Donut or Straka Chuck

[Thomas Canfield]

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This is new thread to show the Donut or Straka Chuck that I made after visiting Kelly Dunn in Hawaii and later seeing the article in AAW magazine. This is a prototype (yeah, sometime I will build a lager one) that has served well. The first photo shows the back of the 1" plywood (15 1/2"D) with 3 1/2" aluminum Pencil faceplate and 6 holes on different diameters, or 3 in close with the 3 larger holes at angle (Kelly said for shining light inside workpiece to check bottom). Second is chuck mounted on my holder and using a PVC section with wood block for extension inside a natural edge bowl shown off with shelf liner inside. Third shows the bowl mounted with the donut held by 2" bolts added to 6" long all thread and coupling nuts for length, and Fourth shown complete chuck on lathe with the holder still on the ways. The foam pad is closed cell foam from McMaster Carr and really too soft. Next time I will use something firmer since this takes a set and makes adjustment for centering hard. I did draw circles on the foam to help with centering and inserting bolts.

Use a template when doing the drilling to allow for making additional donuts in future a need requires. My donuts are mostly 3/8" and some are 1/2" scrap (the one shown is actually used 1/2" treated). I cut the hole at an angle to provide surface for contact and use slit poly tubing to provide a soft face, but have also used the rubber shelf lining for small hole. Bolts are 5/16" carriage bolts.

[Thomas Canfield]

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Additional information:
This shows a rack that sits on the Powermatic leg to hold the Donut / Straka Chuck and donut plates, and also the rack to hold the different lenght bolts, wing nuts, washerss, and 6" all thread with coupling nuts.

The other pictures show a Texas Valley Norfolk Island Pine hollow form about 3 1/2" D by 8" H that originally had a foot like a and lamp, bottom originally turned using a jam inside and tailstock to turn down to a small section cut off with chisel and sanded. While buffing it got away from me and lost part of the foot in too many pieces to find. The donut chuck was my only option then to work on the bottom, and I had to cut one of my "blank" plates with small hole. Worked like a charm.

[John Keeton]

That is a well thought out setup! I like the idea of the PVC extension and I could see where that would come in handy. Good idea with the holes for shining a light, too! Thanks for posting.

[George Guadiane]

GREAT STORAGE IDEAS!!!
I already have a set of rings, but I also have a gob of threaded rod sets that I invariably have to sort out to find the lengths that I need... I'll be using that "useless" space under my headstock to store the rings AND I'll make a rack like yours to sort the rods once and leave them organized.
I also want to make notice of the clear tubing. It is a much lower profile than the glued on foam rings that I cane up with, so I'll make THAT change. I'll probably use a larger diameter center tube for when I do bark edge bowls.
NICE, Thank You!

[Thom Sturgill]

Nice setup. Here's another idea I've seen something similar to (I know people that do this for jamb chucks):

Take some scrap blocks, say pine 2x6, whatever is handy and cheap, and cut them round and turn a groove that your pipe (or fitting) will fit into snugly. Then when needed fit one on the pipe and turn it to fit inside the bowl. Line it with a simple paper towel and you've supported the bowl inside and out. You can also turn a shallow groove on the face of the backing plate so that the pipe automatically centers- doesn't need to be more that 1/16"

[Christopher K. Hartley]

Good work Thomas, it has a bit of a new twist to it judging from the normal ones I have seen and made. You should take some time and make a tutorial that could be shared by others in the future. Thanks for sharing.:)

[Wally Dickerman]

I used a donut chuck for a lot of years on a lot of bowls and HF's. I prefer to have no padding at all. I find that I get a more solid cut when the rim of the bowl doesn't rest on padding. I can't recall ever damaging a bowl in any way. I do have a small amount of padding on the donut at each bolt. That also keeps the rest of the donut from coming into contact with the bowl.

I prefer to have just 3 bolts instead of the 4 or 5 that some do. You don't need more than 3. I prefer 1/4 inch plywood for the donut because it has a little give but not enough to damage the piece.

Hey folks, I saw the original. I got the inspiration for the donut chuck when I visited Jack Straka on the Big Island in Hawaii in 1986 and saw one in use.

Wally

[Bernie Weishapl]

That is a good looking chuck and like the storage idea.

[Rob Cunningham]

Good looking chuck and accessory storage. I like the PVC idea too.
What are the larger holes near the faceplate for?

[Thomas Canfield]

This was started in response to Ron Bontz http://www.sawmillcreek.org/showthread.php?t=152108. Thanks for your comments. Some additdional thoughts in answer to above replys:

1. Make the largest diameter disk that you can use on your lathe, allowing some clearance to ways. Disk should be at least 3/4" plywood or thicker if over about 12". (Mine was made from scrap speaker cabinet and that dictated size). The only problem with the large diameter is slow speed limit for smaller pieces. Maybe you want 2 donut chucks (I do have one for Jet mini also but not near this good).
2. A dedicated faceplate should be attached and left in place. Faceplate should be shimmed if required to have disk spin true to minimize truing the face for flat surface. Remember this will be a LARGE spinning object and you want best spin possible. The good thing is that one is usually only working on a small diameter in the center and bottom can be blended to sides. The problem comes in with trying to make concentric cirles to match original turned bottom.
3. A template should be made and kept to provide the correct drilling pattern. Template and donut disks should be marked for installation orientation. Gang drilling of backup disk and donuts USING A DRILL PRESS OR DRILL GUIDE makes faster work. 3 bolts work for most and are easiest to balance, but 6 bolts provide more holding and would seem better for flexible donuts.
4. Large holes are for shining light inside from back of headstock to assist in checking bottom thickness for thin translucent materials - optional.
5. Donut disks thickness could probably be 1/4" plywood depending on diameter and mass of workpiece. 1/4" does not give much surface contact but easier to install poly tubing (easy to slit straight pulling through a hole across razor blade).
6. Soft face is optional, but adhesive backed foam applied allows for marking circles to help with centering of workpiece. Without foam face, a workpiece on a pad would be easier to shift on the lathe to center. Experts will have to give opinion here. (Maybe I will try none on my next one).
7. The use of the PVC spacer and jam block were shown for idea of flexibility of the donut chuck. I am now considering making a center hole to accept a tenon on extension piece or a block to accept the PVC extensions.
8. Carriage bolts are used. A bolt was inserted into the bolt holes on the donut disks and the square shank under head impression made for future use to hold the bolts and allow tighting bolt using wing nuts.

[Michael James]

Nice job, and thanks for taking the time to post this. I definitely need one... soon!:)
mj

[Gene Hintze]

Thank you Thomas. I have had most of the components for making a donut chuck for some time now but have never gotten around to doing it. This will be my Saturday morning project.

[John Keeton]

Hey folks, I saw the original. I got the inspiration for the donut chuck when I visited Jack Straka on the Big Island in Hawaii in 1986 and saw one in use.

WallyGreat comment, Wally. The richness of your varied experiences is priceless.