Looking to buy/ for info on optical comparator overlays

matthewlee · Apr 5, 2020

Hi

Im looking for a good source of new or used overlays for a 12" comparator I have.
I could use a thread pitch, radius or angle or ?
If you have some used ones for sale let me know or know where I could get some without spending $100 each for them.

Thanks
Matt

boslab · Apr 6, 2020

The ones I had were just laser printed OHP sheet, clear plastic stuff,
There were thicker acrylic scribed and inked plates at x10 scale, they were just done my hand on a drawing board, fairly easy though rotering pens are annoying when they dry out!
I’ve made them on a photocopier using OHP film and a copy of machinery’s too
Mark

Gordon B. Clarke · Apr 7, 2020

boslab said:
The ones I had were just laser printed OHP sheet, clear plastic stuff,
There were thicker acrylic scribed and inked plates at x10 scale, they were just done my hand on a drawing board, fairly easy though rotering pens are annoying when they dry out!
I’ve made them on a photocopier using OHP film and a copy of machinery’s too
Mark

I've often done similar for special features on items. Easily drawn on an old drawing table on transparent material.

A thread profile should be very easy to draw.

http://flexiblemeasuring.com/images/support/manual/1basic/1.09.pdf

rjs44032 · Apr 7, 2020

Hi Matt,

Just a thought:
Years ago we printed our own overlays from CAD on an HP inkjet printer. We used overhead projector stock (like cellophane designed to be used in printers) . I think you can still get it at Staples or Office Max etc. Anyway we were surprised at the quality and accuracy of the printed overlays. If I recall the HP printer was not an expensive model. Hope this helps.

Oh and it gives you the flexibility to print nominal, upper, lower limit profiles for your parts on the same sheet.

Best Regards,
Bob

sneebot · Apr 14, 2020

These guys supply at least some of the optical comparator manufacturers:

Optical Comparator Charts - Visual Inspection Products - Optical Comparator Charts

sfriedberg · Apr 14, 2020

While I support the idea of printing your own overlays, if you are actually using them to check parts, it is imperative to double-check the overlay as-printed. It is extremely common for printers and copiers to slightly distort, by scaling in the paper-travel axis. I have seen a badly setup copier expand the travel axis by 5%, which is gross.

In addition to X-Y axis calibration, you want to make sure that the overall CAD/print/copy process came out to the correct real-world scale. So I would put three extra points on the overlay, one pair widely separated on X, the other on Y, and both a known model distance. Then when you get your print or copy, verify the actual distance between the points.

M.B. Naegle · Apr 14, 2020

I've picked a couple used glass screens up from Ebay for our J&L comparator. The screen that came with it had all the data rubbed off, so I kept it for a backing and bought a couple basic Mylar screens from J&L. They're not the cheapest, but good OEM quality. Also have a ream of the printable projector film that we can print anything else onto.

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Looking to buy/ for info on optical comparator overlays

matthewlee

Hot Rolled

boslab

Titanium

Gordon B. Clarke

Banned

rjs44032

Hot Rolled

sneebot

Stainless

sfriedberg

Diamond

M.B. Naegle

Diamond

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