Form 1 M2 Mortar Build

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propeine
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Form 1 M2 Mortar Build

Post by propeine »

This is going to be a very long running thread but last month or maybe it was march, I filed for a 60mm mortar. It will NOT be authentic due to cost but it will be as true to form as I can get while managing to keep buying vs machining in check. I have amassed enough drawings/info from other owners to turn the tube and cup to spec. The bipod assembly and baseplate I have less info on but I probably have enough to make a functional albeit not exact replica. I like to think that 70 years ago when my lathe was made there was a man or woman doing the same thing to aid the war effort. Not likely but it is a cool thought.

Since the cup is not an NFA firearm until there is a tube attached I opted to start there while I waited for my form 1 to process. Yesterday in the mail I received a 6.25" x 3.5" diameter chunk of 4140 Q&T. Then the problems started. My chuck is evidently only big enough to hold 3" on the OD. I thought the jaws were reversible but they are not. I make suppressors normally. Not big things. So what to do...well I have a drill press and some Starett layout tools. Mark the centers on both ends, mark an offset hole inside the 3" mark so I can make a section fit the chuck, drive in a dowel pin in the offset hole. Turn a sacrificial dead center in my head stock and mount the whole thing between centers. Mind you I've never done any of this but it seemed like as good a plan as any. I rang my step dad who was a machinist for 35 years (and recently handed down his kennedy boxes full of awesome things since he's retired) and he confirmed that my game plan was sound.

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By the end of the night I had spent way more time than intended getting the OD to my specification of 3.156. At 10 minutes per pass (100ish rpm, .006 IPR, .050 DOC) there is a lot of standing around. The first 4 passes were light to get everything concentric and it rattled like a sum'bitch from the interrupted cut and my drive pin engaging/disengaging. Any faster RPM's even with good brazed carbide and chips turned stringy and dangerous. More DOC or IPR and I'd stall my drive belt which is intentionally set kind of light to keep from breaking parts.
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T-Rex
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Re: Form 1 M2 Mortar Build

Post by T-Rex »

I'm bookmarking this, keep it going.
I'd love to make a mortar.
I've seen how you can make rounds from the Al Bud Light bottles, filled with concrete.
Completed Builds www.silencertalk.com/forum/viewtopic.php?t=79895
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Tony M.
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Location: FL

Re: Form 1 M2 Mortar Build

Post by Tony M. »

Looking forward to following this one!

I've been thinking about a Mortar for a while, I've got a couple of black powder Coehorn mortars, but a modern(ish) mortar would be a lot of fun!
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Capt. Link.
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Re: Form 1 M2 Mortar Build

Post by Capt. Link. »

If this is not exciting news I just don't know what is. :D :D :D :D :D :D :D :D :D
The only reason after 243 years the government now wants to disarm you is they intend to do something you would shoot them for!
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=79895
propeine
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Re: Form 1 M2 Mortar Build

Post by propeine »

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Time for bed but this is where I'm at. Right hand side OD is to size. I was going turn the left hand side down to a cylinder at 1.775 (size of the ball) but decided the extra steel would help while opening up the inside. Roughing out the bore first to 1.625 depth and minor diam for 2 27/32-12 threads. Do finish work on the bottom of the bore and spot the firing pin hole from the inside.

Yes surface finish is s--t on the left. Its still got a lot to be roughed out and running in back gear all the time lets me move more material faster.
propeine
Silent But Deadly
Posts: 385
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Re: Form 1 M2 Mortar Build

Post by propeine »

So I may have accidentally clicked buy it now on this...
Mortar 60 mm Parts WW2 | eBay

Also parts are being cut for my base plate next week. Thanks to some measurements from others and the power of 3d CAD the only purchased part his the hemispherical cup and some hardware for the swing

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Uses this hollow hemisfphere for the receiver portion...$1.77
http://www.kingmetals.com/Catalog/ItemC ... =208&NSM=Y
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