Diamond turning a spherical mirror- roughing and work holding

Ultra precision with da Haas?? Video going over the diamond turning process and metrology/interferometry in a little more detail soon.

[@janbeck8269]

Always a good day when you release a new video!

[@cylosgarage]

Thanks Jan!

[@robertfontaine3650]

That's just crazy and very very cool.

[@Audiobungalow]

This series is so awesome. Thanks Cylo!

[@uhaudoh5444]

That aperture and focal length 😂 Not on purpose though. Bravo sir. Bravo.

[@xtevesousa]

What stops the pull from the bolt from bowing the mirror?

[@cylosgarage]

The groove in between the coupling teeth and the rest of the mirror, visible around 1:07. This helps isolate the clamping stresses and distortion.

[@lhnova]

Watching this, does turbulence from the air blast introduce any unwanted cutting tool movement/noise?

[@cylosgarage]

no doubt, but it's not the limiting factor here. The vibrations from the z axis air bearings are the main thing limiting surface finish right now.

[@nickj2508]

Nice precision optical mechanical machining setup and callout to Layton Hale. He noted ~4 years ago that for best placement in self-seating condition of Kinematic interface that there is a minimum CoF typically less than 0.3 @~55°. 60° can cause a locked interface. Also @3:35 maybe worth noting and Rx Ry Rz, 6 faces 6 DoF.

[@phrozenwun]

Have you tried running your air bearing with large molecular gasses? I am thinking that butane or one of its ilk might have a higher effective viscosity (not really sure of the right terminology here) that would damp out vibrations better.

[@cylosgarage]

Eric marsh has done some research on this and found there can be some benefits but it’s down at the single digit nanometer level. Ive got bigger issues to address first :)

[@evren.builds]

Looking forwards to the measurements! Congrats on the 69mm aperture with 420mm focal length :D

[@JulianMakes]

Wow! This is so cool.

[@SpencerWebb]

Super cool!! 👍👍

[@jonahlowe7649]

I would love to see a 10,000 foot overview on building this lathe I hope to oneday build a much bigger version (24x144) Also how reasonable is it to make your own granite parallels? The three plate method is easy enough and I expect it to take me a few weeks to get it that smooth.

[@leonordin3052]

China has 1m long parallells for like 150 dollars w shipping. Lapping will work but it is probably worth it to go all in on diamond grit. It is a couple times faster than carbide grit theoretically. Buy grit powder not pre made oil mixes. You will save a lot of money. You need like 20% grit and rest water, oil, isopropanol or whatever you want to use. Also you should not underestimate how long and boring it can become to do lapping. You will probably save time doing small parts first to learn to do it right, at a certain grit you want a certain finish before moving on to the next. Good luck if you try it out.

[@jonbeno9926]

It's like a cute little fixed Stewart platform

[@andax2007]

Nice!

[@billclark5943]

What grade of aluminum are you using for the mirror?

[@cylosgarage]

6061-T6

[@billclark5943]

@cylosgarage we've made them from 1100 but it's rare in anything but sheet. You looking for a job with a big Aerospace company?

[@fregaman]

what material is that? aluminum?

[@cylosgarage]

Yes 6061

[@jimsvideos7201]

Did I ask you before if you were interested in spinning out a flat (to 100 microns or so) blank? A reasonably robust, optically pretty-good first surface mirror is relevant to my interests.

[@cylosgarage]

What diameter? And do you mean nanometers?

[@jimsvideos7201]

@@cylosgarage 4 inch diameter maybe? I do mean microns; I'm sure even modest effort would get you a lot closer but I don't need anything deliberately that flat. My use case is common photography and that is pretty forgiving.

[@entropy_labs]

I thought telescopic mirrors were hand ground...

[@nerddub]

not this one

[@mitchwright1558]

Very nice. patent # ?

[@cylosgarage]

US6065898A

[@BuildItAnyway]

Very shiny

[@cylosgarage]

yet, not shiny enough...