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9/22/2017 12:11:25 AM
Posted: 9/4/2005 3:03:01 PM EDT
I have the PMKMS kit. The receiver is too thick to allow the trunnions to just slide in. Should I grind on the trunnion or the receiver?

Any tips would be appreciated

Thanks
Link Posted: 9/4/2005 5:18:03 PM EDT
It's my understanding that you need to grind the trunnion. I'd ask a few more people about how to do this before you start though. Need to make sure you take off metal equally from both sides of the trunnion.
Link Posted: 9/4/2005 6:01:54 PM EDT
you have to mill the trunnion .6? off each side
its too much to just grind on you will end up making a mess of it
Link Posted: 9/5/2005 5:32:49 AM EDT
If you have access to a surface grinder, you would need to take about an 1/8" (3mm) off each side.

Also, the rear tang and FCG if they are tight.

I think this is why the 1.0mm receiver is more popular.
Link Posted: 9/5/2005 6:43:04 AM EDT

Originally Posted By harley_nut:
If you have access to a surface grinder, you would need to take about an 1/8" (3mm) off each side.

Also, the rear tang and FCG if they are tight.

I think this is why the 1.0mm receiver is more popular.



I read that G.T. uses a surface grinder for this too.

1/8" off ech side?!?!?! = 1/4" total?!?!?

I was thinking only .6mm (.023")off each side = 1.2mm (0.047") total

This receiver is .6mm thicker than std.
Link Posted: 9/5/2005 9:17:17 AM EDT
[Last Edit: 9/5/2005 4:03:34 PM EDT by Chtmg]
1. Narrow your trunnions. Because the extra thickness of the shell is on
the inside (if it were on the outside, the axis pins would not be long
enough)you will have to narrow your front and rear trunnion by .6mm on each
side.
It is important that you do it evenly on each side so the barrel and the
rear tang stay in the middle of the receiver. We do it on a surface
grinder.

A handy person can figure out how to do this with much simpler tools.

2. Deal with the narrow groove on the trunnions. The top rail of the
receiver slides into grooves machined into the side of the trunnions,front
and rear. This groove is too small for the thicker top rail on our
receiver.

The first thought would be to widen the groove. Two things make this not a
good idea. First, the trunnions are very hard, and difficult to machine.
Second, you would have to made the cut symmetrical to the groove-it is
important that the barrel trunnion be at the right height in the
receiver relative to the bolt rails, so if you cut the extra metal at the top of
the existing groove, the trunnion would drop down in the shell, and the bolt
will drag in the bolt rails.

The right way to fix this is to narrow the top rail from the bottom
only. You can carefully file or dremmel the bottom of the top rail until the
trunnion will slide onto it. Note that if you removed the material from
the top of the rail, you will be lowering the trunnions again, with the same
bad effect on the bolt fit into the bolt rails. This is really not a
difficult thing to do. We considered doing it to all of the shells we sell without
trunnions installed, but we decided it was not a good idea.

3 Selector lever. Selector levers from a milled receiver will work fine
without modification. The wall thickness on our shell is identical to
the milled receiver. With selector levers from a 1mm sheetmetal shell, you
will have to open up the gap between the inside and the outside parts of the
selector just a bit. We are including a piece of the metal we make the
shell from as a gauge, so this will be very easy to do.

Global posted these instructions. You should have got a sheet with this information when you got the receiver. I got a sheet for each receiver I ordered. I used a mill to narrow the trunnions and that worked out well. Measure your trunnions they gave a ideal measurement but I don't have it at home, I will post dimensions tomorrow.

I found the dimensions:
The design dimension is 30.8mm, with a tolerance of .1mm plus or minus. So in SAE, a finished size of 1.213" ideal, no narrower than 1.209", no greater than 1.217".

You should measure your trunnions before removing any metal. I think there is a slight differance in manufactures to warrent checking.
Link Posted: 9/5/2005 3:42:33 PM EDT
[Last Edit: 9/5/2005 3:44:25 PM EDT by tapeo1]

Originally Posted By 89Saleen:

Originally Posted By harley_nut:
If you have access to a surface grinder, you would need to take about an 1/8" (3mm) off each side.

Also, the rear tang and FCG if they are tight.

I think this is why the 1.0mm receiver is more popular.



I read that G.T. uses a surface grinder for this too.

1/8" off ech side?!?!?! = 1/4" total?!?!?

I was thinking only .6mm (.023")off each side = 1.2mm (0.047") total

This receiver is .6mm thicker than std.



Um, I think it's 0.3mm off each side for a total of 0.6mm. Any reason why you didn't go with the 1.0mm Global receiver instead?
Link Posted: 9/5/2005 3:52:58 PM EDT

Originally Posted By tapeo1:

Originally Posted By 89Saleen:

Originally Posted By harley_nut:
If you have access to a surface grinder, you would need to take about an 1/8" (3mm) off each side.

Also, the rear tang and FCG if they are tight.

I think this is why the 1.0mm receiver is more popular.



I read that G.T. uses a surface grinder for this too.

1/8" off ech side?!?!?! = 1/4" total?!?!?

I was thinking only .6mm (.023")off each side = 1.2mm (0.047") total

This receiver is .6mm thicker than std.



Um, I think it's 0.3mm off each side for a total of 0.6mm. Any reason why you didn't go with the 1.0mm Global receiver instead?



At the time this was the only receiver they offered. I've had this receiver and the parts kit for almost three years now. I'm just recently finding time to build it.
Link Posted: 9/5/2005 4:07:39 PM EDT
[Last Edit: 9/5/2005 4:13:05 PM EDT by Chtmg]


Um, I think it's 0.3mm off each side for a total of 0.6mm. Any reason why you didn't go with the 1.0mm Global receiver instead?



