Making a Replacement Glass Chart for an Optical Comparator | Lufkin Ultrascope 1200A | MicroVu 400 

James, while the error may only be slight, spacing your 40 arcs that way isnt spacing them at 0.1 inch, because the point is offset from the centre line, the measurement will be the tangent length of the point from the centre, so your arc spacing will be something like 0.101" (no I havent worked out exactly the measurement)

You did a great job on this. Now we just need to have a DIY optical comparator design for the rest of us! Thanks for the great video.

For future projects where you want frosted glass, take a look into frosted glass vinyl film. Has an adhesive side that you apply directly to clean glass and gives a superbly regular frosted look and would probably be more durable than the paint. Application of it can be finicky. Obviously very very clean glass and work space, I use very dilute soapy water and float the film on that them squeegee out the liquid. Best results after several days of drying out.

I have used the same frosted paint on the interior of a lamp globe. The heat from the led bulb made the coating lift and peel off the glass. Mario.

Regarding the silly small windows - I usually hit CTRL+ALT+R to reset the window positions to default which fixes it for a while till it breaks again...

Well I now know how to custom mark glass with a laser, and do a good job of it! Thanks for the video!

Guess I never thought about it but I guess those would have been glass back then. the optical comparitors I've worked around were ancient from the 1980s, but new enough to use calibrated plexiglass charts

You can use offset to space out the arcs

I would also have chosen back-side etching and frosting just for the purposes of cleaning. Was wondering if sandblasting a piece of glass, then etching on the same surface, would that work? I think it should.

Easy way to make those 1/4 circles would be to use the offset tool, you can't array them but you have to use the distance from the sort so not really much better. Also the easy way to fix that small window is to undock it by moving it slightly using the header, then it grows to fit. I've had this problem lately too. (edit) just as I say that it works on some dialogs and not others, worked on The pattern window for me but I could not get the same thing working with the offset one. (edit 2) tried again but this time I moved the dialog from the upper right and it popped right to the correct size. wierd

Probably won't be able to frost with diamond compound on one with gauge lines on the back - you'd scrub some of the Cermark off. I'd suggest frosting it _before_ etching with the Cermark. The etching should be at least as thick as the frosting, and probably thicker, so it'll just 'write' right through it.

I think you might be compromising the accuracy of the laser with the air hose hanging off the back. Since they have no tool pressure, they aren't designed to be all that rigid and just the weight or drag of the tubing could be moving the arm around a bit. I have a 3D printer with belts on both sides of the Y travel, and even it was always having odd surface finish problems until I changed the filament path so it stopped randomly catching on part of the frame.

Nice work. I expected you to do the frosting using a sandblasting cabinet. But the spray looks quite okay.

Hey James, Applied Science did a video 10 years ago discussing how he machines glass plate on his mill. Might be of interest to you

That is pretty damn amazing....

What about the indexes at the top of the machine? Is it my eye, or is the glass indexed a few degrees positive of the viewer? Look at the teeth top and bottom in the glass. James, if I watched EVERY video you made with the volume muted, I'd think I can do what you are doing. WRONG! You make it look simple. The way you got in Fusion, it's like you wrote the program. Your work is excellent, and I enjoy watching.

print it on paper and you can draw all you want...and those pins will hold it

This was an amazing method to remake an unobtanium part! There is another popular RU-vid channel called Mr. Carlson's Lab. Paul is an electronics and radio enthusiast and one of his specialties is refurbishing old radios. He often mentions how difficult it is to refurbish the old glass dials. I think the two of you could do an interesting collaboration.

James, to all those; woulda, coulda, shouldas.....this project by far has to be the MOST informative, well executed and just plain GREAT you tube video of all time.....it shows innovative thinking, precise and technical execution all wrapped up in an understandable and enjoyble storyline. To do what you did with this is ABOVE and BEYOND......you raise the bar to the Nth degree.....Hats off to you on this one !!!!!! Keep em coming.......

And just like that, James has a new business supplying folks wanting to restore their comparator. This was a really cool video, I have zero experience with CNC lasers and it's interesting to see what can be done.

Hey James, great video! RE the circular pattern box being too small, I think its because its docked to your sketch palette, if you grab the top bar you can break it free then resize all you need.

I continue to be blown away with what technology has give us. For not much money in equipment ( but lots of know how) you can produce some amazing things that were unheard of for a hobbyist not so long ago. Very informative and interesting thanks.

