Gunsmithing Can't find a long enough boring bar for a good price. Or deep hole, small diameter boring. ?

[TresMon]

Ok,
I've gone to work for a nice doctor and friend that has a small class 3 gunsmithing business on the side. He's designed & ordered a bunch of CNC'd monocore suppressor baffles in a kinda generic size, that I'm supposed to open the exit hole up for various calibers, etc. They come from the CNC shop with a .25" exit hole.

Now we have orders for two 45 cal suppressors. I made an extended shank for a 15/32" drill (.469") and drilled through all the baffles and the end of the core. (He wants a .5" exit hole.)

I have over 15 years experience as a full time machinist...but every solution I have thought up- he doesn't have the tooling. And an extra long length boring bar that will work is special order and over $300. His business is just as much for fun as profit, with his medical practice keeping the class 3 biz afloat. He's not into paying a lot for tooling.

Within these parameters... about all I've came up with is to buy a length of 7/16" dia. pre-hardened and ground drill rod ($24) & tack-weld a small square HSS lathe bit 90 degrees on the end and grinding it to cutting shape. I'm thinking thats the most rigid boring bar I can come up with on the cheap.

Any other ideas? If memory serves, the core is 10" long.

Thanks!

 

[...]

ream it?

https://www.mscdirect.com/product/details/02341451

 

[TresMon]

Good thinking thanks. That reamer is too short.

 

[...]

just found a longer one....about the longest i can find

https://www.grainger.com/product/GRAINGER-APPROVED-1-2-Chucking-Reamer-11V391

you could always ream one side, flip, then ream the second


you can also do the same thing with a 3/8 boring bar

http://www.shars.com/products/indexable-cutting/boring-bar/3-8-sclcr-indexable-boring-bar

i think youll run into a lot of flexing if you try to make a 10-12" boring bar thatll fit in a 1/2 in hole

 

[fdkay]

Work slowly and incrementally with this (I would get a couple of smaller ones):
https://www.ebay.com/itm/1-2-Aircra...2-Long-M7-HSS-Lifetime-Warranty-/181767293356

 

[DAVETOOLEY]

Chucking reamer and extend the shank if needed. I've done it many times.

 

[GH41]

Work slowly and incrementally with this (I would get a couple of smaller ones):

Please say your kidding. He's probably already screwed the pooch by drilling it the first time.

 

[fdkay]

Please say your kidding. He's probably already screwed the pooch by drilling it the first time.

It came "pre-drilled" , if you do it carefully, it will follow the pre-existing hole.

 

[CaptNemo]

It came "pre-drilled" , if you do it carefully, it will follow the pre-existing hole.

Or use a piloted reamer.

 

[diverdon]

Wire EDM. If it is his hobby price should be no object.

 

[TresMon]

Chucking reamer and extend the shank if needed. I've done it many times.

I have been thinking along those lines. Or a piloted counterbore....and machining an extra long pilot.... Thanks.

 

[TresMon]

Wire EDM. If it is his hobby price should be no object.

Nice, but I think a plunge (sinker) EDM is more handy for gun work.

 

[JMcBurn]

https://www.alvordpolk.com/special_tools/special_coredrills_2.asp

custom drill with a pilot?

 

[TresMon]

https://www.alvordpolk.com/special_tools/special_coredrills_2.asp

custom drill with a pilot?

It;s a good thought thanks!