Specs/measurements for MT drawbar arbors

B

bhofmann

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I use a Clausing 8520 vertical mill that has a 2MT spindle taper. I am making a M10 drawbar for use with tooling that is specific to this drawbar thread. I want to ensure the length of the new drawbar is appropriate. I currently only have one piece of tooling with M10 thread, and if I were to make the drawbar the same length as the existing imperial drawbar, I only get less than 1/2 turn of thread engagement for this tool.

Are there specifications for drawbar style tooling/arbors relative to the axial position of the drawbar thread hole relative to the arbor taper and for the depth of the tapped hole for arbors with 2MT taper and M10 drawbar thread? I have not been able to find anything relative to this on the net, only the dimensions of the taper itself. Any assistance would be appreciated.

-Ben
 
A cure for the problem could be an drawbar threaded on both ends with an adjusting nut to vary the length as needed; another nut is permanently secured to the same end of the bar (by a pin) to remove it from the adaptor or arbor; this is how most all milling machine drawbars are made, except those on vertical mills like a Bridgeport.
 
As mentioned above make what fits your machine.
You do not need specs and measurements for a machine that you have at hand, measure it directly.

If making a drawbar for a machine that you will never see or be able to measure then detailed drawings will be required
 
My preference is to make the drawbar in such a way that is most likely to work with any tooling I would acquire in the future that also has M10 thread. Hence the desire for knowledge of any standard dimensions that may exist.


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Fair enough. To my mind, the 10mm tool you have on hand would have been made to any standards that might exist.
Re the length of the drawbar, bemmychree in post no.2 sounds good to me.
Re the 10mm thread spec. use normal universal 10mm thread specs. That's what tool makers are using. Bear in mind that a close fit is not required nor desirable for a drawbar. The drawbar has to spin easily in and out of the tool. Check the depth of the female thread in the tool you have on hand and calculate using 2/3 of that for engagement. The threads do not have to hold much torque and must never jam.
Hope that helps.
 
I am just about to tackle the same situation on my Clausing 8530. I want to get a face mill, but most seem to be M10 rather than 3/8-16. I think a custom drawbar made to fit is in order. I am reading various threads on face mills now to try and figure out which one to buy. Lots of insert choices and number of flutes.
 
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