Totally counterintuitive. I've done a fair bit of metalwork sanding and polishing, so I naturally assumed that optical polishing would be similar, only using something harder and flatter to grind the surface. It never occurred to me that the rotational grinding process would use something ductile, yet get better results. Thank you very much for the excellent explanation.
In metalworking terms, it would be very similar to using an aluminum, copper, or tin lap (as in watchmaker's "black polishing"). You want your lap to be softer than the material to be cut. Your lap becomes a matrix to hold the abrasive particles in place, and the cutting happens on the material that can't just grab and hold the abrasive. (Tin, by the way, gives absolutely amazing results when polishing steel. It's just _really_ stringy to machine when you're initially making the lap. Save it for your finest - sub-micron - grits.)
Very informative yet old video on lapping metal parts by rotation. Check this: czcams.com/video/fnoVV-RWIWY/video.html It vey clearly explains "how it's made".
I feel there’s a general misconception when it comes to lapping a polishing that is a result of focusing on the lap material. As the first comment responder noted the lap only hold the cutting media. There are three fundamental rules for cutting to occur, though I only usually remember two. The important one here is that the cutting “tool” (in this case lapping or polishing compound) MUST be harder that the workpiece. The second is that there must be relative motion. The third escapes me. But in either case it is not the lap that cuts the work piece but the embedded abrasive. Apologies for the lecture comment but lapping and polishing seem to be no different fundamentally than any other metal removal process; hard removes soft. In the case of polishing silverware presumably there is some residual polishing compound on the cloth that is the effective mechanism for removing the oxide layer. Also, if I’m glaringly wrong please correct me. 👍 Edited for autocorrect errors.
Flat-out the best vid on making flat optical surfaces! Clearly thought out well, I couldn't pitch in any criticism. It's almost like we're on the same wavelength.
What a cheerfully bright comment! I for one found the video very illuminating, and it seemed to polish out all the rough spots in my dull and hazy knowledge. You could say that it expanded my bandwidth....
The true test of whether someone has mastered a field is their ability to explain it to the uninitiated in a clear and concise manner, you sir are a credit to the field.
How did I end up watching 12min of "how to polish something to the nm scale?" But you explained it so well that I understood it without any previous experience in polishing glass or anything for that matter
This is really good, so well detailed. It seems over the years there has been a lot of demonstrations of optical grinding/lapping, lots of "recipes" so to speak, without any detailed explanation as to why it works. I'm coming out of this with a deeper understanding of the process, only took 12 years, but better late than never!
I have been interested in optical engineering for a long time now and yours is the first channel I have seen that covers it well. So thank you for making such excellent videos.
I work in the optics industry for a couple of years now and I have to say that your channel is a real treasure! Your videos are both, highly educational and entertaining. Keep up the outstanding work!
I used a machine like this in the 90s to flatten hydraulic motor parts. Instead of pitch, the wheel surface was steel, and the surface was kept flat by adjusting three rings which also kept the parts in position on the wheel. We'd check it a couple times a day by washing the abrasive off and placing an optical flat on the wheel. But other than that it worked the same way.
@@myselfremade I worked on Eaton and Sauer-Sundstrand axial piston pumps and motors. We would replace pistons and cylinder blocks and send them out to be resleeved/refinished.
@@stickyfox ah very nice. I have an Eaton series 1 pump. 5.4 cubic inch variable displacement model. Installed on my truck. Great pump 👍 wish I had a 11 cubic inch fixed displacement piston motor to go with it but instead I am using a Geroler. It does ok but slightly less optimal.
The principle looks simple, its just a tar and turntable, but those who tried working with glass, especially polishing and making it precise, knows that its extremely hard, takes years of practice and patience. Great video.
I have been polishing precision optics for 12 years, I really enjoyed the video, thank you. I do the final polishing of the optics on a spindle in a zerodur plate with holes, I put planes with weights in them, according to a similar principle. pitch polishing pad for the night I turn over on a plate smeared with Regipol with good flatness
I've always thought there was something almost magical about being able to make incredibly accurate optical surfaces, flat or otherwise, with no precision tools whatsoever. I ground my 6" parabolic mirror by hand, and figured it to 1/20 wave accuracy on a pitch lap, with no references other than the Foucault test. Very nicely done. Subscribed. cheers from sunny Vienna, Scott
@@robertmccabe8632 Indeed. I use this principle to keep my sharpening stones flat. Using silicon carbide abrasive, I grind A against B, B against C, and C against A.