The window problem is everywhere in fusion, just grab the titlebar of the little window and undock it from the sketch panel thingie, then you can grab the lower corner of it and drag it to size =)

RE: bunch of arcs 12:00 Draw 1 arc, no pattern of points. Select the arc, click Modify/Offset (Hotkey = O) type in the offset value you used in the original pattern, use a parameter (ArcOffset). You can only offset the original. BUT! copy the text, ArcOffset* Now that's in your clipboard, you can select original Arc press O on the keyboard CTRL V, and type in the next value, 2 then 3 then 4 then blah blah blah, you get the idea... Get into a little rhythm and this can go relatively quickly. Alternative - get into API programming for Fusion and create this feature yourself. If I could come up with with a solid use for this type of feature I might consider doing it, but it's a bit of a bother for an edge case scenario like this.

Never thought i'd be recommended a video on an optical comparator. I used to work in precision manufacturing, dealing with tungsten carbide parts and tooling, and let me tell you... I wore a groove down in the factory floor between by workstation and the comparator with diamond paste. Granted, the one we used was the size of a small car, lol. We never had issues with the charts availability, the bulb, however... I remember cost us over several thousands of dollars to replace.

You did a really nice job on that. I have frosted glass in the sand blasting cabinet. You might want to give that a try. Thanks for the great videos.

I'm curious to know what you used to cut the glass and whether you did anything to the edge to make it safer to handle.

Awesome video, Fusion lessons…tks, great build/discussion/demonstration….need to order 1 as I almost go blind/crazy with my current screen viewing in a dark room

Very timely. I have a Nippon Kogaku (Nikon) 6 that came with plain glass and only cross hairs. I bought a mylar overlay of one pattern but want to make my own as well, specifically for checking threads (metric/UNC/UNF/BA etc). This same Fusion360 approach will work for printing on mylar or tracing paper. Thank you for the (as always) clear education. These are superbly useful tools, esp. when cutting 80-100 tpi threads, you can verify that your cutting tool is ground and set properly.

When you talked about etching glass, I at first thought about traditional etching - glad you found a modern technique, because HF definitely falls under "things I'm glad I don't work with."

Another thought, maybe sandblasting the glass first to permanently frost it, and then lasering the Cermark would give the most robust result?

@Clough42 if you unsnap the modifier windows in fusion, it will allow you too resize it and will usually remember the change after you resnap it. Running fusion in windowed mode tends to squash the modifier windows i have found. Or if something happens while running that forces a resolution change.

Excellent. Cermark on Glass looks to be a real winner. Also appreciate you using Lightburn a bit more. Was good to see someone else "using it like I will"

I have a simular optical compactor. With broken glass. How much to have you make one?

I can tell you the spray frosting holds up just fine. We didn’t like the “porthole” window in our side bathroom, so we replaced it with a different one that wasn’t frosted for privacy. We taped off the inside of the window frame after installation and sprayed that rattlecan frosting on the glass on the inside of the window. 15 years and it looks exactly the same.

I've got a vintage tube radio that I volunteered to restore. The dials are in pieces. Now I know how to recreate them in F360. I don't have a laser etching gizmo but just being able to recreate them is going to be handy. I don't have them with me and I'm a little concerned that the scales are nonlinear.

I have done a number of art glass panels as part of a door or window for my clients. While I haven’t actually done the frosting of the glass, I have provided the artwork and watched a skilled glass etching artist go through their paces. Drawing on that experience, I would be very interested to see what the the laser marking results would look like if the glass panel had been sandblasted first - in this case with an ultra fine blast media. You might want to check locally to see if there is a glass artist with etching and sandblasting facilities. But this is a great video and once again you have proven your resourcefulness. As one of the Fusion 360 insider team members, I commend your CAD work - Move over LARS - James is about to displace you in the YT community. LOL. Thanks for this interesting video.

Really enjoyed this and have never liked so many comments, some great ideas there. I have said it before but the way you explain Fusion360 is first class. A mini series on Fusion would I’m sure be well received.

Cutting glass: I had 10 circular porthole glasses to replace - different dimensions. CAD drawings and off to a waterjet cutter. They were perfect. You can always clean up the edges. In the water cutter shop, their second machine was cutting a huge hinge out of a 10" block of steel!

Sandblasting the glass with fine grit works great for frosting glass and it is really durable. I am now going to pull the trigger on a XTool D1. Thanks for the great video.

Maybe sandblast the back first and then etch it

I have the same problem with the pattern tool window being too small. The problem has been there for a few months now. I think the Fusion team wanted to clean up the screen a bit and make it more minimalistic. Unfortunately, the usability suffers immensely. Too bad. However, you can click the two small arrows in the upper right corner. This enlarges the window to the previous standard size. But, the window has to be enlarged every time. Unfortunately, Fusion does not remember the setting. Keep it up!

