Machining a Washer - Procedure

I have a piece of 4mm steel 80mm x 80mm. I have to form a 4mm thick washer, 80mm od x 72mm id. What is the correct procedure to do this ? Thankyou

I would hold in a 4 jaw chuck, centre it up. Bore the central hole, cut the corners off then hold the plate in the centre hole using the outside of the jaws, then machine the outside to finished diameter....

Others may have their own preferred method

Roger

You don't say what lathe you have but if its one of the lighter variety its worth knocking the corners off first with a hacksaw or angle grinder to reduce the clunk, clunk, clunk when you start machining down to round. Not good for the machine especially if its an older one with many hours on the clock and inevitable wear / slackness.

Clive.

Or don the tin hat and trepan them off.

Hi Roger

If you want the 4mm thick washer to be faced on both sides and parallel to each other I suggest you need to start with say 5mm thick plate, in any case plate thicker than the washer final thickness to allow for facing.

Emgee

Facing washer probably best done with suitably shaped soft chuck jaws.

I'd go for trepanning, less waste involved and can use the corners for bits and pieces.

The only thing you have to be careful of when trepanning large diameters is one can get a bit carried away with the speed and burn the tool.

Michael W

Edited By Michael-w on 03/04/2017 17:45:01

Surface finish depends on what the washer is for...

As the washer will only be 4mm by 4mm in section, I strongly advise against boring it out before knocking the corners off. Unless you approach it very slowly, it will distort, slip and may twist off the chuck. held by the outside or teh inside a 4mm wide washer of that diameter will distort if held by a chuck.

Drill a hole dead in the middle and fit it on a mandrel and turn to the OD. Use an M8 or M10 thread and a big nut/washer to hold it nice and tight so it doesn't spin.

Then make a simple trepanning tool like a flat ended d-bit from 3mm or 1/8" HSS or silver steel hardened and tempered, and use this to cut a groove to remove your washer. Take it very easy near the end and when it starts to break through you may want to break the washer free and debur rather than trying to cut it completely free.

Neil

A silversmith would bend a ring from square steel wire and weld/braze the join. Much less waste, see. A blacksmith might do the same if the wire was 10mm or more ...

Cheers, Tim

Perfect excuse to buy a plasma cutter.

80 x 80 square material and you want an 80mm diameter washer with presumably a concentric 70mm hole?

You will almost certainly end up with a washer with 4 flat faces on the OD. So start with a larger piece of material.

Frankly I wouldn't do any of the dangerous, haphazard or frankly odd practices described. Sorry if that offends chaps but really.

Treat yourself to a piece of larger diameter bar. Face it off, drill and bore the 70mm hole, turn the OD to the required 80mm and then simply part it off at the required thickness. Undoubtedly others will disagree but that frankly how I would do it

Why go to the trouble of trepanning the corners ?

You will have 4 interrupted cuts every rev getting an 80mm circle out of an 80mm square plate and just to save 4 tiny triangular bits of steel that will never get used again ?

So for saving 4 silly corner chances are you break a trepanning tool or rip it out of the chuck and you have to start again.

Like you are going to find 'em in the chip-tray anyway.

Saving tiddly "useful" bits is something I need to get over. Probably 'undreds of small but too big to bin bits around my place that I really need to go through, man up and (mostly) bin. Example just been doing an 1" (ish) angle iron job maybe 50 offcuts in the 1" to 2" long range. OK keep a few for diddy brackets but there are already 40 or 50 similar size in t'box.

Getting back to the original job I'm with MadMike and would start off with a bigger bit of material. Preferably round so no worries about corners. Last time I did similar I hole sawed it out of flat bar and cleaned up to size. But that was in alloy and about 130 mm diameter.

Clive.

Edited By Clive Foster on 04/04/2017 01:05:37

I've looked at the size again and realized you can't do it without an interrupted cut simply due to the size of the plate, in this case you're better off hacking the edges off and turning the o.d with a turning tool.

Michael W

Sounds like a faceplate job to me. You have four corners to clamp it by and providing the 4mm plate is flat it should be good enough. If it is just a washer, then I am sure a few thou shy on the dia will not matter. Set up on the faceplate, you will need to make sure it is accurately centered, hack out the middle, and bore to size. Saw the corners off and as much waste as you can. Ideally a four jaw self centering chuck can be used to turn the O.D.

I made a large stainless washer yesterday, albeit of different dimensions to fit a Belfast sink in the new garage.

Inner was hole cut undersize with normal hole saw in pillar drill running slowly with lube.

Outer diameter was then cut with small hand guillotine oversize. I then place the rough washer in the 3 jaw, in expansion mode, and sized the outer rim, swapped the jaws over, and held the now finished outer in order to bore to size.

In my case the washer was thinner (so I could use a guillotine) and larger, but I've used a similar method by clamping the donor plate to a sheet of plywood and used two different sized holesaws to get the starting annulus, still all done in the bench drill.

Obviously cut the inner hole first, so you can still hold the blank; the drill centre hole in the plywood is enough to guide the bore for the larger hole saw. Just replace the drill bit in the hole saw with a suitably sized length of plain rod to run in the hole in the plywood sheet.

I can't remember what it was for, but I've done similar with 4 or 5mm stainless plate in the past to make something similar to what you're trying to achieve; it would have been a spacer for one of the motorbikes or the Marlin.

Regards

Bill

Roger M-Machine in Darlington advertise 80mm bright steel bar for around £4.00 per inch or, if you want to turn the OD to size, 90mm for around £4.50 per inch depending upon the metal spec. Full price list is on line. Hope this helps.

Edited By MadMike on 04/04/2017 16:07:07

Was going to put this in the "What did you do today" post but decided it would do better here.

THIS IS A WASHER.

16" diameter with 7" hole being trepanned out, 30 mm deep.

Tool is approximately 6mm wide x 12mm deep. 250 rpm, power feed set at "steady as she goes"

I don't know what the feeds are on this machine as all the number have worn off the feed plate.

Now that bit IS worth saving.

Edited By Michael-w on 04/04/2017 23:03:50

JS, looks like your'e pushing that chuck beyond it's limit !!!!!

Emgee