Small boring bars

[Alex]

Hello group!

Just ordered a 4-jaw chuck, but before contruction can begin I need some very small boring bars for machining the cylinder barrel. Do you know where these can be purchased?

Thanks and merry Christmas
Alex

 

[Capt Turk]

Take a piece of HSS and grind what you need. Just takes a few minutes.

 

[Alex]

Wow, you're quick!
I'm not really sure how to grind it. Do you have a picture or link?

 

[Bogstandard]

If you are willing to wait until tomorrow, I hope to be doing a bit about making small boring bars for the flywheels on my build of a finger engine. Quick and dirty and easy to make with a bit of drill rod.


John

 

[Alex]

I sure am! ;D

 

[deere_x475guy]

I'll be waiting to see also. ;D

 

[wareagle]

This will give you guys an idea of what a ground bit may look like. Play around with the rake angles for your application, but this should give you an idea for grinding a bit for boring purposes. Hope it helps.

The drawing is looking at it from the top, and the bottom little piece would be looking at the cutting end with the top up. This is shown with quite a bit of rake angle just for illustrative purposes.

 

[Tin Falcon]

Alex here is a pic of a couple of home made ones.

The top one is ground from a HSS tool blank. It is a flea market find.

The lower one I made from a piece of 3/8 drill rod/ silver steel it has a quick heat treat with a little propane torch and a motor oil quench. I turned it on the lathe hardened it then carefully ground the tip. I have not had the nerve to try the one I made on steel but it works well on brass and aluminum.
Hope this helps. Between these photos and Wareagle's diagrams you should be able to figure it out.
If you want to buy one try enco
http://www.use-enco.com/CGI/INSRIT?PMAKA=379-2510&PMPXNO=944770&PARTPG=INLMK32
or MSC
http://www1.mscdirect.com/CGI/GSDRVSM?PACACHE=000000039567545


The advantage of carbide is it will allow for a deeper hole for a given diameter.
Tin