Parting on 9x20 lathe

[zaebis]

Ok just got my 9x20 out of the box, wiped the oil and took it for a spin. All is well (a few bolts gave up right away but no biggie). I am having a hard time with parting my stock on it. I bought a holder and HSS blade, alighned it with a tailstock to be at the same level but still cant get the parting to work. It starts ok but as it comes closer to the center (almost complete), frequently breaks or at least starts to produce howling sound. I am parting aluminum at 600 rpm. What can be wrong?

[williams480]

The SFM is reduced as you go toward center, and the cutting forces increase.
There a couple of things you can do.
Make sure your part-off blade is a few thou. above center (rule of thumb for inches is - .031 X blade width in inches).
So for a .094" wide blade you need to be at least .003" above center.

The other is to run a higher RPM and back off on the feed rate as you get near the center.
HSS should run about 300 SFM in Aluminum, for a 1" piece of stock
this equates to 1146 RPM (3.82 X 300 /1.00), a smaller diameter will need more RPM, larger will need less.

Good Luck !

[escott76]

If you aren't using it, some kind of lube is a necessity.

[ibuildstuff4u]

Another problem to look at is the stock hold down plate for the tool post. It is very week and needs to be up graded to a four bolt design. The original plate will allow the tool post to flex easily and could be causing your problems. If you do a search you will find a ton of plans to make this new part. It's a pretty easy project and one of the first up grades you really need to do to this lathe to make it work nicely.

Hope that helps!

Dale P.