Holdfast Vacuum Chuck

[Fred Belknap]

I have the Holdfast Vacuum system and it has been giving me some problems. Below is a picture of a bowl and if you look in the center you can see where the edge of the vacuum chuck has left an indent in the bottom of the bowl. The system says there needs to be 12 on the gauge to safely hold a bowl. On this bowl I had about 13 or 14 on the gauge, not near as high as it can go. This is not the first time I have had this problem. I get it with both the 6" and the 3.5" chuck. It is near impossible to sand out the ring. My question is, has anyone else had this problem and if so what did you do to correct it. I'm the kind of person who would rather buy a tool than make one if possible. I much prefer making bowls to making tools.


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[Tim Rinehart]

Fred, I admit I'm a bit confused on nature of 'ring'. Is it a depression, or imbedded dirt? I have a hard time figuring why it should be difficult to sand out with a good 2" sanding disc, starting around 120 or so.
I will offer one suggestion, and that is prior to vacuum chucking it, shellac the inside of the bowl to help seal it, and stiffen the fibers a bit, especially in area near where the chuck will sit. If you don't want shellac out near natural edge...just keep local at bottom and sand out when done.
I am guessing these chucks have some pretty tough materials to cause a depression like that. May want to buffer it with some closed cell neoprene gasket. The veneer equipment sites is where I bought mine to work with my PVC chucks.

[Jon Prouty]

Hi Fred,

I get the same thing - really irritating. I ended up removing the two gasket rings and turning down that center protruding ring by almost two thirds. I left enough for the two gaskets to stay put but removed enough to get rid of the problem. Once these gaskets are dead, I will remove that protrusion completely and use closed cell sticky back foam from Hobby Lobby (8.5" x 11" sheet for less than a buck). Just last night I made a 4" drum from a piece of maple and a PVC coupling - I bought a Beall spindle tap to tap the wood. I'm gonna make a 6" one as soon as I can find a short hunk of pipe.

Anyway, cut that rib down and you won't get that mark.

Cheers!
Jon

[Paul Williams]

No legitimate experience here, but it sounds to me like you a crushing fibers. I would try reducing the vacuum and/or padding the edge of the chuck.

[John Keeton]

Fred, similar to Jon, I removed the gaskets, but only rounded the edges of all corners and no longer have the problem. I pull about 23" on my system.

[Michael Ginsberg]

I had the same problem , particularly on soft woods... Removed gaskets, rounded edges, then rubber cemented the o-ring back in place. Problem solved.

[Fred Belknap]

Thanks everyone and you can be sure before it gets used again both chucks I have will be worked on.
The ring in this piece which is hard maple was deep enough to catch your fingernail on. I remember using a hot iron and a wet cloth to remove compression dents in flat work. I used a wet paper towel and a hair drier and to my surprise most of the indent went away. I did a little sanding and almost as good as new. If you turn it just right under a good light you can see a faint line in a couple spots. I doubt anyone would notice it unless they knew where to look.

[Tom Hardy]

I have the same problem on my holdfast. Rubber Chucky vacuum seals have a gasket, they say will stop that. I just haven't ordered one yet.

[Allan Ferguson]

Have the same issues. Thinking about adding different gasket, but will round out the edges and try that first.