Shafts between centers

Hi folks, I'm not a turner, but a friend wants me to make some shafts
for him. They have to be turned between centers as part has to be
ground later. Material is mild steel, all shafts have a large end & a
small end. Large end about 3/4", & 3"long, small end (the one to be
ground) 5/8" longest one 8", others a bit shorter.
I plan to cut the material to length & center drill both ends, but if
I use a drive dog, how do I machine where the dog is? If I start with
a longer shaft & part off the stub where the dog was I can't drill a
center exactly on center.
My idea is to cut to length, center drill, machine 5/8" diameter
(leaving 5 thou. for grinding) & machine as much as I can of the large
end, leaving about 10 thou. to go, & then removing the dog & hope that
I can get enough drive from the center to bring the part not yet
machined down to the 10 thou. too big size & finish with a light cut
to size.
Please help with a better (correct) way of doing this.
T.I.A. Ian sutherland. Oz.
Reply to
Ian Sutherland
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zsutherland snipped-for-privacy@yahoo.com (Ian Sutherland) wrote in news: snipped-for-privacy@posting.google.com:
Why can you not get a center back on center after parting off the drive dog area? You need to leave about 0.01" on the area to be ground anyway (grind stock) leave it long enough for the dog, part off, turn it around, indicate it back in and center drill the end.
Reply to
Anthony
Rx:
Saw cut. Chuck, face, and center drill 2 pls. Change to centers, live or greased dead center, drive dog and drive plate. Poisonous white lead is good on a dead center.
Drive stock and turn 3/4. Flip stock and add a copper penny or pad under dog screw. Drive stock and turn 5/8. Done. (I think)
The thing about the centers is you can take the part in and out as many times as you want and it always sets up in the same position reliably, unless you catch a chip.
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Reply to
Doug Goncz
Do they still make spur centers?
Jim
Reply to
jim rozen
from the lathe dog you would still have a hole for your center?
Reply to
Ahernwill
Parting off between centers? Are you crazy? You _never_ part off between centers! Phil
parting off the part
center?
Reply to
Phil Kangas
Hi guys, thanks for the reply's, I knew there had to be a way to do this, just didn't think of the obvious, of course the above poster is correct, just flip it after one end is done particularly if I do the small end first, any mark from the penny will disappear with the grinding. Thanks for a great group. (I read the posts every day.) Cheers, Ian Sutherland.
Reply to
Ian Sutherland
Thanks, now I know what to do with all those extra pennies. I'm just about out of alluminum shims i use under the chuck jaws.
John
Reply to
john

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