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Discussion Starter · #1 · (Edited)
Hello,
whille replacing the arbor bearings on my unisaw, I noticed extra movement on the front trunnion. The trunnion had a crack clear through Just below the worm gear.
I have seen some used trunnion available for about 100$ plus shipping.
how interchangeable is a trunnion?
will it require fitting to the part with the gear?

thanks Ed
 

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just get it rewelded. thos its likely the same cost as that used trunion.
 

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Ole Nail Whooper - Retired Moderator
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Years back, I popped the one on my saw in half. I took it to a welding shop and he brazed it back together, it is still holding after all these years. They charged me something like $30 back then.
 

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If your area is anything like mine, good luck finding a welder! And if you do find one, I doubt they'll even look at it for 30 bucks.

If you're looking at $50 or more to fix it, I would buy a new part.
 

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where's my table saw?
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I've never welded cast iron, but I have brazed it using an Oxy-Acetylene torch. Almost any "competent" welder either hobby or pro can braze that crack together in a matter of minutes. Mine was a completely cracked off neck on a metal cutting bandsaw. It was in two separate pieces which I "V" ground and clamped together.
There may not be "new" pieces? If used off Ebay then, possibly fine and it may fit OK? If you repair yours by brazing, you know it will fit.
 
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four decades ago I brazed a broken joint in my wife's heavy steel ironing board - its still working fine :)
 

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I’m certainly no expert, but considering the stress on this part, I think it needs to be welded. Not everyone can do that. I know a couple welders who will not weld cast iron. There are welding shoos that specialize in it.

Unless he can find someone who knows what they‘re doing and will do it $50 or less, IMO he’s better off buying the new part.
 

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if you can find one to buy, and you are happy with that, go for it.

google welders in your area. then take it to them so they can look at it. a good shop won't even blink at that job.
 

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where's my table saw?
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if you can find one to buy, and you are happy with that, go for it.

google welders in your area. then take it to them so they can look at it. a good shop won't even blink at that job.
Enough speculation by "arm chair" experts please. As someone who has actually done, MIG, stick and torch welding and torch brazing I am not an expert, but familiar with those processes. I have owned oxy-acetylene torches for 55+ years and a 225 AMP stick welder about 50 years. When I broke the neck on the cast iron 2 wheel metal cutting bandsaw many years ago, I brazed it together. It's not "welding" and the heat range is lower and more distributed allowing the metal to heat more uniformly than welding. It needed to be reassembled precisely to maintain the parallelism of the axles so the blade would track correctly.

The setup and clamping needed to be precise and the break could not be completely ground away or the registration of the two parts would be lost. The section was about 2" X 4" and about 1/4" thick. I was certainly no "expert" back then and "hobby welder" would fit my skill level. I had nothing to lose and needed my bandsaw back working, so I went ahead and brazed it. That was 25 years ago and it's still working just fine. I say take it to a "machine shop" not a "welder"" who may be more used to construction type welding than the precision a machine shop would likely encounter. They will also know how to fixture it together for the best alignment.

My latest big welding project was a tandem axle trailer:
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Enough speculation by "arm chair" experts please. As someone who has actually done, MIG, stick and torch welding and torch brazing I am not an expert, but familiar with those processes. I have owned oxy-acetylene torches for 55+ years and a 225 AMP stick welder about 50 years. When I broke the neck on the cast iron 2 wheel metal cutting bandsaw many years ago, I brazed it together. It's not "welding" and the heat range is lower and more distributed allowing the metal to heat more uniformly than welding. It needed to be reassembled precisely to maintain the parallelism of the axles so the blade would track correctly.

The setup and clamping needed to be precise and the break could not be completely ground away or the registration of the two parts would be lost. The section was about 2" X 4" and about 1/4" thick. I was certainly no "expert" back then and "hobby welder" would fit my skill level. I had nothing to lose and needed my bandsaw back working, so I went ahead and brazed it. That was 25 years ago and it's still working just fine. I say take it to a "machine shop" not a "welder"" who may be more used to construction type welding than the precision a machine shop would likely encounter. They will also know how to fixture it together for the best alignment.

My latest big welding project was a tandem axle trailer:
View attachment 440222 View attachment 440223 View attachment 440224
my apologies, i did not realize that you were the only poster qualified to respond to this thread. Thanks for the heads up!
The question was not about welding, the question was about how interchangeable are the parts?
OP i also apologize to you for offering alternatives to your dilema.
 

