(Dave Ficken) wrote in message . com...
"Dean" wrote in message ...

Apparently, there are 2 types for the Harrison. One uses a drawbar ( which
I'm used to in other lathes ) and the other uses a chuck. I think I'd
prefere the drawbar type, but they seem to sell a lot more of the chuck type
for some reason. If any of you have had experience with tube collets for the
M250 or similar that use a chuck or drawbar I'd love to hear about it. I
cant find any info on Harrison/Colchesters web site so I would appreciate
any tips or warnings you might have before I go and spend the money. They
ain't cheap.

I think the answer may depend on your intended use. If you are
planning on production quantities rather than "one-off" work, the
answer may be different.
I love the Hardinge/ Sjogren collet chucks for "one-off" type work,
however I realize that they have limitations when it comes to
production work. For production work, the lever type draw bar setup
can't be beat. Also, the Hardinge/Sjogren type chuck can get difficult
to use when lots of coolant is being used (tightening the wheel gets
difficult.)
I like the ease of switching back and forth between a collet chuck and
a 3 or 4 jaw chuck or faceplate. Changing from a draw bar setup is
more involved, unless you have the collet taper built into the spindle
(like Hardinge).
The type of work I do involves frequent switching back and forth
between a collet setup and a chuck or faceplate. Again, your mileage
may vary depending on the nature of the work you do.

Regards,
Dave Ficken
Meridian Machinery
http://www.mermac.com

Dave's comment about the Hardinge/Sjogren is helpful, thanks, but
there is another angle. I figure most face-mount collet chucks are
bought by people who simply want to use a collet style e.g. 5C that
won't fit in their spindle. Your M250 accommodates a 5C so you
actually do have a choice. I have never used the face-mount style but
what with the overhang it creates more opportunities for inaccuracy.
In general the drawbar and 5C/5MT adapter don't get in the way unless
you need to feed a long piece of 1"+ stock through the spindle.