This is the most satisfying and informative presentation I've seen in ages. As a photographer I really appreciate the craftsmanship required to produce high quality optics. My hat off to you Sir! 🎩
If you think that is impressive the Laser Interferometer Gravitational-Wave Observatory uses interferometry to detect changes in length less than a 10 thousandth of the diameter of a proton.
At work here in Germany they got mad at me for filing like this....that you work in nm tolerances and do so as well made me really happy. The understanding of why one would do it so they just couldn’t understand. Also an amazing video, very informative. Keep up the good work!
This video reminds me of how profound our technological advancement has been. Just think of how many different people had to cooperate and dedicate basically their entire lives to engineering better solutions in the relatively niche field of precision optics. Using a high viscosity fluid as a lapping surface? How the hell did anybody come up with that? Stuff like this just blows my mind.
Very clear and detailed explanation, best I found so far (and no irritating background music). Cool how you built the turntable from a washing machine motor and rollerblade wheels!
Last minute had the information I didn't know I needed. Blocking pitch does put pressure on glass held to a backing. All the old film of spectacles and camera lenses show blocking, but these are not expected to be accurate to fractions of a wavelength. OK now I will also avoid lots of messy cleaning up as well.
I'm an optical fiber telecommunications technician. We used to have to polish the end faces of our connectors when terminating them. 3 different ratings of polish paper and polishing in a " figure 8" motion. It was tedious. Faster speeds and the need for lower reflection at the connections has us using fusion splicing and factory terminated connections, now. No one misses " puck and polish" terminations.
The closest thing I do is knife sharpening, but I always wondered about stuff like straightness, flatness, and smoothness. This videos was very interesting.
good to see that physics works all engineers experience the same when going down to nanometers no matter what kind of engineering they are doing and that is that solid material is moving ( slowly )
This is very interesting. I read somewhere that for lapping of silicium wafers they use some chemicals instead of abrasive particles. I can't imagine how precise they must polish wafers for 4nm technology.
It's generally a combination of both. If you use a chemical that etches your surface while you are polishing, you can use a very mild (or soft) abrasive agent, which results in a smoother result. By the way, when you use Cerium Oxide to polish glass, chemical interaction also helps speed up the polishing process. For wafers the actual flatness is less important that the smoothness, since modern wafer steppers make a heigh map of the wafer to correct for the total thickness variation when clamping a wafer to the chuck. Modern technology wafers are indeed incredibly smooth and flat (from the dimension of individual components to that of the full chip)
No idea why this is in my recommended, but very interesting. I'm amazed this kind of thing can be DIY with the proper knowledge and materials. I would consider myself a maker more in the software area, it's always cool to see what other people are working on. Keep making!
Newtonian liquid is just a liquid / fluid. Classic. Water, alcohol, glycol, air are all newtonian fluids for example. So, it is not "special" in any sense. Optical pitch has just very high viscosity. There are fluids that are special, and they are called non-newtonian. There are many types of non newtonian fluids and they all have various applications and fascinating properties. :D There are some non-newtonian (visco-elastic with non linear sheer relationships), that are also used in optical polishing, but that is rather very different method.
You are right about the fact that a lot of common fluids are showing Newtonian behavior. But there is also quite a lot that are behaving non-Newtonian such as paint, yogurt, ketchup, toothpaste, so in that sense non-Newtonian fluids are also very common. I guess, all fluids are special, but some are more special than others ;-).
@@HuygensOptics That is true. Non Newtonian fluids are also common. They are just harder to analyse :) ketchup is weird indeed for example. Or magnetorheological fluids, used btw for very precise polishing in optics. Learned about it just few days ago. :D
Thanks for the video, it's very informative. So the polishing table is an aluminum disk with a motor stator attached to it, and you press the pitch lap by using a granite plate, but I was wondering if you could share what the pitch lap substrate is made of? It looks like a few inches thick disk. Is it also granite?
No actually in this particular case it is borosilicate, which has a thermal expansion coefficient that is about 3 times lower than granite (which is an advantage). You can however use granite without problems if you have good temperature control.
I think there is a tradeoff. It would certainly help, but investing in climate control may not be worth it. Also, it seems heating the plate and then weighing it down removes enough deformity in a small amount of time. These techniques are fascinating.
