Thread: Help Wood lathe Not turning Round objects

How much sanding do you do?

How old is the lathe?

BJT,
is the wood that you use completely dry , or is it still a bit green ?
And do you get the object finished in one go , or does it take a few sessions over a period of days ?
How do you go about changing the bowls around on the lathe , to work on the other part of them. Do you use orientation marks to line the piece up in the chuck ?

Jock

Hi BJT,
Try testing the spindle, for being bent.
Use your tool rest, locked off & very close to the Spindle, & rotate by hand.
Should give you a fair indication.
Regards,
issatree.
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Thanks for all your comments....will try to clarify the situation some more...

I am not at the sanding yet....still need to get it round....

The lathe is about 7 yrs old....but it is not a very expensive one....

I put the wood on the NOVA Chuck several times....when making a bowl form....I take it off the chuck for a week or two and then put it back on.......but it is never round.....

The pens I am trying to turn are dry wood...I take them off and on the mandrel several times and they are uneven....one side will have a lot of wood needed to come off and the other area I will almost be on the brass tube... the mandrel does not look bent...

Could the headstock be out of adjustment ?? How can I tell that ?? Do I want to know that...
Thanks for your help...BJT

Originally Posted by BJT

I put the wood on the NOVA Chuck several times....when making a bowl form....I take it off the chuck for a week or two and then put it back on.......but it is never round.....
BJT

""I take it off the chuck for a week or two and then put it back on""

That could be part of the issue right there . Wood moves

BJ ,
what lathe do you have ? Others on here may have the same one and experienced spindle runout problems

Yep.

And with your pen mandrel, don't tighten the tailstock up hard. Just seat the cone lightly and then add a pinch.

That said, mandrel shafts can be bent so chk with a straight edge.

Good luck.

I bought a cheap-a$$ed pen mandrel which turned out to be true enough but the thread through the gnurled nut was so crooked it would bend everything out of alignment with ease - t'was easy fixed by replacing with a standard 6mm nut but now I have to chase a spanner

Moral to this story Check your nuts !

Hmmm - from the amount of runout you describe for both spindle and bowl turning it is difficult to tell what the problem might be without sighting it.

If you have the chuck mounted and grab the chuck can you get any movement of the chuck and the shaft it's attached to? Only needs to be a tiny bit in a worn bearing and that will do it.

Put centers in both the head and tailstocks and bring them together - they should align. Now turn the power on and they should remain aligned with the head stock spinning. Then very carefully apply some pressure to the spinning headstock center with a piece of wood or the back of a gouge - still aligned?

If so then get a square (very) piece of timber, only short so it mounts firmly and mount it in the Nova chuck. Bring the tailstock center to the end of the timber and see if it's in the center. Sometimes inserts for chucks are less than perfect and that may be the reason.

Try that and see where we get to.

Jamie

1+ on what Barnsey said about the chuck insert. Some major retailers in the US were selling their own generic insert (Nova has now asked them not to). The generic is not as long as the Nova insert and will not seat properly causing run-out. If you got a $6-7 insert you probably have a generic.

Thanks for the help/suggestions...

I finally bit the bullet and bought a new mandrel to turn pens.....now the pens are turning round without any flat spots....not oval.....

I tested and tested my old mandrel and it appeared not warped or bent....but I guess that was the main problem.....

No sure why the bowls don't turn evenly on all sides...because I use a Nova Chuck...I do remount the piece several times on the chuck....anywhere on the chuck...so this could be the problem with that.... at this time not going to worry about the uneven bowls... just take one problem at a time... BJT

With the bowls try increasing your speed, use a sharp gouge and take off fine shavings. If you feel a shudder or vibration through the gouge then back off and slow down your rate of progress.
Pete.

When you demount the bowl with the intention to remount, mark where jaw #1 gripped and go back to that spot. That'll reduce run-out.

Originally Posted by rsser

When you demount the bowl with the intention to remount, mark where jaw #1 gripped and go back to that spot. That'll reduce run-out.

Good advice for spur drives too. For drives with removable points, mark the grub screw location; for those without, scratch a mark on one of the teeth, and transfer the mark to the workpiece. And clean the MT socket.

Even CNC manufacture doesn't eliminate all differences, owing to construction tolerance.

Cheers,
Joe