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Optical Comparator for Home Office Suggestions ?

a2t

Plastic
Joined
Jul 16, 2018
Hey all,

I need a optical comparator for my home office. Small, as lightweight as possible, and hopefully significantly less than $5K.

This needs to have a DRO with some basic geometric capability, like hole diameter, radius, angle. I dont care about integrating with a CNC, printing screen shots, edge detection, or anything like that.

I'll be measuring small gears that are .020" thick teeth, with tiny root radius. Its very hard to do with calipers.

Any suggestions ? Im looking on ebay, and see lots of used equipment in various conditions.

I found a Mitutoyo PH14LS w/QM-Data 200 dro that looks like it would fit the bill.

I also took a trip down to MSC the other day and checked out their Fowler bench top unit for $3200. What a piece of garbage that thing was, Im shocked anyone buys anything from Fowler at this point! It was maybe worth $500 but would be useless for any sort of accuracy which defeats the point.

Any other suggestions highly appreciated !

Paul
 
How about a measuring microscope? Either add your own optics X-Y stage from Newport or Thor, or buy a complete unit. You can get an idea of what's available on the cheaper end from Ebay: eBay - Page Not Found but if you check out Zeiss or Mitutoyo you can find higher-end setups.

Let us know what you wind up with.
 
dont know anything about measuring microscope but ive been staying away from vertical projector comparators because sometimes the gears im measuring are also attached to a shaft thats a few inches long. I thought (and I could be wrong so tell me) that the vertical projectors and the microscopes all seem to work great for very thin objects that you can lay down on the glass, however I need to account for several inches of z axis depending on whats being measured.

will definitey check out micro-vu. Ive seen a few, but honestly after making the guys at MSC unpackage the Fowler (which looks identical) I was pretty heart broken. Hopefully microview is better made than fowler. It was almost a kids toy ... for $3200.

that mitutoyo PH14LS - is that the same as a PH A 350 ? If so, it will weigh over 300 lbs. Im not sure how the heck I would be able to get that into my home office ...
 
...If so, it will weigh over 300 lbs. Im not sure how the heck I would be able to get that into my home office ...
Do you have a roll cab or a rollaway toolbox? They have pretty beefy casters.

I used a 42" roll cab to move a granite surface plate into my inspection room.
 
I'm with Milland on the measuring microscope.

My home-brew soluton is a stereo microscope with a cross hair reticle and a stage with a small Mitutoyo x-y DRO. Spent under $1K. Very clear images, nice depth of field. Basically set the cross hairs on one feature, set the x-y table to zero, move the cross hairs where you want, and there's your measure in either inches or mm. The stereo microscope is a permanent resident on one of my benches. The x-y table (small and light) is put under the boom stand as needed. Mine has 6" travels.

Initially used an old American Optical "Cycloptic" with a trinocular tube as the microscope. Now it's a Meiji trinocular, with a bit wider field of view and full zoom.

Add a small precision rotary table to the stage and you also get angle measurements.

Stereo microscope is handy for all sorts of other reasons. Just seeing something like a .35mm thread gage next to a small screw is a challenge with my old eyes. Not so with a bit of light and magnification. A trinocular head on the scope makes documentation easy, should you want or need it.
 
Ok that does sound good although radius and diameter also very important how do u measure that ?

For $3800 used or $6750 brand new I could get that without any sort of home brew needed. I don’t really know how to build up the whole set up either using the microscope plus stages plus dro

I'm with Milland on the measuring microscope.

My home-brew soluton is a stereo microscope with a cross hair reticle and a stage with a small Mitutoyo x-y DRO. Spent under $1K. Very clear images, nice depth of field. Basically set the cross hairs on one feature, set the x-y table to zero, move the cross hairs where you want, and there's your measure in either inches or mm. The stereo microscope is a permanent resident on one of my benches. The x-y table (small and light) is put under the boom stand as needed. Mine has 6" travels.

Initially used an old American Optical "Cycloptic" with a trinocular tube as the microscope. Now it's a Meiji trinocular, with a bit wider field of view and full zoom.

Add a small precision rotary table to the stage and you also get angle measurements.

Stereo microscope is handy for all sorts of other reasons. Just seeing something like a .35mm thread gage next to a small screw is a challenge with my old eyes. Not so with a bit of light and magnification. A trinocular head on the scope makes documentation easy, should you want or need it.
 