The algorithm sends me to strange places sometimes, but it sure can be a fascinating journey. Today I learned something I did not know yesterday, thanks.
Very good stuff. I've done my share of glass pushing, long long hours of manual work. I tried to make 200mm flats but I constantly got into troubles in 1um (two rings) level... Perhaps I return to them sometimes, even though I hardly remember why I started making them LOL (ok it was some cassegrain telescope idea, and another for testing other flats)
Excellent. Very happy I found your channel. Honestly, as a nerd in training, a good friday night for me includes such terms as nanometer and interferometry. Looking forward to your next video! Edit: trainings -> training
Flat implies “not curved” when these are curved surfaces. It’s really about the size of the deviation from the theoretical shape of the required surface.
1:25 I love how that's a huge piece of what I'm sure is expensive equipment using off the shelf roller blade wheels. You can clearly see the painted design on them lol
10:00 So not necessarily, and not usually to that degree. Yes, surface plates do have stricter requirements for local flatness vs overall flatness. For instance a grade AA surface plate of 18x18 in, has an overall flatness requrement of 50uin, but a local flatness requirement of only 35uin, so that would definitely need to be checked for whatever specific surface plate you're using.
I've been having a go at marking crude lenses from polycarbonate , the tyre pattern got me thinking. I had previously seen brief footage of a lens factory circles on domes and lots of white liquid, Your explanation has helped me understand the process, I'm not willing to sacrifice my record player or washing machine , but I do have some granet and microwaveable casting rubber.
i am a machinist by trade and when i was initially linked this video, and i only saw the title, i thought "oh great some charlatan is going to talk about taping sandpaper to a piece of float glass" but i was pleasantly surprised to see that was not the case and this is the real deal. subscribed. have you considered trying a cast iron master surface for the weight? as long as the room is at least loosely climate controlled, you could theoretically have a more economical option for a even flatter surface than the granite plate
In principle cast iron would work just as well as granite. The CTE is around 10-11 ppm, so compared with granite (8ppm) this is only slightly higher. And because of it's higher thermal conductivy, it will get to thermal equilibrium (and retain it's original shape) quicker than granite. So it would in fact be a better choice as a material. However, don't know how easy it is to make a cast iron disk of 400mm in diameter with a flatness of approx 1um. By the way, granite is not an expensive material.
@@HuygensOptics i know that in metrology cast iron is preferred for master surfaces, because it is more dimensionally stable and easier to make very (beyond AA grade) flat. for your specific use, it would also help as cast iron is denser so it would be heavier for the same size. that is why it came to mind.
@@SuperAWaC Actually in some super accurate machines, aluminium with internal cooling channels can be preferred too. This is because aluminium has way higher thermal conductivity (about 3 times higher than iron) and can be stabilized better, down to 0.1°C. Of course if you deal with big loads and need very high stiffness the cast iron or granite are preferred, but with low loads, aluminium counter intuitively can be even better. I can't find source and machines doing that right now, but I do remember seeing some year ago.
I am a Tool & Die machinist and horologist and it made me happy to see there are other intelligent machinists watching things like this. I would second the use of a cast iron master plate. There is a guy who comes once a year to certify the multitude of granite surface plates we use in my shop and the man that does this is one of the rare ones who actually can re-lap the granite plates back into spec for flatness using a Master cast iron plate using aluminum oxide abrasives of various grades. Cast iron master laps are always made in pairs of three to get true flat reference surfaces- I know they are still made but I am not sure who you go to to buy one but if you had one I am certain you would get better results since they are what are used to correct even the granite surfaces
@@movax20h I do know that many coordinate measuring machines have ways that are aluminum which is hard anodized and then lapped to extreme tolerances. It wouldn't surprise me if the very high end ones are also liquid cooled. I do know that they are kept in tightly temperature controlled environments with any heat sources removed (such as computers and humans) and put into different rooms, which is probably enough. But it would take longer for the whole machine to soak back to equilibrium if that environment were disturbed.
growing up in a machine shop makes me fascinated at what high precision milling can do. I'd take parts home and use the machined metal parts to play with.
Do you always use the same grit to polish? If not, do the grits find themselves trapped in the pitch? Do you have to use different pitch plates for each grit?
