I need to make some clamps for attaching the vertical head on a P&W3c mill.
The features on the clamp are all circular, with radii ranging from about 2" to 4"
Rather than milling each piece one at a time on a mill with a rotary table, I figured turn a disk on the lathe with the cross-section profile of the clamp and then slice it like a pizza (a seven-section pizza, oddly).
I have a piece of 3/4" thick 8" diameter steel that I can use.
Question is: what would be the best way to hold the work?
I was thinking this:
Start with a a 2" diameter chunk of aluminum rod, face in the lathe for perpendicularity and flatness
Drill three holes (tap size) on a 1"-1-1/2" diameter circle in the center of the disk
Bore matching holes in the aluminum and tap them
Open up the tap-sized holes on the disk to clearance holes (tap holes first was to get accurate location for the aluminum)
Bore the soft jaws to fit the aluminum rod (using soft jaws because of the larger contact area)
I should probably face the soft jaws to ensure that the disk sits flat.
Mount the aluminum in the soft-jaw chuck and face to get a flat surface
Bolt on the disk
I figure I should make a profile template that fits into the clamp so that I can machine to where the template fits my machined disk.
Any other ideas?
Steve
How do I hold this
Re: How do I hold this
You're going to make 7 of those pie-shaped clamps?
I would probably turn them all as you suggest from one piece. It looks like the stock could be held normally with vice jaws - face/turn the back side, then flip and turn/face the steps. Then I would probably drill the holes for each clamp as a place to clamp for milling out each piece of the pie, probably on a RT. Once set up there, you should be able to mill the relief. You might need a pallet with drilled/tapped holes on your RT.
I would probably turn them all as you suggest from one piece. It looks like the stock could be held normally with vice jaws - face/turn the back side, then flip and turn/face the steps. Then I would probably drill the holes for each clamp as a place to clamp for milling out each piece of the pie, probably on a RT. Once set up there, you should be able to mill the relief. You might need a pallet with drilled/tapped holes on your RT.
Standards are so important that everyone must have their own...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...
Re: How do I hold this
My rotary table doesn't fit the mill I have operational right now, so the cutting will be hand or bandsaw (ouch!), then cleaning up the sides on the mill.
The face that is down in the picture only has a counterbore in the hole, so that can be done on the drill press or mill at the same time as the hole is drilled. No turning will need to be done on the back face.
There is the little relief on the clamping tab which ensures that it clamps out at the widest part and not just in the middle. That will be a quick job on the mill using a fixture or some clamps on my pallet to hold it.
I drew it out a while back and it worked out to 7 pieces. I might make it 6 just to give me more room for messing up the saw cuts.
The face that is down in the picture only has a counterbore in the hole, so that can be done on the drill press or mill at the same time as the hole is drilled. No turning will need to be done on the back face.
There is the little relief on the clamping tab which ensures that it clamps out at the widest part and not just in the middle. That will be a quick job on the mill using a fixture or some clamps on my pallet to hold it.
I drew it out a while back and it worked out to 7 pieces. I might make it 6 just to give me more room for messing up the saw cuts.
Re: How do I hold this
If you turn them on the lathe, why is a rotab needed? You'll have all of the concentric surfaces from the turning operation. Just chuck the piece and turn it. The pie pieces will leave some waste, but all of your radii will be done. If you don't have a chuck big enough to hold the 8" piece, mount it to a face plate. I'd drill the holes first, but undersize such that a SHCS will fit down in the work, recessed so you aren't cutting the heads of the screws. Then after it's done, saw out each pie piece and drill the holes to size. The only mill work needed, would be cleaning up the edges, and the what-looks-to-be square-sided recess along the clamping edge.
Re: How do I hold this
Here's what I'd envision. Sorry for the line errors. All I have on my work laptop to draw with is Visio.
Re: How do I hold this
How do you cut out the pie pieces, and then how do you hold them to finish the edges and then locate the hole, without a rotab?
Standards are so important that everyone must have their own...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...
Re: How do I hold this
That's exactly what I am thinking.
Bandsaw them, then clamp them in a vice and mill the edges to finish. The sides are not important dimensions.
For the holes, I will just use a pointed tool in the lathe to draw a circle. Then I can just estimate the position - the distance from the edge is more critical than where along that circumference.
I might just go with six, as it will give me more leeway to mess up with the bandsaw, and then I can also use the 60-hole indexing feature on my bull gear to mark the exact position along the circumference of the scribed circle,
Steve
Re: How do I hold this
The radius on the outer edge will, of course, determine how big of a piece you have to start with to do it this way. The width across the wide end will determine how many pieces you can get out of one circle. Once you have the turned features in the workpiece, it's not much more work to make the 7th piece, IMHO.
Dave
Dave