I have a Micro Vu like this one if your interested?
D17B4E52-D811-435F-A116-1099E817EB51.jpg
I would like $750 for it, doesn’t have the read outs, I’m sure those could be sourced for a lot less than your budget?

If your interested I can get pictures and specs, it can be moved around easily with a hand truck.

Kevin
 
Ok that does sound good although radius and diameter also very important how do u measure that ?

For $3800 used or $6750 brand new I could get that without any sort of home brew needed. I don’t really know how to build up the whole set up either using the microscope plus stages plus dro

Paul -- Diameter is easy - move the cross hair line to one edge. Set zero. Move to the other. Read diameter.

Radius is more difficult. Divide by two.

More seriously, if these are fillet radii you can use the templates car2 describes. For a lot of non-critical work you could probably just lay a radius gage or two on the table or part and use it in comparison. Amazing how much easier things are once you get see what you have. Could be that a known-good tiny gear would be enough to sort gears and spot problems?

There are really only two major parts to this:

1) A stereo microscope, likely on a boom stand and with gooseneck LED lights you can adjust to best show whatever features you're measuring.
2) Some sort of x-y table with dials or readouts, maybe rotary as well, to put underneath

You probably already have some sort of x-y, rotary table to put on a milling machine. This could get you started while you make or buy a much lighter and easier to manipulate linear slide table. My little table was formerly a bit of Parker "Daedal" kit, retrofitted with genuine Mitutoyo caliper type DRO's. Slides easily, nice damped, and seems good to .0005". Could do better accuracy with glass scales of whatever length or even micrometer scales (pictured earlier in the thread) for small stuff. Stuff like this shows up all the time used and is fairly cheap new. For example, Sherline makes small (4" x 10" travel, say) x-y table out of aluminum, plus rotary tables, that are light and built a bit more accurately than the same junk from China. New, Parker's Daedal or the Newport stages will be more. If you want a DRO rather than dials, those are easy to buy and install.

If you're using this thing every day, need the accuracy, and don't need the space (check the size out), the Mitutoyo is a decent choice at $6K. Still, only a 4" x 8" travel, pretty bulky, and $4-5K more than you need to spend if reading to more like .0005" than .00005" will do the job.
 
The Fowler is a Micro Vu. The do seem flimsy and certinaly are not a J&L, OGP or a Mits but they do work.
At this price tag the expensive optics can't be used so there is some trade off and at real, real small feature sizes this can get in the way.

I'd go toolmakers or measuring microscope with a video attachment however the "couple inch' standoff to clear the shaft is a problem without special optics.
Edmunds optics sell long distance variable power video microscope lens but these are expensive starting at $1700.
At a 50mm standoff which is "a couple of inches" it can be done with cheaper more convention optics.
Minimum feature size to be checked and longest needed standoff has to be known to know the setup needed.

The video attachment will allow you to use your computer screen to do distance, radius, and angle measurements if they fit in the field of view of the camera. Most of these cameras come with software that allows you click on 3 points for a rad, 3 or four for angles, 2 for distance, etc.
Mic heads and/or DRO are needed if the feature is too big for the picture and then you are are your own doing the math as this free software does not interface to DRO or scales.

I know the base model seems like a toy but the little Fowler setup is not a bad deal if it fits your use and can handle the accuracy you need and I still use one of the original 10" maybe 20 lbs total M-Vu guys from the 70's.
This will be a backlit arrangement, a microscope will likely be a frontlit. There is a difference.
You might like front, for a microscope this is normal. For an optical compartor you have to pour in a lot of light to make this project onto the screen.
Backlit and alignment to the light beam and collimation gets fussy for anything with depth (like gears).

You start with resolution 6-sig needed and/or min feature size and shape, then max feature size to be checked, and then standoff required followed by speed needed.
And you have to keep in mine the budget for the user application and need.
That has to be in the world of Say What Bob???:nutter:???.....No worries.......I have never walked into a user who understands all this gobblely-gook bull shit stuff.

Knowing exactly or generally what sizes min/max, gauging tolerances along with max shaft stand may help us here.
A few generic sketches or pictures with sizes of this and that are worth a thousand words.
I can't tell you how to measure your parts if I don't know all about your parts.
Anyone who does without this info is making a guess.
Bob
 
I went ahead and bought the mitutoyo ph14LS comparator with the XM data computer on it. was a great deal at $3800 shipped, comes with 10x lens, will be super heavy duty and last forever.

should be a chore to get into the house but will figure out. Need to get a table for it.

