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GlockSmack
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Posted: 10/1/2007 11:17:22 AM EST
I seem to remember someone posting something about a poor man's bending jig that used some angle iron and washers from Lowes awhile back. I've tried searching through the sticky's and posts, but don't see any mention of it. Does anyone have the post or URL?

Thanks
maxxx93
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Posted: 10/1/2007 11:22:11 AM EST
maxxx93
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Posted: 10/1/2007 11:28:10 AM EST
toennee
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Posted: 10/1/2007 12:42:43 PM EST
This was on here a few weeks ago.fhttp://www.ar15.com/forums/topic.html?b=4&f=51&t=98202
GlockSmack
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Posted: 10/1/2007 1:45:24 PM EST
Thanks all, that last post was the one I was looking for!
JohnB_greenAK
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Posted: 10/1/2007 7:51:17 PM EST
[Last Edit: 10/1/2007 7:55:15 PM EST by JohnB_greenAK]
I've got all the parts for this myself....maybe $30 at Home Dopet.

Just waiting for my flat(s) to arrive....

I'm also thinking of buildng a "poor man's press" using the same iron stuff and a small auto bottle jack...
"You will find wars are supported by a class of argument which, after the war is over, the people find were arguments they should never have listened to."

--from the intro to "Falsehood in Wartime, Propaganda Lies of the 1st World War&#
JohnB_greenAK
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Posted: 10/8/2007 8:38:33 PM EST
Got my kit and used the rear portion of the receiver (after removing the buttstock) to measure the gap in the outer jig element...

34.5 mm +/- .2mm

What I did was tightened the nuts on one side, and left the other side just tighter than finger-tight...I adjusted the width by turning the loose nuts 1/6th turn (outer one first, then the inner when expanding; inner nut first/outer one last when contracting) I eventually got it down to 1/12th turn and called it good.

Double-checked using the front portion, it fits with about 0.3mm gap (+/-0.015 when centered)

This is, of course, using my "calibrated eyeballs" and a $1.99 HF plastic micrometer...but it seems close enough for my purposes.

Heh heh heh....can't wait till I get some more time off....this might be the start of a frantic, albeit short-lived hobby, due to the supply of kits)...
"You will find wars are supported by a class of argument which, after the war is over, the people find were arguments they should never have listened to."

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mstang88s
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Posted: 11/21/2007 11:10:40 AM EST
Here is my version of the poormans flat bender. I used the flat with pre-bent top rails.
Just have to instal lower rails and center support and harden it. Made with 1 1/4 flat bar and 3 x3 x1/4 angle that I had lying around shop. I spent $6 for nuts and bolts. The bolts at the end of the flat bars helps support them so they don't bend.

JohnB_greenAK
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Posted: 12/8/2007 7:01:38 PM EST
[Last Edit: 12/8/2007 7:03:43 PM EST by JohnB_greenAK]
Bent my first blank with the Home Depot Bend-O-Matic the other night...worked great! Easy turning of the 6 nuts (1/2 turn each, center-to-outer; 6 bolts = 1 each end, 1 in gripscrew hole, one in trigger hole, two in mag well), didn't even break a sweat.

Minor nudging with a vise and a Mk. I Hammer, Sledge to remove little oddities and all is well...

Until it came time to bend the upper rails. Measured twice, clamped tight in an angle iron frame, and again using the Mk. I Hammer, Sledge...they (in concept) turned out straight and well, but it *seems* that they might be a smidge too low. (I used the trunnions to measure, it still seems about 1mm too short)

What is the standard way to measure/mark/bend the uppers on a complete flat? Or should the uppers be bent before the flat itself?

I also noticed that I might be able to use the lower rails in some fashion to locate the uppers...anyone have a technique for this?
"You will find wars are supported by a class of argument which, after the war is over, the people find were arguments they should never have listened to."

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milo47
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Posted: 12/12/2007 9:41:40 PM EST
Sounds like your fubar'd there. The lowers must "gide" the bolt into the front trunnion to close and lock correctly and lowering them to compensate won't work. From all I've seen you need a side plate with the correct height to fold the top rails on to. I have not bent one myself, so I don't really know crap here but I don't see how you can fix one if it's off. Maybe just call it a learning experience and get another flate. Good luck.
Wakko
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Posted: 12/13/2007 12:42:55 AM EST
Can someone post pics of it in use? Not quite sure how you're doing it.
cyrus
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Posted: 1/2/2008 3:58:40 PM EST
I've built a "poor man's jig" (PMJ?) and tested it on some scrap steel pieces, with decent results.

I'm using flats with pre-bent top rails from cope's dist. and Romy G kits, and I've got one problem and perhaps one sweet idea.

Problem: the lower rails, in order to fit the bolt carrier, have to be moved perhaps 4 mm higher than the holes in the receiver flat would indicate! Yikes! Is this a typical problem? I imagine that spot welding the lower rails "high", where they belong, and then drilling the holes in the receiver flat all the way through the rails, will solve the problem. But could this weaken those holes too much?

Idea: spot weld the lower rails onto the receiver flat BEFORE bending it. This would be a piece of cake with the poor man's jig and pre-bent top rails, and it would let the builder use unmodified spot welding tongs!

The only problem I can anticipate is that the flexing of the flat while it was being bent could cause the rails to pop off or warp. Has anyone tried this?

