Action truing fixture

IdahoCTD

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Buy a back plate from Shars (50-60.00) and a piece of heavy wall tube. Weld the two together, bore and turn it true, and then drill and tap your screw holes. It will make a good chambering fixture as well and work well for short barrel threading/chambering.
 

bigngreen

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I tried welding once to a back plate and it was scrapped because it warped it, my last version I mounted like all other chucks are mounted, cut a shoulder and bolted from the back, cheap, simple and repeats so we'll I can remove the chuck and reinstall it and not have to redial.
You can make next level pivot screws by installing a construction ball or tooling ball into the end of the screw then make a swivel foot with a small imbedded magnet.
 
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IdahoCTD

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You can thread it on as well. If you make a recess on the back plate as well as the tube and weld the ID first and only weld small strips it will minimize warpage. Bolts do work though.
 

bigngreen

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BigNgreen , Mc Master-Carr shows 3 types of swivel head screws even low profile ones. Which do you use? I would only hold something with these up to 2" OD. Thanks
I choose the largest size foot I can get through the hole, not the low pro ones, they work excellent. There are ones that are larger than the bolt that you can pop the foot of and on, I use them for a chuck design for holding barrels, grind a v or a 1.25 radius on the foot and it holds barrels perfect with no movement and excellent holding while letting you move the barrel and not force it.
 

Mram10us

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The action I did last night held fine with standard screw ends. Brass tips are easy enough to to make and radius if the standard feet ever slip
 

Mram10us

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You can thread it on as well. If you make a recess on the back plate as well as the tube and weld the ID first and only weld small strips it will minimize warpage. Bolts do work though.
Makes me wonder if tack welding thru some holes in the back plate would work fine. I’ll leave mine as is because it mounts in the 3 jaw well and the action still needs dialed in anyway.
 

bigngreen

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I don't understand wanting to weld anything to a cast iron back plate that is made for clamping, clamping also helps with keeping the harmonics down to help surface finish especially with threading at speeds we tend to. Trying to even come close to properly welding it needs to be welded glowing hot then cooled over a day or more, slower the better, just straight up welding will certainly crystalize the backplate, the proper rod for welding will cost more than the back plate, the rod I use is insanely expensive BUT I've welded some crazy things back together and it held. Not to mention balancing issues, there is a reason they are made for clamping!
 
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Mram10us

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I don't understand wanting to weld anything to a cast iron back plate that is made for clamping, clamping also helps with keeping the harmonics down to help surface finish especially with threading at speeds we tend to. Trying to even come close to properly welding it needs to be welded glowing hot then cooled over a day or more, slower the better, just straight up welding will certainly crystalize the backplate, the proper rod for welding will cost more than the back plate, the rod I use is insanely expensive BUT I've welded some crazy things back together and it held. Not to mention balancing issues, there is a reason they are made for clamping!
I was wondering if it would work. No one is saying you have to so don't worry. I ask questions when I want an answer so I can better understand it. I have welded my whole life, but never tried cast to stainless, thus the question. You keep putting exclamation points, so I'm not sure if that is frustration or what.
 

jrock

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I sort of stumbled on a good ideal like the swivel studs. I put trimmed down 40 cal case bases on the ends of my screws and nothing moves. Works better than small turned brass tips. Want to try larger turned brass tips as I think the small ones have too much stress on them and they squish.
 

Mram10us

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I sort of stumbled on a good ideal like the swivel studs. I put trimmed down 40 cal case bases on the ends of my screws and nothing moves. Works better than small turned brass tips. Want to try larger turned brass tips as I think the small ones have too much stress on them and they squish.
Great idea! I’d heard of using pistol cases before and totally forgot. Thanks. Great input. I’ll try it
 

ntsqd

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My friend in the power generation industry tells me that SS to carbon steel is best done with 309 filler rod. Apparently they do that sort of thing quite often, and some of those welds have to endure some pretty extreme conditions. (There's at least 10,000 ways to die in a power plant.)

Cast ferrous is a carp-shoot. Sometimes it's cast steel, which welds fairly nicely if given consideration for it's sometimes large thermal mass. If it is cast iron you're in for it. There literally 1000's of different cast irons. Some weld beautifully with the proper filler rod, others won't weld at all no matter what process and/or filler rod is used.

All of which is to say that unless I knew exactly what the back plate was made from I wouldn't try to weld to it. Weld your tool body to a plate and BOLT that to the back plate. I'd key that plate so that it can't move in X or Y on the back plate or rotate about the Z either. Then the bolts only hold it in place.
 

Mram10us

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My friend in the power generation industry tells me that SS to carbon steel is best done with 309 filler rod. Apparently they do that sort of thing quite often, and some of those welds have to endure some pretty extreme conditions. (There's at least 10,000 ways to die in a power plant.)

Cast ferrous is a carp-shoot. Sometimes it's cast steel, which welds fairly nicely if given consideration for it's sometimes large thermal mass. If it is cast iron you're in for it. There literally 1000's of different cast irons. Some weld beautifully with the proper filler rod, others won't weld at all no matter what process and/or filler rod is used.

All of which is to say that unless I knew exactly what the back plate was made from I wouldn't try to weld to it. Weld your tool body to a plate and BOLT that to the back plate. I'd key that plate so that it can't move in X or Y on the back plate or rotate about the Z either. Then the bolts only hold it in place.
I won’t be welding it, It just gets me thinking when someone shoots down ideas before explaining why. So many posts on here are people saying “don’t do it” rather than, explaining processes and letting you decide.
 

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