I'll take a picture of this all once its set up. Should be nice.
 
Do NOT, EVER, EVER, EVER get that Fowler bench top unit, it's Harbor Freight quality, at best, and that's being generous.

The Mitutoyo PH14LS is a bit cheaply constructed, but definately worth $5K in decent condition (the DRO has a bit odd keystroke sequence, but you can get used to it). Personally, I'd hold out for something older, but mechanically sound (Scherr-Tumico, J&L). Stick to a DRO that is common (the grey Heidenhein/Metronix or the red-LED 1970s Micro-Vu DROs are really intuitive and reliable).
 
Heres some pics

Faro installed on the Vere optical table (still have to machine the correct plate to mount the faro to the table)

IMG_0072.jpg


IMG_1095.jpg


IMG_1096.jpg



The comparator does a good job on the small gears I measure alot of. Its plenty bright and the DRO is new and working well. Not bad. It is heavy as hell, Im still trying to figure out how to move it into my office, and I will need a stand to rest it on. Mitutoyo makes a cabinet for it but its like $600. I can probably get a heavy duty table for it for 1/3 that. Can someone tell me why the heck the screen has dotted cross lines, and the dots arent even straight ?! It makes measuring pretty difficult. Ive got the screen rotated so the solid cross hairs are being used, but those are so dim they can be hard to read. Also, inexplicably, the solid cross hairs do not extend to center, rather they stop about an inch away. I was going to buy a new screen but fear all the 14" mitutoyo screens are that way for some reason that i cannot understand...

Anyways, Im pretty happy at this point. Thanks for all suggestions on here. Im still looking to buy some sort of fixturing kit for the faro table so I can hold parts steady while measuring them. If anyone has good suggestions for that let me know. Some of those fixturing kits cost more than the comparator ...
 
I have two comparators in my Home Shop:

J&L PC14 with motorized z travel that looks a bit like this:
PC14.jpg

I like it because it has a small footprint in the shop and can be stuffed into a corner. It is a quality machine for an oldie. Paid @ $500.00 with all the accessories but no DRO.

The other is an Apex 10 inch that looks something like this:

Apex10.jpg

Not up to the quality of the J&L. But this thing is the bomb when you want to grab a comparator and take it to the surface grinder, or to the tool grinder, or the lathe or the mill etc. it weighs about 30 Lbs and came with front illumination and a carrying handle!! It now has a J&L lens that I fitted and calibrated to 40x on its little 10" screen. It cost me @$100.00 a few years ago.

Just to give you some ideas in your search. Hope you find this useful.

Best Regards,
Bob
 
The offset cross-hair lines are so you can see the edge exposed from one side and the edge coming up to the line on the other side. It helps make more repeatable readings because the judgement of "where the edge is" varies. I have found best of all with narrow parts is two parallel lines where the part image is centered between lines with a small bit of clearance left. The eye is quite sensitive to centering things.
 
Ok im sure its for some reason I dont know of. But when you are measuring across, its easy to forget if you based your starting point at the cross hatch that was on the left or on the right of the center of that cross line. So if you guess wrong, you would be off by 0.020" or so. which really defeats purpose of the comparator, just whip out a tape measure and eyeball it ? I will just "write down" which dotted cross hair I chose to base starting point off of, left or right.

also, what is kinda odd is the dashed line itself is VERY thick, which should impart +/- .005 at least just on line thickness.

Ive rotated the glass 45 degrees because at least mitutoyo did make that cross hair solid and very thin. But its faded so kind of hard to read.

Last complaint, then Im done! The cross hairs dont intersect at center point. What the heck. This means you have to go up or down on the screen about an inch to actually get the crosshair to begin.

Again, Im sure this is all for some metrology reason Im unaware of, but Ive used plenty of comparators before and never quite seen a screen with cross hairs this retarded.



The offset cross-hair lines are so you can see the edge exposed from one side and the edge coming up to the line on the other side. It helps make more repeatable readings because the judgement of "where the edge is" varies. I have found best of all with narrow parts is two parallel lines where the part image is centered between lines with a small bit of clearance left. The eye is quite sensitive to centering things.
 
Stay away from that Mitutoyo PH14. Both optical, and mechanical junk. Obviously, you need something used. Micro-Vu is good, as is Jones and Lampson, Scherr-Tumico etc.
 








 
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