Anyone recognize this type of reamer? It was found in a tool chest with a lot of gun related stuff.
The number is 19183-110 and there seems to be a tradmark "M" in the middle. About 6" long?

Looks like it might be a necking reamer

Looks like a counterbore or step reamer to me. Used to make a countersink for a cap screw head to sit below the surface.

dave

I think Dave is right, your pics aren't quite sharp enough to tell but it looks a LOT like some aircraft counterbores in my box except yours is slightly shorter.
Regards, Joe

Hard to see, but I agree with ssdave and JD

As I read the markings it is not marked "9183 - 110 but is marked "19183-110".

My assumption is it is a step-down counterbore reamer intended for making a hole for a machine screw measuring .191 +" at the end of the hole for the head of the screw, and .110" at the major thread diameter end of the hole.

I would assume also that it is virtually zero tolerance at the thread end to better align the screw with the hole it threads into in a second piece of metal (a "base" piece), to prevent cross-threading due to any potential "cocking" of the screw in the hole in the piece this reamer was used on..

If you "mic"ed it for cutting area diameters you could learn if those assumptions are right or wrong.

But then, without an actual eyeballing of it, it could be anything.

Thanks AC, you are correct, I had the number wrong. I will measure it this week and see if that works but I think it's too large to be .110.

quote:

Originally posted by Recoil Rob:
Thanks AC, you are correct, I had the number wrong. I will measure it this week and see if that works but I think it's too large to be .110.

You are welcome Rob. If it is not larger than .125" it may not be for zero clearance as I guessed, but might still be for a .110" diameter threaded end of a machine screw.

Actually I suspect it is for some standard numbered screw...like a Number 10 or a number 12, but all my machinists' books are still tucked away from the move, and I don't have any of those screws unpacked to mic the diameters of them, either.

Hope you can figure it out. I always hate to have reamers lying around in good shape that I don't know what I can use them for....

I guess you do too, or you wouldn't have cared enough to ask us AR-freaks.

quote:

Originally posted by Alberta Canuck:
I always hate to have reamers lying around in good shape that I don't know what I can use them for....

I have a drawer full, I once bought the remaining stock of cutters from a defunct industrial supply store and I don't even own a milling machine!

Want some of 'em? I have a few left that I'll never use.
Regards, Joe

Ordinarily Joe, I'd leap at that offer!!

Now that we are moved into this tiny crypt they call a house down here in the "greater" Phoenix area, I don't have a mill, or a lathe I could even hang a milling attachment onto, anymore. Makes me want to shreik in agony every time I walk into the shop and see a couple of dozen as yet unthreaded and unchambered barrel blanks sitting there, along with a wheeled multi-drawer tool chest full of chamber reamers...and another one full of high quality masuring devices. There are even several still brand new actions in my vault waiting to be fitted up for their fair share of trips to the woods and hills.

So, thanks very much, but will have to pass. More good tools and no way to use them would just make things more bleak.

Boy, do I miss actually being able to make useful things with my own hands....!!!!