M1928 Thompson Receiver Production

[reconbob]

Hey all. Things have been a little slow here so I figured I post a couple

of photos of the receiver production line. These are 100% machined receivers

ready to assemble and shoot. This line has been set up and running

since April. Most of the operations are set up on a Mazak H400 horizontal

machining center with 6 pallets and a tool magazine with 90 tool capacity,

although we only need about 60 tools (many of which are custom made or

ground to our specifications) to make all models of the Thompson. Specialized

fixtures are mounted on the pallets. The steel blanks or receivers are put

in the fixtures which are automatically loaded into the machining compartment

when that particular program and fixture are run.

Shown is a photo of a M1928 receiver that has just had the bolt pocket and

H-lock machined. 16 tools and 17 programs are required to do this. 3 of the

tools are custom grinds, the rest are stock. The receiver is mounted in double

vises on a "tombstone". Being held on its side the chips from machining fall

away and do not clog or damage the cutters. The tombstone is rotated

into 3 different positions to machine the pocket, the H-locks, and the breech

entry fillet. The entire program wil run un-attended.

Back in the day if you had 17 operations you would have 17 machines and

17 operators, each machine set up for a specific cut with a specific tool. Today

you have one machine with multiple tools.

These receivers and the guns assembled on them using original parts

are every bit the quality, strength, fit, and finish of Savage Commercial guns

of the 1930's. Alas, we can only sell to PD's and Class 2, etc.

 

M1928 receiver on tombstone:

 

http://i51.photobucket.com/albums/f392/reconbob/IMG_1768.jpg

 

Closer view of M1928 receiver on tombstone:

 

http://i51.photobucket.com/albums/f392/reconbob/IMG_1769.jpg

 

Tool magazine (newspapers are to soak up coolant):

 

http://i51.photobucket.com/albums/f392/reconbob/IMG_1766.jpg

 

Turn table holding pallets and fixtures dedicated to Thompson receivers:

 

http://i51.photobucket.com/albums/f392/reconbob/IMG_1767.jpg

 

Finished M1928A1 on Philly O receiver:

 

http://i51.photobucket.com/albums/f392/reconbob/IMG_1052-2.jpg

 

 

Bob/Philly O

Edited January 18, 2011 by reconbob

[bug]

Wow. That is impressive.

 

Is there much hand finishing needed after removal from the work center?

 

Bob D

[atc310r]

Wow Bob thanks for finally posting some info on this operation! It's pretty cool to see the machines you use in production!

 

P.S. Can I pay a little extra to get a receiver with the bolt cavity milled out like the one in the pictures? HAHAHA How much crap does the BATF give you when you are a class II manufacturer?

[darrylta]

Great work Bob and all for less than $1,000 per full auto receiver.

Seeing this makes me think evil thoughts, shame on you. :-)

-Darryl

Edited January 18, 2011 by darrylta

[reconbob]

The receivers are deburred - filed and polished to remove the sharp

edges left by the cutting tools - by hand. To do a complete receiver requires

the receiver to be held in 6 different vises or fixtures on the machining

center, and deburring is required each time. Some people use vibratory

machines to deburr but we do it by hand because its a better job and preserves

the blanchard ground finish on the sides.

The extractor slot and the drum slot fillets, are done on separate CNC machines.

The H-lock side-shaping (the initial cuts leave small ridges on the sides of the bolt

pocket that have to be smoothed for the H-lock to function) is done on a manual

machine by hand using a custom ground tool.

 

Bob

[atc310r]

What tool do you use to do the extractor and drum slots exactly? I have always wondered how you make a square cut, and you charge an additional $50 for it in the receivers so it can't be that easy to do.....

[reconbob]

The drum slots can be done with keyway cuttters. The extractor slot

is done with a shaping tool. Shapers were much more common than milling

machines 100 years ago. A shaper uses a non-rotating tool which moves

back and forth (or up and down) across the surface to be machined peeling

away a thin chip with each pass.

The receiver is stood on end and the shaping tool is long enough to

pass all the way thru the front of the receiver down to the bolt pocket.

