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jam chucks

1. Cheap wood or scraps you don't want to use for anything else
2. Softer than the work piece, so the piece dents the chuck and not vice versa. But not too soft (Pine can be too soft)

Poplar works well for most things.
 
Ply is fine. Used aspenite up at school, cheap and available, though it was not ideal. Groove, wedge, turn. If you use aspenite, watch the splinters!

Key is to leave a center mark on the bottom that IS a center mark.
 
Wes nailed it. I use whatever is handy. I do keep a fairly large piece of MDF and Plywood handy. MDF is not the best but will work quite fine for some pieces. Plywood is better but depending on the project will use just about any wood laying around.
What are you trying to Jam Chuck? Although this is a very good method there might be other methods we could recommend.
 
The only thing I would add is that a cup style jamb chuck to hold a ball or pin style jamb chuck for pepper mills should be turned from solid wood and with the long grain parallel to the lathe bed.

I like green wood for The ball jamb chucks. The reason for the end grain is for the unlikely event you can't get the workpiece out it is easy the split the endgrain to release the work undamaged.
When I make these chucks I bore a hole through so that a wooden dowel can push the piece out. Usually a whack with a mallet on the chuck or a gentle push with the dowel will pop the ball out.
However if I've hollowed a ball to a thin wall too much force from a dowel will damage the piece and better to split the chuck.

I've got a couple of cherry jamb chucks I've been using on small bowls for ten years or so.
They are working fine for me. I alway use a paper towel of thin foam between the wood and wood.
I use any handy scrap wood should be crack free. I usually use green wood. I also have wire basket on wheels where I put them.

Have fun ,
Al
 
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Thanks for the information. I can't for the life of me remember where I read or heard that.

I use jam chucks for bowls, pepper mills and other smaller projects. I like the idea of having them in one location so I can reuse them as needed.

Thanks again,

dave F.
 
Another good tip. DRill a hole in the center of the jam chuck. All of my faceplates and chucks have holes in the center. When you get a bowl or box stuck on a jam chuck it's really nice to have a hole in the center of the waste block so you can push a dowel through and push on the work to get it off. Not that I've ever had that problem of course. It was a "friend".
 
I tend to use scraps of construction lumber like 2 x 10, 2 x 12 or even Microlam pieces. Ask around at construction sites and remember to check for nails. Not sure about not using Cherry. Maybe it leaves a colored mark?
 
I also use scrap 2x construction lumber. I have glued up a couple pieces of 2x8 side to side, so I have a really large dia jamb chuck. MDF works well also, because it is so much softer than most woods.

One more hint...which works well for me. Relying exclusively on friction to hold the piece in the jamb chuck, might not always work. What I often do, is put some blue painters tape on the rim of the vessel...which makes the jamb fit a bit tighter. I then use some dabs of hot melt glue...gluing the tape to the jamb chuck. Then, after prying off the finished bowl, the tape (and any attached hot melt) comes off easily.
 
Do you have to make a new chuck for each diameter bowl or do you make your bowls a standard diameter?

What about natural edge bowls?

Thanks for the feedback - livin and learnin

Dave F.
 
for natural edge bowls I don't use a Jam chuck per say. I think of jam chucks as a tenon that fits inside the lip of the bowl and holds it. You can get buy without a taiilstock if it fits really good and your cutting technique is good.
for natural edge bowls I use scrap of wood with rubber on the tip and my tailstock holds it in place. The rubber drives it and the tailstock keeps it aligned. This only works of course if you have an accurate center mark in the bottom when you turn it around.
The Jam chuck I mentioned above will work without a center mark because you are referencing off the lip. The bowl usually runs truer but if you've had any warp at all may not even it or will only fit snug at 2 points and isn't as solid.
 
hockenbery said:
When I make these chucks I bore a hole through so that a wooden dowel can push the piece out. Usually a whack with a mallet on the chuck or a gentle push with the dowel will pop the ball out.
However if I've hollowed a ball to a thin wall too much force from a dowel will damage the piece and better to split the chuck.

Al
Click to expand...

Another advantage of the hole through the jam chuck is that you can sometimes use compressed air to dislodge the jamed turning. This would be less likely to damage thin wall turnings.
 
john lucas said:
Another good tip. DRill a hole in the center of the jam chuck. All of my faceplates and chucks have holes in the center. When you get a bowl or box stuck on a jam chuck it's really nice to have a hole in the center of the waste block so you can push a dowel through and push on the work to get it off. Not that I've ever had that problem of course. It was a "friend".
Click to expand...

I'm glad you consider me a friend...
Oh...you weren't talking about me?
 
Apart from what others have suggested, I would recommend either poplar or sycamore. Both tend to be inexpensive, easy to get in a thickness sufficent for jam chucks, and both tend to be quite stable.
 
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