Vacuum Chuck Marks

[Endless Pursuit]

Getting a nasty black ring on my finish when I reverse a bowl to finish turning the bottom and sand/finish the outside. Aside from the special vacuum foam sheets, any other way to prevent this? I’m using the HoldFast brand of equipment.

Thanks,
Jeff

 

[Dee2]

I use PVC reducers and WallyWord (white) foam sheets on my homemade vacuum chuck. No marking/marring. Don't know about special vacuum sheets. All you need is a flexible, closed cell foam and smooth surfaces on the chuck and bowl, IMHO.

 

[blackhawk]

Jeff - I use Holdfast also. I have never gotten any black marks on my bowls. It sounds like the bowls are slipping in order to create the black marks. On your next bowl try making an alignment mark on the chuck and bowl and see if they become misaligned while turning. You may need the next size larger chuck, more air pressure, or lighter cuts.

 

[SabertoothBunny]

My experience is that black mark is from the chuck holding wet wood. Never have had it happen to wood that is fully dry.

 

[Endless Pursuit]

Thanks for the replies. I think Brad is on to something... I’ll do a test.

 

[Endless Pursuit]

Brad was right. No marks if I don’t use the tail stock.