Mini MK2 Mod 1
#1
So, my lathe is getting close to being ready to make some chips and I think that this would be a good first project once I learn how to actually utilize the features of my lathe.

As an Explosive Ordnance Disposal (EOD) Technician we use a wide array of tools but the MK2 Mod 1 has been around almost since the beginning of EOD. During EOD school when I had the choice of what tool to use I found that for probably 90+ percent of all applications this little baby would do the trick and do it really well. Whether it was expose the contents of a paper bag or remove the end cap from a steel pipe bomb the .50 cal dearmer works wonders. Yes, it is officially known as a dearmer, which to me means that we made up our own word. But anyway, here are some pictures of the tool and then my hand drawing with dimensions.

My idea is to actually shrink this down to a .30 cal dearmer and use the 30-06 as the cartridge that would be inserted. "I have no plans of attempting to use this as an actual tool, it is for display purposes only." The reason that I want to use the 30-06 is that when John Moses Browning designed the .50 BMG for anti-aircraft use he realized that there was no need to reinvent the wheel and if the 30-06 worked really well (which it does) then a bigger version do really well also. Now, I'm going the other way because 30-06 brass for a display piece is readily available and inexpensive. The .50 BMG is more difficult to find and generally commands outrageous pricing. I am also doing the smaller version because the MK2 Mod 1 is quite large and heavy. Aluminum would make it lighter but for whatever reason I want to keep it in the carbon steel form.

The first picture is a 50% version made in aluminum sold by Bombs Away. I don't like it being in aluminum and I don't like Bombs Away so I'm not trying to advertise for them but it is a really fancy little kit.


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#2
So, my dad suggested that I start in aluminum because it wouldn't dull my tools while I learn. So I bought some 6061 and started trying to do some turning. Here is the result and the beginnings of an aluminum .30 cal dearmer.


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#3
After work I put some more time in on the lathe after watching some more of TomG's videos. I got almost .25" off the diameter of the stock so I really feel like I have accomplished something Thumbsup According to my calculations my final OD will be 1.2" with a total length of (IIRC) 4.35"

I will have to check the drawing but it is hung up next to the lathe for reference. I probably should have made a copy rather than using the original Rotfl

For those that are watching thanks for watching and I really feel like this thing will take shape this weekend. Maybe not completed but look like the final product externally.


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#4
Ain't it cool watching a part start to take shape. Toms videos are an amazing resource for guys like us, lots of enthusiasm without a ton of experience. Keep the photos coming as you make progress. Is that aluminum your turning? If so the finish could be a bit better, show a picture of the bit setup and I bet you get some good advice and a better finish.

Shawn
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#5
It IS aluminum and I'm sure I could but I don't have a grinder ATM so I'm working off what the lathe came with. I got 12' of 3/8" square steel to practice shaping my own tools. Just need to get the grinder. Then I'm sure that finish will be a lot better!
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#6
12 FEET of 3/8" square steel? Is it just mild steel?
That may not be the best material to practice on but it'll sure heat up and burn your fingers like HSS can. Rotfl

As important as the grinder is the wheel for HSS is equally important, don't expect to grind HSS well with the "round paving stones" that come with the grinder. I'm using a Norton Aluminum Oxide 60 grit wheel.
60 grit sounds coarse but it doesn't feel coarse and produces a nice finish on the HSS tool.
Busy Bee 12-36 lathe, Busy Bee Mill drill, Busy Bee 4x6 bandsaw, Homemade 9x17 bandsaw, Ad infinitum.
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#7
It's "cold rolled" but yes I'm pretty sure it's just mild steel. TomG recommended practicing with cheap steel to get the angles and stuff down since HSS is a lot more expensive. I think he says that he uses 60 grit. The ones I was looking at have a 60 grit stone on them. TomG's video says he uses a 60 and a 100.
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#8
(02-26-2014, 08:21 AM)SnailPowered Wrote: The ones I was looking at have a 60 grit stone on them. TomG's video says he uses a 60 and a 100.

I somehow doubt if the grinders your looking at have Aluminum Oxide wheels. If they do, your good to go, but don't load'em up with cold rolled steel.
Busy Bee 12-36 lathe, Busy Bee Mill drill, Busy Bee 4x6 bandsaw, Homemade 9x17 bandsaw, Ad infinitum.
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#9
Yeah, I doubt they are aluminum oxide but they said 60 grit. I figured I would use the wheels that came with it for practice then get good wheels. I will take some pictures of the turning tool I'm currently using.


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#10
get yourself a fine and coarse stone from someplace like Norton, and a STONE DRESSER, and I don't think that there are aluminum oxide stones on Tom's grinder.
dallen, proud to be a member of MetalworkingFun Forum since Apr 2012.

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