Member postings for Bill Davies 2

And, reading the patent, the author refers to a cycloid. The Wikipedia article on cycloidal gears says (paraphrasing) that it is formed by a point on a circle rolling on another circle (base circle). If the rolling circle is infinitelty large, it is a straight line, and the curve is an involute.

Given that involute gears were common by the time of these patents, and the diagram showing the generation of the end of the probe (fig. 4) shows a circle rotating without slip on a straight edge, I'm surprised that it wasn't described as an involute.

But I'm talking to a small audience, perhaps only myself.

But thanks, MG, it was an interesting rabbit hole to explore. Sorry, Bo'sun for hijacking your question.

Bill

Considering accuracy, it's worth viewing one of Joe Piecziyski's videos (Joe Pie) on youtube, regarding the errors in using plunger and lever-type dial indicators: This refers to angle of contact with the work rather than preciion of internal mechanism, which I take to be the OP's concern. As an inspector, I used long travel plunger type dial clocks for checking tooth size on gear shaper cutters. The lever-types were used for comparing close to the zero reading.

Errors in usage of dial indicators

Thanks, Michael, for locating the patent, and its reference to the British patent. With your careful attention to detail, I am surprised that you didn't pick me up on the angle of the body, when I should have said the angle of the probe.

British patent - they didn't waste any time in applying for the US patent!

Bill

The verdict DTI probe uses an involute form, like our workshop gears (but not clocks), so that a given linear movement of the work gives a proportional angular movement to the probe, which is displayed on the dial. The body should be at an angle to the workpiece so that the probe is tangential to the work, and no, I don't know that the pressure angle should be.

John, the CC indicates that those collets were made by Crawford. That doesn't help you much as they were collet manhufacturers (hence CC). The collets look reminiscent of lathe collets used earlier in my life, such as South Bend.

There was some discussion in 2015: Posting No. 112438

From that thread, Michael Gilligan converted some scans, here are some sizes: MG's album of collets

And a list of externally threaded (C-type) collets here: C-type collets

Bill

The Colchester Student was widely used in technical colleges for training craft and technician students. They were provided with 3 and 4 jaw chucks, faceplate and a driver for between turning between centres. The Master, which appeared in some training centres, was used in production workshops.

If the lathe is on good condition (e.g., state of headstock bearings, bed) then it would be a good choice. The general appearance of the lathe will tell you a lot about its history. If you aren't experienced, it would help to take a knowledgeable friend along. Not that it will (almost certainly) be 3 phase, i.e., main motor and suds pump. 2$V bulb, if I remeber correctly.

Bill

Justin, depending on your lathe size and accesories, you could do it with a faceplate and clamps. Drill and bore the middle, then clamping off the bore, turn the outside diameter. Lacking a faceplate, a metal plate or even wood atached to a spigot to hold in the chuck would suffice.

Bill

Rooossone, accepting your comment about over-engineering, you may be aware that gratnell trays are generally supported on thin steel runners (about 1.1mm including paint), bent to an L shape, with tabs that locate in slots in the square steel tube. I can vouch that these thin supports can carry a significant load. If you could cope with bending thin gauge steel, you would still get plenty of welding practice.

Unfortunately, these only provide a side view, so the detaiils are not available.The 'joggled' tabs project sideways from the image:

Gratnell tray steel runners

This video shows the square U-shaped section that the tray slide in, the metal ones operate in the same way.

Plastic runners

Bill

See: Isolating transformer symbols (IEC standards).

Seems to be a slightly corrupted version of Pr01-029.

Bill

Michael, I searched for a TWAIN API, as I'm sure you will have, and the few I checked seemed commercial.

The Linux community, with its preference for open architecture, has a protocol for back-end operation (sounds unpleasant...), called SANE.

SANE (Wikipedia)

It may serve your needs, one user wrote his own PC version to drive TWAIN: Sanetwain however, this, too, is long in the tooth.

I have no experience with these software, but I have an old version of PSP languishing on an earler laptop, to drive a scanner. Windows 11 seems to lose certain functionality.

Bill

They are probably 'grain of wheat' bulbs, surprisingly tiny filament bulbs. I used to buy them for physics and electronics projects when I was a school technician. Since LEDs became ubiquitous, they are rather expensive.

Bill

Pro Star and UK Drills share the same geographical address. Their websites look different, but the category list on the left hand side shows the same categories in the same order.

Bill

My older LED 'spotlights' have a blue tint and low output. I'don't know whether that is slow deterioration, but the more recent LED lights are much better.

I have several of the IKEA lights, I find that the light tends to flicker, which I attribute to the low voltage and/or current being unable to clean the switch contacts. I read someone's blog a while ago, replacing the switches with silver contact switches, less prone to this problem.

Bill

As I'm sure Bazyle knows, but for the sake of others, the thread mill isn't a tap and is programmed to move around the hole synchronised with its movement downwards forming the pitch.

But he is of course correct about short machine taps .

Bill

I've used the green polyester felt from Hobbycraft to line an old steel micrometer case. It's very thin, but cushions the old micrometer. I glued it using contact adhesive.

Bill

We called it pack carburising, cast iron boxes filled with short charcoal sticks, similar in size to the charcoal used for drawing but perhaps 3/4" long. Multiple boxes heated in a large muffle furnace, left to cool overnight. Case hardening refers to the hardened 'case' around the softer, tougher core, after the part is reheated and quenched. I don't recall a tempering process but it's a number of decades ago.

Bill

Yes, I agree. Given construction, I'd say an amateur made item. Given the relatively small range that the plunger looks to be adjustable, probably just indended for the installed the indexing disc or gear. So, possibly for a specific (repeated) job.

Bill

Stephen, I've sent you a PM.

Bill

Diaform videos

Used on a large surface grinder: Diaform on surface grinder

This shows the operation, especially the rotation of the follower - if you haven't seen a Diaform, the pantograph action is easy to understand, but the rotation around the tip of the diamond is less obvious: Use of Diaform

Which do you have, Steve?

Bill

Or alternatively...

Diaform dresser - a pantograph used to dress forms onto grinding wheels, using a template to provide the form. Where I worked, they were used to dress wheels for grinding hobs and gear shaper cutters. Can be set to various reduction ratios, I think we used usually 20:1.

It uses a diamond lapped to a shallow angle with a specific radius on the tip. Diamond The follower used against the template is a magnified version of the diamond shape. I don't know whether they are much used now, but there seem to be plenty of firms making or relapping the diamonds. I don't have the pantograph, but I have one of the mounted diamonds left.

Bill

Peter - see PM.

Bill