Quick Change Toolpost accuracy

dave9

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Jan 1, 2017
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So, I have a cheap quick change tool post. It's the wedge type, it doesn't say anything on it except Made in China, so I don't even know the brand. It takes the 250-xxx tool holders. I just picked up some cheap tool holders and was pretty impressed by the fit and finish.( HAH! I just came up from an experiment and one of the set screws broke when I tightened it! ) I mean, they were 11 bucks a piece. I bought some 18 dollar a piece tool holders a year or two ago, and they only fit on the side of the tool post, not on the front, and they were a little rough. The knurling wasn't great on the height adjustment nut, and the surface was pretty rough where they cut out the slot for the tool. The new ones are much nicer finish-wise.

So I'm wondering what I'm not getting, since it's not an Aloris or anything. ( Obviously well tempered set screws for one thing ) . I have some Borite 1/2" carbide insert tools that take the little triangular inserts. I centered the tools so they don't leave a little nib on a facing cut, and then I put the toolholder on the side of the tool post, and switch the tool around and they don't leave a little nib on a facing cut.
And I've taken them off and put them on a few times and they still make a nice smooth facing cut.

Obviously, set screw aside, if I can't tell, then it doesn't really matter. But I'm curious if you can check a tool post for accuracy, and what you would check if you did check it. Or is what I did the test?
 
Since you set each toolpost/tool position individually, repeatability on the height is really all that matters. That's assuming, of course, that once you get a particular tool dialed in, it stays there.

Buy more toolholders. And set screws.
 
Jbolt just did a very thorough test of several QCTP holders. I did a search but couldn't find it. His results should answer your questions.

Tom S.
 
I found his test searching Google this morning. Damned if I can find it now. Basically, it's what I thought, it apparently suits my needs since I can't find anything really wrong with it. Part one was done early December 2016. I'm interested to see part two.
 
The important question is not how accurate a tool is, rather how much accuracy do YOU require of it.
 
Thanks for the link. I found the first part searching Google but I couldn't find part two to save my life.

hah! How much accuracy do I require of it? I use dial calipers 99% of the time. :big grin:
 
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