37mm anti tank gun build....non-DD

Demilitarized vehicle weapons and static display accessories
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Andy Cole
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Re: 37mm anti tank gun build....non-DD

Post by Andy Cole » Mon Dec 19, 2016 3:50 pm

Here are some pics of the work done today on the trunnion plates.
I was able to make the bosses. Originally they were cast in to the recoil buffer tube. Mine are 1 inch wide, half inch thick plate, which is cut to fit inside a piece of channel iron. The channel is welded to a the trunnion plate.

I tack welded the the plate into the channel so that it would not move during drilling. I drilled and tapped three 1/2 inch holes in each side. I also drilled 1/4 holes for alignment pins. Those alignment pins were welded in solid from the back.

The bosses were the placed in the appropriate spots, and multiple pass welded. 1/2 inch grade 8 bolts hold everything in place.

I still have to machine the actual trunnions, which will be inserted into holes yet to be drilled into the plates and then solidly welded. I've yet to decide If I'll round over the tops of the pates before or after drilling for the trunnion.

Of course everything will get a good polish to remove the scale etc before painting.

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1943 Willys MB285433 D.O.D. 12-3-1943
1951 M100 trailer D.O.D. 3/51
1951 M37 Truck D.O.D. 5-28-1951
M3 37MM ATG
M3A4 Hand Cart
Wife D.O.Delivery 7-21-1979
Boy D.O.Delivery. 2-15-2007
Girl D.O.Delivery. 4-9-2009
Girl D.O.Delivery. 10-23-2012


Andy Cole
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Re: 37mm anti tank gun build....non-DD

Post by Andy Cole » Tue Dec 20, 2016 10:52 am

Got trunnion plates heated and bent today. Put the barrel blank in for perspective.

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1943 Willys MB285433 D.O.D. 12-3-1943
1951 M100 trailer D.O.D. 3/51
1951 M37 Truck D.O.D. 5-28-1951
M3 37MM ATG
M3A4 Hand Cart
Wife D.O.Delivery 7-21-1979
Boy D.O.Delivery. 2-15-2007
Girl D.O.Delivery. 4-9-2009
Girl D.O.Delivery. 10-23-2012

mmamajor
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Re: 37mm anti tank gun build....non-DD

Post by mmamajor » Tue Dec 20, 2016 11:10 am

This has been a very exciting thread to watch since day one...Great job!
42 GPW 19671 5-18-42 Louisville
42 GPW 53244 7-28-42 Dearborn
43 GPW 116885 5-18-43 Louisville # 20388364
43 GPW 124588 6-28-43 Dallas # 20386887
44 GPW 184360
M-1 Bomb lift
M-5 Bomb Trailer

Andy Cole
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Re: 37mm anti tank gun build....non-DD

Post by Andy Cole » Wed Dec 21, 2016 12:14 pm

I turned the actual trunnions today. The left one has the extended stud that is milled for a key. It is also threaded for a nut to hold the sight bracket.

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Next I installed the trunnions into the trunnion plates. Fortunately I had a punch to match the diameter of the trunnions. The holes were tight so I had to press them in. I will weld them in solid from the back later.

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I don't have the trunnion caps machined or threaded, but I got the recoil buffer and sleigh set in it for a photo shoot.

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The rest of the pics are just because this the first time that it has been outside of the shop.

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More later.
1943 Willys MB285433 D.O.D. 12-3-1943
1951 M100 trailer D.O.D. 3/51
1951 M37 Truck D.O.D. 5-28-1951
M3 37MM ATG
M3A4 Hand Cart
Wife D.O.Delivery 7-21-1979
Boy D.O.Delivery. 2-15-2007
Girl D.O.Delivery. 4-9-2009
Girl D.O.Delivery. 10-23-2012

Andy Cole
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Re: 37mm anti tank gun build....non-DD

Post by Andy Cole » Fri Jan 13, 2017 4:29 pm

I got around to making the shield/guard support and shield.

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It's just held on by "C" clamp now. I still have to make the boss and bracket.

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Last edited by Andy Cole on Mon Jan 23, 2017 1:20 pm, edited 1 time in total.
1943 Willys MB285433 D.O.D. 12-3-1943
1951 M100 trailer D.O.D. 3/51
1951 M37 Truck D.O.D. 5-28-1951
M3 37MM ATG
M3A4 Hand Cart
Wife D.O.Delivery 7-21-1979
Boy D.O.Delivery. 2-15-2007
Girl D.O.Delivery. 4-9-2009
Girl D.O.Delivery. 10-23-2012

Bill, Idaho
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Re: 37mm anti tank gun build....non-DD

Post by Bill, Idaho » Sat Jan 14, 2017 5:01 am

This gets more impressive with every picture!

