No surface grinder. How to make this?

[engineeringtech]

Hello! I have no access to a surface grinder or magnetic chuck.. I want a perfectly flat washer 2.5 cm diameter with a 6mm hole and 2.5 mm thick, steel. I want to harden it. Everything I get off my lathe with a parting tool varies .004 inches (.1mm). I can lap it on a surface plate to get a smooth, flat surface on each side, but that does not insure that the washer has uniform thickness.

I have no horizontal head on my vertical milling machine. I thought I could super glue it to a angle plate, and bolt to the table. I could put a small grinding wheel on an arbor and put it in the vertical spindle and grind the washer that way. But not sure the glue would hold or provide the uniform thickness I want.

Any ideas?

[circlip]

Soft jaws in lathe, bore 1.5mm deep and skim a parted off washer.
See post in Welcome. Regards Ian.

[engineeringtech]

Ok this may sound like a dumb question, but what kind of soft jaws? Is this something I should make? I have never had any soft jaws on the lathe chuck.

[havoc]

Make washer as you do a few tenth of a mm over size. Put bar of alu in jaws and face. superglue washer to face of alu bar. Turn careful to thickness. Heat to remove from bar.

[engineeringtech]

Thanks Havoc. What did we ever do before superglue?

JC

[Tel]

Or make a simple split chuck - bored out to a bit over the diameter of the hole, turn a recess the diameter and depth (thickness) of the washer. Mark the no.1 jaw postion, remove and put a single junior hacksaw cut thru one point where a jaw won't be. Debur, put back in chuck with washer inserted, the rest is easy.

[Tel]

May 28, 2008 19:57:10 GMT engineeringtech said:

Thanks Havoc. What did we ever do before superglue?

JC

Retained some shreds of our sanity? I've never been able to get the stuff to work for me.

[kneedeepinswarf]

You say you want to harden the washer. In this case it would probably be better to grind it flat after hardening in case the hardening process introduces some distortion.
This would normally need a surface grinder, but in Guy Lautard's "The Machinist's Second Bedside Reader" (ISBN 0-9690980-3-0) is a description of a most ingenious home-made grinder. This is very simple, being merely a grinding spindle fixed to a surface plate! Although I have not made one myself, I can see that it should be capable of very accurate work.

[circlip]

Isn't it marvelous Jim, that employers expect miracles from a little outlay? Lots of your contemporaries over there have CNC in their HOME workshops, it seems like you need a budget to visit ENCO, or at least HF. Lots over here have even got DRO's fitted (Now that's one to start a few flames).
Soft jaws for the chuck are exactly what it says on the tin, they replace the hard jaws and allow you to machine a location the diameter of the washer but only deep enough to hold it so you can skim the thickness down.
Tel's solution will be a lot more acceptable to the bosses, and you can probably manage to scrounge (obtain for free) a piece of tube to bore and slit to use as a chuck adapter.
Regards Ian.

Tony problem using cyano is that if you get overenthusiastic when turning, it could be pulled off the mount or excess heat could let it self eject.

[freddo]

Hi JC

Just a thought for the final finish after hardening - glue the washer back to Havoc's aluminium bar (better if there was a little pip on the ally to locate the washer centrally, then stick the bar in the drill press and polish it by bringing it down gently onto a fine carborundum knife sharpening block - same way that the Belgian guy uses for the final sharpen on reground endmills.

Freddo

[paul]

In my experience super-glue hardens thicker in some places than others - I couldn't see that being more accurate than the .1mm error induced by parting off if you want the faces parallel. That said I've used it loads of times but as I only work to the nearest metre it's not a problem LOL. Oh, and I've had a few glued bits part company on the lathe.

[Lurkio]

Does the washer *have* to be 2.5mm thick exactly?
If not, you could make it from nearest size flat stock (use gauge plate (ground stock) if you want to harden it...you should be able to avoid distortion if you clamp the washer between two thicker ones whilst heat treating).

Lurkio.

[engineeringtech]

Hi again,

Sorry I missed all your posts (time difference), and THANK YOU ALL. Wanted to report that the superglue trick worked ok. My washers are 2.5 mm +/- .013 mm. Much better than they came off the parting tool in the lathe. (+/- .09 mm.) Still, as some of you have observed, for an employer owned shop, we are equipment poor. A surface grinder would hold .003 mm easy. I was surprised that the super glue, which was a low viscosity type, withstood the shear forces of facing off the washer. In fact, I had to heat it quite a bit with the torch before it dropped off the arbor.

Kneedeepinswarf (clever) is right in saying I should grind this AFTER hardening. But I am now thinking I will ask the boss to send it out for chrome hard plate. That will avoid the distortion, and be plenty wear resistant for my application.

Lurkio - As you suggested, I initially thought of making this out of precision ground flat A2. But I didn't have the right thickness. And I would have had to rough it to shape, and then turn the perimeter on the lathe. You can't screw it into a piece of barstock with a right hand screw. The lathe cutter will "unwind" the screw.. I didn't have a left hand screw, and with my lathe, I can't set it up to cut from the backside of the work with the spindle going clockwise.

All the suggestions for soft jaws were good too. I'm going to remember that trick.

That's it for now!

[missemmajade]

May 28, 2008 19:57:10 GMT engineeringtech said:

Thanks Havoc. What did we ever do before superglue?

JC

watchmakers used shellac. still do for a lot of jobs. its a good way to hold something for machining!

*EMMA*

[Tel]

May 29, 2008 16:26:57 GMT paul said:

In my experience super-glue hardens thicker in some places than others - I couldn't see that being more accurate than the .1mm error induced by parting off if you want the faces parallel. That said I've used it loads of times but as I only work to the nearest metre it's not a problem LOL. Oh, and I've had a few glued bits part company on the lathe.

Nearest metre? I'd 'eard it was the nearest county.

..... and that you can bore a cannon barrel to within the thickness of a worn bus.

[paul]

All true Tel, all true.