Polishing is the final stage of producing an optical quality surface and there is only one compound used on a given lap. Grinding the surface to a desired rudimentary curve is called grinding, not lapping. Pitch laps do not grind but only polish. The amount of material you'd remove by polishing is miniscule and nobody wants to waste time doing any more polishing than necessary. Grinding a surface starts as a rough cut to quickly give a desired curvature and to remove casting irregularities. Then a succession of finer grits is used to remove the deep scratches left by the previous grit. This is done with a hard tool on the workpiece and an abrasive slurry is run onto the surface. It looks a lot like lapping with a pitch lap, but because the tool is hard, it can be reliably cleaned off when it is time to change to the next finer grit size.
If pitch is a liquid, couldn't flatness be achieved without a reference flat (like the bruiser or surface plate)? Enclose the pitch in a container with walls higher than it and heat it up enough to reduce the viscosity so it flows fast enough for the surface to find its level in a reasonable amount of time, then let it cool down. Surface tension would mess with the flatness near the walls, but closer in should be fine. I suppose you lose the grooves though, darn.
You will have to wait for a long time before the surface reaches submicron flatness. Keep in mind that there is a volume contraction during cooling down. And of course it is not just about getting the tool flat, but keep it flat during processing.
i heard somewhere that telescope mirrors used to be polished hand, because machines could not get as smooth and even surface. To achieve this with machines, they made machine mimic human randomness of motion while polishing.
I've got absolutely no idea why this video was recommended but I'm so glad it was.
Fascinating. Well done.
Same
Same
Same
It's because your subliminally interested in light & optics.
It started when I clicked on a bartender showing how to make optically clear ice cubes for drinks, next day this was in my feed.
Totally counterintuitive. I've done a fair bit of metalwork sanding and polishing, so I naturally assumed that optical polishing would be similar, only using something harder and flatter to grind the surface. It never occurred to me that the rotational grinding process would use something ductile, yet get better results. Thank you very much for the excellent explanation.
In metalworking terms, it would be very similar to using an aluminum, copper, or tin lap (as in watchmaker's "black polishing"). You want your lap to be softer than the material to be cut. Your lap becomes a matrix to hold the abrasive particles in place, and the cutting happens on the material that can't just grab and hold the abrasive. (Tin, by the way, gives absolutely amazing results when polishing steel. It's just _really_ stringy to machine when you're initially making the lap. Save it for your finest - sub-micron - grits.)
You polish silverware with fine cloth which is softer than silver. If you use sandpaper the result would be terrible.
Very informative yet old video on lapping metal parts by rotation. Check this: czcams.com/video/fnoVV-RWIWY/video.html It vey clearly explains "how it's made".
@@gvidas1338 This is great, thanks!
I feel there’s a general misconception when it comes to lapping a polishing that is a result of focusing on the lap material. As the first comment responder noted the lap only hold the cutting media. There are three fundamental rules for cutting to occur, though I only usually remember two. The important one here is that the cutting “tool” (in this case lapping or polishing compound) MUST be harder that the workpiece. The second is that there must be relative motion. The third escapes me.
But in either case it is not the lap that cuts the work piece but the embedded abrasive. Apologies for the lecture comment but lapping and polishing seem to be no different fundamentally than any other metal removal process; hard removes soft.
In the case of polishing silverware presumably there is some residual polishing compound on the cloth that is the effective mechanism for removing the oxide layer.
Also, if I’m glaringly wrong please correct me. 👍
Edited for autocorrect errors.
Flat-out the best vid on making flat optical surfaces! Clearly thought out well, I couldn't pitch in any criticism. It's almost like we're on the same wavelength.
What a cheerfully bright comment! I for one found the video very illuminating, and it seemed to polish out all the rough spots in my dull and hazy knowledge. You could say that it expanded my bandwidth....
@@digitalradiohacker makes me wanna leave my daily grind and do something else
Micronically inquisitive mind lapped up the precision explanations.
If y'all don't cease with immediacy I'm gonna jump into a woodchipper.
😂
The true test of whether someone has mastered a field is their ability to explain it to the uninitiated in a clear and concise manner, you sir are a credit to the field.
How did I end up watching 12min of "how to polish something to the nm scale?" But you explained it so well that I understood it without any previous experience in polishing glass or anything for that matter
It's rather hypnotic.