Andy Cole
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Re: 37mm anti tank gun build....non-DD

Post by Andy Cole » Sat Jan 14, 2017 7:16 pm

Thanks for all of the compliments! I hope that people are not getting tired of pics or updates. At this point it is a labor of love. I work on it when I can. I just want it to be as good of a representation of the original as I can get. Hopefully 90% of the population will think it's original. When I take it apart for final welding and prep for paint I am going to stamp random numbers on all the parts to look more like part numbers etc. I don't have a way of adding exterior casting numbers, so that will be the best I can do.
1943 Willys MB285433 D.O.D. 12-3-1943
1951 M100 trailer D.O.D. 3/51
1951 M37 Truck D.O.D. 5-28-1951
M3 37MM ATG
M3A4 Hand Cart
Wife D.O.Delivery 7-21-1979
Boy D.O.Delivery. 2-15-2007
Girl D.O.Delivery. 4-9-2009
Girl D.O.Delivery. 10-23-2012

Andy Cole
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Posts: 474
Joined: Wed Dec 24, 2008 6:36 am
Location: North Carolina

Re: 37mm anti tank gun build....non-DD

Post by Andy Cole » Thu Jan 19, 2017 2:53 pm

Continuing with the parts that no one will ever see or appreciate. This travel lock-lock was one of the more frustrating parts I've built for this in a while.
Basically I had to make a large hook that is welded to the bottom of the buffer tube. That was easy. Then the travel lock. I made the sheet metal parts of that a few weeks ago and it was not that bad. Machining the actual spring loaded plunger components was not bad. Today was the actual lock that holds the barrel when traveling. I did not have blueprints for this part, so I spent a lot of time looking at photos or originals, and measuring the parts I had and building to fit. Aggravating work. I can't claim that these are 75% accurate, much less 100%, but it works. And like I said...no one is going to lay on the ground and see if these parts are are interchangeable with the originals.
Details; details.....that's where the Devil is right?

Anyway, I hope ya'll are not getting tired of all the pics.

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Here's a short video of how smooth it unlatches the barrel.

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1943 Willys MB285433 D.O.D. 12-3-1943
1951 M100 trailer D.O.D. 3/51
1951 M37 Truck D.O.D. 5-28-1951
M3 37MM ATG
M3A4 Hand Cart
Wife D.O.Delivery 7-21-1979
Boy D.O.Delivery. 2-15-2007
Girl D.O.Delivery. 4-9-2009
Girl D.O.Delivery. 10-23-2012

Jayhawkmickey
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Re: 37mm anti tank gun build....non-DD

Post by Jayhawkmickey » Sun Jan 22, 2017 1:54 pm

Keep em coming. It's giving me encouragement to start my 57mm ATG this spring. I don't have a cnc plasma cutter but I'm thinking of outsourcing it to a nearby shop. What program do you load the drawings into for the computer?
1943 Willys mb,
WWII First Infantry Recon re-enactor,
WWII pigeon equipment collector.

Andy Cole
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Re: 37mm anti tank gun build....non-DD

Post by Andy Cole » Sun Jan 22, 2017 2:55 pm

I have access to a plasma cutting system called "plasmacam"
As far as systems go it is starter quality, but does a ton of functions. It has its own program. Super easy to learn and is Windows based. I bought a CD with microfilmed 37mm blueprints. It is real easy to import drawings. Then you have to basically redraw the part over top of the imported drawing, then delete the old one.

Using the dimensions on the blue print you can then scale it to full size. The table and system that I can use will cut up to 4' wide and 12' long. The table is only 4'x4'
So for longer pieces you have to index it through. The table is rated to hold up to 1" thick, unfortunately the actual plasma cutter wired to it maxes out at cutting 1/2". It does a real good job on 3/8" or less. The heaviest I've had to cut for this project is 1/4". Does super with that.
When you start your 57mm please post pictures! If I can help feel free to let me know. I've got two years of build problem solving experience.

I hope to be able to debut pics of the elevation mechanism tomorrow or the next day.
1943 Willys MB285433 D.O.D. 12-3-1943
1951 M100 trailer D.O.D. 3/51
1951 M37 Truck D.O.D. 5-28-1951
M3 37MM ATG
M3A4 Hand Cart
Wife D.O.Delivery 7-21-1979
Boy D.O.Delivery. 2-15-2007
Girl D.O.Delivery. 4-9-2009
Girl D.O.Delivery. 10-23-2012

Andy Cole
Sergeant Major of the Gee
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Posts: 474
Joined: Wed Dec 24, 2008 6:36 am
Location: North Carolina

Re: 37mm anti tank gun build....non-DD

Post by Andy Cole » Mon Jan 23, 2017 1:37 pm

Here is my abberation of an elevation mechanism. It is a highly modified screw type bottle jack. I think after this I'm about ready to take a break again. My patience is running low. However, I've got it mounted, and it does work.
I made the jack a "stubby" jack. It will lift a little over 5 inches now. Three inches of lift will put the bore horizontal. The additional two inches will depress the muzzle quite a bit. I've not actually checked the degrees of elevation +/- yet.
I'm working on the the other side now, but I'm having a hard time coming up with a viable linkage over to an elevation wheel.

