problems with lathe
 

i have a team cobra pro lathe (the one with the power base)

i've had it for a couple years and it works great. i've never dropped it or anything but recently it started to make a funny sound and when i stop it the comm surface is NOT smooth.

the diamond bit doesn't look chipped from eyeballing it...

anyone experienced this before??

What are you powering it with? What voltage are you feeding the slave motor. Make sure the slave motor is lubed. Check the bit height.

Make sure you use a good oil on the bridge ways.

if the com runs rough(dry) while spinning >>> the cut will be rough as well...

Some lathes have a screw that holds the arm in place so it doesn't walk side to side, others you can just put a pinion on the armature, make sure it's not held in too tight as that can make it want to jump out also. Are the grooves where the arm site worn at all?

Just my opinion, but it sounds like a dull bit. Look at it with a jewlers loop and see.

Try a carbide bit too and see if it cuts any beter.

Good luck
David Root

If the carriage has adjustable gib's,you might want to check them for tightness.

finally got around to it
 

hey!

i know its been awhile - i got really busy with work and haven't had much time for racing...

i FINALLY looked at the bit with a jeweller's loupe and the tip is perfectly fine - no chips. so i tried cutting the comm of an motor i wasn't going to use and found that it only doesn't cut smoothly when moving from right to left, but when moving the bit back from left to right it does leave a smoother finish.

since the bit is not damaged, i am assuming that the guides/bulkheads of the lathe are misaligned.

i emailed team cobra but haven't received a response yet... does anyone know a reliable way to get the bulkheads aligned properly??

Quantum
Coming from an engineering background I would not say that the guides are NOT misaligned but perhaps looser than new. ( since you use the same guides for forward or reverse cutting I guess that the tool block is twisting in forwards or reverse)


Most comm lathes have two grub screws which push on to a slide clamp to adjust the slide tension.
Try tightening these up very slightly to remove the wear which will have occured during use.
They may have lock nuts on them to prevent them self ajusting in use.

Also - Check that the comm is turning in the correct direction so that the tool cuts rather than rubbing.

Then check that the tool is sitting at the correct height to cut.

i'm not clear on what you mean.

if you are trying to say that i should eliminate any slop/play with respect to the nylon shims in the dovetail slides, then i will take a look at that and get back to you...

the worst part is that now i don't have 100% confidence in my lathe... might have to get it aligned just for peace of mind...



:(