The tool moves up and down and indexes along the centerline of the cut

a little at a time shaving the steel and leaving a square notch that runs

all the way thru to the pocket.

It takes a while to do this, and its very difficult to set up, but fortunately

we have the set up on a machine that is used for nothing else. Those

machinists from the old days knew what they were doing - the cutting tool

we are currently using has done hundreds of receivers and shows no sign

of wear. It will probably (knock wood) last until it finally fatigues and breaks

as opposed to getting dull.

I mentioned in a previous post that Kahr has apparently given up on this

process as new receivers have a round hole for the extractor. They are

drilling a small hole for the extractor first, then drilling the larger barrel hole

to avoid this type of cut.

 

Bob

 

[atc310r]

Are you telling me Kahr is cutting corners in their products? That seems so hard to believe Bob! HAHAHAHA

 

So basically the Shaper is like a file, except it takes a bigger bite. Interesting, thanks for the information!

 

I'm guessing you use a 1-1/2 diameter 1/4 thick T-slot cutter (or something like it) to do most of the bolt cavity? Do you use M42 cobalt tools or do you go with something harder because of the volume of receivers you make?

 

I'm not sure if the receiver in the pictures is 100% done, but do you not bother making the 1/4in(?) cut underneath the triangular protrusion in front of the blish lock ramps? I wouldn't imagine this has any mechanical significance to the guns operation....

Edited January 18, 2011 by atc310r

[deerslayer]

Bob, that's a really interesting set of pictures and process, thanks for sharing. I'd love to sit there and watch it all work for a while, almost magic! You should make a video sometime. I doubt any movie type footage of thompsons being made exists from the 40's but wouldn't it be fascinating to follow a hunk of steel through its many machines, jigs and craftsmen and compare that same thing to what you can do today.

 

Funny to describe the "shaper" I recall sitting there with a special FILE making hundreds of back and forth passes before that $50 process was available....

 

OK, now you need to do this same thing for the BAR....did you notice what the BAR kit with the cut receiver sold for?

Dan

[reconbob]

A shaping tool is not like a file, it has only one cutting edge and curls up

one chip at a time. I don't recall exactly but I think it may take 90 passes

to make the cut - 60 for the rough cut, reposition, then another 30 to finsh.

You have a sharp eye - if you follow the contour of the "ceiling" of the

receiver you can see where it tapers a little narrower at the spot in front

of the H-lock cuts. I tried making this cut full width (approx 1.5") but was

never able to do it without breaking the cutter. So they way we do it, and

what you see is it tapering down to 1.25" for the area in front of the H-lock

cuts. The narrower cut does not affect anything - everything functions

properly. When they did this originally they must have made cutters with

thick shanks that would stand up to the heavy cut.

Dan - yes I have thought about a video and will be putting one - or

more - up on the website which is in the process of being redone, or

maybe I can post a youtube link here. The thing that is the most fun to

watch is the chip conveyor! The chips from machining fall into two troughs

at the bottom of the machine. There are archimedes screws which move

them to the end of the trough where they fall into a bottom drag conveyor

which conveys them along and up like an escalator where they fall into

a trash can. Unfortunately we still have to carry them to the dumpster.

 

 

Bob

[atc310r]

It must be a lot easier to finish the M1/M1A1 receivers since they require no under cutting. All you need to do to finish their bolt cavity is cut with an end mill then chamfer the receiver shank slot right? Edited January 18, 2011 by atc310r

[mnshooter]

A shaping tool is not like a file, it has only one cutting edge and curls up

one chip at a time. I don't recall exactly but I think it may take 90 passes

to make the cut - 60 for the rough cut, reposition, then another 30 to finsh.

You have a sharp eye - if you follow the contour of the "ceiling" of the

receiver you can see where it tapers a little narrower at the spot in front

of the H-lock cuts. I tried making this cut full width (approx 1.5") but was

never able to do it without breaking the cutter. So they way we do it, and

what you see is it tapering down to 1.25" for the area in front of the H-lock

cuts. The narrower cut does not affect anything - everything functions

properly. When they did this originally they must have made cutters with

thick shanks that would stand up to the heavy cut.

