drilling 7mm hole in brass shell casing

[mapleman]

so, one wants to make a home-made cartridge pen. Okay - obstacles:
1. Getting the hole centered when no firing pin is centered;
2. Holding said casing still in a vice while drilling, without deforming the soft brass end;
3. Drilling the 7mm with.... a 7mm bit; and
4. Epoxying the brass tube in to be secure in new hole but centered and secure in the shoulder...

That's all

I have made one. And it was a monster. But I want to do more. I have many spent casings that I will probably never get re-loaded. SOOOOO - big question - where do you get a 7mm metal drill bit that is affordable? I have looked in several stores (even autmotive) and struck out. I did not think it would be so hard...

thanks, john

PS - if I am an idiot and it can be found and purchased easily, please smack me

[TDHofstetter]

Like this?

www.amazon.com/Speed-Steel-Jobber-Length-Drill/dp/B0006FI9PW/ref=sr_1_1?ie=UTF8&s=hi&qid=1269314831&sr=8-1

You may need to regrind the end to make it a little more suitable for brass. Brass wants to be drilled with a ZERO RAKE drill bit, ideally - one that scrapes instead of peeling. With care, it'll work with the unmodified bit, though.

Carbon steel is completely fine for drilling brass, as long as you're not drilling super-deep holes in super-thick material.

Brass likes to be drilled bone dry, no lubricant or coolant.

[Doug B]

John, you are experiencing all the issues I ran into making a cartridge pen using the real cartridge. That's why I opted to go with the Penn State pen kit that takes all those issues away. That kit makes it a very easy pen to make and a very nice looking one. And, if you want to, you can substitute your own cartridge portion of the kit and still use the other hardware components of the kit.

A lot of guys who use their own cartridges drill the primer pocket out on the lathe so that it is automatically centered. You need a collet for holding the casing to do that so it adds more cost to the process.

[monty]

The first thing to do is find a cartridge that has the bullet end the same size as or slightly larger than the nib of the pen kit you are planning to use. I use the nib from a slimline for a 287 cartridge and the nib from a designer pen for a 30-30, 30-06 or 300 mag.

Next, remove the spent primer. This is accomplished by using a very narrow punch and inserting it through the bullet end of the cartridge until it seats in the hole where the primer comes through. A few sharp raps with a hammer should drive the primer out.

*************************CAUTION*************************

Be very sure this is a spent primer, if it’s live this will result in a very serious consequences. If your not sure about this step, consult with someone that reloads shells or a gunsmith for advice.



Once the primer has been removed, you will find a nice recess where the primer was, to use for a starter hole to drill the hole for the tube. Next you should size the bullet end of the cartridge with the nib you will be using. The nib you select should be only slightly larger than the nib end of the cartridge. You can use it as is, but you will notice a slight ridge at this junction. To remedy this, I use a tapered punch or drift punch to ever so slightly, enlarge the hole. As you are doing this, be sure to check the size with calipers so you don’t over enlarge the hole. Once you’ve drilled the hole in the primer end and sized the nib end, you are ready to glue in the tube. Most cartridges will be longer than the longest tube supplied with the kit. You can try to take two tubes and make them meet and center in the cartridge, but you most likely will be disappointed with the results. Since both the slimline and the designer pen use 7mm tubes, you can purchase extra tubes that are 10 inches long and cut these slightly longer than the cartridge. The best way to hold the cartridge to drill the hole is to use a collett chuck and drill with your lathe.



The next problem you will encounter is that the nib end of the cartridge is larger in diameter than the 7mm tube. This will make it very difficult to keep the tube centered in the cartridge while the glue dries. One solution that was suggested, that I find works well, is to wrap the nib end of the tube with several layers of Teflon pipe tape. This works well to keep the tube centered. Another way would be to use a piece or two of heatshrink tubing to give a better fit.



