Found a source for Kumata plastic screws in N & Shoulder washers stuff

[sp org div]

Come on you guys, think like an American. This is the disposable era, so just throw the unit in the trash and buy a new one with all the whistles and bells. 
Jeff

[narrowminded]

Your question is a good one.

Most of the measurements I gave are indirect (but better) measurements.

C- the outside diameter of the barrel came from the worm shaft that just fit into the gearbox hole.

The size of E- the hole was also indirect.  It came from measuring one of the many M1.4 screws I have.

The size of B - the lip was exact.  I could measure that.

The measure of A- the diameter of the outside top lip.... was my suggestion.

And D is as stated below.  Actual measure.  But they are too small.  So I gave my recommendation.

Sounds good, Ron.   I was just trying to make sure because the proportions in the picture didn't seem to be that small. 

This should all be OK with the possible exception of "D", the hub length and only if it gives trouble with heat, trying to melt and distort.  I don't think that will be trouble at 1mm  (I assumed you meant .039, not .39 as written) but if it does, would it be OK to go back towards the original measured .020" or so?  Again, I don't think it will be trouble at .04" long but...   Everything else seems fine.

Now, how many?

[narrowminded]

Come on you guys, think like an American. This is the disposable era, so just throw the unit in the trash and buy a new one with all the whistles and bells. 
Jeff

Don't worry, the concept is still alive and well.   I'll probably scrap a bar or two for every good one.  

[u18b]

oops.   Yes,   .039" = 1mm

As for how many, that's tricky.

Almost every Kumata loco needs 4.

I guess the minimum I could use might be 10.
But if I had 40 they would last a while, but would eventually get used.


I remembered I had a KMT E3/6 that was in good shape.    The shoulder washers are good in that one, and I could remeasure.
The measurements I gave were from an old ALCO that had seen some use.

The numbers may not come out different.

[narrowminded]

That sounds good, Ron.  I'm going to run these off at home in the manual lathe.  Let's start with 10 or so and you can make sure they fit as you expect.  We could always do some more later especially with confidence in the fit.  How do you feel about the thru hole  at .055" (1.4mm)? 

I'll leave it up to you if you'd like to remeasure but it seems like you've got it covered.... possible exception of that hub diameter.  That wall at .0015"/ .002", or about half the thickness of a sheet of paper,   still seems suspect to me, especially looking at the picture. But that sure would explain why you need replacements.  We will give it a whirl.

[peteski]

Looking at the photo of the actual parts Ron posted earlier in the thread, my gut feeling tells me that no parts of it are half the thickness of paper.

[up1950s]

Maybe you could modify these
https://www.aliexpress.com/item/200pcs-eyeglasses-glasses-accssories-screws-silhouette-type-plastic-stopper-cover-screw-for-rimless-frames/906767635.html?spm=2114.40010708.4.35.GaZgaJ

and here
http://www.dibbleoptical.co.uk/frame_components/rimless/compression_sleevesplugs_C279.html

And here is a multi size pack
http://www.ebay.com/itm/100-pcs-plastic-compression-sleeves-for-rimless-glasses-Accessories-tools-/151752435497

[narrowminded]

Looking at the photo of the actual parts Ron posted earlier in the thread, my gut feeling tells me that no parts of it are half the thickness of paper.

That's what I'm seeing, too.  I scaled the picture right on the 'puter screen knowing that the screw was 1.4mm, and that's where I came up with my estimate of .008"/ .010" wall.  And the picture doesn't seem to have any shadows.  I wonder if the screw used when they went from plastic to metal is actually smaller than 1.4mm, like maybe 1.2mm.  That could make sense and would get that wall thickness up to .005" or so which, while still a little thin, approaches reasonable.  Something doesn't add up here unless it's a real oops from the manufacturer.  I'm sure Ron will get it sorted soon enough and we'll get some good parts out.   

[u18b]

Been tied up most of the day.

I'm going to measure a different one in better condition.

That yellow photo was actually taken years ago.  I dug it out of my directory from which I'm building my Kumata book.  So those are long gone.

The one I measured was kind of closer to the one on the left.

But I remembered that I have one in better condition on the E 3/6 set I bought and had been stuffed in the back of a drawer.

I'll report back.

[u18b]

Took the measurements again but on a good one this time.  Some readings were about the same - some were a little different.

A  Diameter of the top surface-  measures 2.54mm

B  Thickness of the lip    .50mm

C  Outside barrel    1.85 mm  (this is bigger than before)

D  stock is .50mm  but could be a bit more.  Say .75 or 1mm

E  inner hole for the screw  1.34mm

So since E is the same as before but C is so different, that accounts for the better wall thickness.

[narrowminded]

Ron, those all sound good and doable and fits the picture as well. .   

For tolerances I will use the 1.35mm (.0531") drill for the the thru hole (less than 1/2 thousandth larger).  It may run over a little but if it does, I don't anticipate more than  .001" (to .054").  For the "D" dimension, the hub, I'll use your dimension as the target, +0/ -.002" and +/- .003"  for the balance.  They'll likely be very much on the target but I won't lose sleep over it should one run a little over or under as described.  Does that sound OK to you?

Unless your immediate need is greater, I'll run off 10 pieces now and if these prove out can run some more with any refinements.  Will that work for you?  I should be able to run them this week.

And finally, if this is good, PM an address for shipping.

[u18b]

Sounds good.  Thx.

[dcutting]

Why not 3D print a whole inch of em? Would be pretty easy and cheap, and I have a supplier with one of the new Carbon 3D printers that makes parts almost as good as injection molds do... no fuzz

[u18b]

That's an interesting idea.
And I guess you could design s Sprite eithe list on it.

But would FUD be strong enough?   I thought it was pretty brittle.

[peteski]

But would FUD be strong enough?   I thought it was pretty brittle.

I think that is exactly the problem with using FUD for this high-stress application.