Saw surplus to produce Octagonal shape much nearer the required diameter.

Robert Butler

To be honest, there's nothing to stop you leaving them as is, and just turning down the register to fit your chucks. I have one mounted like this, and it's never caused me any issues. Additionally, you could drill a series of holes around the periphery and make an indexing device. Bonus feature!

Rob

Edit – Nick got there first!

Edited By Grindstone Cowboy on 12/05/2023 12:53:02

Another edit as I can't spell chucks

Edited By Grindstone Cowboy on 12/05/2023 12:53:45

I would guess they are cast iron, so it really should not be an issue to reduce the excess to swarf in fairly short order. Carbide tool, generous feed rate, modest speed, coolant to keep the dust down. Go for it.

Martin

An ML7 will cheerfully take 100 thou deep cuts all day long. That knocks .200" off the diameter. So five passes and your 5" backplate is down to 4" inches already. Couple more and you you are there at 3.5".

You will probably need to use top backgear at that diameter with HSS tooling. Or use carbide xxGT inserts and run a bit faster, maybe 200rpm (lowest non-backgear) and really shift some metal.

Won't take long at all. Making swarf is what lathes are for. The finished job is just the leftover bit after the swarf is successfully removed to its rightful location in the tray. The backplate is only, what, half-inch thick? Not much swarf at all over that length.  Keep your fingers away from it and used a suitable old screwdriver bent over at 90 degrees at the end to safely hook swarf curls out the way as you go.

Another trick, if it is cast iron not steel and so firing off little fragments of swarf all over the place rather than long curls: Take a piece of cardboard (side of a fag packet is traditional), stab a hole in it with a pen or tool bit and slide it over the lathe tool bit shank so it forms a little shield that stops flying fragments going all over the place. Works great on brass and helps with cast iron too.

Edited By Hopper on 12/05/2023 13:10:08

When doing cast iron and producing lots of dust I rig up a clamp to hold the vacuum cleaner pipe to catch the debris (I hesitate to call it swarf) Still cover everything possible with paper, not cloth.

"a few pence over £15"? I'm only seeing them at £26.50, otherwise I'd get a couple too.

Rob

Warco site is now showing reduced sale prices again

If the Backplate is cast iron, place a powerful magnet under where the swarf will fall, and cover it with a few sheets of newspaper ; taking care that it douls not get involved with the chuck.

The magnet will concemtrate a lot of the swarf in a heap.

When machining is finiished, the nwsparer can be caredully folded and the cast iron dust disposed of, with minimum cleaning up the lathe nand its surroundings being necessary.

Howard