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02-05-2012, 05:47 PM | #1 |
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Heat & Peen or....
In replacing/rebuilding certian parts on Model-A's. You have to heat to cherry red and then peen one of the ends of set pins. I don't have a torch set up(small hand held ones with the attached tank do not get
the pins hot enough), so I go over to a buddies house that does have one. No big deal, but I like doing as much repair as possible myself. Is heating and peenning absolutely necessary? What about using a large shop vise as a press to cause the set pin to up-set enough so that there is no way (hopefully) that it will become loose?!?! In particular I am talking about the rear service brake cam shaft/lever set pins. TIA for any and all thoughts on the subject. AMF/Bob-A PS: One thought I do have on the matter is that heating the pin red hot. Causes the whole pin to expand & grow soft so when you pound it to peen it. The whole length of the pin expands to tighten up all available space and makes a stronger set or bond when it cools. Hmmmm.....I probably answered my own question.....silly rabbit that I am |
02-05-2012, 06:13 PM | #2 |
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Re: Heat & Peen or....
A related question that I have, particularly for the front and rear service brake arm pins, is should they be heated while assembled in place or unassembled?
The pins that I have removed seemed to be lose on the bucked end and essentially welded to the lever arm on the peened end, suggesting to me that they may have been heated while assembled. I have been told that the repro pins are soft enough to peen cold but I have also dissassembled some of them that clearly were not tight for very long in service. |
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02-05-2012, 11:06 PM | #3 |
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Re: Heat & Peen or....
I doubt that the factory heated them --too slow, I have used a large vice, it is quite old and when using it one needs top be careful to not crush things ---it sets rivits very easy --strong enough to make a coarse thread 1/4 20 bolt into a 5/16 24 bolt without too much effort, better than heating the rivit it swells the rivit to fill the hole it's entire length -no more looseness between the arm and shaft.
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02-08-2012, 12:35 PM | #4 |
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Re: Heat & Peen or....
Thanks for the info guys. I think I just might try the vice/press procedure and see
what happens. AMF/Bob-A |
02-08-2012, 03:49 PM | #5 |
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Re: Heat & Peen or....
While I hesitate to contradict Kurt, I do believe they would have heated most rivets prior to installation. Why? Because they would have compressed easier and most important of all, They would have shrank and tightened as they cooled. This was the main reason all early skyscraper, steel frames were done wiith hot rivets. However I do believe that a Mapp Gas (Yellow bottle) torch would have been hot enough. It may require making a "nest" of firebrick to contain the heat. JMHO
Terry |
02-08-2012, 04:51 PM | #6 |
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Re: Heat & Peen or....
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When cooled, they would shrink. This would mean that they would pull tighter from outside head to inside peen, but would also mean they would shrink away from the hole in diameter. So the holding force is in friction from the underside of head and underside of peen only. I suppose a bolt does the same thing, losseness in hole and friction only . One would think cold rivets would tighten up both as friction and fill the hole and stay the same size. Maybe I should google it. |
02-08-2012, 10:58 PM | #7 |
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Re: Heat & Peen or....
I heated mine with a 00 tip and oxy/acetylene however air/acetylene would probably work fine. Squeezing one cold in my 5" vise was not acceptable and others have said that peening cold by hammering made a mess.
I used a 3X rivet gun at unknown psi (at least 90). The end of my rivet tool was a little too shallow to form the head "perfectly" however the heads on the originals I looked at varied widely and this worked fine for my driver. Tried to upload photos (mine) but the system will not let me due to "missing security token" whatever that means. |
02-08-2012, 11:04 PM | #8 |
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Re: Heat & Peen or....
pooch, if you merely stuck a hot rivet in a hole and let it cool, yes it would shrink away from the walls and be no tighter than if stuck in cold. However, the wall is heated some and the pneumatic rivet hammer or hydraulic squeezer pounds the metal into the hole hardening it immensely and so it does not shrink away from the hole and if done right there will be friction everywhere and tension in the rivet.
I don't recall ever being able to remove a heat-set rivet from a hole of any depth without drilling the rivet to permit it to collapse inwards when pressed or hammered out. |
02-09-2012, 09:04 AM | #9 |
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Re: Heat & Peen or....
Trying again to upload some photos.... These show before and after of one arm and the riveting setup. I put the arm on a piece of steel for an anvil with two "fat chicks" to hold it in place.
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02-09-2012, 11:15 AM | #10 |
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Re: Heat & Peen or....
Well...., I'm in kind of a dilemia as to what to do: heat & peen or vice & squeeze. I chucked one of the rear brake backing plates with the new
cam shaft and lever unto my 6" vice. Tightened up everything and then brought out my favorite "cheater" bar (an old harley fork tube) and commenced a' cranking on the vice screw type operating bar/lever kiz-mo. Put just about all my manliness into the squeezing and then backed off, a-feared that I might bust the vice's screw mechanism. The plain end of the pin definitely ballooned out some, enough that the pin ain't gon'na drop out any time soon, but not as much as I would have liked, I guess. I "miked" everything (in inches) and this is what I came up with: set pin before squeezing= .317 head on pin & .244 on plain end. Set pin after squeezing= .320 head on pin & .298 on plain end as it leaves the brake lever & .305 on ballooned part of original plain end. Basicly I see a difference of .061 between the pin's before and after diameter, so is that enough to safely hold the pin in and with stand the torque of braking? Whay say ye', who have a heck of a lot more knowlege then I'll ever have about this kind of stuff? Kurt, Terry, Rich? I know this is kind'a anal, but when you are an old fart who is retired and has nothing better to do................ AMF/Bob-A |
02-09-2012, 12:50 PM | #11 |
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Re: Heat & Peen or....
A vice won't do the job, and I'm surprized your vice is still in one piece after using a cheater on the handle.
I'd do it the way Rich did. IF you don't have the air tool, even a hammer will work. |
02-09-2012, 01:51 PM | #12 | |
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Re: Heat & Peen or....
Quote:
Here is my vice (the one Kurt was talking about). Notice the distributer housing sitting on it for scale. I guarantee this vice fully squishes the rivets and allows them to fill the holes. I put an arm on backwards once and tried to get it apart. Won't make that mistake again. I call this a 2 person vice. It takes 2 to put it on the bench and you do not want this baby to fall on your foot. It is a Prentiss Vice Bulldog No. 56 with 6" jaws and can open to like 14". The slide controlling the movable jaw is a fairly tight fit and has lot of control keeping the jaws parallel, it is not a toy. I have put bars on it and worried more about breaking the bench. Do not know how hard these vices are to find, but I recommend one for anyone serious about restoration work. |
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