New Tool for the Shop: Kodak Model 2A Optical Comparator 

My father was metallurgist for ball bearing company for 35 years, I remember one of these machines in office at the plant he worked. He turned it on while I was in there one we looked at the edge of a razor it was amazing.

I love the super-micrometer stage and the fact you can pick up such a fantastic piece of metrology for next to nothing. I already photograph parts and import them into AutoCad and use basically that as an optical comparator. If you replaced the projector and bulb with a decent wifi camera, part lighting and a nice big monitor you could use the micrometer stage to compare fabricated parts with designs right inside the CAD software. Would give the old girl a whole new lease on life!

I have no use for an optical comparator either, Keith. But now I want one!

I've been wanting one like this for years. I just purchased one, same model with DRO as well. $1,000.00 + $125.00 crating + 1,250.00 Postage. Weighs in around 900 pounds. A lot. But, there is none that compare in that price range. None I can find that hit 100X I am pleased you put up this video as I have learned a lot and found Certified Comparator Products mentioned below for parts and service. I can scarcely wait to get it.

Iron Deficiency Disorder! Thanks for giving name to that which we have in common!

Hi Keith we bought one at an auction, a wood worker facility hardly used it very clean, we needed space in the shop so we dismantled it we have parts if anyone is interested for sale. Kodak 2a Oella Saw and Tool

You continue to inspire with your attitude and skill, Keith. One tip: Zeiss rhymes with rice, not geese.

They have been mostly replaced by computerized, lower skilled, higher resolution, less finicky vision systems. For some uses, a smart phone can be used,but not always. We have a giant 30 inch optical comparator with DRO and motor driven axis. I used it regularly until 1993. Then was promoted and moved away not to touch again. But 6 weeks ago was working on a complicated job that intersected with the comparator. No one in the department knew how to run the machine. I doubted my memory. But, wow, after one minor error, accurately measured the component to 0.0002 cross compared to the vision system. I was chuffed.

That thing reminds me of some of the stuff I had to maintain when I worked for Xerox, the mirror will be particularly delicate and only touched with cellulose synthetic 'cotton wool' with some very mild cleaner. The mirror surface is exposed on the face of the glass to prevent any prismatic distortion through the glass. The covering is exactly the same as on a regular mirror, but not painted over with a protective paint. If it is damaged or scratched it can be resilvered anywhere mirrors are made. I used to have to do this a lot on old photocopiers and it restores them to almost new optical condition and is not expensive. No fingerprints at all as the oil corrodes the silvering. Good luck.

Used them a lot working at Wendt-Sonis/TRW/RTW?Kennametal. We used them when grinding precision cutting tools. Making templates for it was fun!

Thanks Keith....l love old machines of all kinds...!

Wow nice too see a new machine i have never seen that one its a good addition I know when you built the shop you where already thinking of a later addition !!Thanks Keith !

Awesome! Love Comparator videos.

Keith, there are MD's that can be of a great help to you with that "iron deficiency disorder" you are afflicted with. Boy, I can see a new and bigger shop in your future...without getting "help." As you are well aware of, one can never have enough tools/machines. Keep on re-building them.

Really enjoyed this episode. You have a great sense of humor that had me laughing loud enough to wake up the dog. Once again im looking forward to the next one.

Once you start using it you'll have no idea how you got by without one. They are perfect for checking radius sizes on a cutter and or parts. As well as checking part features so the are in tolerance. I ran a swiss screw machine and the entire part was < .125" in diameter and < .500" in length. We had templates we would put up on the viewing screen and check all features on one chart. HUGE time saver in production runs.

I had access to one of these during the development of one of our products; it turned what would have been a task probably requiring a couple of hundred of hours of calcs into one requiring ~16 hours of rather boring but extremely effective effort. Suffice to say it was used to define the data for programing 5-axis machining of a complex form. And it did what was required. Neat stuff.

I worked at a microwave waver probe manufacturer and the optical comparators were super useful.

I worked as a thread roller and we used that instrument to compare threads for trilobular bolt shanks, they provided a scaled print for us to compare the part

Comparators are great machines. Old school is sometimes the best school! The good thing is they don’t have the electronics like some of the new stuff! Mechanical features are easier to diagnose! Congrats on the new toy, enjoy!!

I remember seeing those and bigger ones (like a 36" diameter view port). Towards the end the engineers would use a laser printer to print an outline in scale on a transparent sheet. Think the plastic transparency films on an overhead projector. Then they'd just tape them up on the viewport to verify part profiles as a sort of go/no-go production test. They'd also use them for reverse engineering something. They'd tape up blank transparency sheets, trace the outline with a marker, then take it down and label it as they used the optical comparator to measure it. The end result was essentially a hand-draw blueprint they could make copies of and give to whoever.

