ER16 Collet Chuck for Unimat M12X1 Spindle

[rossbotics]

Great work, great write up Paul
Love ingenuity

[Paul Jones]

Thanks Doug,

The "ingenuity" was a round about way to improve the accuracy in machining the collet. Next I am going to try a more direct method for fabricating the ER16 collet chuck on the Unimat. If this works better, I will then make a collet chuck for the ER20 series.

Good to hear from you and looking forward to seeing another on of your precision toolmaker tools.

Regards, Paul

[Paul Jones]

Doug,

I think I just found a way to make the ER16 collet chuck with minimal run out. Tonight I mounted the ER16 on my Unimat SL spindle and took a couple thousands off the chuck OD. I cycled collet on and off the chuck about a dozen times and measured the TIR of the chuck OD. Each time the TIR measured less than 0.0002". This means I can rotate the Unimat head 6 degrees and use my Dremel tool holder and small grinding stone to dust off the ER16 ID taper surface. I am sure I can significantly reduce the TIR of the ER16 collet surfaces using this technique for the collet.

Paul

[NeiljohnUK]

Nice job, whilst I didn't do the whole thing, it did inspire me to buy a ready made er16 collet conversion chuck for an 8mm motor spindle then bore out and thread the internal to match my Emco Compact 5's mill head (14x1mm). The headstock spindle on the 5 is a bolt on flange design, so the next job is to make an adaptor and thread that to suit, though I may go for a much larger series, the 5 factory collet size was er25, so either 32 or even 40!