# Shop Built Diamond tool bit holder



## dnalot (Jul 31, 2013)

Shop Built Diamond tool bit holder

There have been a number of posts on the subject of Diamond tool holders.  They got me to thinking I might want one. So 9 Mo. ago I built a pair of 5/16" holders for my 12" lathe. They worked great but looked a little gnarly as I kind of snuck up on the final design. They have become my go-to tool holder for most everything since building them.

So I set out to build a pair of tool holders for 1/4" bits with a firm idea as to where I was going this time. The design is simple but it works and it only takes an afternoon to make a pair. Starting with a 1/2" X 1.25" mild steel,  I used my band saw to cut out the outline of the part. I then used a belt sander to shape the outside to final form. Next I setup my angle vice and set both angels to between 11 ~ 12 degrees. Clamped the part in place and cut a flat and then cut the 1/4" recess for the bit. The recess should be about .24" deep.  Next I used a steel point to locate the edge of the bit and then jogged over to drill the hole for the screw so that it would just brush the bit. I used an 8-32 pan head but I have ordered a new screw with a little wider head to replace it. Next I tapped the hole and took a file and cleaned up the flat that was milled and gave the part a general cleanup with a file. I then glass blasted the part and "Parkerized" it for two minutes. 

Now the bits I have are made in china so I have to do a little tweaking on them to make them fit. And the screw looks inadequate but I have never had a problem with slipping. In fact I usually have to give the bit a little rap with a hammer to get them loose for sharpening. 

Mark T


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## starnovice (Jul 31, 2013)

Nice. I have a set I bought for the mini-lathe now I can make a set for the 9x20.  Is the 11-12 degrees very critical?  I assume you have to make sure the bit is sharpened to the same angle whatever it is.


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## dnalot (Jul 31, 2013)

My first ones had much steeper angles and worked OK. Anything less than 10 degrees is a problem. On the 11 ~ 12 degree i have sharpened the bit to between 30 & 40 degrees depending on the metal and if I am roughing or finishing.


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## Wizard69 (Jul 31, 2013)

I'm surprised that one 8-32 screw holds the tool reliably.  Have you had any issues with slippage and further how heavy are your cuts?


By the way the tool looks nice!


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## dnalot (Jul 31, 2013)

[quoteI'm surprised that one 8-32 screw holds the tool reliably. Have you had any issues with slippage and further how heavy are your cuts?][/quote]

The pair  I have been using have 5/16 bits and are held by a single 10/32 screw. The screw has a built in washer making it a little broader. I have never had any slippage problem with it and I cut mostly steel. If you want more grip you can countersink the tapped hole a bit and use a countersink screw. It will wedge the bit even tighter but may leave a mark. Or there is room for a second screw. This smaller pair of tool holders were built with 8-32 screws but 10-32 would work but will be close to the limit on clearance. 

Mark T


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## Herbiev (Jul 31, 2013)

Great build. Thanks for sharing. I'm off to the shed


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## Philipintexas (Aug 2, 2013)

Well done, I have the commercial version but it doesn't present the tool at the correct angle for use in a tool post set perpendicular to the lathe axis. I see yours is in a tool holder, does it hold the bit at the correct angle for both turning & facing without re-adjusting between operations?


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## dnalot (Aug 3, 2013)

Yes, you can turn and face if the tool post is set square to the lathe. That is one of the things I love about this tool holder.  

Soon I plan to make a mini set that takes 1/8" bits with and over all width of .5" for making smaller parts.   

Mark T


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## Shawn (Aug 3, 2013)

I just made one of these but your design is much nicer. I will be following your design on the next one, thanks for sharing the idea. 

Shawn


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## dnalot (Aug 4, 2013)

To complete my set I have made a pair of Micro-Diamond tool bit holders. The tool bit is .125" and the overall width at the business end is .345" Overall length of tool is 3.25"

For those smaller parts.

Mark T


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