Thanks, good stuff all the way through, especially the Fusion 360 techniques. Didn’t know the laser would work on glass.

There's no need to use diamond powder abrasive for frosting. Loose silicon carbide wet with water works well and is considerably cheaper. Your are just fine grinding the glass in the same way that is done when manually grinding lenses and mirrors. Either glass or ceramic tile tools work well.

Very cool. I love the old school optical measuring equipment. You could also make it metric with this trick? Hmm- are there graduated markings on dials for the table?

Was anyone else waiting to see if James would try to cut the glass circle with multiple passes with the laser?

Another great video! I really enjoy the format with the Fusion360 demo. I guess I’m in the market for a laser engraver. 😉

James, you can seal the frosting spray in with a clear coat finish if you're worried about it's durability. I've used both matte and gloss on top of the frosting spray with zero issues. The glass looks amazing, thanks for the video!👍👍

I just bought a MicroVu 400 optical comparator from eBay. My screen from what I can view on the pictures is fine. You did a great job showing us how to do this. I wish I could learn Fusion 360 but I don't seem to have a mind that understands the terminology. I'm 71 and struggle with all that you have to remember in order to draw what you want. Thanks

Se dieron 200 vueltas y explicaciones... para algo tan simple y no poner detrás un papel diamante ¡¡ y listo...!!

James, I have a similar machine MicroVu HP500 with a broken screen. Is there any possiblity of paying you to mfg replacement from my comparitor? Thanks for the interesting video.

you can frost glass with...I believe hydrofluoric acid. It's nasty stuff, but if you look around you can find kits for the DIYer.

Really no one has figured out that most recordings will not pick up a lawnmower as it is a very repetitive sound that most modern microphone compression algos dealt with this 5+ years ago? But I'm sure your science here is solid...oh there's the lawnmower sound now... you can't like ask your neighbor to wait an hour? Science! EDIT: You couldn't wait? Science!

Glass and metal tech here, you could also try a frosted/obscure or transparent film. Some good 3m fils (and heaps of others) will give a more even and optically better viewport, also easy to replace/consistent and will protect the marks from oxidisation. You can also acid etch the glass but this process leaves it extremely susceptible to oils as they are almost impossible to remove. We normally get our acid etched glass in already finish 3 or 6mm sheets and toughen or heat treat after cutting to alleviate the issue. Its diy if your have the time too if you can’t get it cut to size. If you wanted to bring these to market my recommendation would be: 2 or 3mm Low Iron clear glass (no need for scientific grade), un-toughened/untreated (the film will add safety should it break) and then the best transparent film you can find. Honestly, with all that said, I can’t believe it worked so well with the frost spray- a perfectly serviceable result for sure!! Great job!

I am wanting to do this myself for the optical comparatorI am restoring. Where did you find the glass? I have not been having good results searching for "7.75in glass disc" and the like. Good work on this.

The IBM typewriter factory in Lexington Kentucky had dozens and dozens of these Optical Comparators.

I think you missed a trick. For the mark 2, you could add metric units in the upper quadrant, or on a separate disk. I know the mere thought of metric brings some of you on that side of the pond out in a rash, but being able to compare your test piece to metric units can be useful.

Awesome, I wonder how Mr. Pete’s optical comparator is and if it could use a new glass. I have an Ender 3 S1 Pro and apparently I can get a laser for it…no idea the quality or what it can accomplish, but fun to think about. Great video!

Add construction lines, draw circle for first arc, offset multiple the first arc (circle), in trim using a fence command trim between construction lines. But this is old CAD talking I haven’t used fusion at all. If it still works the same offsetting the trimmed arc should work as well. Edit command may be array not offset

Drafting mylar has a frosted finish for the ink to stick (old fashion ink drawings). I sprayed the backside of my plain glass with a VERY light coat of 3M or some other contact spray. I can't remember if I sprayed the maylar also, then placed it on the glass and trimmed the edge with a razor blade. It is perfect for placing laser printed objects on clear laser film that can be placed on the optical comparator screen.

Great video and presentation of an application for the Laser. Alas, you have once again raised a wistful lament (and lust) for your well-equipped shop; however, on my list for the lottery winnings spending time with Giada & Stanley in Italy are still at the top.

"I need you to make me one of theese" Just one? Ok, I'll make 10 different ones and give you the best. Having all the markings on the back seems to be best for both durability and readability. 👌

Anyone else around here realize how frickin' *DIRTY* your monitor is around 6 min. in? HAHAHA. Great video!

