ground or milled?

Hey all

Is it possible to tell by eye if the displayed surface of the following part (top in the picture, not the screw/nut) was finished by
grinding or milling?



Stefan

I have no idea why it matters, but to me it looks like it was Blanchard ground. They probably filled the table with them and ground them as a big batch.

ewlsey said:

I have no idea why it matters, but to me it looks like it was Blanchard ground. They probably filled the table with them and ground them as a big batch.

Click to expand...

agree the cross hatch lines would indicate the mill cutter diameter or the Blanchard wheel diameter..looks like a large wheel Blanchard. Perhaps a through feed grinder with a Blanchard type wheel.

and I have made fp1 stops by simple milling, and they work just fine, it doesn't matter....
(unless you happen to have a blanchard grinder...)

So the question is..

Are the parts hardened and ground, or milled and hardened?

Perhaps neither, soft through and through....

Thank you all for your comments!

The interest in this is of pure curiosity and eagerness to learn (never heard about a blanchard grinder before...). For contemporary practical use it is, I totally agree, of no importance.
But, if such a machine is going to be part of a private or public collection, going to be documented and may be in need of an overhaul/replacement of parts, these details can not be underestimated. So please do not laugh at such scrutiny.

The part was made in 1949.

It is definitely "hard". May be not easily visible from the picture, in my hands, to my eyes, it shows typical case hardening patterns.

Best, Stefan

Blanchard and Madison grinders have a plate mounted wheel that rotates over the part using the face for grinding. Cross hatch lines are produced by the crossing of the front edge and back edge of the wheel. A deliberate out of tram can produce a one way cross line used perhaps for tool grinding of carbide or steel to produce a bur or chip free edge to one part edge (the lead or the follow). Yes the out-of-tram would be so slight it would (may) not show in measuring the part.

Normal use is having the wheel dead tram so the cross hatch is equal. These grinder are very accurate and provide very fast stock removal.

If this part was made in 49 I'd say the odds are very high it was done on a Blanchard.

What is a "through feed grinder with a Blanchard type wheel."?

tdmidget said:

What is a "through feed grinder with a Blanchard type wheel."?

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Google Double disc grinder.
Besley being the common old school one. Very fast. Make a Blanchard look like a snail on small parts in volume.
Think 1000s per hour.

often small odd shaped part the chucking stock usually less than 0.2" material thats used to hold part in a mill vise is removed by a Blanchard grinder with magnetic vise
.
doesnt take long and often a lot of parts all on the magnetic vise at the same time so often it is done relatively fast

tdmidget said:

What is a "through feed grinder with a Blanchard type wheel."?

Click to expand...

There is an A model Blanchard which has a chuck with a big hole in the middle. The mag chuck is built in pie shaped sections that can be turned on and off independently. You load one side while the other side is grinding. Kind of like a pallet changer.

The Blanchard and Madison type grinders were very common and easier to set up but most often did only one side at a time often with parts held on a magnetic chuck that held the part or held the block-in s for non magnetic parts. High skill to assure the wheel cutting forces going both ways would not loosen the holding of block-ins. It was not uncommon to set many parts at one chuck loading. Or to set many parts tipped on wires or angle parallels so to produce an angle on the part. Sometimes the tram would be slightly tilted to assure the forces would push one way. Some times the table would not be set full under so only one wheel direction would be used on the part.

Through feed machines might process one side with a rotary or straight feeding the part under or past the wheel or sanding belt.

Double disc through feed machines with the wheels or abrasive belts horizontal or vertical could process both sides at the same time. A rotary cage might be used or simply a continuous feeding the part on a flat belt on a slide table. The wheels or belts direction would push the part to bump or register on a solid stop of the through fixture. Often the through feed machine would use creep feed so the part only need pass the wheel or belt once and come out a finished size. The OPs part if a high production part would be a good candidate for a double disc or other type of through feed grinder..