ER32-R8 Toolholder Drawbar for the BP Mill

[Ulma Doctor]

i recently purchased a ER32-R8 toolholder from Ebay.


i didn't realize the drawbar threads were M12x1.75 vs the 7/16"-14tpi of the standard drawbar in my BP.
i got a piece of M12x1.75 all-thread and a short hunk of 3/4" hex brass to make a new drawbar.

i drilled/tapped the brass hex for the M12 thread, cut off the all-thread to length and chamfered the ends.
i installed the all-thread into the brass hex and then cross drilled a 1/8" bore for installation of a split pin to retain the all-thread.
i did a little buff up on the brass to make it pop and installed the works onto the BP.




i look forward to working with the ER32 system on the BP!


as always, thanks for looking!

 

[Lo-Fi]

That's annoying! Mine came with the usual 7/16 thread, though I think there was the metric option.
I use mine a lot. If you're dextrous and get some spare nuts to load a few collets in, it's not too much slower than a Jacobs chuck for centre, drill, ream, tap etc. type ops.

 

[darkzero]

Nice job Mike!

Yup that is annoying. My 2 Bison ER-40 chucks are 7/16. I had no idea R8 tooling is available with metric draw bar threads, I thought only Morse Taper collets came both both ways. Do some import mills come with metric draw bars for R8 spindle tapers? I have not heard of this before, just curious is all.

 

[Ulma Doctor]

That's annoying! Mine came with the usual 7/16 thread, though I think there was the metric option.
I use mine a lot. If you're dextrous and get some spare nuts to load a few collets in, it's not too much slower than a Jacobs chuck for centre, drill, ream, tap etc. type ops.

I’ll be sure to get extra nuts to do as you suggested, thanks for the information!
I’m sure I’ll get excellent use!

 

[Ulma Doctor]

Nice job Mike!

Yup that is annoying. My 2 Bison ER-40 chucks are 7/16. I had no idea R8 tooling is available with metric draw bar threads, I thought only Morse Taper collets came both both ways. Do some import mills come with metric draw bars for R8 spindle tapers? I have not heard of this before, just curious is all.

Thank you DZ!
I didn’t know either about the different threads.
I had 2 other asian mills other than the BP, both in the 728/730 class- both machines had R8 spindles, both had 7/16” drawbars.

There may be some brand(s) of machine that takes the metric drawbar, but i have not ran across one yet.

Thanks for reading

 

[Aukai]

Necessity......

 

[markba633csi]

Mike why did you use brass? Won't that wear fast? Or is it supposed to be sacrificial?
-Mark

 

[Ulma Doctor]

Mike why did you use brass? Won't that wear fast? Or is it supposed to be sacrificial?
-Mark

my other drawbar has a 3/4" hex head, i had some 3/4" hex brass and some 3/4" 6061 Hex aluminum on hand.
i went with the brass due to the higher yield strength.
when it gets mushroomed, i'll chuck er' up and knock of the high spots