This is it! You can make parts in high detail when comparing drawings to parts. You can also do the other way round, picture to part. If you have some dimensions, it should be pretty accurate!

Keith, Please don't wipe your objectives like that. The dust and grit will scratch up those lenses in no time. Use lots of Qtips or lens paper with a good lens cleaning solution. Try to roll the dirt off with Qtips and throw them away after each roll. A little alcohol on a Qtip works as a degreaser. Xylene works well also.

Totally cool Keith I am so excited for you ! and jealous. and curious all at the same time

THANK YOU...for sharing. I see an addition in your future.

Congrats on the new addition to the shop Keith. Looking forward to learning about the comparitor.

Very cool!

You can get a radius guage circle to put on the front, works well for checking tools and parts. Also transparent overlays to rough check contours. I use a newer style with DRO and all the fancy buttons. Wish we had that high of magnification!

Looks like a real nice one. I look forward to seeing you use it. For cleaning lenses that are really dirty it’s good to start with a fine soft brush.

Awesome.... congrats!

You're the king of vintage operating manuals, Keith... time to find one for this.

Very cool Keith!

Hi Keith. Great to see I'm not alone in suffering this disorder!! I could use one of these also. It would make my cockups even more impressive!!

Years ago, a business next door manufactured precision needles for needle valves. It was aerospace stuff, so the tolerances were extreme. They had one of these machines to check every part produced. Got to know these people really well and they showed me how it worked. I thought it was pretty amazing, considering the tolerances they were working with. This is the first time I’ve seen one since. Very cool. 👍

Saw one of these used a couple of years ago to measure the physical properties of high voltage cable insulation at a factory in S. Korea. Very cool.

Yeeeeeehaaaaaw!! Spontaneous shopping is the best Keith! Awesome machine :)

That machine looks very well built. These were the kinds of machines that put man on the moon. :-)

Very cool. Interesting instrument. Good video. Thanks, it's appreciated.

Those are great for measuring small and odd-shaped objects. I used one every day back in the late 80's for measuring hand-ground cutters.

Life would be dull if we limited ourselves to only what we need.

Hey Keith, nice purchase! We use these all the time at work. You can print out clear overlays that are held on the screen and matched to the actual parts under the viewer. Often we will define and MMC (maximum material condition) and LMC (least material condition) boundaries based on design tolerances. If the part fits between the boundary, it's good to go. 👌

Good equipment for check angles and dimensions of the bevel gear that just made good luck !

Great tool, as a retired QA engineering inspector these are a must have piece of kit in most inspection departments.

Optical grinders weren't required for our plastic injection molds but every stamping die shop in the county had several. The common Boyer-Schultz surface grinder dial increments functioned for us but the stamping die optical grinders augmented their profiles with optical comparer scopes to sharpen an internal corner or form a profile to an overlay while grinding.

Keith there is a Monarch lathe on Ebay right now with a tracer atachment on it

Something new to learn, good fun.

I personally love your and Adam Booth's collecting habits (his channel inspired me to start watching Keith's channel). I love seeing these old iron machines brought back to life, and the rediscovery of the tools and techniques need to use and maintain them. One of my other favorite channels features a 100yo large form wood planer that was refurbished and used on a boat building project. Those "making" skills continue to be useful today, as not everyone has access to a 6 axis CNC mill :)

I work in an airfoil mold shop in Cleveland. We had at one time four J&L comparators with 36” screens. They were great for checking airfoil forms. We used 10X and 20X lenses and custom made carbide styli with .005 and .010 radii at 3 degree draft. The bulbs were around $700 and then we converted them to halogen. Sadly, the main reason we got rid of them was nobody made an accurate plotter for making Mylar charts anymore. We couldn’t find used heads on the internet and nobody manufactured replacement parts. They were great machines! Sad to see them go. We inspect everything with 3D cameras now. Slower than the comparator, but it shows the entire cavity.

Lovely machine! Clock and watchmakers use them all the time. Nowadays the digital microscopes have superseded even the swiss OCs. I am doing some research to see if I can find one that will let me do measurements of angles, radii and distances. Of course with a digital version you don't need a gantry crane :)

I've used these for checking on super-tight tolerance tooling. We're talking wire dies that needed to be +/- a thou or less at 0.032" ID. Super useful for checking bore sizes, especially if you have a production run of things you need to inspect. It can be helpful to use color filters to give you more contrast on the different light beams sometimes, depending on what you're looking at.

That instrument looks to me like all the optical components could use a thorough clean especial the screen. You'll probably find there's a thin film of oil that's built up the glass and especially that screen from being around spinning hot lubricated machines putting volatile organics into the air.