The next question is what glue to use to glue the tubes in with. There are 3 to choose from; CA, epoxy and polyurethane glue (i.e. Gorilla glue). First off, I would rule CA out, as it will not make a strong bond between the brass. Epoxy will work well, but I prefer polyurethane glue. My reasoning is that since it expands as it cures, it will fill in the void inside the cartridge making a better bond. Once the glue is dry, you can cut/file the ends of the tube down to the casing.


If you want the look of an actual bullet, you can use a 30 caliber bullet for the nib. I use a FMJ hollow point. If you choose this method, you don't need nor want to flare the end of the cartridge as I told you earlier. To start, use a collet chuck to hold the bullet while you drill a 7mm hole from the back. Once you hit the lead, you should be able to pull it completely out leaving only the jacket. I now solder one end of the brass tube in the bullet, insert it and "set" it in the cartridge and solder the other end. Then carefully trim off any excess brass. You are now ready to press in the transmission to the proper depth.




When I turn the top end of the pen, I use the cartridge as a bushing so the joint will match up perfectly.



As I said in the beginning, I’m sure that there are more was to do this. If someone offers another way, I’m more than willing to try it, but so far I find that this method works well for me. And be willing to experiment, try different ways on your own. You’ll be surprised what you can come up with.

[Ruffnek]

One thing I learned is to drill a pilot hole with a twist drill bit and then go to the 7 mm. The twist drill is pointed so it stays centered in the cartridge and the hole is centered. Of course, I use new casings that already have a small hole for the primer but I think the same thing would apply to a fired cartridge.

For holding the casing, I stuck some 120 grit sandpaper on the jaws of a hand screw with spray adhesive. The sandpaper helps it get a grip with light pressure so that the casing doesn't distort.

I put a narrow wrap of tape around the end of the brass tube, where it goes into the narrow end of the cartridge. That keeps the end centered inside the cartridge while the CA glue solidifies. The other end is even with the butt end of the cartridge, also CA glued in place.

Finally, the 7mm bits can be ordered from any of the pen kit suppliers...Penn state Industries, CSUSA, Arizona Silhouette...etc.

Hope this helps.

[monty]

Mar 23, 2010 7:31:11 GMT -6 Ruffnek said:

...Of course, I use new casings that already have a small hole for the primer but I think the same thing would apply to a fired cartridge....

Once you remove the spent primer, you have the same hole. Or you can buy used casings with out the primer a little cheaper than new ones.

[Doug B]

That's some very good info guys. Someday I'm going to make my own, but just for my own self - that's a lot of work.

And, you did not mention the issues with drilling the actual bullet. That was another thing I never quite got right when I was trying to make a bullet pen using the casing and bullet.

I'm going to have to get into the right mood to do one of those, but I'm sure it will happen one of these days.

Thanks for all that info.

[monty]

Mar 23, 2010 20:31:28 GMT -6 Doug B said:

And, you did not mention the issues with drilling the actual bullet. That was another thing I never quite got right when I was trying to make a bullet pen using the casing and bullet.

If you (or anyone of you for that matter) make it to the Houston area, give me a shout and I'd be happy to do a demo of this for you.

[Doug B]

I'll definitely take you up on that if I ever get down that way Monty.

[mapleman]

Hey Tim, thanks for the link. I love it - $1.30 for the bit, $7 for shipping. I am trying to find a decent, affordable set so that I have a gost of sizes... But that "jobber" bit is a good start for me...

Doug,
The main reason I am stuck on making pens from real cartridges is b/c i have so many from my favorite rifle... if not for that, i probably would not go so crazy...

monty,
thanks for the great primer. you may need to repeat that for the tutorials section! The one that I made, I had the bit centered within a couple thou --- one can perceive the off-center when twisting, but not too much. Anyway, i made up a bunch of epoxy and pre-pressed the nib onto the brass and then epoxied it. it was wierd, cumbersome, and difficult. but it did work.

Cody,
Did you find that the sandpaper marked up the casings at all or was it so light that it buffed out?

thanks,
John

[Ruffnek]

Did you find that the sandpaper marked up the casings at all or was it so light that it buffed out?

As long as the casing isn't allowed to turn, any marks are negligible.