Dan - yes I have thought about a video and will be putting one - or

more - up on the website which is in the process of being redone, or

maybe I can post a youtube link here. The thing that is the most fun to

watch is the chip conveyor! The chips from machining fall into two troughs

at the bottom of the machine. There are archimedes screws which move

them to the end of the trough where they fall into a bottom drag conveyor

which conveys them along and up like an escalator where they fall into

a trash can. Unfortunately we still have to carry them to the dumpster.

 

 

Bob

 

When you say dumpster you do mean for recycling/selling the considerable scrap and not for the trash collector, don't you?

Great photos; thanks for posting. Really looking forward to seeing some video of the work in progress.

[fortyfivecal]

thanks for sharing the photos Bob. i work in a cnc machining shop, and often think about using our cnc machines for machining TSMG parts. as you know, just having he machine is only part of the picture, jigs/fixtures are often not considered, you can't work on the part without a repeatable means of holding it in a manner to allow the tool(s) to have access to the area in need of machining. jigs and fixtures require good old ingenuity, thanks for helping keep the tsmg's alive!

[reconbob]

The chips go in the dumpster and end up in a landfill. I think right now

scrap of this type is maybe $20-$30 a TON. It has no value. If we were machining

aluminum or brass different story.

And yes, the M1 bolt pocket is a simple pocket with no undercuts.

 

Bob

[GUNGUY45]

The chips go in the dumpster and end up in a landfill. I think right now

scrap of this type is maybe $20-$30 a TON. It has no value. If we were machining

aluminum or brass different story.

And yes, the M1 bolt pocket is a simple pocket with no undercuts.

 

Bob

 

+1, I work in a Pattern shop(think foundry), we PAY a recycling Co. to take our mixed steel scrap. The Aluminum, that's another story....

[2ndArmored]

Are you telling me Kahr is cutting corners in their products? That seems so hard to believe Bob! HAHAHAHA

 

Actually they're literally NOT cutting corners. That's part of the problem! :slap:

[Elbow]

Hey Bob, You ever think about making semi-auto receivers?? Or 14.5" barrels (oal 16" with comp)?? Thanks

[fortyfivecal]

Hey Bob, You ever think about making semi-auto receivers?? Or 14.5" barrels (oal 16" with comp)?? Thanks

 

elbow, how much interest do you think there would be in an intermediate tsmg barrel length, that would comply with NFA rules, yet when coupled with a standard compensator, would be shorter than the current carbine barrels?

 

i ask, because i'm about to market new manufacture tsmg barrels, G.I. toleranced chambers, so no issues of short chambers, and while the barrels are cnc machined, i've removed the cnc turn lines so they more closely resemble the originals. i'd considerd an intermediate barrel length, but i'm not sure if the market would support the effort, your thoughts?

[Elbow]

Hey Bob, You ever think about making semi-auto receivers?? Or 14.5" barrels (oal 16" with comp)?? Thanks

 

elbow, how much interest do you think there would be in an intermediate tsmg barrel length, that would comply with NFA rules, yet when coupled with a standard compensator, would be shorter than the current carbine barrels?

 

i ask, because i'm about to market new manufacture tsmg barrels, G.I. toleranced chambers, so no issues of short chambers, and while the barrels are cnc machined, i've removed the cnc turn lines so they more closely resemble the originals. i'd considerd an intermediate barrel length, but i'm not sure if the market would support the effort, your thoughts?

 

 

It's hard to say what the current market would be for 14 inch barrels because of the economy. However, nobody is currently making them. I would think some Thompson owners would like to have this option and would switch out the barrel heart beat. I do recall alot of people asking how to cut down the barrel and to have a working comp in the past, but there is no real easy option out there. I have cut mine down and reduced the barrel end and made a threaded ring for the comp, but I really don't trust it 100%. I think if word got out you could sell more than you may think. It's all in how you market something like this. I know I want one or two in the 1928 ribbed style.

