Cutting concentric rings (washers) on lathe

[darryl]

Gary, I totally misunderstood what you were asking. Since you clarified, others have given the answer, which is the trepanning tool. I do this often in plastic and in wood, and from that I know that you need a rigid tool assembly. This might be best done on a mill, where the mass of the table will help control chatter. It will help to have a considerable mass carrying the cutter as well.

[Spin Doctor]

This could also be done in a mill too. Same tools as a lathe but then the parts will drop straight down

[CCWKen]

Yep, and you better have a good measurement or a catchers mit too!

I hate when partings break through and go flying.

[SGW]

Yeah, trepanning is what you need to do, and the trick is to be sure you have enough clearance on the side of the tool to allow for the curve of the hole.

[Spin Doctor]

Definitely a job for a trapanning tool. Thionk of it dasically as a cut-off tool that goes in from the face. SPI has some really nice ones that one should be albe to copy with out too much trouble. You could also use a HSS cut-off blade as long as you make sure you have clearance on the side towards the lathe poerator. Make sure your set up is as rigid as you can make it. Use plenty of coolant and clear the chips out. Had to trapan a 15" diameter gear off of a part when we wanted to save the teeth for something else. Hd to go in about 1 1/2". It did get interesting. This is also the basic process that they make the field joints of the Solid Rocket Boosters for the Shuttle

[Joel]

Trepan them out.

[gkman11]

Clarification:
Material 1/2" mild steel
Concentric rings - one inside the other- all having the same center.
for example:
6" OD 5" ID
4.75" OD 3.75" ID
3.5" OD 2.5" ID
etc.

[darryl]

Many rings cut from an 8 in sq plate sounds like not a large diameter for the rings. Use a hole saw, lube, and go halfway from each side. Layout a series of pilot holes that will allow you to cut discs from the material without overlapping the cuts. If there's to be a relatively large id, then hole saw those out first to near finish diameter, then lathe a plug to press fit, with the pilot hole in it.

[ERBenoit]

What is the material? What size is the thru-hole? If you are making "washers" I would layout the center and O.D. Start from there,layout a diameter large enough to clean up, then, drill, ream or bore through hole to dimensinon necesary. Saw of as much as of the corners as possible. This will minimize the "hammering" effect of the interrupted cut. Turn a stub about 1/8" shorter than the plate thickness, fitting the I.D. of the plate. Tap a hole and secure plate to stub with a flat washer ( I use machined washes, they are thicker) and a SHCS. If you have a finished I.D. that you cannot cover using the above method, say 6 1/2", I would proceed as follows: use the method above, the I.D. of the hole, O.D. of the stub is as you see fit, since it will be removed later, turn the O.D. on all work pieces. Then bore the I.D. The concentricity you require will determine how you should hold the work when boring the I.D. The shape of the tool should be as recommended for the material you are turning, since that is what you are doing.

[gkman11]

What kind of tool shape and method can I use to cut several concentric rings from an 8" square of 1/2" plate on a lathe without a lot of waste?
Thanx,
Gary