There are two sides to the receiver so you must take 0.6mm on each side.


I have built on both and the 1.6 are stiffer, the only problem is narrowing the trunnions. I am happy with both models. I haven't decided which to use for my Yugo 92 build.
Link Posted: 9/5/2005 4:11:21 PM EDT
Isn't the total difference between a 1mm shell and a 1.6mm shell equal to 0.6mm? Divide by 2 and you get 0.3mm for each side.
Link Posted: 9/5/2005 4:18:19 PM EDT
Just send it to GT and have them do it for you.
Link Posted: 9/5/2005 4:44:15 PM EDT

Originally Posted By socandyman:
you have to mill the trunnion .6? off each side
its too much to just grind on you will end up making a mess of it



socandyman is right - 0.6mm off each side (I got confused).

The surface grider is still the way to go. Global Trades can do it for you if you don't have the equipment.

And 0.6mm is 1/32" not 1/8" - sorry.

(allthose years in engineering school and still can't add)
Link Posted: 9/5/2005 4:55:50 PM EDT

Originally Posted By harley_nut:

Originally Posted By socandyman:
you have to mill the trunnion .6? off each side
its too much to just grind on you will end up making a mess of it



socandyman is right - 0.6mm off each side (I got confused).

The surface grider is still the way to go. Global Trades can do it for you if you don't have the equipment.

And 0.6mm is 1/32" not 1/8" - sorry.

(allthose years in engineering school and still can't add)



LOL...just making sure
Link Posted: 9/5/2005 5:17:48 PM EDT
I guess I'm confused. If you take off 0.6mm from each side, in total that adds up to 1.2mm .... Doesn't that seem to be too much being that the difference between a 1mm rec and 1.6mm is only 0.6mm???
Link Posted: 9/5/2005 5:23:02 PM EDT

Originally Posted By tapeo1:
I guess I'm confused. If you take off 0.6mm from each side, in total that adds up to 1.2mm .... Doesn't that seem to be too much being that the difference between a 1mm rec and 1.6mm is only 0.6mm???



You have to shave .6mm from BOTH sides of the trunnion to fit inside the receiver. A surface grinder works great. The trick is to check the thickness and grind a little and check again (repeat).

I have the rear trunnion finished except for the top groove needs to be widen.
Link Posted: 9/6/2005 8:14:04 AM EDT

Originally Posted By tapeo1:
Isn't the total difference between a 1mm shell and a 1.6mm shell equal to 0.6mm? Divide by 2 and you get 0.3mm for each side.



Like everyone who's built on the Global 1.6 it's .6mm shaved on both sides. Think about it and remember it's external difference is the same as a 1mm receiver. Internal difference is .6mm on right side and .6mm on left side hence need to shave .6mm on both sides. Have to shave the furniture, top rails, in my case the bolt carrier and widen the grooves. Built Tonka tough but I will never do it again. I'll stick with 1mm.
Link Posted: 9/6/2005 9:44:07 AM EDT

Originally Posted By Lakemoor:

Originally Posted By tapeo1:
Isn't the total difference between a 1mm shell and a 1.6mm shell equal to 0.6mm? Divide by 2 and you get 0.3mm for each side.



Like everyone who's built on the Global 1.6 it's .6mm shaved on both sides. Think about it and remember it's external difference is the same as a 1mm receiver. Internal difference is .6mm on right side and .6mm on left side hence need to shave .6mm on both sides. Have to shave the furniture, top rails, in my case the bolt carrier and widen the grooves. Built Tonka tough but I will never do it again. I'll stick with 1mm.



Thanks! I get it now... makes complete sense... I dunno what I was thing before
Link Posted: 9/8/2005 6:37:36 PM EDT
damn it!
all you guys just settle down out there! I,ve built 2 on these it's.018 to .023" per side depending on the trunnions original width. it can be cut by milling or surface grinding.
r1150r
Link Posted: 9/9/2005 1:18:52 PM EDT
Anybody have problems with the fit of the bolt carrier? Mine seems kinda tight....
The grooves are wide enough, but I noticed that the back of the receiver is a little pinched -
I'm guessing the rear 'trunnion' will hold it square, so I'm waiting for that to get shaved before I do anything about it.
And - You countersink the front trunnion holes to fit swell-neck rivets - correct ?
Link Posted: 9/9/2005 4:01:48 PM EDT
[Last Edit: 9/9/2005 4:03:11 PM EDT by motorcityman]

Originally Posted By 89Saleen:
I've had this receiver and the parts kit for almost three years now. I'm just recently finding time to build it.



You have had it that long, wow. When my receivers come in i cant seem to think of anything but them, lol. A receiver sitting in my safe along with a parts kit is like a Crack rock sitting in a crack heads pocket, you have more Will than me brother. I just dont know whats gonna happen when i order ten receivers next week for my up comming builds lol. McM
Link Posted: 9/9/2005 4:40:40 PM EDT

Originally Posted By nbjly:
Anybody have problems with the fit of the bolt carrier? Mine seems kinda tight....
The grooves are wide enough, but I noticed that the back of the receiver is a little pinched -
I'm guessing the rear 'trunnion' will hold it square, so I'm waiting for that to get shaved before I do anything about it.
And - You countersink the front trunnion holes to fit swell-neck rivets - correct ?



The top rails might need a little work, I believe the measurement is 25MM across. You may wind up filing a little to fit. The 1.6 receivers are thick enough that the swell neck rivets are not needed. After the metal is removed from the trunnions there is not much left of the of the divot on the trunnion anyway.
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