Back in 1972 when I worked at Bennett Respiration company making medical respirators parts for them anyway precision. I use an optical comparator pretty much like yours except for it had like a shower curtain in a circle in the front so you can get it out of the shop light. I would recommend changing the bulbs to something brighter myself because that's the one thing I remember if these comparators and they get into larger magnification the light drops off to dim. may be converted to LED so you can get some good bright light with no heat.

if the HOUSING is getting hot over the bulbs... check the cooling fans for the bulbs.. those are probably Projector bulbs and they should have cooling fans that run all the time and allow you to turn the bulbs off by rotating the knob but leave the fans running for a minute to cool the bulbs before shutting completely off.. just a thought..

Years ago I was a product development engineer for Kodak. There was room off the parking garage below the Van Ness Office (overlooking SF Bay) that had 7 or 8 comparators of various sizes/prices. I had to rob parts off one to get something in the field working. It wasn't my product line, but those were the days that if you could help out, you did and no one worried about cross product budget charges. I realized the machines had been there a long time. So I left a BIG note on them with my home phone that if these were ever going to be scrapped out or destroyed, I'd like to have one. Many years (15?) after leaving Kodak I got a call from someone saying Kodak was selling the Van Ness office and if I wanted one of the Comparators, come and get it. Catch was I had to take them all... Tomorrow. I had to pass... logistics were just not going to work. Great find Keith, I'm sure you'll find many uses for such a tool as years go by.

I LOVE those Ziess lens wipes. I use them for my eyeglasses, as well as my camera gear!

I remember one from school while working on my apprenticeship. Sensitive thing for sure. Someone sure goofed in the design dept eh.

I was not aware of IFD, But I have this disorder too. When I first saw the tap on the comparator screen I thought it was a sward fish bill. Thanks for telling us it is a tap. Nice machine!

You know what, you got a good deal, and that thing is a cool machine even if you don't ever use it. So it can go in the corner of antique/cool stuff I'd say.

If there was a layer of dirt on the lenses then you should expect to have a layer of dirt on the light bulbs, the back of the screen, and the electrical connections. I'd replace all the wires and connectors and clean all the connection lugs as that could cause low voltage to the lights and hot spots at the connections which can be a fire hazard as well as causing permanent damage to the equipment. Don't forget to check the light bulb bases for dirt, corrosion, and bad electrical connections since the heating and cooling they experience can cause the connections to loosen over time. Congrats and good luck!

Dropping the main unit back down onto that dirty base would’ve driven me up the wall. It is driving me up the wall. Lol. Anyway, congrats on the purchase! Absolutely love this channel because I get to learn so much from you. Thank you for sharing!!!

I am thankful to you having "iron deficiency disorder". I never knew these things existed!

I used one of these working at a production shop making parts for timers. I has some rejected parts which looked fine by eye, but were butt ugly under the comparator. It became part of the routine quality check as profile was very important .

Dad used to use one. Great for QA analysis.

I like that Keith! I'm retired and started buying old tool toys. In Dasher

Hey Keith, Several uses that come to mind would be, setting up a boring head for a diameter minus a little of course. Check any of your cutters that have inserts to make sure they are set parallel to the center line of the tool. Works great on phased inserted tools since you cant mic across the inserts. And lastly for doing form grinding, once your grinding wheel is dressed with radii or angles. Take a piece of card stock with the wheel spinning and touch the card to the wheel to pick up the features. Then put the card on the comparator and measure the features. There are a bunch more uses too. Mike - Plus8Precision

Saw one of these about 20 years ago, when I was temping at an engineering, they were re-profiling ball joint rollers. They placed some sort of tracing paper over the screen which had an arch drawn on it, they then put the rollers on the table and and once they had focused and aligned the the roller they would compare the shadow the roller cast on the screen against the curve of the tracing paper.

Mine come in yesterday. Outfitted with a Quality Measurement Systems Autocomp I 2-Axis Digital Read Out. Overhead light not working, missing 32X and 64X lenses. Has the overhead mirror fixture for the table and various spare parts. No vise. Works well, and fun. Very dark at 100X but still valid. The DRO has several useful functions. I could use manuals for both if you have come up with any. Thanks! Mark

It was good to see you using proper lens cleaning wipes. I cringe whenever I see someone clean a lens with facial tissue or (OMG!!) paper towel.

Nice!!

that gantry crane is gold.

I use one of these shadowgraph machines on an almost daily basis for making the delicate business end of surgical instruments. We use OHP transparent film with the profile of what we want to make on it, then its a case of shaping the metal untill if fits the profile. They are also very useful for getting the cutting angle correct on drill bits and lathe cutting tools when machining pivot pins than fit into countersunk holes.

Love it, it’s funny when you build a part from 40 year old drawing and they measure the part with modern machine. Anyways good video.

oh, i once saw this at a surplus store, never knew what it was!

