05-05-2015, 09:45 AM
Ed's recent post on machining 4140 leads me to a quick question regarding the machining of the hex drive end of the drawbar.
I currently have two lathes at my disposal. My 18 x 60 and my friends 10 x ? My lathe has a top speed of 425 rpm, whist his tops out at 1600 rpm. My spindle through hole is 2-5/8", his is 1-1/16"
My options are to feed the 2m long bar of ø30mm through my spindle and turn each of the parts individually, parting them off once completed or turning a piece long enough to get the required number of parts out of down to ø27mm and then finishing them to size on his lathe. Whilst typing this I have realized than I have 3mm diameter in which to experiment with DOC etc and see what finish I can get. If I'm not happy on my lathe, I can then move to the faster one. Unfortunately neither have auto feed.
I have a ER32 collet set and a hex collet block, which will allow me to quickly and accurately index the round stock to mill the hex. However, my largest ER32 collet is ø20mm, which is too small to accept the (turned to diameter) stock. In the absence of a dividing head, my plan is to assemble the drawbar and then use a ø13mm collet to index it off of the 12.7mm shaft.
I'll clamp the large diameter in the vise and use my angle plate as the surface against which the hex collet block registers. I'll also set up a stop, so that the part is machined from the same reference point for all six sides.
Does that make sense?
I currently have two lathes at my disposal. My 18 x 60 and my friends 10 x ? My lathe has a top speed of 425 rpm, whist his tops out at 1600 rpm. My spindle through hole is 2-5/8", his is 1-1/16"
My options are to feed the 2m long bar of ø30mm through my spindle and turn each of the parts individually, parting them off once completed or turning a piece long enough to get the required number of parts out of down to ø27mm and then finishing them to size on his lathe. Whilst typing this I have realized than I have 3mm diameter in which to experiment with DOC etc and see what finish I can get. If I'm not happy on my lathe, I can then move to the faster one. Unfortunately neither have auto feed.
I have a ER32 collet set and a hex collet block, which will allow me to quickly and accurately index the round stock to mill the hex. However, my largest ER32 collet is ø20mm, which is too small to accept the (turned to diameter) stock. In the absence of a dividing head, my plan is to assemble the drawbar and then use a ø13mm collet to index it off of the 12.7mm shaft.
I'll clamp the large diameter in the vise and use my angle plate as the surface against which the hex collet block registers. I'll also set up a stop, so that the part is machined from the same reference point for all six sides.
Does that make sense?
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