Making .047x.020x.003 washers

[90LX_Notch]

At Cabin Fever my very small Elmer's Tiny would not run.  One issue that I discovered was that the flywheel under certain circumstances  would bind with the base of the column.  There are several ways to go about correcting the situation but I chose to shim the flywheel.  In  order to do this a .047 OD by .020 ID by .003 shim was necessary.  Obviously, this is not a stock item, so I built a simple small die set to make the shim/washer.

The die set was made from some scrap aluminum and 1/8 dowel pins.  The pins are pressed into the lower half of the die set and a sliding fit is used for the top half.  This is necessary to ensure that the punches line up to in order to produce concentric shims/washers.

The die set was assembled and the .020 hole was drilled through the top half and .060 deep into the bottom half.  The  .047 hole was drilled and reamed all the way through both halves.  Then the bottom half of the die set was counter bored from the bottom leaving clearance for the shims/washers to dropout as they were punched. 

The .020 punch was produced from a piece of music wire.  The punch was originally touched up on the disk sander to make it "square".  This resulted in a punch that created a burr. To correct this, the punch was assembled in the top half of the die set and  the assembly was sharpened on an India stone until the punch face was square.  It was then honed on an Arkansas stone.  This resulted in a burr free .020 punched hole.

The .047 punch was made from 1/8 dia W1 tool steel that was not hardened.  A .020 pilot was turned onto the end of the punch.  This pilot is used to ensure a concentric shim/washer.

Picture one shows the brass with a .020 hole punched.
Picture two shows the brass located on the pilot of the .047 punch.
Picture three shows the die set in the arbor press.
Picture four shows the .047 punch after it the arbor press has been applied.
Picture five shows two shims/washers after the .020 punch was correctly sharpened and four that had unacceptable burrs.  The piece of wire is .016 diameter for size reference.
Picture six shows the assembled die set with an M&M for size reference.

A few notes-

The actual dies are just holes through the aluminum die set.  I only needed one or two shims for this to work; therefore, I felt that the aluminum would hold up fine.

The .047 punch was left unhardened for the same reason.

The dies were stoned after drilling to remove burrs.  If they were deburred normally with a center drill they would not work properly.

The faces of both the dies and punches must be square in order to punch clean holes.  Also, the punches must be a sliding fit or they will work more like a draw die and not produce cleanly punched parts.

-Bob

[b.lindsey]

Wow, can you say "small" ?? Nicely done Bob!

Bill

[sshire]

I'm amazed, as usual. At CF, I couldn't see the ¼ scale tiny without a magnifier.

[crueby]

I would have eaten the M&M while taking apart an old watch to find a suitable washer!

[philjoe5]

Nice work Bob.  How's she running now?

Cheers,
Phil

[cheepo45]

Great explanation and pictures! I will put this in my memory bank!

[BillTodd]

Very impressive :-)

At the works, we have similar sized spacers made for traveling wave tube construction, they're photo etched (we tried both laser and punched)  from various thicknesses (thinnesses?) of moly sheet.

Bill

[90LX_Notch]

Thank you gentlemen.

I have to say this, and it might sound silly,  but I was as "pumped" when the first washer was punched as if it was the first time an engine ran.  I let out a big "Yeah!" and fist pump.

Phil- I've been sick the past few days with a sinus infection and haven't moved any further with reassembling the engine.  I made the die set when the site was down.

BillTodd- The washers aren't instrument grade for certain.

-Bob

[90LX_Notch]

An update:

Having served it's purpose I decided to "test" the die set.

First I punched .0015 Precision Brand steel shim stock making two washers. 

Then I punched .002 feeler gage steel stock for another two washers. The picture is of the .002 feeler gage stock.

The feeler gage material did cause a minute bit of damage to the die.  It basically caused small chamfer like rings at the start of the bores.  The washers have a very slight burr from this.  The "strip" has a .0002-.0003 burr around the punched holes as measured with a micrometer.

I'm amazed at the performance of the aluminum as a die.  My hope was to get one marginal brass washer at best.  It's punched around ten brass and four steel washers.  If the burr gets real bad, all that should be needed is to drive the dowels out and take skim cut with a flycutter and lightly hone with a stone.  I'm sure there is a limit in size to where the aluminum would work, but for very small washers in limited quanties, it does work.

-Bob