Anyone know what these are for?

[Enough!Participant @enough]

I recently purchased the contents of an ex-toolmaker's toolbox …. whole stack of external mics, depth mics, internal mics, calipers etc and a load of misc stuff. There's one set of bits that I can't identify (see pic). Does anyone know what they are?

They are solid cylinders, same height as diameter and are in sets of four. I have 1", 3/4" and 1/2" sets (the 3/4 set is missing one piece). They have a polished finish similar to slip gauges and I suspect are accurately sized.

[Enough!Participant @enough]

Measurement/Set-up pieces from tyoolmaker?

[Mike PooleParticipant @mikepoole82104]

They are Hoffman rollers and are very accurately sized both diameter and length. It would seem they are for use as standard sizes, I suppose for setting or checking other equipment.

Mike

Edited By Michael Poole on 13/05/2016 01:34:31

[John McNamaraParticipant @johnmcnamara74883]

Like measuring dovetails

**LINK**

Regards
John

[Enough!Participant @enough]

Michael …. thanks for that. It certainly narrows it down and at least I know what I'm looking for.

John …. Are you saying that measuring dovetails is their intended use or was it just a suggestion? I'm sure they could be used for that but, if it is their prime intended use, it seems odd that the sets come with (apparently) only one of each size. And why have the height accurately the same as the diameter? Plus gauge-pins seem to be the tool of choice for dovetail measurement.

[Anonymous]

I used one of mine for accurately gauging the curved slot in an expansion link during the final draw filing, after CNC milling, which was programmed to leave the slot approximately 2 thou undersize:

Andrew

[HopperParticipant @hopper]

They are just bearing rollers out of rather largish bearings. Not intended originally for any specific use in the toolroom. But often used in place of precision parallels when clamping stuff in position. Very handy for putting behind items being clamped to the lathe face plate, or under items in milling vice etc. Will fit in odd shaped jobs where parallels migh t not. Could be used for measuring dovetails too. Or a thousand other uses for spacing or measuring.

[John McNamaraParticipant @johnmcnamara74883]

Maybe I was a bit brief when I said "Like measuring dovetails", cylinders are often used in measurement. this was just one example,

in a word they are handy.

Regards
John

[John FieldingParticipant @johnfielding34086]

Also used with a Sine Bar for setting angles accurately.

[MikeParticipant @mike89748]

I used to have one given to me by a retired engineer for checking the accuracy of micrometers. Dodgy memory seems to suggest he said the one he gave me was part of the measurement system on a Newall jig borer. Can anyone confirm that?

[Enough!Participant @enough]

I've seen another reference to their use in checking mic accuracy … particularly prior to using the mic for over-wire checking of threads.

Perhaps the reason for the accurate height as well as diameter is for use on mics with different anvils?

[DustyParticipant @dusty]

Mike I can confirm that Newall Jig Borers did use a system of rollers for setting co-ordinates on the machine. I am afraid that all this is in the dim and distant past and I cannot recall exactly how the system operated. We ordinary toolmakers were not allowed into the Jig Borer cage other that to collect a component that had been bored. The Jig borer himself treated the rollers as if they were made of gold, cleaning them and putting them back into their storage unit after use.

[MikeParticipant @mike89748]

Thanks, Dusty. My memory, at 75, is not as bad as I had feared!

[mechman48Participant @mechman48]

+1 for Hoppers comment… rollers out of bearings, I have a couple kicking ( not literally ) about in my garage/workshop parallel storage drawer.

George.

[Mark CParticipant @markc]

I am not convinced they are just bearing rollers. Often big rollers in bearings do not have the end face ground as those in the picture. They often have a depressed end with just the outer 25% or so finished to size. I would be inclined toward the Hoffman roller suggestion but who knows just by looking!

Mark

[HopperParticipant @hopper]

Might be just a matter of terminology. Hoffman made plenty of roller bearings. Not sure if they had dimpled ends back n the days of yore, or plain. Certainly the boxed sets seem to have the plain ends, perhaps suitable for wringing together like Jo blocks? (in which case we probably wouldn't want to be using them for packers or parallels!)

 

Edited By Hopper on 14/05/2016 14:52:00

[Michael GilliganParticipant @michaelgilligan61133]

Following Hopper's excellent lead … Here is a set with a little more information.

However: Going back to the original question, it looks like some lucky toolmaker had sets of four [perhaps they were hand-me-downs from the Metrology Lab.]

MichaelG.

.

Edit: Look at the Calibration values on the second picture in my link.

Edited By Michael Gilligan on 14/05/2016 15:18:34

[Ed DuffnerParticipant @edduffner79357]

Made some proper angular knurls using the straight knurls I made a while back and have been turning and knurling more brass knobs.

Also sorted out, for the most part, a parting off issue. Cleaned a load of splashed oil from the belts and pulleys in the change gear area of the lathe. I think this contributed to the poor parting and having the lathe on the higher belt (gear) setting. Whilst parting off it would suddenly grab and blow a fuse in the back of the control panel (good job I bought a box of 100 fuses!).

Had an idea to make a splash guard for the change-gear quadrant.

Completed the PCB for the Steve Ward indexer I'm building with a proper PCB, not my own etched effort. Temporarily powered by a 9v battery and It's Alive!

Ed.

[Mike PooleParticipant @mikepoole82104]

Here is some info from the NPL on Hoffman rollers.

Mike

[Ed DuffnerParticipant @edduffner79357]

Sorry folks, I posted what I did today in the wrong thread.

Ed.

[Chris DentonParticipant @chrisdenton53037]

Strange, I bought an old toolbox at a car boot sale with loads of lathe and milling tools and it had some of these in.

[Enough!Participant @enough]

Posted by Michael Poole on 14/05/2016 18:48:21:

Here is some info from the NPL on Hoffman rollers.

Thanks for that, Mike ….. looks interesting.

[HopperParticipant @hopper]

Interesting. It seems the boxed sets of "proper" Hoffman rollers, per NPL and pics, comprise one of each sized roller, and not multiples of the same size as found in the OP. As such they would be used for measuring/calibrating/comparator. EG, setting the dial indicator to zero on a dial gauge/surface table comparator so that manufuctured items could then be put under the dial indicator to get a quick but precision reading of whether they were over or under the nominal size.

The OP, having four, or three, of each, suggest to me they were used for parallels or packing pieces as many of us do at home with various rollers and even races pressed into such service.

You would think that "proper" Hoffman rollers used for precision setting of comparators etcwould be kept in their box in the toolroom store, not kicking around in some toolmakers box, which would be ok for packing pieces providing they were not bashed around to hard.

Edited By Hopper on 15/05/2016 05:59:00

[Anonymous]

Here's my set:

They live in their box in the toolroom, aka the dining room. Although the finish is excellent they don't show any inclination to 'wring' together. The finish is visibly less fine than my gauge blocks. Of course they are secondhand, from Ebay I think? I've only ever used them for gauging; I wouldn't dream of using them for packing.

Andrew

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