Making a large washer.

I am needing to form what can best described as a large washer out of 3mm mild steel late.. 39mm dia centre hole, with a 89mm outer edge.

Could any of this be done on a lathe or milling machine ?

Could I just cut and grind the outer dia and then finish off on a lathe ?

Justin, depending on your lathe size and accesories, you could do it with a faceplate and clamps. Drill and bore the middle, then clamping off the bore, turn the outside diameter. Lacking a faceplate, a metal plate or even wood atached to a spigot to hold in the chuck would suffice.

Bill

on turning steel, can you start off with something only vaguely round (or even square) and slowly chip away at the high bits until its round. It is what I would do with wood but not sure what can be done with steel.

If you cut a bit of 3mm plate into a square, then cut the 4 corners off you can hole in the 4-jaw and bore the hole. Then change to 3-jaw with the jaws inside the hole and expand the jaws to hold the work while you turn the OD. Corners can be cut off before or after the hole is done

Edited By JasonB on 09/06/2023 15:53:53

Hacksaw an octagon 90+mm AF. Mount in 4 jaw chuck and drill / bore 39mm hole. Then mount in 3 or 4 jaw using this hole and carefully turn the 89mm dia.

Edit; Jason beat me to it, can't compete with the pictures either.

Edited By Clive Brown 1 on 09/06/2023 16:17:07

An 1.5" washer may well be about this dimension ? Try a fastener company ! Noel.

and if i only have something to make a 36mm hole, can I turn out the rest of it ?

Hole saw or Rotabroach type annular cutter in a tailstock is a good start to save time drilling and boring. I think this is what you are thinking. A large drill that size in a lathe and in material that is that thin may cause problems.

Martin C

Sounds expensive for a one off. I'd use Jason's method

You could make one on a mill, but having a rotary table would simplify things. The hole could be bored first. If the lathe is big enough, that would be my first choice.

Having an objectively excessive collection of Starrett hole saws I can generally find one quite close to the needed inside and outside sizes which minimises the amount of lathe work involved.

A certain care is needed when doing the lathe work to stop the nascent washer from twisting out of position in the chuck leading, at best, to misshapen inside and outside diameters. At worst the thing pretzelllises before self ejecting from the chuck.

Which is annoying.

The grooves in the jaws aren't guaranteed top hold the thin part in a secure and stable manner. The job is most at risk when taking the corners off the outside. The more sides you cut initially the lower the knock-knock-knock forces at each corner making it much easier for the chuck to hold properly. Clive Brown advises starting with an octagon rather than square which is what I used to do before getting into hole saw collecting.

Trapping a piece of suitably thick wood, MDF, particle board or similar between the embryo washer and the chuck jaws to act as a sacrificial support can help. No need to make it tight on the centre or terribly round. It just needs to sit under where the tool is cutting.

As with so many such jobs belt and braces set-up is frequently not needed. The job going fine when just held in the chuck. But taking that extra care costs little time when "thats the way you do it".

Clive

Hi Justin look up trepan it’s the easiest way

to cut a large washer out of a flat sheet of metal

in the lathe

hope this is helpful

steve

Hi Justin look up trepan it’s the easiest way

to cut a large washer out of a flat sheet of metal

in the lathe

hope this is helpful

steve

+1 for Jason's method!

Howard

For holding reasonably thick stock larger than the chuck:

Tap it and screw it on a threaded rod or preferably long bolt with the head behind the jaws.

And remember: Usually the most efficient way to remove metal is sawing. Interrupted cuts isn't doing your machine any favors either.

Edited By Fulmen on 09/06/2023 21:16:56

Effective though trepanning is grinding the tools can be tricky if you've not done it before and don't have a good guide with decent pictures. As ever it gets easier the larger the job is. Grinding a satisfactory tool to handle holes under 400 mm, 1 1/2 inches or so without putting excessive force into the sheet can be quite difficult.

It's important to fix the sheet securely to the substrate as there is significant force trying to make things ripple. Worse with thin material.

I can, and have, both ground the tool and done the deed successfully but I'd rather not. During my efforts I didn't have that nice warm fuzzy feeling of proper understanding with everything under full control.

Clive

You could mount the raw material on a relatively small arbor to turn the OD and then make up a beel chuck to bore bthe central hole to size.

Deburring may well have to be a manual opoeration.

Howard

@Clive: Same here. I recently made a couple of 5mm deep grooves, 23/29mm dia in mild steel. I broke 3 cutters and was sh*tting bricks the whole time.

Boring bar would be a good way to open the hole up to 39mm from whatever your largest drill size is. The job is only 3mm thick so not a lot of time involved. Saves the expense of buying a hole saw etc.

And cutting the corners off as Jason shows above is generally easier than trepanning, which is kind of like parting off on a curve so the tool needs to be ground just right for it to go smoothly.

I would do this on a lathe and start by the making the inner hole using drilling and turning.

If the thickness of the washer has tight tolerances, now would be the time to face one side of the washer.

For the outer diameter I would clamp the inner hole on the 80 mm 3 jaw chuck from my mini lathe (the faced side towards the chuck).

Face the other side of the washer.

Turn the outer diameter + 0.5 mm) using the trepan method or turn the outer diameter using modest depth of cut.
Turn the outer diameter to the final dimensions.