This is really good, so well detailed. It seems over the years there has been a lot of demonstrations of optical grinding/lapping, lots of "recipes" so to speak, without any detailed explanation as to why it works. I'm coming out of this with a deeper understanding of the process, only took 12 years, but better late than never!
This video reminds me of the optician who fell into a lens grinder and made a spectacle of himself.
That's not as bad as the glass blower who accidentally inhaled and now has a pane in his chest.
@@MikeWiggins1235711 Still not as bad as that chef who, while cooking some some chicken broth, fell into the pot and made a laughing stock of himself.
Clearly, I didn't see that coming.
@@Cynthia_Cantrell Did you hear about the guy who wondered why the baseball kept getting bigger and bigger, then it hit him.
Reminds me of the lab technician who spilled some acid on himself. Really left him fuming.
I have been interested in optical engineering for a long time now and yours is the first channel I have seen that covers it well. So thank you for making such excellent videos.
I work in the optics industry for a couple of years now and I have to say that your channel is a real treasure! Your videos are both, highly educational and entertaining. Keep up the outstanding work!
jeez why didnt youtube algorithm recommend this to me earlier??? Its fascinating!!
I used a machine like this in the 90s to flatten hydraulic motor parts. Instead of pitch, the wheel surface was steel, and the surface was kept flat by adjusting three rings which also kept the parts in position on the wheel. We'd check it a couple times a day by washing the abrasive off and placing an optical flat on the wheel. But other than that it worked the same way.
its not the same as true level
@@hindugoat2302 Reality is poison! I can't live like this!
@@stickyfox lol nice answer.
Did you happen to work on pistons and cylinder bores too for a hydraulic piston motor?
@@myselfremade I worked on Eaton and Sauer-Sundstrand axial piston pumps and motors. We would replace pistons and cylinder blocks and send them out to be resleeved/refinished.
@@stickyfox ah very nice. I have an Eaton series 1 pump. 5.4 cubic inch variable displacement model. Installed on my truck. Great pump 👍 wish I had a 11 cubic inch fixed displacement piston motor to go with it but instead I am using a Geroler. It does ok but slightly less optimal.
The principle looks simple, its just a tar and turntable, but those who tried working with glass, especially polishing and making it precise, knows that its extremely hard, takes years of practice and patience. Great video.
I have been polishing precision optics for 12 years, I really enjoyed the video, thank you. I do the final polishing of the optics on a spindle in a zerodur plate with holes, I put planes with weights in them, according to a similar principle. pitch polishing pad for the night I turn over on a plate smeared with Regipol with good flatness
One of the most clearly explained process ever seen on CZcams. Beautiful. I feel like building one of these now.
Hats off to your narration... I simply was thrilled. I am a retired engineer, 73 yrs.
It's hard for me to believe but, I lapped and polished for 20 years (Gator Diamond, Inc) and didn't know half of this info. Thanks, Bill
I've always thought there was something almost magical about being able to make incredibly accurate optical surfaces, flat or otherwise, with no precision tools whatsoever. I ground my 6" parabolic mirror by hand, and figured it to 1/20 wave accuracy on a pitch lap, with no references other than the Foucault test.
Very nicely done. Subscribed.
cheers from sunny Vienna, Scott
if you like that; then the three plates to make a surface plate is another example of this principle (though wil hardish surfaces)
@@robertmccabe8632 Indeed. I use this principle to keep my sharpening stones flat. Using silicon carbide abrasive, I grind A against B, B against C, and C against A.
This is the most satisfying and informative presentation I've seen in ages. As a photographer I really appreciate the craftsmanship required to produce high quality optics. My hat off to you Sir! 🎩
I've been polishing for a year now. This was super informative. Putting images to techniques helps me understand more of what I do all day long lol
Using interferometric fringes to test optics, what an ingenious setup!
If you think that is impressive the Laser Interferometer Gravitational-Wave Observatory uses interferometry to detect changes in length less than a 10 thousandth of the diameter of a proton.
@@kellymoses8566 luckily we don't need *quite* such precision for optics :)
At work here in Germany they got mad at me for filing like this....that you work in nm tolerances and do so as well made me really happy. The understanding of why one would do it so they just couldn’t understand. Also an amazing video, very informative. Keep up the good work!
Excellent vector drawing demonstrating the constant angular velocity.
