If I have my rear scap receiver section middle scrap peices and my fron scrap peice from my M53 kit how do I determine the propper over all lengths?I see the jigs guys have built and I will make a copy.
Is there a drawing to go by or do I use components to determine the lengths or... before I start welding.
What's the best jig?
How to determine receiver lengths for welding?
How to determine receiver lengths for welding?
DONT TREAD ON ME
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gunslingerdoc
- Stabshauptmann
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- Location: middle, MS
Basically you assemble the parts using them to determine spacing. Top cover sets your rear piece, bipod and booster catch for the front end, the 'trunion'/cam piece will set you middle gap. It also helps to make sure it fits on the mg3 tripod. Once I got mine jigged up I measured OAL with a straight edge. Check Pirates posts I think the OAL without booster was 37 and some fraction inches. Mine by luck was right on after I tacked it together. I then finished welding it. Another good suggestion for the front end is to use a laser bore sighter to make sure you get it on straight - its the hardest part to weld straight.
Smooth is Fast
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Pirate
- General
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- Location: 1/2 mile from the beach in S Fla.
The correct overall length is 37 11/16". there is a dwg here with dimentions but I don't
think all are correct as a couple didn't match my receiver. if you install the top cover
it will set the rear. the tabs that locate the trunnion locate the middle and the front
should be set to the 37 11/16 dimention.
think all are correct as a couple didn't match my receiver. if you install the top cover
it will set the rear. the tabs that locate the trunnion locate the middle and the front
should be set to the 37 11/16 dimention.
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88comm
- Stabshauptmann
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- Joined: Mon Jun 06, 2005 7:31 pm
- Location: South Central Pennsylvania
Alternative to Jigs for welding
I welded mine up the other day, did not use much in the way of jigs. I do have a straight, flat table that helped. Also used a good 2' metal ruler.
Most of my work was with a few clamps and small pieces of metal. Also used pieces of copper under the metal.
First I welded the metal block to prevent a FA bolt from ever fitting for use. Mine is located (on the receiver) in the front of the grip stick. I removed the metal "hooks" that are on the front of the grip stick. The block fits inside the grip and acts as a hammer stop. It also extends into the reciever, preventing a bolt with FA trigger ears from ever getting by it. The block is also threaded, so a small (1/4-20) button head allen bolt is used to retain the front of the grip stick
Tack welded parts together, then by eye looked at the alignment. Also checked by feel and with the straight edge.
Tack welded opposite sides, checked alignment.
Got it all together, tacked only.
Took it to the bench to assemble all the parts to see if alignment is correct. This is a good step, as you can cut and reweld if it isn't.
Mearsure overall length. right now its 1/16" short. What to cut to add 1/16"?
Front piece to barrel guard is correct, bipod fits perfect and both bipod mount holes are identical sizes.
Weld under trunnion is correct, as trunnion fits with very little slack in the reciever/trunnion "window".
This means the back weld, for the buttstock, is too close together. Because this is already tacked, it is an easy fix.
Cut one weld with a 4" abrasive wheel, spread it a little, tack it again. Roll it over, do the same thing, cut spread and tack. Check length.
ABOUT THE WELDING WITHOUT FIXTURES
The human eye can be trained to recognize variations to a few thousandths of an inch. This reciever is not that close. Tack it, LOOK AT IT from all sides, bend it, hammer it a little, tack it again. LOOK AT IT AGAIN. LOOK SOME MORE. If you still don't like it, cut it apart and do it again.
Use your fingers to feel for even surfaces (after it cools) They will tell you if its aligned.
It can be done this way. I will get pix in as I can get to it.
One more thought on welding (I'm using MIG). Tacking introduces minimal heat to the reciever. There is no reason why you cannot do many small welds, letting them completely cool inbetween. This should prevent some of the distortion we so worry about. This thought, in combination with the lack of rigid jigs or fixtures will work as an alternative method for assembling a semi-auto reciever. PS clean all welds and weld areas with a wire brush before welding, to get the most strength from the weld.
OK - lets hear some feedback
Most of my work was with a few clamps and small pieces of metal. Also used pieces of copper under the metal.
