) the other day (followed a thread from this group) He has a page that describes making cole jaws from plywood for a oneway chuck. I tried it (first try) & the jaws were way off. I imagine that I drilled the holes wrong. It was my strategy to drill holes while the circle was whole & make sure they fit the base jaws & then round the disc and bandsaw from there. When the holes in the ply didn't line up, I bandsawed anyway & met disaster-- anyway Question: Could I turn a disc and turn a recess to match the bump out on the back of the outer jaws & actually use the jaws as a drill guide? They ARE case hardened-- I don't imagine that a hss drill would round out the holes. Thought I'd pass this on to the group before maybe voiding my warranty with Oneway. PH---
Start with the "flat jaws" from Oneway... They're inexpensive (for Oneway *g* ) jaws that are designed to add your own clamping or holding system to..
After using ring clamps, a sock on the face plate or chuck, tuner's tape on a face plate of wood blank, and everything short of Voo Doo, I broke down this weekend and ordered a set of Jumbo jaws.. I'm tired of mickey mousing bowls just to save $80.. YMMV
Don't use 'em as drill guides but *do* use 'em as guides: find some nails or centre-point drill bits that snugly fit into the jaw holes and use them punches. If you put one in each hole of a jaw (and they fit properly) then you can use your free hand to hold the jaw level & in position while you give each nail a quick tap. This saves you from accidentally moving the jaw when using only one punch and moving it from one hole to the other. ;]
Personally I position all 4 jaws on the blank, keeping the same 1,2,3,4 order that they go on the lathe and tape around the outside to keep 'em snugged together. I also like to add some spacers (the same size as the kerf on the saw I'll use to divide the blank) between the jaws to allow a more accurate finish, but that's just me. [shrug] Doing it this way it's easier to use *3* nails... line up the jaws with the pencil marks on the blank and put nails in two opposing holes. eg. The outer holes of jaws 1 & 3. Tap 'em in enough that they'll hold the jaws in position. Use the 3rd to centre-punch the rest. Easy.
Don't drill the holes for the hold-downs until /after/ the blank's cut up and test-mounted on the jaws. Once 'tis mounted, assuming it fits , close the jaws as far as they'll go, spin 'em up and use a pencil to mark a circle for the diameter wanted. You can always add others later for the sizes you need as you need 'em. Shut 'er down, remove the blanks from the jaws and subdivide each quadrant @ about 20 to 24deg from the edges. Whatever angle you use, make sure all are the same! Then centre-punch & drill the hold-down holes at the intersections of the angled lines & circle.
Pre-measuring & drilling in advance is all very nice if you /know/ nothing will go wrong, but in my case...
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