Am I the only one that loves this type of stuff, but at the same time, completely understands how boring most people probably would find it?
This video reminds me of how profound our technological advancement has been. Just think of how many different people had to cooperate and dedicate basically their entire lives to engineering better solutions in the relatively niche field of precision optics. Using a high viscosity fluid as a lapping surface? How the hell did anybody come up with that? Stuff like this just blows my mind.
Thank you, i always wanted to know how it was done. Very clear description.
Very fascinating seeing someone so specialized and advanced in their field, thank you for sharing.
Very clear and detailed explanation, best I found so far (and no irritating background music).
Cool how you built the turntable from a washing machine motor and rollerblade wheels!
Hello youtube algorithm...thank you for suggesting something I didn't know i needed to know
physicist here, every single video of yours is mesmerizing, I have no words!
Fascinating videos, with plenty of details. Thank you for all this useful info and diagrams!
Last minute had the information I didn't know I needed. Blocking pitch does put pressure on glass held to a backing. All the old film of spectacles and camera lenses show blocking, but these are not expected to be accurate to fractions of a wavelength. OK now I will also avoid lots of messy cleaning up as well.
I'm an optical fiber telecommunications technician. We used to have to polish the end faces of our connectors when terminating them. 3 different ratings of polish paper and polishing in a " figure 8" motion. It was tedious. Faster speeds and the need for lower reflection at the connections has us using fusion splicing and factory terminated connections, now. No one misses " puck and polish" terminations.
The closest thing I do is knife sharpening, but I always wondered about stuff like straightness, flatness, and smoothness. This videos was very interesting.
good to see that physics works
all engineers experience the same when going down to nanometers
no matter what kind of engineering they are doing
and that is that solid material is moving ( slowly )
I have always wanted to see Mach 3 used in a unique way like this. BRAVO !
I can't shake the feeling that I'm learning knowledge that I will never need to use!
Agreed. Like watching This Old Tony.
Using a Fisher and Paykel motor driven by a VFD is genius! So much simpler than the old belt and pulley reduction.
What a fascinating microscopic world lies behind these seemingly primitive (to the layman only, of course) machines!
Prachtig werk! Ik heb me altijd al afgevraagd hoe die dingen zo vlak konden worden gemaakt.
This is very interesting. I read somewhere that for lapping of silicium wafers they use some chemicals instead of abrasive particles. I can't imagine how precise they must polish wafers for 4nm technology.
It's generally a combination of both. If you use a chemical that etches your surface while you are polishing, you can use a very mild (or soft) abrasive agent, which results in a smoother result. By the way, when you use Cerium Oxide to polish glass, chemical interaction also helps speed up the polishing process. For wafers the actual flatness is less important that the smoothness, since modern wafer steppers make a heigh map of the wafer to correct for the total thickness variation when clamping a wafer to the chuck. Modern technology wafers are indeed incredibly smooth and flat (from the dimension of individual components to that of the full chip)
The explanations you give is perfect. Even a brick can understand this.
Clear and precise explanations along with fascinating footage. Thank you. Subbed.
This is an excellent way to do low speed control with a VFD. Thank you for the good idea.
I wasn't aware how much I like this content
No idea why this is in my recommended, but very interesting. I'm amazed this kind of thing can be DIY with the proper knowledge and materials.
I would consider myself a maker more in the software area, it's always cool to see what other people are working on. Keep making!
"proper knowledge and materials"--including an old washing machine motor and rollerblade wheels.
this filled in some gaps in my knowledge, really great stuff.
I would have never guessed that you'd use a malleable disc to do the polishing. Really fascinating to see how this is performed, thanks for the video!
This gave me a moment of connectivity to my Grandad. He ground rifle scope glass for a few years. Now that’s not flat but more of polishing
Newtonian liquid is just a liquid / fluid. Classic. Water, alcohol, glycol, air are all newtonian fluids for example. So, it is not "special" in any sense. Optical pitch has just very high viscosity. There are fluids that are special, and they are called non-newtonian. There are many types of non newtonian fluids and they all have various applications and fascinating properties. :D There are some non-newtonian (visco-elastic with non linear sheer relationships), that are also used in optical polishing, but that is rather very different method.
You are right about the fact that a lot of common fluids are showing Newtonian behavior. But there is also quite a lot that are behaving non-Newtonian such as paint, yogurt, ketchup, toothpaste, so in that sense non-Newtonian fluids are also very common. I guess, all fluids are special, but some are more special than others ;-).