First I welded the metal block to prevent a FA bolt from ever fitting for use. Mine is located (on the receiver) in the front of the grip stick. I removed the metal "hooks" that are on the front of the grip stick. The block fits inside the grip and acts as a hammer stop. It also extends into the reciever, preventing a bolt with FA trigger ears from ever getting by it. The block is also threaded, so a small (1/4-20) button head allen bolt is used to retain the front of the grip stick
Tack welded parts together, then by eye looked at the alignment. Also checked by feel and with the straight edge.
Tack welded opposite sides, checked alignment.
Got it all together, tacked only.
Took it to the bench to assemble all the parts to see if alignment is correct. This is a good step, as you can cut and reweld if it isn't.
Mearsure overall length. right now its 1/16" short. What to cut to add 1/16"?
Front piece to barrel guard is correct, bipod fits perfect and both bipod mount holes are identical sizes.
Weld under trunnion is correct, as trunnion fits with very little slack in the reciever/trunnion "window".
This means the back weld, for the buttstock, is too close together. Because this is already tacked, it is an easy fix.
Cut one weld with a 4" abrasive wheel, spread it a little, tack it again. Roll it over, do the same thing, cut spread and tack. Check length.
ABOUT THE WELDING WITHOUT FIXTURES
The human eye can be trained to recognize variations to a few thousandths of an inch. This reciever is not that close. Tack it, LOOK AT IT from all sides, bend it, hammer it a little, tack it again. LOOK AT IT AGAIN. LOOK SOME MORE. If you still don't like it, cut it apart and do it again.
Use your fingers to feel for even surfaces (after it cools)
They will tell you if its aligned. It can be done this way. I will get pix in as I can get to it.
One more thought on welding (I'm using MIG). Tacking introduces minimal heat to the reciever. There is no reason why you cannot do many small welds, letting them completely cool inbetween. This should prevent some of the distortion we so worry about. This thought, in combination with the lack of rigid jigs or fixtures will work as an alternative method for assembling a semi-auto reciever. PS clean all welds and weld areas with a wire brush before welding, to get the most strength from the weld.
OK - lets hear some feedback
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drooling idiot
- General
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i wouldn't fixated on that 1/16 th of an inch.
first thing is these guns are metric so they don't line up with any standard English measurements.
second, i have three receivers done and a 4th finishing this week-end and everyone of them finishes BETWEEN 37 5/8" and 37 11/16" on my tape measurer
i think the receiver is actually 95.6 CM but i suck at metrics
first thing is these guns are metric so they don't line up with any standard English measurements.
second, i have three receivers done and a 4th finishing this week-end and everyone of them finishes BETWEEN 37 5/8" and 37 11/16" on my tape measurer
i think the receiver is actually 95.6 CM but i suck at metrics
"good , bad, .....I'm the man with the gun."
Its amazing anything works right around here with a bunch of
over-age juvenile delinquents running the place.
Its amazing anything works right around here with a bunch of
over-age juvenile delinquents running the place.
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88comm
- Stabshauptmann
- Posts: 177
- Joined: Mon Jun 06, 2005 7:31 pm
- Location: South Central Pennsylvania
Thanks - That's nice to know. I wasn't sure if that was important or not.
I did visit BRP and talked with Brian some time back. He had some interesting insights on the weapon. He mentioned that the tooling/machines that these were originally built on was old equipment bought from the US, surplus to the automotive industry in Detroit. Purchased in the 20's and 30's, it was equipment that helped to rebuild Germany after the 1st World War. For this reason, some of the parts are inch measurements, while others maybe metric. As I recall he pointed out that the main spring is 1 3/16" in diameter or something like that.
Interesting trivia
I did visit BRP and talked with Brian some time back. He had some interesting insights on the weapon. He mentioned that the tooling/machines that these were originally built on was old equipment bought from the US, surplus to the automotive industry in Detroit. Purchased in the 20's and 30's, it was equipment that helped to rebuild Germany after the 1st World War. For this reason, some of the parts are inch measurements, while others maybe metric. As I recall he pointed out that the main spring is 1 3/16" in diameter or something like that.
Interesting trivia