Hard metal ?

[tnixon44]

Trying to drill part no.67 for BRP firing pin....Not having any luck with it been through two drill bits running press around 900 rpm w/cutting fluid any Ideas out there ??? One of the bits is a dewalt cobalt bit....



Thanks, Tom

[tomcatshaas]

try carbide

[oakrodent]

You have to use a straight flute carbide drill bit, nice and slow with lots of cutting fluid, and make sure you clean the chips out of the flutes. Not only are these drill bits very expensive, they like to brake if they get jammed up

[Shift1]

I used a carbide center cutting four flute end mill when I did mine

[tnixon44]

What size straight flute did you use?
Thanks, Tom

[Lima]

I found I could drill a small pilot hole with a very small end mill (like a dentist would use on a cavity). Nursed the rest with various drill bits. Worked it from both ends. Metal seemed a bit softer once it started cutting. Was a PITA for sure.

Anyone try and aneal it before cutting then harden later?

[oakrodent]

3/16 straight flute carbide McMaster Carr has them $19.87 p/n 8882A19 I hope this helps

[tnixon44]

Thanks all for the reply's!!! This is only my second build...I thought an Mp5 was tough...

Thanks, Tom

[tomcatshaas]

same thing for the hole in the buffer screw. Use carbide.

[tnixon44]

Tomcat,Guess thats the next question ...What size did you use for the buffer hole
Tom

[tomcatshaas]

Tomcat,Guess thats the next question ...What size did you use for the buffer hole
Tom

1/4"

[GMONEY]

Heat with Mapp Gas Torch to bright orange then drill from the opposite side of the hole. When done re heat treat piece.

[USNmars]

here is my ghetto way of doing it. I did 3 so far. Go and get a masonry bit, yup a tiny masonry bit. I put the part in my vise on my drill press and put the drill on its lowest speed. Using no cutting fluid it chewed right through it. I found if i used cutting fluid, it wouldn't do anything. Slow and steady gets it done. They are effortless to drill with a masonry bit.

[mgfun]

Wow. A masonry bit. That is so interesting. I would have never even thought about that. That's a little tidbit that can be used some day, somewhere.

Regards,
mgfun

[oakrodent]

Really a masonry bit ? ? Heat with Mapp Gas Torch to bright orange then drill from the opposite side of the hole. When done re heat treat piece. ? ? Come on guys. If you are going to put one of these together, it's is going to cost you a little scratch. Buy the carbide bit, better make it two, because if you never used one, bet you brake the first one as soon as you get too many chips in it. I bet you also try to reuse the ratchet plate, that should really make it look like a Gomer Pile put together.

Seriously, The MG-42 can really hurt you if you assemble it incorrectly or try to cut corners. This is a build where the " Devil is in the details" and if your are careful and do a good job on it it should turn out correctly. Once together and it is running, they are a blast to shoot, but still you need to know what your doing or you can have a VERY BAD DAY.
Just my two cents

[Matt]

natural selection at work