Cutting pullies on a rotary table on a mill

This sounds crazy enough to maybe work. 20 minutes would be a lot faster than the 4-step pulley I just made. Mine took me about six hours on a small lathe. I chucked up a piece of aluminum, then bored and reamed its central bore. Then, in the same chucking, I mounted a specially ground tool in a boring bar and stroked the keyway. Then I mounted it on a mandrel and mounted it in the lathe and faced it fore and aft then turned it round and then turned the steps and then took the parting tool and turned all the corners and parted everything to depth and then swiveled the compound and turned all the sides of the vees. Then I took it to the mill and drilled and tapped the set screw. It isn't too hard, just quite a bit of work. It doesn't have much runout, especially when you compare it with die cast step pulleys.

Grant

frank wrote:

Sounds like you did it about like I would, but I suspect the time was due to your small machine. It would go a lot faster on his atlas. If I had the lathe I wouldn't even consider doing it on a mill.

It doesn't have much

If you'd learn to rough your parts before finishing, runout would be a thing of the past (assuming you used proper machine procedures, that is!). It is not good practice to machines parts to size on one side, then turn a second side, especially when removing a lot of material. Good policy dictates that you would leave about .05" on the surfaces for finish machining, which would remove any runout you would have from stress relieving. It also helps prevent damage to your work because finishing operations tend to be much lighter, thus demanding much lighter chucking pressures..

Harold

The key problem is the large pulley cannot be cut on the lathe. It will not fit.

The only other power tool I have to do the work is a mill/rotary table, and since I have to set that up to do the work on one pulley, it seems like a good idea to just cut all 4.

But in practice I would probably cut one pulley on the lathe while the mill/rotary table chewed away at one pulley.

My Atlas has a 1/2 hp motor and the Bridgeport has a 1 hp motor. Blowing through

6061 T6 with not-that-high precision seems to be a function of motor hp and little else. The mill wil be quicker.

How about making your own? Precut it with something that fits more or less and do the rest with your home built cutter.

Nick

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Do you have a stub arbor for conventional milling cutters (those for horizontal mills)? If so, what you might be able to do is first cut a groove to the depth of the pulley's needed 'V' with a standard one, then take a somewhat wider one, and have it ground to match the profile of the 'V'. (This will need someone skilled at using a Tool and Cutter grinder, but will result in pulleys with all 'V' the right shape. (It will also probably fill the shop floor with chips. :-)

I would be more tempted to use a horizontal miller with the rotary table -- but that is in part because I *have* such a miller.

Probably the most critical feature would be the design of the clamping part on the stub arbor -- you run the risk of running into the next sized step with the hub -- unless you started out with a rather large milling cutter before modifying it to 'V-groove shape. Be sure to lock up all axis motions which don't need to move, as this is going to be asking for chatter with a vertical spindle mill.

Good Luck, DoN.

Do you really need a pulley larger than a 10" for that lathe? Seems awfully large to me.

John Martin

A perfectly valid question.

The fact is the standard pullies are a specific size. Regardless of what size they are, they are a specific size. Does one actually NEED the standard pullies? No; my lathe has been run without them for at least a decade.

The first reason (pulley) size matters is the cutting tables that came with the lathe. They are all wrong if the pullies are wrong. Second, I bought a nice visual aid -- essentially a 3-dimensional graph, where the common cutting issues on this lathe are addressd. It is useless if the pullies are wrong. Third, just for the sake of completeness, it would be nice to have the standard pullies. Finally, I do have all the tools required to make the pullies, so this seems like a good project.

A few years back I cut some pullies out of solid aluminum for use in some very nice snatch blocks. This was done on my mill, using a ball endmill and a rotary table in vertical mode. It was a near tangental cut, and I cranked the table on the mill to get the right depth.

When my neighbor moved out he gave me (literally) a pile of very heavy cutters for horizontal mills. They have removable teeth. Right now I am thinking about an R8 stub arbor using one of these removable-tooth cutters. I can grind three teeth -- left, right and bottom -- to make the cut.