Ideas_01

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Two optical inspection devices which used to be found commonly in better class toolrooms and inspection rooms were the ShadowGraph and the Toolmakers Microscope .

The ShadowGraph shone an enlarged silouette of a workpiece – such as a special shape lathe tool – onto a screen where the profile could be closely inspected for size and shape . Could be a plain screen but usually it was onto a screen with a selection of graticules , circles , angled V’s and rulers etc for accurate assessment . Sometimes the screen had a one off particular purpose shape accurately drawn onto it – for example a gear tooth profile .

Could also be used for testing the fit of one component against another – for instance a punch and die set .

Microscope was similar in purpose to ShadowGraph but with direct viewing of face of workpiece and the additional capability of studying surface finish and minor defects . Again screens were available for accurate comparisons .

Also some microscopes could be fitted with X – Y compound slides tables so that work could be inspected in different places and very accurate profile measurements could be taken .

Not so many of either to be found now but they still turn up and lots of used ones for sale .

This thread though is about the application of something similar in home workshops using modern imaging technology .

A third optical inspection device more commonly found in science labs than industry was the travelling microscope . Usually one or two axis they were used for taking very accurate length and profile measurements .

With a modern digital camera , a bit of DIY electronics and software , some CAD and optional use of milling machine as a mount all the above functions can be realised very easily in one unit and provide a very useful facility .

Michael Williams .

Edited By MICHAEL WILLIAMS on 15/02/2014 13:21:44

[JasonBModerator @jasonb]

I've seen a few people using USB microscopes to see things close up in the workshop, and there was a link to a guy the other day who had a small camera on his toolpost with screen behind the lathe.

J

[Michael GilliganParticipant @michaelgilligan61133]

Michael,

Excellent topic for discussion … I look forward to seeing it develop.

I have two Toolmaker's Microscopes; both [like much of my stuff] under restoration, and also a very nice Travelling Vernier Microscope, which I have mentioned here before.

Although the image acquisition and analysis side of things has become so easy over recent years, I would just mention that the optics can be very important if one intends to take measurements. The objectives in a proper ShadowGraph, for example, are "telecentric" which [in practical terms] means that they project the image in the correct proportions, without exagerated perspective.

The best book that I know on the subject is:

Engineering Optics: The Principles of Optical Methods in Engineering Measurement

by: KJ Habell and Arthur Cox

Published by Sir Isaac Pitman & Sons, 1948, with several revisions and reprints.

… Highly recommended to anyone with a serious interest.

MichaelG.

[John Stevenson 1Participant @johnstevenson1]

I look forward to the article.

ME or MEW ?

[Michael Cox 1Participant @michaelcox1]

Michael,

Following an article by Malcolm Parker Lisberg on another group I built a USB microscope/ shadowgraph using a cheap USB miroscope. This uses digital tyre depth guages to allow accurate calibration of the instrument.

Full details are shown here:

**LINK**

Mike

[jason udallParticipant @jasonudall57142]

I have a “loupe” sold as the “poor mans shadow graph”…variety of scales ..modest magnification..pocket portable. ..great for when your bench instruments can’t move or the object fit on the stage.
I also use a usb microscope but the pocket device is more used because of its portability. .
…

[Rik ShawParticipant @rikshaw]

Some years ago before I had eased myself back into the hobby I was at a car boot sale and found someone selling a toolmakers microscope. I pulled out my wallet out to hand over the tenner asking price when a hand grasping a tenner reached over my shoulder – the seller accepted it and that was me "blown out" as they say. I still think back to that incident and reflect that although not being violent by nature, that was the nearest I had come to wanting to kick someone in their soft parts for many years.

Even years before that, my great mate at work who taught me the ropes re: cutter grinding introduced me to a new machine on the shop floor. It was a vertically reciprocating grinder designed to grind form tools. It utilised a screen on which an image of the tool being worked on was projected and the operator used X and Y axis hand wheels to guide the wheel. You sat on a stool in a booth with a curtain behind to exclude any light.

I cannot remember the manufacturer of the machine but I do remember that my mate was quite a dab hand at doing some good work on it. I on the other hand found it very difficult to co-ordinate which way to turn the handles. Imagine trying to turn a smooth ball end shape on the end of a piece of rod using the cross feed and saddle feed on a lathe using a pointy type tool and you'll get the idea. "Never mind" said mate one night (it was permanent nightshift back then – yukkk!) "Another ten years and you'll be as good as me".

I know I can say that I used the next ten years travelling in directions as far away from that machine as possible.