@@HuygensOptics That is true. Non Newtonian fluids are also common. They are just harder to analyse :) ketchup is weird indeed for example. Or magnetorheological fluids, used btw for very precise polishing in optics. Learned about it just few days ago. :D
@@movax20h which field do u study this?
So fascinating the science and math that goes into allowing us to achieve this. I would have never guessed it was pitch
Thanks for the video, it's very informative. So the polishing table is an aluminum disk with a motor stator attached to it, and you press the pitch lap by using a granite plate, but I was wondering if you could share what the pitch lap substrate is made of? It looks like a few inches thick disk. Is it also granite?
No actually in this particular case it is borosilicate, which has a thermal expansion coefficient that is about 3 times lower than granite (which is an advantage). You can however use granite without problems if you have good temperature control.
As a Polish, I approve of this video
i have no idea why CZcams recommend me this video. What more fascinating
is i watched it until end, and still have no idea what is that.
When you shut the machine down overnight, is it necessary to maintain the lab at a cool temperature to minimize pitch movement?
Nah...you just use auto tune. Everybody does these days. Hehehe
@@shannonpincombe8485 That's how those T-pain sunglasses are made.
I think there is a tradeoff. It would certainly help, but investing in climate control may not be worth it. Also, it seems heating the plate and then weighing it down removes enough deformity in a small amount of time.
These techniques are fascinating.
@@shannonpincombe8485 I respect the pun
They run 24hrs
Hi. Огромное спасибо за ваш вклад в образование !
Today is the day i understood why tires have grooves
I had no idea about any of this. Fascinating.
Thank you kind algorithm for bringing me here. This was very interesting.
The algorithm sends me to strange places sometimes, but it sure can be a fascinating journey. Today I learned something I did not know yesterday, thanks.
Your channel deserves more subscribers
its amazing how a bumpy surface can grind down to the nanometer range
It's only bumpy on the macro scale.
Thank you for making and sharing this video! Great content and very informative!
This video made me happy.
Very good explanations with great schematics. Great video overall.
Very good stuff. I've done my share of glass pushing, long long hours of manual work. I tried to make 200mm flats but I constantly got into troubles in 1um (two rings) level... Perhaps I return to them sometimes, even though I hardly remember why I started making them LOL (ok it was some cassegrain telescope idea, and another for testing other flats)
Awesome work! I am going to try this...
Today this was recommended to me and I watched till the end
Great information thanks for sharing 🤠
Excellent. Very happy I found your channel. Honestly, as a nerd in training, a good friday night for me includes such terms as nanometer and interferometry. Looking forward to your next video!
Edit: trainings -> training
I'm lapping this video up!
Flat implies “not curved” when these are curved surfaces. It’s really about the size of the deviation from the theoretical shape of the required surface.
Your videos constantly inspire me to want to build my own lenses for different optical projects. Thank you for sharing your designs and knowledge!
Very good to know, sure I’ll use this someday
I work at Sydor in Engineering nice video man!
Very nice thank's for sharing
I love the combination of washing machine and industrial PWM
I didn't need to know this, but I'm glad I do now.
1:25 I love how that's a huge piece of what I'm sure is expensive equipment using off the shelf roller blade wheels. You can clearly see the painted design on them lol
Fascinating, and very well explained! Thanks a lot!
hats down, top grade quality video, so rare
10:00 So not necessarily, and not usually to that degree. Yes, surface plates do have stricter requirements for local flatness vs overall flatness.
For instance a grade AA surface plate of 18x18 in, has an overall flatness requrement of 50uin, but a local flatness requirement of only 35uin, so that would definitely need to be checked for whatever specific surface plate you're using.
Windows xp for life my man nice work!
I've been having a go at marking crude lenses from polycarbonate , the tyre pattern got me thinking.
I had previously seen brief footage of a lens factory circles on domes and lots of white liquid,
Your explanation has helped me understand the process, I'm not willing to sacrifice my record player or washing machine , but I do have some granet and microwaveable casting rubber.
Really well made video! Great job.
Now I want to build one!