Any possibility to make video showing construction of that optical comparator? To me looks like mythical device. Yes there are some descriptions on the net but no one showing real parts and their sizes.

as a glassblower, watching you opt for the spray frosting was hella cringe. I know others on here have likely commented that it should have been sandblasted. stay away from acid etch creams, the ammonium bifluoride is almost as terrible/deadly as HF.

You may be able to frost the glass with etching acid paste (or etching acid, but that's going to be a pain to set up). I don't know if that will screw up the CerMark, though it might be possible to frost first then do the CerMark

There's a city near where I grew up called Lufkin and that's what drew my attention. Unsure if it's just the Texas accent's that changed the pronunciation or if the man it was named after last name was just pronounced differently but interesting.

Is it possible to make an overlay from transparent plastic and burn the nomenclature and scales you want with the laser?? What type of laser machine do you use? Thanks

Thanks for posting this. is it typical that the glass is etched or did some of these come with "plastic" overlays that can be swapped out? I just picked one of these up and have started to do some digging. Thanks in advance

Why is is called a comparator? From the name I was thinking of a device like a fingerprint comparator, which works the a similar way as this but there are two of them and you compare the fingerprints on each one.

You could also try frosted vinyl. My dad owns a sign shop and uses frosted vinyl a lot on store fronts! We used some on our bathroom window and it looks great!

Robin renzetti needs your help he made one with dimond and a Razer Blade but it only has crosshairs now.

Unless I missed something - why not start off with properly frosted glass on the back?

Very nice results.

I'm curious if white markings would show up better than black.

So we are rapidly approaching the era of diy unobtanium. Time to update those patent and copyright laws to reflect the era.

As always a great video. The biggest thing this does for me is giving me new ideas on ways to use my laser I hadn't thought of before. Glass is tough to work with. Thanks.

Considering a new unit cost is $10K, this is the way to go. I did find many lenses for sale though.

Looks great! The only thing that bugs me is that the new chart seems to be rotated by a few degrees in comparison to the original one.

The frosting reminds me of the cataract I had in my left eye.

you can use inkscape, gimp, krita, etc. and set the dimensions to scientific units and get exact dimensions.

How did you verify the scale after you made it? Could this be certified?

It’s very rare I see things that I didn’t know existed but you got me.

James, I'm not a fusion 360 user but worked a lot with different CAD packages and I would search for "offset" to create multiple arcs evenly spaced. Maybe this helps. (offset distance, number of copies would be ideal as an input here) Thank you sir! Best, Job

Sandblaster work's good for frosting glass

Why did yall not put the glass on at the correct angle? The alignment lines are right there.

Optical comparaters are neat if you have a use. Thanks for the video, keep on keeping on.

Degree markings seems not to be aligned to the holes right. The whole thing ist somehow shiftet.

So, my MicroVu 400 needs just this. To be blunt, how much?! My processes are mature and familiar. Its worth more to me to keep what I have. Thank you for your work.

Excelent work! Really like result!

What would the results would be like if you etched the glass with the laser before CerMark was sprayed on and then the CerMark was applied. Would the pits in the glass be filled? The marks would be more resistant to abrasion, and it may be possible to frost the glass mechanically without removing them. The alignment would need to be perfect in order to do this. You could probably use a machinist square and dowel pins through the holes in the glass to align it to the laser. I believe they make a white version of CerMark as well. It would be interesting if you could layer on different colors.

Could you put a very fine frosting, mechanically or chemically, and then laser etch over cermark onto the frosting? I’d guess that would be pretty durable

First, optical comparators just became ebay investment opportunities. Second, how wide did those low power marks turn out to be? Third, do you think it would blow up tempered glass?

Very interesting material... But why don't laser graphics on an already frosted glass? Thank you!

Looks fantastic. Just a thought. I noticed that there is a bright spot at the center and am wondering if one of the LED flat panels would provide a more even back lighting for the comparator.

My only criticism is the choice of typeface, it would have been nice if you could have matched the original more closely, rather than just using the default (and not very nice) Arial.

Great little project! Very enjoyable to watch your process. Are you planning on doing more videos with the benchtop cnc? Specifically very interested in getting it aligned and trammed well

if the zombies ever do come, I'm coming to your house

James, thank you for a great video. We are a producer of optical comparator glass screens and overlays. We are always on the hunt to find more contemporary methods for the process we use in our manufacturing. We will pursue some of the techniques you demonstrated to see how they work in our environment and if they meet our standards for precision and durability. Thanks again for your channel.

Acrylic instead of glass? Cuts well on the laser