As said, clean is the key. You need to clean all lenses, glasses, screen, etc. Of course a LED light may also help. To look at a cutter or a surface, a microscope is better. But for measuring and comparisation of a part this devices are more htan helpful. Good find. They are not even near cheap, bought new, so getting one for a good price is always nice.

I would LOVE to have an optical comparator. Thanks, John

I used a optical comparator for some years adjusting a cutting head on a boring bar for cutting rolls for making tubing in a Kocks SRM Mill

I would think you could download a manual from the internet, you can for everything else. I love your videos, I am addicted to the stoker motor videos.

Hi Keith, A nice bit of kit... if you have the space and budget why not... Take care Paul,,

It will be useful as a very accurate protractor, one who is in favor of tractors.

New Tool or New Toy Mr. Rucker? You can be honest for you are amongst friends. 😉

Gday Keith, there’s nothing wrong with an iron fix, you will probably use it more then you think, I brought a cheap digital microscope for checking lathe tools and I found myself using it more and more, I’d be lost without it now, thanks for sharing mate, take care

I once used an optical comparator....except this one was computer driven. Instead of you looking at the round screen you looked at the computer screen. This was a six figure machine and the owner would let NO ONE touch it unless you were taught how to use it because it was possible to crash it because of the way it worked. I was the only one outside the company allowed to even go near it.

If you find the higher magnifications to be really useful you may want to relocate the comparator to a corner where you can more easily block stray light from hitting the screen, perhaps with a heavy curtain? As others here have suggested, do some more careful cleaning of lenses & mirrors, straighten out the hood, etc and figure out your best ways to turn off any lights that are hitting the machine when it is in use. In a machine shop we always fight for more light to see better, but in an optical shop the focus [yes, a pun] must be on keeping the surroundings dark so that faint images are visible. It is all great fun! Enjoy your new tool, I'm envious!

I have the same disease, didn't know the name untill now, thanks keith

Keith, the more magnification that you have on the machine the darker it will be, that's completely normal with optics. For example, if you have a camera lens with a long focal length, the image will appear darker through the lens, compared to a lens with a short focal length. So a 55mm lens will be brighter than a lens with a focal length of 200mm.

A good cleaning of lenses and mirrors with higher quality stuff, and definitely a switch over to a much much brighter and cooler LED projector bulb will be super helpful.

You probably don't want to put a more powerful lamp in there, you already noticeed how hot that one gets, depending on the holder and wiring to it, you could cause melting problems It's probably something like a projector lamp, and maybe a bit specialised at that power.

I wanted to reach into the screen of my laptop and clean the grunge off the base before you put the instrument back, but couldn't get my hand there fast enough. I predict you will have a lot of fun with that device.

Get some rust reformer and apply on places like the rim of that rusty door. It will stop the rust, make it sandable, paintable or just plain better looking. I get it in spray cans at HF and always have one somewhere within a reach.

My time of using optical comparator was for setting inserts on a multitude of cutters for large wood molding machines. Some barrell cutters had dozens of inserts and they all had to be in the same plane for proper finishing. I am sure the comparator would be just as useful for setting inserts on face/shell mills. Nothing more annoying than having that one insert a few tenths higher than all the rest

There is nothing like a new tool to play with

So that little microscope attachment for my phone and a dollar store protractor do not compare favorably to this. But mine only cost 8 bucks and fits in my pocket! Thanks for the video...had no idea something like this even existed!

That's it Keith, I blame you, I've just won an optical comparator off Ebay, got a trip to Kent on Monday to pick it up! I fear you may have started a new trend among home shop owners.

Soo much more cleaning of lens and aptures also bulbs need cleaning aswell ;-) Great video!

The design/draftsman had one of these in his area where I retired from and they mainly used it for designing and tweaking steam turbine blade specs. It had a lot brighter screen than yours though.

I bought a scrap table top optical comparator and did a full rebuild on it, video on my channel. Fantastic bits of kit you will use it for all sorts of measurements. Great for angles and really good at checking out lathe tools. You will find its not a machine you will use every time you get in the shop but they are invaluable for checking out unknown parts, threads, angles, tools and difficult to measure features on webs etc. Love the videos old iron was just so well made!

Keith, Every place I have seen those used they were in a darkened room to keep down the ambient light. Trane had one in the sharpening room and the room was always rather dark even though there were windows in the walls and door. Those bulbs are probably projector bulbs. You might be able to install LEDS as replacements.

Good morning Keith.

really really to cool for school.

You have a real jewel there, Keith. Kodak made beautiful optical equipment, back in the day. Can you imagine anyone making a piece that heavy today? We had a unit very similar to yours in our experimental engine fabrication department. It was always busy.