Many thanks. So same thing for seal faces
Really nice knowledge!
i am a machinist by trade and when i was initially linked this video, and i only saw the title, i thought "oh great some charlatan is going to talk about taping sandpaper to a piece of float glass" but i was pleasantly surprised to see that was not the case and this is the real deal. subscribed.
have you considered trying a cast iron master surface for the weight? as long as the room is at least loosely climate controlled, you could theoretically have a more economical option for a even flatter surface than the granite plate
In principle cast iron would work just as well as granite. The CTE is around 10-11 ppm, so compared with granite (8ppm) this is only slightly higher. And because of it's higher thermal conductivy, it will get to thermal equilibrium (and retain it's original shape) quicker than granite. So it would in fact be a better choice as a material. However, don't know how easy it is to make a cast iron disk of 400mm in diameter with a flatness of approx 1um. By the way, granite is not an expensive material.
@@HuygensOptics i know that in metrology cast iron is preferred for master surfaces, because it is more dimensionally stable and easier to make very (beyond AA grade) flat. for your specific use, it would also help as cast iron is denser so it would be heavier for the same size. that is why it came to mind.
@@SuperAWaC Actually in some super accurate machines, aluminium with internal cooling channels can be preferred too. This is because aluminium has way higher thermal conductivity (about 3 times higher than iron) and can be stabilized better, down to 0.1°C. Of course if you deal with big loads and need very high stiffness the cast iron or granite are preferred, but with low loads, aluminium counter intuitively can be even better. I can't find source and machines doing that right now, but I do remember seeing some year ago.
I am a Tool & Die machinist and horologist and it made me happy to see there are other intelligent machinists watching things like this.
I would second the use of a cast iron master plate. There is a guy who comes once a year to certify the multitude of granite surface plates we use in my shop and the man that does this is one of the rare ones who actually can re-lap the granite plates back into spec for flatness using a Master cast iron plate using aluminum oxide abrasives of various grades.
Cast iron master laps are always made in pairs of three to get true flat reference surfaces- I know they are still made but I am not sure who you go to to buy one but if you had one I am certain you would get better results since they are what are used to correct even the granite surfaces
@@movax20h I do know that many coordinate measuring machines have ways that are aluminum which is hard anodized and then lapped to extreme tolerances. It wouldn't surprise me if the very high end ones are also liquid cooled. I do know that they are kept in tightly temperature controlled environments with any heat sources removed (such as computers and humans) and put into different rooms, which is probably enough. But it would take longer for the whole machine to soak back to equilibrium if that environment were disturbed.
growing up in a machine shop makes me fascinated at what high precision milling can do. I'd take parts home and use the machined metal parts to play with.
Amazing video!!
MAN! this is so smart! the rollerblades to unload the bearing axially!
Do you always use the same grit to polish? If not, do the grits find themselves trapped in the pitch? Do you have to use different pitch plates for each grit?
Polishing is the final stage of producing an optical quality surface and there is only one compound used on a given lap.
Grinding the surface to a desired rudimentary curve is called grinding, not lapping. Pitch laps do not grind but only polish. The amount of material you'd remove by polishing is miniscule and nobody wants to waste time doing any more polishing than necessary.
Grinding a surface starts as a rough cut to quickly give a desired curvature and to remove casting irregularities. Then a succession of finer grits is used to remove the deep scratches left by the previous grit. This is done with a hard tool on the workpiece and an abrasive slurry is run onto the surface. It looks a lot like lapping with a pitch lap, but because the tool is hard, it can be reliably cleaned off when it is time to change to the next finer grit size.
If pitch is a liquid, couldn't flatness be achieved without a reference flat (like the bruiser or surface plate)?
Enclose the pitch in a container with walls higher than it and heat it up enough to reduce the viscosity so it flows fast enough for the surface to find its level in a reasonable amount of time, then let it cool down. Surface tension would mess with the flatness near the walls, but closer in should be fine.
I suppose you lose the grooves though, darn.
You will have to wait for a long time before the surface reaches submicron flatness. Keep in mind that there is a volume contraction during cooling down. And of course it is not just about getting the tool flat, but keep it flat during processing.
Well made video, and very interesting!
Great video!
this is extremely interesting.
thank you
i heard somewhere that telescope mirrors used to be polished hand, because machines could not get as smooth and even surface. To achieve this with machines, they made machine mimic human randomness of motion while polishing.
Great video, Christiaan would be proud if he was here today!
Thank you, for precise explanation of the process.