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1943 Willys MB285433 D.O.D. 12-3-1943
1951 M100 trailer D.O.D. 3/51
1951 M37 Truck D.O.D. 5-28-1951
M3 37MM ATG
M3A4 Hand Cart
Wife D.O.Delivery 7-21-1979
Boy D.O.Delivery. 2-15-2007
Girl D.O.Delivery. 4-9-2009
Girl D.O.Delivery. 10-23-2012

Bill, Idaho
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Re: 37mm anti tank gun build....non-DD

Post by Bill, Idaho » Tue Jan 24, 2017 4:59 am

Kind Sir:
PLEASE pace yourself and don't get "burned out"! You have literally a world class masterpiece in the works. As I've said before, I built a drag racing "Funnybike" from the ground up, essentially doing what you are doing here. I personally understand the frustrations and gratification during the process. Thank you for taking on such a project.

It shows character, talent, and initiative.

Andy Cole
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Re: 37mm anti tank gun build....non-DD

Post by Andy Cole » Wed Jan 25, 2017 3:10 pm

In order to maintain progress, I chose to do some mindless fabrication today.

I've been looking online for a while for 6 inch diameter hand wheels. I've had no luck finding one like I wanted, so I decided to make one.

It's not perfect, but it looks closer than any I could find online...... Cheaper too.... If you don't count time.
37mm traverse wheel rod.jpg
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37mm traverse wheel bent rod.jpg
37mm traverse wheel bent rod.jpg (199.09 KiB) Viewed 1529 times
37mm traverse wheel ring and parts.jpg
37mm traverse wheel ring and parts.jpg (246.88 KiB) Viewed 1529 times
37mm traverse wheel.jpg
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Last edited by Andy Cole on Mon Jul 24, 2017 12:13 pm, edited 1 time in total.
1943 Willys MB285433 D.O.D. 12-3-1943
1951 M100 trailer D.O.D. 3/51
1951 M37 Truck D.O.D. 5-28-1951
M3 37MM ATG
M3A4 Hand Cart
Wife D.O.Delivery 7-21-1979
Boy D.O.Delivery. 2-15-2007
Girl D.O.Delivery. 4-9-2009
Girl D.O.Delivery. 10-23-2012

NZM305
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Re: 37mm anti tank gun build....non-DD

Post by NZM305 » Wed Jan 25, 2017 8:18 pm

Looks good Andy :D

Andy Cole
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Re: 37mm anti tank gun build....non-DD

Post by Andy Cole » Thu Jan 26, 2017 5:07 pm

Since I was in the knob making mood, I decided to make an attempt at the elevation knob. I can't find one of those either.
So here is how I decided to fabricate this cupped and scalloped knob. I had to get creative. It was made from 4 different pieces.
37mm elevation knob 1.jpg
37mm elevation knob 1.jpg (254.27 KiB) Viewed 1529 times
I stacked the two scalloped pieces, and tacked the edges. I intentionally left the inside in a stair step so that the cone would be able to fit better and be supported. The circular piece was hammered into a cone over the horn of an anvil. I didn't know how much to cut out for the overlap so I cut it out and welded the seam when It was the way I liked it.
37mm elevation knob 2.jpg
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37mm elevation knob 3.jpg
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After centering the cone in the scalloped pieces I welded the bottoms together. The entire thing was placed over a piece of 1.5 inch cold rolled for a mandrel and secured into the vice. I got so excited that it actually worked, that I forgot to take pictures, but what I did was heat the cone with an oxyacetylene torch and hammered it down. The excess was cut off, and the three edges were welded solid.
37mm elevation knob 4.jpg
37mm elevation knob 4.jpg (208.66 KiB) Viewed 1529 times
The piece of cold rolled was cut to length and center bored on the lathe. A 1/4 inch Key slot was cut in the back end. The hub was then welded in...then the grinding began! There is a bit of weld bead left in the cone. I plan to try and chuck the rear of the hub into the lathe and turn the inside a bit and hopefully get rid of that. If not it should be hidden under the firing plunger.

The blueprint says that it would have been made out of malleable cast iron. That gives me a little freedom to leave some of the pores and pits from my work. Hopefully once it is painted it will look like solid cast.
37mm elevation knob 5.jpg
37mm elevation knob 5.jpg (152.34 KiB) Viewed 1529 times


More later.

Andy
Last edited by Andy Cole on Mon Jul 24, 2017 12:25 pm, edited 3 times in total.
1943 Willys MB285433 D.O.D. 12-3-1943
1951 M100 trailer D.O.D. 3/51
1951 M37 Truck D.O.D. 5-28-1951
M3 37MM ATG
M3A4 Hand Cart
Wife D.O.Delivery 7-21-1979
Boy D.O.Delivery. 2-15-2007
Girl D.O.Delivery. 4-9-2009
Girl D.O.Delivery. 10-23-2012


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