Jam (jamb) chuck versus spindle sander fitting

[David Metzman]

I turn some pepper grinders and salt shakers so a jam chuck comes in handly. I see that Penn state sells them.

https://www.pennstateind.com/store/CJAM10C.html

I already have a drum/spindle sanding kit for a drill - similar to:

https://www.amazon.com/ABN-Drum-Sanding-Kit-Attachment/dp/B07LFKTD4N/ref=sr_1_15?dchild=1&keywords=spindle+sander&qid=1609688914&sr=8-15


Are the inside fittings from the drum sander the same things as jam chucks?

Is it better just to turn my own out of wood or plastic.

I have tried the drum insert and find there is some play in it - it is rubber on the outside. Are Jam chucks stiffer? IF purchased jam chucks are good, any recommendations?

thank you,
David

[Dave Mount]

I've not used these, so my response may not be as directly helpful as it should be. . .but I won't let that stop me. My concern would be how true these would run. The advantage of a shop turned jam is that it is guaranteed to run true.

There are a thousand ways to turn peppermills, but I don't use a jam chuck. I'm not at all suggesting my way is better than any other, I just bring it up here because it doesn't require any additional fixture, other than a scroll chuck, which most of us have.

I turn the stock round between centers and put a tenon on the end that will become the "head". I then remove the drive center and put the tenon in a scroll chuck, using the tail center to make sure the blank goes into the chuck true with the original centerline. I then drill the bottom counterbore and then the main body boring on the lathe, stopping 1/2" to 1" short of where the parting will land between the head and lower body. Change the drill chuck to a cone shaped live center and use it to stabilize the opening in the bottom. Turn the lower body profile, sand, then part the body from the head. Mark the center of the top end of the body and drill the last remaining bit of the main body boring on the drill press. This is just a storage compartment so it doesn't need to align perfectly with the boring you did from the bottom. The reason I do it this way is that it allows me to be sure the opening in the top of the lower body is centered, which it might not be if I bored all the way through from the bottom and the bit wandered a little on the way. The blank for the head is still in the chuck, so I drill the small bore hole through that, all the way through where the parting cut will land. Turn the tenon to register the top to the body, then shape and sand the top, then part it off.

Like I said, lots of ways to do it, but this one works well for me and doesn't require a purchased or shop made jam chuck, so another option for you.

I realized I skipped a step in there -- I never bothered to purchase a 1-1/16" Forstner bit, so my main body bore is 1". I use a scraper to enlarge a short section of the lower end of the 1" until it fits the lower insert of the mill kit.

Best,

Dave

[David Metzman]

Thanks - that is helpful. David

[Dave Mount]

After I wrote that I realized I was making some assumptions about your mill/shaker design. Some salt/pepper shaker kits have a metal sleeve that goes all the way through, basically lining the storage chamber. The bore for these has to be straight, so drilling from both ends like I describe could cause problems. In that case I'd drill the whole length of the body at one time before shaping, then turn the body true to the bore, which requires a jam chuck (or something) to drive the piece while centering the bore. I'd still opt for a shop turned approach because of the guaranteed trueness.

One approach to this problem that is more easily reusable and a little more adaptable in its fit is to turn the part of the drive piece that goes inside the bore in a slight taper, starting with a diameter a little bigger than the taper. Then using a bandsaw or hand saw to cut two kerfs down the length of the taper, at right angles to each other, which turns the part inside the bore into four fingers that can flex a little bit. As you snug your blank onto this, the fingers compress a little and will fit snugly even in pieces that differ a little bore diameter. Push the blank onto the chuck with the tail stock and center to keep it aligned as you push it on.

Rereading my explanation it sounds muddy. Drew a little sketch to help (I hope, not much for hand drawn artwork).

Best,

Dave

448704