[reconbob]

We (Phila Ord) do make West Hurley/Kahr pattern semi auto receivers

with the 1/10" step for the semi auto trigger frame. 80% machined receivers

are the same price as the standard full auto pattern recever we make -$295

for the basic receiver and options pertaining to the engraving, extractor slot,

and finish (parkerize or military blue) could add another $50-$175.

The 100% machined receiver for the WH/K pattern which is completely

finished and ready to asemble-and-shoot is $650. Both of these receivers

are 4140 steel with all of the precision machining, fit, and finish which we

are known for. The 100% machined receiver can only ship to FFL since it

is considered a firearm.

M1927A1 pattern 80% and 100% receivers are almost ready. Most of

the work is the same as the full auto receivers. I still need to finish scaling

the patent number block program so all 13 patent numbers can be engraved

on the side (as opposed to only 12 on the WH/K) and I have to figure out

the different actuator slot.

I also have 14.1" barrels in the works. I checked with the ATF and sale of a

short barrel is legal in itself, but if you install it on a rifle you must also

PERMANENTLY attach the compensator to bring you out to 16" or the gun is

classified as a short barreled rifle. The barrels I am making have the same

contour as an original GI barrel so you can use an original GI front grip. I

honestly do not know how many potential customers there are for such a

barrel, but since we are doing 10.5" barrels anyway, what the heck.

I have a lot going on here right now - lots of receivers and finished guns

to make, so I am not sure when the barrels will be ready. But .45cal is a good

man and it sounds like he is also on the case.

 

Bob/Philly O

 

 

[fortyfivecal]

Hey Bob, You ever think about making semi-auto receivers?? Or 14.5" barrels (oal 16" with comp)?? Thanks

 

elbow, how much interest do you think there would be in an intermediate tsmg barrel length, that would comply with NFA rules, yet when coupled with a standard compensator, would be shorter than the current carbine barrels?

 

i ask, because i'm about to market new manufacture tsmg barrels, G.I. toleranced chambers, so no issues of short chambers, and while the barrels are cnc machined, i've removed the cnc turn lines so they more closely resemble the originals. i'd considerd an intermediate barrel length, but i'm not sure if the market would support the effort, your thoughts?

 

 

It's hard to say what the current market would be for 14 inch barrels because of the economy. However, nobody is currently making them. I would think some Thompson owners would like to have this option and would switch out the barrel heart beat. I do recall alot of people asking how to cut down the barrel and to have a working comp in the past, but there is no real easy option out there. I have cut mine down and reduced the barrel end and made a threaded ring for the comp, but I really don't trust it 100%. I think if word got out you could sell more than you may think. It's all in how you market something like this. I know I want one or two in the 1928 ribbed style.

 

 

thanks for your input Elbow. you hit on where i am right now, how to market these barrels. i'm trying to offer an alternative to using original barrels, due to the increasing scarcity and cost related to limited supply. to, the new manufactured ones i've inspected had the chambers undersized, or mis-formed radius blend, which requires gun-smithing. i'll have to give the intermediate barrel more consideration.

 

again, thanks for your feedback.

 

Dave

[troll]

I would be interested in a 14"" with a comp to make it 16". I also always wanted to build up a semi with a "full sized" receiver with Blish cuts. I thought about having some sort of block to prevent a FA bolt from working, as required. Maybe cutting down the top of a FA bolt (around the actualtor) and using the FA firing pin with a striker rod (similar to the Kahr system) to get ignition. Of course I have no money or machine shop.

 

I will be looking for the M1927 receivers when they come out. Maybe you could offer a semi colt stamped barrled action that could use existing Kahr parts?

 

My gun, while reliable, has a lousy finish and off-center stampings.

 

I am sure that Kahr would be POed if "Thompson" was stamped on a firearm receiver.

[couchcommando]

ReconBob, I want to work for you. I would do it for no pay too. Just a receiver or 2, every now and then.

[cschultzy56@yahoo.com]

I know this topic is old but if you're still making receivers I work at a class II shop in Houston and we'd be interested in buying one from you. If you still have the ability to make them please PM me.

[reconbob]

Yes still making receivers and guns. I will send you the info.

 

Bob/Phila Ord