DIY Toolholders

The least rigid aspect of your lathe from a toolholder perspective is the compound. If you want better rigidity using a QCTP, switch to a solid toolpost like discussed in this thread.

As far as your idea goes, machining the pocket for a carbide insert is not a trivial undertaking. They require 10ths level precision, often have difficult profiles to achieve on a manual mill, and complex angles. I'd must rather machine slots and drill/tap for holding screws than to tackle the complexity of making a pocket at -7° angle for a DCMT insert.
 
Challenge accepted, @davidpbest . :cool:

I've made several carbide bit holders, and got acceptable performance from them. But. . . "acceptable" is not, and never will be, a scientific term of merit. I've got the material and desire to build a "QCTP bit holder", and a question of whether or not it will be any better.

Nothing left to do but give it that ol' college try and make some chips. . . just as soon as this new hip upgrade will let me.
 
Aloris makes this one, there are copies out there too.
 
Shotgun said:
It seems that every Youtuber machinist has a video on making toolholders. Take a big block of steel. Cut the dovetail down the whole thing. Chop to individual length. Mill a slot and then drill and tap holes. Then you use the drilled-tapped holes to clamp a bit holder in the slot.

Those last couple of operations are quite a bit of work. When using carbide tooling, wouldn't it make more since to mill a landing directly on the nose of the holder for the bit? The point of making the holders in the first place is so that you can have a separate holder for each tool. Why not skip the extra steps and end up with a tool that will be much more rigid at the cutting face since it doesn't have to transition through as many connections?
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I like the idea of dedicated toolholders. I have the same tools in the same holders for years, which is what you are suggesting. Perhaps you could consider mounting some inserts upright for tangential cutting.
 
Shotgun said:
Challenge accepted, @davidpbest . :cool:

I've made several carbide bit holders, and got acceptable performance from them. But. . . "acceptable" is not, and never will be, a scientific term of merit. I've got the material and desire to build a "QCTP bit holder", and a question of whether or not it will be any better.

Nothing left to do but give it that ol' college try and make some chips. . . just as soon as this new hip upgrade will let me.
Click to expand...
If by ”BIT” you mean industry standard carbide inserts, you might find the following video interesting.


I’ll be interested to follow your progress.
 
FOMOGO said:
That's a pretty interesting design. Have never seen one before, but looks very versatile. Mike

View attachment 411887
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That tool is an Aloris #20, which I own and use frequently. It comes in handy if you have a solid tool post and need to alter lead angle.
This tool has an articulating head that can be rotated and secured in 12 indexing positions at 15° intervals. The tool consists of a QCTP mounting block and a bolt-on cartridge that acts as the insert toolholder. The tool is proprietary to Aloris and is available in sizes to fit AXA, BXA, and CXA tool posts.

The insert is a triangle shape with zero clearance angle (similar to the WNMG trigon insert), and is double-sided with six total cutting faces. Inserts are available from Aloris and several other manufacturers. Since the insert has a 0° clearance angle, the insert is held in a negative rake, making this tool suitable for aggressive material removal. The rotating head on the cartridge gives this tool unique positioning ability and lead angle flexibility.

This tool takes a triangular insert with 3/8" I.C., and although it has a zero clearance angle and is held in a negative rake, the TNMP33x variety has a positive cutting edge for use on softer materials like aluminum.
 
Thanks for the info David. Cheers, Mike
 
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