Shop Built Diamond tool bit holder

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dnalot

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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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.25 Diamond.jpg


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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.
 
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.
 
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!
 
[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
 
Great build. Thanks for sharing. I'm off to the shed :)
 
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?
 
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
 
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
 
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

Micro-Diamond-2.jpg


Micro-Diamond.jpg
 

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