Linkert idle bleed slot question?

[exeric]

I agree, a lot of history and skills have been lost. Obviously, that was done with machine tools of the time, and it was a reliable, accurate, fast process done at a high production rate. I am always fascinated by precision parts from a by-gone age because some of those items couldn't be reproduced in a production quantity today. A lot of people today think we are far advanced of out ancestors; but the more I learn about the past, the more I think we are regressing as a culture.

[MassHarley]

Cotten,

A 4/0 size jewelers saw is .009" / 0.23mm wide and has .017" / 0.43mm blade depth.


http://www.esslinger.com/jewelerssaw...izeschart.aspx

Mike

[BigLakeBob]

So Bob!

You have a spindle to drive such a hair-thin endmill down in that hole?
How many do you expect to break? How would you even expect to index down in that hole?

Mike!

I don't see any scroll blades that are only .009" wide; The Princeton Scientific sounds hopefull, but I cannot view it until I get home to a PC with Adobe....

And Exeric!
A "brooch" basically gets us back to a feeler gauge with saw teeth, and one that would insert through a .052" hole.
Making the indexable guide to produce hundreds of thousands of carbs would be the hard part. (But it wouldn't explain the M74B anomaly.)

Meanwhile, digging in my watchmaking tools, I have retrieved a handle, and now must make a saw from a feeler gauge.

Fluxing only the big hole with a capillary pipette seemed to work, as the #70 hole was easily finger-drilled.
Locating the big hole required more patience, but I am now atleast up to Schebler design.

Now to bring it back to Linkert specs.

How sad that so much History has been lost and forgotten.

....Cotten

Take it easy there Cotton, all I said it that I can buy them, I did not say I could perform that duty. My machines do not run that fast. There are machines with 30,000 or more rpm spindles that can handle that end mill, that is why they make them. I ran a jig grinder with a 175,000 rpm head and I have ground .015 diameter holes, so yes I dilled a .009 hole then ground it to a precision diameter in a precision location. I think the same guy that worked at HD and made the springer front ends also worked at Linkert in the evenings, kept all the secrets to himself then the chap died on us and took all this knowledge with him.

[exeric]

Take it easy there Cotton, all I said it that I can buy them, I did not say I could perform that duty. My machines do not run that fast. There are machines with 30,000 or more rpm spindles that can handle that end mill, that is why they make them. I ran a jig grinder with a 175,000 rpm head and I have ground .015 diameter holes, so yes I dilled a .009 hole then ground it to a precision diameter in a precision location. I think the same guy that worked at HD and made the springer front ends also worked at Linkert in the evenings, kept all the secrets to himself then the chap died on us and took all this knowledge with him.

I bet that same guy spelled broach; brooch. Just kidding Cotten, I know you must have been an English major in a past life.

[pisten-bully]

How sad that so much History has been lost and forgotten.

Cotten, how about a trip to Windsor, Vermont and the American Precision Museum? They're stuffed to the rafters with old machine tools, some on display but most are in storage.... you never know, you might find the answer as to how that tiny slot was manufactured in great quantities!

Visit their website, here: http://www.americanprecision.org/

Have a good Easter!

[Robert Luland]

If they used a punch and die, then how did they make the male punch and the female die? Just stirring the pot a little. Remember, no edm, laser or cad back then.

Ok, now lets take it one notch further. So lets say they had a round receiving die that the carb body slid over and the rear mounting holes slide onto to studs. The carb body is then fastened into place and down comes the die. Keep in mind that it didn't take a lot of pressure to punch this. It could be done with a lever hand punch easily. People your over complicating this. Linkert was in the business of making carbs as cheap as possible and pumping them out as fast as possible. You bring a jewelers saw in to this equation and your out of business. A brooch on something that soft and thin in my mind would make one hell of a mess. A brooch is for cutting in keys of one shape or another in a cylindrical (Any shape Hole for that matter) hole. That thing was punched plain and simple. Three minutes per carb and out the door. Bob L

[exeric]

A broach (brooch) is a progressive cutter and can be long, and tapered enough to be easy on the tool. Like you said Bob, there no doubt was a fixture that held the body securely, and in the right place. I also agree that a die would would also have been practical. I worked with a guy that spent many years at National Broach in Michigan. He often bragged about the miraculous things they could do with a broach.

[MMasa]

Cotten
I'm with you. I doubt that it was milled originally. End mills that small didn't exist back then. I am however a metal cutting tooling engineer in my real life. I can get end mills that are 0.001" and yes, I have a 50,000 rpm spindle that can run them if needed. Also, why would a shaper have to work from inside of the carb? As far as tooling goes, I doubt that it would have been a standard off the shelf cutter, but being a tooling engineer, I can visualize the shaper bit that I would use.
I personally think that it was done with a 0.009" jewelry saw along with a fixture for holding and moving the body.
Mark

Mark!

A shaper would have to work from the inside of the carb bore, as no conventional tooling is going to fit in a 5/16" hole, 3/8" deep, and then cut through .030" of bronze.

As far as Bob's cavalier notion of just milling the slot, making the cutters themselves would be a feat un-matched today; .009" endmills are available for cutting circuit boards, but not .030" long.
Nor could a mill be long and thin enough to cut as close to the wall as the botched M74B example I posted.

I can only imagine that it was a reciprocating saw.

....Cotten

[T. Cotten]

Mark!

The shapers of the era that I am familiar with were large and clumbsy contraptions. I have never encountered anything that could work a tool down in a hole like that.

I think we can dismiss mills and punches, Folks,..

A punch deforms the top surface downward, and puckers out at the bottom.
There is no evidence of such.
It would be disastrous at the interface where the disc closes as well.
If the bore was machined afterwards, then even more than .030" would have needed to be perforated.

And then explain the M74B miss-cut that I posted previously, if it was a guided punch.

A broach so small is basically another saw blade, as Mark suggests.

Linkerts are humbling.
(HX Scheblers are diabolical.)

Meanwhile, I must carve a saw/broach from a feeler gauge.
How much should I charge for this operation, Folks?

....Cotten

[Robert Luland]

Yep, we"ll use a saw blade while Luigi holds up the entire production line, precisionally working every slot with his Grandfather's saw that was handed down to him just before he made the boat out of Sicily. Get real! These people were in the business of production and making money. Bob L

[Steve Swan]

Is it possible to see any marks on edges of slot to suggest a machine operation ? seems unlikely, but could slot have been cast ?

[harleytoprock]

Hey, the blade broka agena! Bring Luigi more sauseech and a newa blade.

[T. Cotten]

Is it possible to see any marks on edges of slot to suggest a machine operation ? seems unlikely, but could slot have been cast ?

Steve!

I can only post more pics, and I myself have no pattern-making experience, but a .009" slot is pretty delicate to imagine to be cast, and the variances are too great.

It does lead to another question I have, about the seat for the lowspeed lift-lever spring collar, but I shall save that for now.

....Cotten

[T. Cotten]

Well Folks,..

After soft-soldering, re-drilling, sawing the slot, and honing the bore oversize to eliminate disc wear, it looks like this (attached).

The existing bronze cut piloted my saw quite well.

We may never know how the slot was originally produced, but this is the best repair I can accomplish at this time.

One might wonder how a Schebler might perform with such a slot, but that's blasphemous thought, of course.


....Cotten

[exeric]

Very nice work Tom.