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where's my table saw?
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The question was not about welding, the question was about how interchangeable are the parts?
anyone done this?
How would anyone know who has not had the exact same issue.? That's kinda remote.
If you get a used Ebay part, you are taking a chance unless you can verify it's fitment buy contacting the seller and get part numbers.
 

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how interchangeable is a trunnion?
will it require fitting to the part with the gear?
I'm not sure how to interpret your first question. Do you mean any trunnion, or one made for your saw model? I'm going to assume you mean a trunnion made for your model.

Having sad that, I'm not familiar with your saw, but here are my thoughts. Since you haven't gotten an answer yet, maybe you can figure it out yourself. When I first read your post, my thought was why wouldn't it be interchangeable (assuming the new part is made for your saw model) and why would it require fitting to the part with the gear? I doubt that parts were custom made for each saw, hand fitted, etc. I would think all parts were made to a specification and the saws were pretty much just assembled without any modification or fitting. So, maybe by looking at your saw and parts and how they fit and act together, you can make a decent assumption about it.

Not your question, but I think at some point I saw a discussion on reinforcing a trunnion. From memory, there were various ideas (maybe even something as easy as filling the recessed area with epoxy). You might want to look into this. Again, I'm not familiar with your saw, but maybe this is a weak spot and you can do something to avoid it happening to a replacement trunnion. Or, maybe at some point they modified the part to make it stronger (which would then go to your original question about whether the improved part would work without modification). I'm sure you aren't the first one to have a cracked trunnion, so I bet there is something on the web about it. It's just going to take some research.
 

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my apologies, i did not realize that you were the only poster qualified to respond to this thread. Thanks for the heads up!
My reply was not aimed at you, except to recommend a more specific type of expert welder.
I know and have used several local machine shops and a few metal fabrication shops, they are much different in the tools and techniques and their skill levels when it comes to welding. I've had welding done on 3/8" wall 12" x 12" tubing by a fabrication shop, and welding of replacement scraper bucket blades by another fab shop. My machine shop friends can do TIG, MIG and even wire EMD cutting, very precise stuff for making firearm sight bases. That shop actually precision milled a no. 7 Stanley plane bottom for me to flatten it and remove some rust pitting. Another gunsmith friend of 35 years has a machine shop business in his 3 car garage with 4 vertical milling machines, Bridgeports or clones and he also does very precise work. I have a vertical mill and two metal lathes, so I'm not a "one trick pony" and limited only to woodworking. These skill were accumulated out of necessity over many years having farm tractors and equipment and building custom trucks etc.
 

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where's my table saw?
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Hello,
whille replacing the arbor bearings on my unisaw, I noticed extra movement on the front trunnion. The trunnion had a crack clear through Just below the worm gear.
I have seen some used trunnion available for about 100$ plus shipping.
how interchangeable is a trunnion?
will it require fitting to the part with the gear?

thanks Ed
My advice is to contact the seller for the exact part numbers. If it's a match then there should be no issues.
My alternate advice, have yours brazed. It's a simple repair for a knowledgeable welder.
My next is a more of a question. What made the original one break?
This should be remedied before and repairs or replacements are made.
 

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I don’t think a lot changed in Unisaws from maybe 1975 until 1990 and parts among those saws are likely interchangeable. The one place where there might be some variation would be left tilt vs right tilt.

The folks at OWWM.org might be able to help source a replacement part.
 

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I don’t think a lot changed in Unisaws from maybe 1975 until 1990 and parts among those saws are likely interchangeable. The one place where there might be some variation would be left tilt vs right tilt.

The folks at OWWM.org might be able to help source a replacement part.
Because the unisaw has been made for years the folks a owwm will know whichn years are interchangeable parts. Ebay is okay and now with money back guarantee.
 

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I too would just get it brazed or tig welded. Preheat and post heat are also advised to the welder doing the repair. If he doesn't know what he is doing the part can/will crack right next to the weld along the HAZ. I bought a Harbor Freight 12 inch sander on sale many years ago and when I got home and opened it up I found the leg was broken clean off on one corner. It was a 30 minute drive back to HF so I called to see if they had another one so I could swap it out and had him check it before I drove down. I told him I could just fix this if he didn't have one to swap if he reduced the price. He said sure. Then said the other one was broke in the same way. I said I would come down and buy that one too for the reduction in price. I think I gave them $60 each and I was happy. They were about $129.00 each back then. Here is the model I got:


And here is the repair I did to the first one as the second one is still in the box for a spare:

Wood Wood stain Gas Hardwood Fixture
 
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