etc.  


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#25 apfever

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Posted 11 December 2018 - 02:46 PM

So I just removed the needle bearings. The rear one was somewhat loose and came out with just using my finger to pull it out. The front one, where the larger crack is, was more difficult. I ended up using the 1.5" shaft to lightly tap it out from the back side. Came out with issue, but I was sure not to use too much force. Unfortunately, both cracks are worse than I thought. The rear one is a straight shot going back slightly more than an inch and it is not that wide. The top one splits into two directions and where it splits it is slightly raised on the inside. The split occurs about .8" in so the bearing would be right over it. Each split is about .75" long. Not impossible to fix, just more work. 

 

When I removed the top bearing it had a very thin metal sleeve wrapped around it. I'm guessing it was installed that way by Criterion to make it tighter. It is not the culprit for the crack, because the rear one is cracked as well and there is no sleeve, but I don't think it helped the situation at all. The rear bearing looks like it could be cleaned up and reused if necessary, while the top bearing has a few small cracks in it (12 o'clock in the picture). Now that I am writing this out it dawned on me that I may have caused those small cracks in the bearing when tapping on it with the 1.5" shaft. Oh well, new bearings were on the menu anyways.

It seems to me this mount took a fall. You stated part of a crack is raised relative to the rest so I'd think a side shock from a fall. Since the mount has been modified anyway, it would be easy for an owner to take it apart and shim a bearing after a fall.  Criterion may have been starting to hurt at that time but I don't see them installing shims on a major crack to send it out the door.  I could see factory shims being used but not on known damage like that. 




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