lathe cutting circles

I need to cut 5" circles out of 1/2" steel square plate. I will have
to bore a 1" hole in the center.
Whats the best way to do this with a lathe.
Reply to
chuck
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If I had to do it I'd try the following:
1. Oxy cut the circle oversize. 2. Drill & bore the 1" hole in the center. 3. Mount the plate on a mandrel of some sort and turn the od to size.
I'm sure our guru's here will have lots of better ideas! :)
Reply to
K Ludger
Torch, saw, whatever, close to a circle but a bit oversize. Drill hole in center. Bolt with a 1" bolt. Put several nuts on the bolt and line them up. Now you have an arbor to turn plates to size.
karl
Reply to
Karl Townsend
I need to cut 5" circles out of 1/2" steel square plate. I will have to bore a 1" hole in the center. Whats the best way to do this with a lathe.
Reply to
chuck
chuck fired this volley in news:93657769-d75e- snipped-for-privacy@r27g2000vbp.googlegroups.com:
Didn't you just ask this, and get answers?
Cut a bunch of 5.25" square plates. Knock off the corners, too, to save lathe time and interrupted-cut frustrations.
Drill the center of each. Stack all the plates on a 1" bar, with jam nuts at each end to tightly clamp the plates together into a "solid rod" of octagonal blanks. It can't hurt to loctite all the disks together. Heat will re-separate them when you're done. It also can't hurt to cut a small "hub" for at least one end, to ensure they stack exactly square on the rod.
Turn to size between centers, or between the headstock chuck and a tailstock center.
It sounds like a lot of setup, but goes very fast once the tools are made.
Or, you could just have them cut on an abrasive water jet machine, or a honkin' big laser cutter.
LLoyd
Reply to
Lloyd E. Sponenburgh
I don't know 'best' or even good & fast, but some slow, tedious ways to cut one on an old 10" belt-drive lathe are
Large hole saw Trepanning tool, like a cutoff bit but ground to the curvature Cut off the corners with a bandsaw Rough it out with a torch or plasma.
I saw the corners and then round the blank because the hole saw and trepanning tool are likely to jam, and heat may harden the cut line. YMMV on a larger machine. The vise on my 4x6" bandsaw won't hold large squares securely at an angle either horizontally or vertically so I C- clamp them flat on the table.
After sawing the corners you could rough quite close to the line by clamping the drilled blank(s) upright in a mill vise on a rod or bolt shank that rests on the vise jaws. Mill off the top, loosen and rotate a little, mill off the next corner, etc, all by eye without measurement. Cut crosswise, chips flying toward the column, otherwise the blanks may shift. If you rough to within ~1/8" then the light cuts necessary when the work is on a mandrel or stub arbor won't take too long. I've had the best luck and fewest jams with a narrow bit such as a TPx insert or the HSS equivalent, mounted point-in like a threading tool. It's much easier if you can drill extra holes and bolt the blank to a face plate.
Jim Wilkins amateur machinist
Reply to
Jim Wilkins
chuck fired this volley in news:93657769-d75e- snipped-for-privacy@r27g2000vbp.googlegroups.com:
Didn't you just ask this, and get answers?
Cut a bunch of 5.25" square plates. Knock off the corners, too, to save lathe time and interrupted-cut frustrations.
Drill the center of each. Stack all the plates on a 1" bar, with jam nuts at each end to tightly clamp the plates together into a "solid rod" of octagonal blanks. It can't hurt to loctite all the disks together. Heat will re-separate them when you're done. It also can't hurt to cut a small "hub" for at least one end, to ensure they stack exactly square on the rod.
Turn to size between centers, or between the headstock chuck and a tailstock center.
It sounds like a lot of setup, but goes very fast once the tools are made.
Or, you could just have them cut on an abrasive water jet machine, or a honkin' big laser cutter.
LLoyd
Reply to
Robert Swinney
It all depends on what equipment you have to work with. With a good lathe I would just chuck the piece using stops in a four jaw chuck and cut them round, half a side at a time, then drill and bore your hole.
By stops I mean hex bolts set into tee slots of the chuck the heights of each bolt set so that half the thickness of the plate extends beyond the jaws of the chuck so you can cut it. Remove the jaws and cut the tops of the bolts so they are even and you can bank each plate against them. Put the jaws back and chuck up the piece using a scale to get the piece centered in the chuck by measuring from the outside of the chuck to the four sides.
With a solid lathe you will have no trouble with the interruped cut. If you lathe is not that sturdy, waterjet would be another way to go. Steel suppliers will usually cut the plates for you at a nominal charge if they are supplying the material. Cutting through burned out material can be a minor problem. Grind off the slag before you put it into your lathe.
John
Reply to
john
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, down near the bottom of the page. I used a cutoff bit, it was scraping a bit on the inside cut (about 6" diameter) but it worked, might work for a 5" cut if you grind back the lower edge of the cutter.
H.
Reply to
Howard Eisenhauer
I bought a bunch of 5" x 1/4" disks and I think they have them up to 3/8". If you need the full 1/2", could you bond two of the 1/4" together? Sure would save a lot of time!
Reply to
Buerste
Thanks all for your ideas. I have a SB10K lathe, I don't think it could handle interupted cuts. I'll use a torch to rough cut then the lathe.
Reply to
chuck
Thanks all for your ideas. I have a SB10K lathe, I don't think it could handle interupted cuts. I'll use a torch to rough cut then the lathe. ================================
O/A can leave very very hard edges/slag that is tough on tooling.
My buddy made thousands of circles about this size, but from 1/8 material. Cut in squares, drilled, mounted on an arbor with staggered corners, and let'er rip -- metal flying all over the place.
Mebbe you can do the first two steps, and bring them to someone with a heftier lathe (15"), to do the rough turning, which goes pretty quick. May not cost much. Depends on how many you have to do.
They make rigid hole saws (even carbide) that will do this, as well. Will likely need a bridgeport or equiv, can finish on a lathe.
Reply to
Proctologically Violated©®
My 10L handles interrupted cuts well. The only real problem is slip when driving the disk from a small diameter shaft.
jw
Reply to
Jim Wilkins
I do this often. first, grind off any slag. In the lathe, I've had much better luck with an extremely deep cut and a very light hand feed. You get almost no interuption this way. If you use HSS it will dull quickly. You can either resharp often or use brazed carbide.
Karl
Reply to
Karl Townsend
Chuck a 5-1/2" hole saw in your lathe. Hold the plate against a pad center in the tailstock ram. Feed the tailstock ram to cut out a disk.
Chuck a disk and bore out the center to 1".
Mount one or multiple disks on an arbor and turn the OD to 5".
No bandsawing. No water jet or plasma cutting. No torch cutting. No interrupted cuts. All done on the lathe, as you asked.
John Martin
Reply to
John Martin
The other thing you could do is have your metal supplier cut them off a 5 inch round bar. Then just face and bore them.
John
Reply to
john
that is a much easier lateral thinking approach. bandsaws these days do pretty accurate slicing work. Stealth Pilot
Reply to
Stealth Pilot

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