search for expanding lathe arbors

cheap screw solution to locate off bore: Clamp bar stock in chuck. Turn to size. Drill and tap taper pipe thread in end. Leave bar in chuck to minimize run out. cross cut end of bar with hack saw and debur. taper pipe plug will expand arbor enough to hold gear when torqued.

to locate of teeth faces use a plate with a taper hole matching the taper of the bevel gear and three dowel pins to locate off the teeth faces. Clamp the plate to the face plate, bore the tapered hole with compound and leave attached for minimum run out, clamp the gear in the hole using dowel pins to locate off tooth faces. Bore hole to size, then use expanding arbor to machine gear as required.

Let the group know what works!

On Saturday, February 1, 2014 2:56:33 AM UTC-5, F. George McDuffee wr

That is a good way to make an arbor to hold a part for machining. But in m y case I want an arbor so a part can be rotated and any out of round can be seen. And I would like it to be useful for bores from a bit under 2 inche s to bores of three or four inches.

On the current gear being worked on, the bore is now a bit over two inches . The final bore might be as much as 2 15/16 ths. So almost an inch bigge r.

This might be useful, but I hesitate to use a plate with a tapered hole to hold the dowels. The little gear is a bit over a foot in diameter. The l arger gear is more than two feet in diameter. So maybe use bungee cord to pull the pins into the gear faces. The problem is that the dowels do not f it snuggly, but may be good enough for a reference. Currently the thinkin g is to use the gear teeth as cast. We do not have a mill big enough to ma chine the teeth of the larger gear and I am not sure if the mill is big eno ugh for the smaller gear.

Dan

I'd probably chuck up a piece of scrap and machine a countersink in it that's the same angle as the bevel and clamp it into the conical recess with a washer that's been bored out enough to let the hub stick out and that's held to the other piece with three screws. .

If you want it to be REALLY acurate, you can use 3 dowell pins, appropriately sized to pick up on the involute instead of the major, (hold them to the gear teeth with stick wax while you're tightening the fixture washer)

"F. George McDuffee" wrote in message news: snipped-for-privacy@4ax.com...

I have trouble imagining this.

Say you have a ring cut from flat plate, somewhat smaller than the gear OD. You drill the ring for as many parallel, evenly spaced , axial dowel pins as the gear has teeth. When you place the ring upside down onto the gear so each pin fits between two teeth, does the plate automatically fall parallel to the base of the gear's pitch line cone, so that you could mount the gear on a rotary table and indicate the ring to level and center the gear?

I think it does, and you need only 3 or 4 dowel pins.instead of the full set.

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Given these are bevel gears, the best bet for a gear face locator pin might be a round magnet.

Given the size of the parts relative to the machines, some of the old time machining books will have some hints. railroad and ship machining would be a good place to start.

One old time "arbor" kluge is a "cats head" mandrel

This is not the cat's head that goes over irregular barstock, e.g. hex, so it can run in a steady rest, but is a mandrel with 2 sets of stout hex head screws set at 120 (or

90) degree angles that can grip the inside of bore. [Most likely 3 at 120 is better as this gives more room to swing the wrench to adjust the rear set] By adjusting the screws the workpiece can be tilted and offset relative to the mandrel. I've never used one, and they look to be a real PITA to adjust, but would seem to do what you want, and should be relatively cheap/easy to make.

Lindsey Books had many reprints, but is no longer in business.

Your Old Time Book Store bought most of his inventory. Their website is

try

also see

sounds more interesting all the time. be sure to let us know how things work out.