small boring bar holder

**Frank S** · May 25, 2021, 01:48 AM

I needed a holder for a 3/8" shank boring bar. The logical choice was a scrap cemented cutter by drilling a hole in the end to the depth of length of the boring bar shank, then cross drilling and tapping for a standard 3/8" flat point grub screw

small boring bar holder-20210520_130750dd.jpg

I can always silver solder a new carbide on the 5/8" square

**NortonDommi** · May 25, 2021, 05:16 AM

Hello Frank,
I found that old injector needles in the 9 litre and up sizes make great small boring bars in a holder similar to yours. Very good quality steel with Vanadium, Chromium and Molybdenum among the ingredients. Takes a mirror polish and hones razor sharp. They make excellent trepanning tools as well.

**metric_taper** · May 25, 2021, 08:10 PM

Originally Posted by NortonDommi

Hello Frank,
I found that old injector needles in the 9 litre and up sizes make great small boring bars in a holder similar to yours. Very good quality steel with Vanadium, Chromium and Molybdenum among the ingredients. Takes a mirror polish and hones razor sharp. They make excellent trepanning tools as well.

From your 9 liter reference I'm thinking this is some sort of llarge engine injector. But I have no clue what this injector needle is.

**NortonDommi** · May 26, 2021, 04:50 PM

Originally Posted by metric_taper

From your 9 liter reference I'm thinking this is some sort of large engine injector. But I have no clue what this injector needle is.

You are correct. Diesel engine fuel injectors have a 'needle' inside the nozzles. When fuel is supplied to the injector pressure upon a land on the needle lifts it off its seat and allows fuel to flow in some designs, others can be electrically operated.
The needles are made of a high alloy steel that makes excellent tools such as small punches, lathe tools, scribes, gravers etc.

If you visit a fuel shop or maybe a heavy equipment workshop, truck shop they often have a pile of old nozzles in a scrap bin. For a small donation to the social club you can usually get a good supply.

**Toolmaker51** · May 26, 2021, 09:40 PM

Originally Posted by Frank S

I needed a holder for a 3/8" shank boring bar. The logical choice was a scrap cemented cutter by drilling a hole in the end to the depth of length of the boring bar shank, then cross drilling and tapping for a standard 3/8" flat point grub screw

Click image for larger version.

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I can always silver solder a new carbide on the 5/8" square

3/8"? 5/8"?
Didn't think Frank S had ANYTHING so small...

Meanwhile, anything dual duty is a plus.

**Frank S** · May 28, 2021, 08:39 AM

Originally Posted by Toolmaker51

3/8"? 5/8"?
Didn't think Frank S had ANYTHING so small...

Meanwhile, anything dual duty is a plus.

On those rare occasions I do need to bore things small than 0.500 Its at those times that I can appreciate 1 of my 2 small 12x36 lathes
I have just about managed to get my 1956 Sheldon 12x36 tightened and trued up enough to be a halfway decent toolroom lathe. I still want to do away with the 8speed belt drive with the 1 1/2 HP motor for a 5 HP 3 ph motor that I have and a 3ph VFD I figure by going to 5HP even at the slower speeds it should still have sufficient torque if not then I will incorporate a 3 or 4 sp transmission from a riding lawn mower

**Toolmaker51** · May 28, 2021, 09:56 AM

per Frank S
do away with the 8speed belt drive with the 1 1/2 HP motor for a 5 HP 3 ph motor that I have and a 3ph VFD I figure by going to 5HP even at the slower speeds it should still have sufficient torque if not then I will incorporate a 3 or 4 sp transmission

A good plan. Lots of potential in a transmission, beyond what power alone can do.

**Frank S** · May 28, 2021, 12:17 PM

Originally Posted by Toolmaker51

per Frank S
do away with the 8speed belt drive with the 1 1/2 HP motor for a 5 HP 3 ph motor that I have and a 3ph VFD I figure by going to 5HP even at the slower speeds it should still have sufficient torque if not then I will incorporate a 3 or 4 sp transmission

A good plan. Lots of potential in a transmission, beyond what power alone can do.

Well I really don't like multi groove pullies as a means of speed increase or reduction more especially when more than 2 multi groove pullies are required

**Toolmaker51** · May 28, 2021, 02:18 PM

Agreed, matched belts aren't hard to buy yet, but legwork involved digging up triple and quad sets. Diefiler has a tiny rubber band length, the cutter grinder is O-ring and shorter yet, lathe 3x has old set but still in terrific shape, keyseater none at all is 4x.
Good thing the belt driven mills are easier.

Not readily available in this little burg, which I think funny. Literally the main thoroughfare named "Belt Highway".
Could just be me........