Thanks!

johnQpublik
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Posted: 1/15/2008 7:49:37 PM EST
I'm kind of new to the building of AKs, so please excuse my ignorance. But why couldn't the lower rails be mig welded in place in stead of spot welding???
stevec22
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Posted: 1/15/2008 8:11:15 PM EST
tag
stolat
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Posted: 1/30/2008 10:26:20 AM EST
thats what I am wondering. I have a mig but no tongs. Until I saw this I was going to go for the laser cut reciever and weld the bends. I think I am not going to do that. I might just spend the $ and buy the jig.
stolat
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Posted: 2/3/2008 9:25:22 PM EST
so can the rails be mig welded?
mykrowyre
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Posted: 2/17/2008 10:52:19 PM EST
Yes, you can mig weld the rails.. (done it)... but this poor man's jig screwed me over the weekend.

It bent my blank ok, but not in the shape I intended. The problem was the flat stock.. it's 1) not flat, and 2) not square.

This is my 2nd build btw, and I first tried pulling the flat into the jig with bolts... the bolt broke. Then I tried banging it in with a hammer. no luck.. creases but no bend. I started to bend it by hand and then saw that the flat was bent in the wrong places.

Arrghh... is one flat in the trash. Going to re-think this before I trash another flat.

mykrowyre
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Posted: 2/20/2008 3:05:30 PM EST
Regarding top rails 1mm too low:


Originally Posted By milo47:
Sounds like your fubar'd there. The lowers must "gide" the bolt into the front trunnion to close and lock correctly and lowering them to compensate won't work. From all I've seen you need a side plate with the correct height to fold the top rails on to. I have not bent one myself, so I don't really know crap here but I don't see how you can fix one if it's off. Maybe just call it a learning experience and get another flate. Good luck.


I folded one and the top rails were almost 1/8" too low because the jig I bought was fubar and the seller dissapeared. I had to actually trim the hand guard to get the tongue to fit into the receiver once the trunion was mounted. I just made sure the lower rails were lined up, had to trim just a hair off of the cross bushing so the bolt wouldn't make contact, and tada it works great. Feeds fine, no issues whatsoever. Can't even tell it's too short.

1mm is not critical when you are talking about something with 2mm slop all over the place. Thats the beauty of the design.

mykrowyre
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Posted: 2/20/2008 3:09:15 PM EST
[Last Edit: 2/21/2008 3:48:13 PM EST by mykrowyre]
BTW, tried again, this time getting my 1-1/4" flat bar stock from lowes instead of home depot. The home depot stuff was not flat and the sides not square. It looked like hell. The lowes stuff has slightly rounded sides, but is very flat and square. I bought a brand new 3/8" drill bit and bolted the two bars together and drilled all of the holes. Just bent a flat and it worked great. Lots of work (I only used 3 pull bolts, so I had to bend the sides a little by hand to get past the 30 degree bend mark) so in the future I will use all 6 bolts to pull the flat into the jig.

Make sure you put bolts at the ends to hold the bar stock together... thats where I screwed up the first time... the stock bent and separated and my flat was trashed.







hobo1958
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Posted: 4/17/2008 4:48:08 PM EST
Another newbie question for the experts, I'm assuming the inside dimension of the flat needs to be 1.250". The flats I'm using are .041" in thickness, how do I calculate the inside dimension of the jig? 1.250+.082"(flat thicknessx2)=1.332" how much should I add for clearance maybe .002"-.003"? Any help is appreciated. I'm using 7/16" -A2 tool steel for the jig frame. I'm using ground flat stock instead of angle iron and milled end blocks instead of threaded rod, I just need to know what thickness to mill the the end blocks for the inside dimension of the jig, I'm thinking maybe 1.334-1.335 but I want to make sure first from someone experienced.

Thanks
mykrowyre
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Posted: 4/24/2008 10:07:54 PM EST
I just guessed and added the thickness of the flat x 2 to the inside dimensions of the jig.
StagArmslower
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Posted: 9/7/2008 12:57:57 PM EST
Relay to the question about mig welding the rails.
It could be done from the outside of the receiver after driling the small holes (size of the spot weld) in the receiver and spot welding the rails that way, filling the holes. It is mig welding method in car industry. I thing I'm going to do it this way.
predatormaster
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Posted: 10/21/2008 12:53:44 AM EST
[Last Edit: 10/21/2008 1:19:34 AM EST by predatormaster]
Tag, elections comming!

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mykrowyre
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Posted: 11/23/2008 5:41:39 PM EST
Originally Posted By StagArmslower:
Relay to the question about mig welding the rails.
It could be done from the outside of the receiver after driling the small holes (size of the spot weld) in the receiver and spot welding the rails that way, filling the holes. It is mig welding method in car industry. I thing I'm going to do it this way.


I can be done but it's difficult. I have tried 4 times and failed each time. The problem is that the rails are heat treated and the receiver is not, so it's hard to get good penetration without burning a hole in the receiver.

A spot welder is the way to go. It's worth the $100 no doubt about it.

COMMAND450
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Posted: 2/19/2009 12:00:42 PM EST
theres a method to welding on rails with a mig welder, and it will be even stronger when done right. the problem is its much more work........

just depends on if you like the original spot weld look vs a smooth out look.
SOC
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Posted: 2/19/2009 12:51:12 PM EST
Originally Posted By mykrowyre:
Originally Posted By StagArmslower:
Relay to the question about mig welding the rails.
It could be done from the outside of the receiver after driling the small holes (size of the spot weld) in the receiver and spot welding the rails that way, filling the holes. It is mig welding method in car industry. I thing I'm going to do it this way.


I can be done but it's difficult. I have tried 4 times and failed each time. The problem is that the rails are heat treated and the receiver is not, so it's hard to get good penetration without burning a hole in the receiver.

A spot welder is the way to go. It's worth the $100 no doubt about it.



Just heat treat the receiver before you weld.

IMO It's an AK AK's are rough, spot weld it.

However I've drooled over some rivetless, seamless, AK's that look like they were machined out of solid billet from the muzzle break to the Rear stock tang.
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