What does diamond turned mean?

I keep on seeing this term applied to mainly aluminium parts saying they have been "diamond turned"

what does this mean?

Mpp cameras have DT parts last made in 1988 so its not a new thing

See here **LINK**

Martin P

Turned using a diamond-tipped [as distinct from diamond-shaped] tool

MichaelG.

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Edit: Martin found a good link whilst I was typing.

Edit: Probably worth noting that the idea is much older than MPP ... Horological jewel makers used shards of Diamond for hand-turning Sapphire and Ruby.

Edited By Michael Gilligan on 02/03/2020 08:40:14

Edited By Michael Gilligan on 02/03/2020 08:54:54

Link

Wiki has a good explanation

Edited By Clive Brown 1 on 02/03/2020 08:41:03

So going back to a simple MPP camera knob why would you use a diamond tipped tool rather than a normal tool?

in the 60's to 80's

.

To give that lovely multi-coloured reflection ... perceived quality !

... Compare iridescent beetles, Compact Discs, etc. 

MichaelG.

Edited By Michael Gilligan on 02/03/2020 09:01:22

When I had to work for a living they had a diamond turning machine. It was in it's own air conditioned room and sat on it's own huge concrete pad. It was used to make optical mirrors from 6061 T6 al.alloy. Workpieces would come off the machine finished with an absolutely amazing finish, which despite being from al. alloy didn't corrode. Don't ask me why! The DT process took tiny (shallow DOC) cuts at startling rpm. Very expensive machine.

Got to go The Boss is breathing down my neck wanting the PC

cheers

Bill

Diamond turning used to be used for re-finishing commutators in DC motors and generators to prevent the copper smearing across the insulator segments.

Russell

The Wikipedia article is interesting but does rather overstate the technology needed to produce optical finish standards.

The high speed plain bearing Holbrook C lathes, originally developed for the atomic weapons folk to handle materials that couldn't effectively be ground, were also supplied for diamond turning duties. We had a sample originally made on one such machine in the "aren't we wonderful" section display cabinet back at RARDE which was well up to decent optical standards. Whatever ones views on the overkill nature of supplying a full on tool room lathe with all the trimmings for basic plain turning duties a steel spindle spinning in white metal bearings is hardly high tech.

These days diamond turning tools, especially for alloy wheel refurbishment and similar duties are Poly Crystalline Diamond (PCD) inserts. Same sizes and styles as the usual carbide, CBD etc but diamond in the matrix. Nice thing about modern inserts is they can take reasonable cuts and are often able to handle roughing duties as well as finishing. The alloy wheel folk need diamond tools due to the alloys being incredibly abrasive.

Clive

It is possible that actually they are referring to an "engine turned" pattern on the knob in the shape of diamonds - what we could also call knurling. Such patterns can be produced on a "straight line" machine. A/k/a guilloche. Ian asks in the 4th post "why would you apply this to a simple camera knob" - well, to make it easier to grip!

My experience of diamond turning was the finishing of commutators on A C Delco windscreen wiper motors.

Tony

I used to do bits of consultancy work with a company which makes intraocular lenses for cataract operations. They were turned to shape from acrylic plastic using a CNC lathe with diamond tipped cutting tools

John H

the knobs in question were supplied as lengths pre knurled and then diamond turned

I was just surprised to learn such an expensive process on a lowly camera part

But as Micheal G said you can see an iridescence in the top....would you not see that with any other type of cutter?

Same category as "machined from billet" and gold plated mains plugs.

Decorative "diamond turning" leaves the surface like a record and the grooves catch the light and give a holagram rainbow coloured effect as you move the item in the light. Common on some alloy car wheels etc. Not always cut with a diamond.

Edited By JasonB on 02/03/2020 13:17:09

If you were a company called Micro Precision Products

Surely you would ... just to prove you could.

MichaelG.

I don't think that i would describe a MPP as a "simple camera" The "plate" and Field cameras were definitely not! They were beyond my wallet, and lived up their maker's name!

Howard

Howard

I was always under the impression that MPP’s were rather cheaper than the competition and looked down upon by the cognoscenti

having said that i suppose even £75 was a lot in the 50’s and 60’s

having said that I’m quite happy with my models that i own

certainly Basil Skinners book talks about the lack of funds at the factory for development