View Full Version : Best source for really small boring bars?

09-30-2006, 06:57 PM
I usually get stuff from ENCO, but I can't seem to find a boring bar that's smaller than 1/4". Are there any discount sources for a smaller bar?

Thanks for the help.


09-30-2006, 07:03 PM
Make one.......

09-30-2006, 07:11 PM
... from a drill bit.

09-30-2006, 07:18 PM
Serce - -
A drill blank is a fine start.
An endmill is even ready to go.

because carbide's modulus of elasticity is so high, I might suggest that you learn how to cut a boring facet on a carbide drill blank.

HSS practical limit is 5 or 6 diameters deep, but carbide will do 10, 11, 12 diam's deep.

Example: A 3/32 drill blank with a boring facet ground on the end will do holes of ~ 0.095" dia up.

Hth Ag

Tin Falcon
09-30-2006, 07:37 PM
1) To purchase try MSC not discount but good selection.

2) other options for making one besides the good ones already mentioned. Grind one from a HSS tool bit or turn one from drill rod heat treat with a small torch and oil and grind finished shape

kind of like a dis.....


the HSS one i picked up at a local frea market. A box of bits for a couple bucks a few years back. The round one I made from drill rod.
Falcon Tin

10-01-2006, 06:19 AM
Tin Falcon was nice enough to help the new guy, Evan and wolf were being
flippant , read between the lines, 4 posts enco primary place he bought stuff. He was a new guy and you guys offered no help. Behavior like that makes some new guys continue to lurk,, who want's be put off like when asking a honest question . allen

10-01-2006, 06:46 AM
He is on a HSM site, this is a basic tool,He should learn how ro make one.

Most New guys are like flies here.
Alguy,I see you are quick to critisize your forum elders, but offered no help to the newby.

Peter N
10-01-2006, 07:44 AM
Have a look on the J & L industrial supply site, I'm pretty sure thay have micro boring bars in the catalogue somewhere there.
Probably won't be discounted though.


10-01-2006, 07:55 AM
Tin Falcon was nice enough to help the new guy, Evan and wolf were being
flippant , read between the lines, 4 posts enco primary place he bought stuff. He was a new guy and you guys offered no help. Behavior like that makes some new guys continue to lurk,, who want's be put off like when asking a honest question . allen

Quite right. This is a HSM site, and should be a place where newcomers should feel comfortable to ask advice and very basic questions, and be encouraged rather than blown off.

Instead replies like "Make one...from a drill bit" I suggest offering advice on how to do it, or at least a photo of such a cutter.

10-01-2006, 08:09 AM
Travers Tool Co. www.travers.com used to sell weeny boring bars...they probably still do....

I've generally found Travers to be a little cheaper than MSC www.mscdirect.com

Scrap Master
10-01-2006, 08:47 AM
Thinbit is excellent...the mini bores are nice.


10-01-2006, 09:38 AM
The "make one ... from a drill bit" conveyed the right message but may have been better in one sentence ;)

A broken center drill can also make a stout little bar. You'd need to grind the diameter down a bit behind the cutting end, for clearance.

If you have any shops in your area, you might visit a few and ask for broken carbide boring bars. I picked up some small Micro100 solid carbide bars that were discards due to damage to the grooving or threading geometry. Not from a shop visit though, they cost me a few bucks each at a used machine dealer.


10-01-2006, 09:47 AM
Nothing flippant about my suggestion. It may not have occured to someone that a drill bit is a perfectly good source of high speed steel. The process of making it isn't exactly rocket science. I make the assumption that most people will realize a grinder would be handy. You then use the grinder to remove everything that doesn't look like a boring bar. If you don't know what a boring bar looks like then the problem is much more basic. However, that was NOT implied in the original question.

10-01-2006, 10:09 AM
I've never purchased boring bars from this outfit, but it was recommended by someone when this question was posted sometime in the past.


I'm generally in a rush when needing a small boring bar, so I'll make them out of drill rod. I've exceeded all rules of thumb for depth of bore in relation to bar size, but I've not trashed any parts, yet.


10-01-2006, 10:40 AM
Thanks for the info. I will try to grind my own-- I think I have some HSS round tool blanks somewhere.


10-01-2006, 02:34 PM
Sercerflyer, I made one from an allen wrench. The allen wrench is pretty stiff and has two parallel surfaces, which helps for mounting. I slit the end of the allen wrench with the Dremel cutoff wheel, used a broken small carbide bit and silver soldered it in the slot. You can go really small with this. Of course the longer piece of the wrench you leave out of the tool holder the more of a whip you will experience, but if you make repeated smal cuts, and extend the wrench only as needed, you will get there. Vic

Tin Falcon
10-01-2006, 04:05 PM
George :
You do not need a round HSS bit to use as a blank. I have several similar to the one in the photo all ground from 1/4 square bits. I even have one ground as a internal threading tool. Just take your time and keep the bit cool.

10-01-2006, 07:19 PM
like Orrin says, don't completely discount the idea of making one from tool steel, ie drill rod. the advantage is that you can remove all the material you need to quickly with the lathe and file or mill then harden. while hss stands up to the heat of higher removal rates, in the home shop we sometimes sacrifice removal rates for the convenience of home made tooling. It will do just a good a job, just don't let it get hot, ie lighter cuts and coolant.

Norman Atkinson
10-02-2006, 02:40 AM
Having a small homeworkers or hobby wirkshop, I was interested in the various comments about making one's own tools.

So I thought that I would count up just how much information which I possessed on this subject. My first reference had no less than 19 pages on the subject. I suspect that I will be guilty of repetition but George Thomas's
Model Engineers Workshop Manual( Tee Pubs) is a mine of information.