Rik

[BazParticipant @baz89810]

Rik, it sounds as though it was an Optical Profile Grinder you were working, I worked one many years ago while employed by a Diamond Tool manufacturer. Our particular machine was made by a company called Wasino. If I remember correctly the projector overlay was drawn out 50 times full size and the wheel was constantly going in and out of focus as it traveled up and down. Not a machine that I looked forward to working!

[Harry WilkesParticipant @harrywilkes58467]

Shadow Graph have been dragged into the 21st century they now fit them with sophisticated electronics and fir them onto optical sorting machine that dependant on size sort fasteners at phonominal speeds checking for length, thread,head and even the recess of fasteners with torx or allen drives !

H

[Oompa LumpaParticipant @oompalumpa34302]

Looking at the Dan Gelbart videos highlighted in the Rotary Laser Centre finder thread I was inspired to build a magnifying video display. So far I have bought a reversing camera for a car complete with 7" LCD monitor.

That is as far as I have got though as I need to obtain a magnifying lens for the camera, which requires me doing a bit of research so I need to allocate some time to it. I am quite hopeful that it will help out when I am turning some of the smaller components I work on.

graham.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Oompa Lumpa on 15/02/2014 21:38

… That is as far as I have got though as I need to obtain a magnifying lens for the camera, which requires me doing a bit of research so I need to allocate some time to it. …

.

Graham,

Depending how well sealed-up the camera is; you may find that the lens can be unscrewed.

If so; a couple of turns should make it focus much closer [the lenses are usually very short focal length]

MichaelG.

[John HaineParticipant @johnhaine32865]

I have just uploaded some photos to an album called Microscope showing one that I have fitted to my Novamill. Unfortunately the forum software doesn't seem to allow you to rotate the images! Above is one showing the microscope fitted via a bracket on the side of the mill head, viewing a tc tool tip sitting on to of a vee block.

the basis of this was an Aldi special buy which was quite a nice mic with a couple of eyepieces and a 4 lens turret, but also with a USB eyepiece that you can use to view or capture the image on a PC. I removed the lowest magnification objective and fitted it in the bottom of a piece of aluminium tube (part of an old bicycle seat post that fractured), with the other end bored to take the USB eyepiece. I think the photos are self explanatory. I think this is a mechanically much more solid arrangement than trying to mount one of the little self contained USB microscopes as these don't have very satisfactory clamping arrangements.

you can use the software that came with the microscope, or Centrecam, or as in one of the photos in the album the Mach3 video plugin. The picture shows the image of the tool tip. Using the table jogging you can focus the microscope, and move the object by precise amounts to measure it or calibrate the graticule.

I've only seen the microscope once in Aldi, they don't seem to be regular items, but I guess they may be available from other sources.

[Michael GilliganParticipant @michaelgilligan61133]

Neat installation, John

Nicely done!

MichaelG.

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hi John ,

Excellent .

Always nice to see pictures and explanations of projects that have a bit of thought put into them and which actually work out in practice .

Regards ,

Michael Williams .

[Oompa LumpaParticipant @oompalumpa34302]

Posted by Michael Gilligan on 15/02/2014 21:50:53:

Graham,

Depending how well sealed-up the camera is; you may find that the lens can be unscrewed.

If so; a couple of turns should make it focus much closer [the lenses are usually very short focal length]

MichaelG.

Thank you for that, I will investigate this, could be a simple mod then.

graham.

[noel shelleyParticipant @noelshelley55608]

Good evening gentlemen, This all brings back memories of my apprenticeship in the late 60s at Coventry Gauge & Tool, Kandux division, in Gt Yarmouth where we made optical comparators . Using 1 or 2 Q/I lamps to illuminate the object the image was passed through a lens to focus, then via two large mirrors ground in the works to bring the image to the frosted screen, which could be up to 60" square. We had 50p pieces in the factory before they were released as we made the inspection machines for the Royal Mint.

The part under inspection was mounted on a free moving XY table. Movement in the X & Y planes being by 2 large bodied micrometers reading to .0001". With the advent of digital measurement mechanical micrometers can be picked up for just a few £s and robbed of their heads for the above purpose. Just a thought.

Best wishes Noel

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Michael Cox – Hi ,

I couldn’t get your link to work at first and couldn’t see what you’d done . I’ve had better luck this time and have been quite interested to read about your project . Like John’s it seems a very tidy job .

Question now is what is the most suitable camera/microscope to use for general purposes ??

I had in mind originally an actual camera so as to get wide field imaging but the two of you have used narrow field microscopes .

Needs some thought .

Regards ,

Michael Williams .

[Ian S CParticipant @iansc]

I'v Got an old overhead projector, I tried it out when I got it, and I think it will work quite well. Ian S C

[Author]

Posts