How to find exact hight on a lathe

Rcdizy

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I have a quick change tool post on my King brand 14x40 lathe.

I recently bought a MT3 tool holder so I can drill from the tool post. I am looking forward to trying this because I can use the DRO for exact drilling depth, and clear chips easier and "Bird peck" easier on deeper holes. So nI hope this works.

Finding the centre from front to back wont be a problem because I can use the cross slide DRO to find centre.

How can I accurately find the exact up/down centre so I can set and forget the hight on the MT3 toolholder?
 
If you don't have one, get an MT3 center. and a straight center. Put the straight center in the 3 jaw, and the MT3 in the holder. then just adjust the two points to match each other.

I guess you could also start a hole with the tail styock, then with a drill in the MT3 holder, align it to the hole.
 
As I understand it there will be a drill chuck on the MT3 arbor in the QCTP.
I would chuck up a short dowel pin in the spindle chuck and another dowel pin of the same diameter in the drill chuck.
Line them up on the same axis using a straight edge over both pins until there is no daylight showing.
Repeat to confirm by switching the dowel pins from one chuck to the other. Bear in mind that the lack of repeatability of the spindle chuck and drill chuck might require that you average out several readings.
 
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This will turn out to be a thorny question here I suspect.

I do this often on CNC lathes with QCTP's, I loathe these in every possible way. The way that works for me is sure to be incorrect but I will tell you anyway.

Place an indicator in the lathe spindle and spin it around the tool and adjust the tool post accordingly.
This will get you in the ballpark but not where you want to be, QCTP's are not terribly accurate when used this way. Then spot drill a piece of scrap from the tail stock, mount the drill and run it into the spot by hand and observe visually how far from center the drill point is, the movement will be obvious. Adjust it until it stops moving from center.
Drill hundreds of holes and call it a day.
 
Once the tool holder is on height you will need a way to align the axis of the drill chuck parallel to the axis of the spindle.
 
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You know how to find center on the in and out direction, it is just the same process on the vertical centering, just "cut and try", or rather peck and try, adjust the tool vertically until it is centered, as proved by drilling a hole the diameter off the center drill's pilot, this is the same way as commonly used to center the tool on the cross feed axis. Folks try to overly complicate this task, it is quite simple. There is no need to indicate anything.
 
Joe Pie has a great video on setting lathe tool height. Not specifically on setting a drill in a QCTP, but the concept he shows will help, I believe.
Dhttps://www.youtube.com/watch?v=1MrjnIcscxI Darn sure took the quesswork out for me, and when the lightbulb lit, I had to grab my shades:big grin:
If the link won't work for ya, because I am a total noob at MANY things, just go to Joe Pieczynski, and look for the "Lathe tool height" video. He has helped me a whole bunch, just because he is a natural born problem solver, and just happens to run a very successful machine shop:cool 2:
 
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