Hofmann Rollers

[Martin KyteParticipant @martinkyte99762]

Came across a set of Hofmann Rollers a couple of days ago. Would someone like to enlighten me as to their function and usage please and fill a gap in my knowledge.

Thanks Martin

[Julie AnnParticipant @julieann]

I used mine for gauging the width of the slot in an expansion link. The expansion link slot was CNC milled a couple of thou undersize and draw filed to fit the appropriate Hoffmann roller. The matching die block was then filed to fit the slot.

For anyone who doesn’t know, these are Hoffmann rollers:

Although they don’t look it the height and diameter for each roller are the same.

Julie

[Nigel Graham 2Participant @nigelgraham2]

You can also use such rollers for calibrating measuring instruments.

[duncan webster 1Participant @duncanwebster1]

If you have absolutely nothing more interesting to do you could have a read at this from NPL

[Charles LamontParticipant @charleslamont71117]

They can be useful for measuring things like the width of a dovetail (with a bit of trig.)

[Martin KyteParticipant @martinkyte99762]

<p style=”text-align: left;”>Thanks for the replies, simpler than I thought.</p>

[gerry maddenParticipant @gerrymadden53711]

As someone who’s first employment was at the site of the company that made these things, I have been on the lookout for a good set for a while. Sadly, the remaining sets all seem to have at least one part missing, have an excess of corrosion or have been dreadfully abused during industrial activity by people like Julie  🙂 . These poor things should never have been allowed to leave the standards room.

Gerry

[howardbParticipant @howardb]

A tidy set of these is available from G & M tools – £25 + postage

Set of Hoffman Rollers 80210006

[gerry maddenParticipant @gerrymadden53711]

Lots of rust staining on the lids padding, but none on the rollers. However the rollers are rather matt in texture suggesting a touch of cleaning has been going on, which isn’t good for the dimensions.

Gerry

[Bo’sunParticipant @bosun58570]

Anyone know if they made a metric version?

[JasonBModerator @jasonb]

Is there any advantage over their length/dia proportions compared to a set of pin gauges which tend to all be one length? Metric Pin gauges are available.

Also why the name rollers and not “gauge cylinders” or similar as they just seem to be a round gauge block.

[gerry maddenParticipant @gerrymadden53711]

As far as I know, metric versions were never made.

As regards their use Jason, if I’m honest, I think they were more of a sales advertising gimmick, than a serious metrology tool. They certainly weren’t the most accurate rollers that could be made, and their short length is a handicap. I don’t think I have seen any with an original inspection certificate….but I may be wrong.

Gerry

[Michael GilliganParticipant @michaelgilligan61133]

It is curious [and nothing more than that] to see that although specifically produced in Imperial dimensions … the document linked by Duncan cites millimetres for all the checks.

MichaelG.

[JasonBModerator @jasonb]

Although the metric values do seem to be based on 10ths of a thou to 4 decimal places and the diameter to half that.

[Michael Gilligan]

On Michael Gilligan Said:

It is curious [and nothing more than that] to see that although specifically produced in Imperial dimensions … the document linked by Duncan cites millimetres for all the checks.

MichaelG.

Are you implying indirectly[and nothing more than that] that you cannot measure an inch in metric?

(Tongue in cheek comment)

[Michael GilliganParticipant @michaelgilligan61133]

🙂

[Nigel Graham 2Participant @nigelgraham2]

Gerry –

Rather than handicap, those ones are not short for a specific reason, perhaps – such as using with a sine bar?

[Bo’sun]

On Bo’sun Said:

Anyone know if they made a metric version?

Individual balls for ball bearings are available from suppliers.

Individual rollers for bearings are similarly sold:

https://simplybearings.co.uk/shop/Loose-Balls-and-Rollers-Loose-Steel-Rollers/c23_5043/index.html

[Nigel McBurney 1Participant @nigelmcburney1]

Back long ago in apprenticeship days ,the company had a set off Hoffman rollers, and could be drawn from the stores, the slip gauges on the hand could only be used with the bosses approval , his reasoning was that if the Hoffman rollers were looked after they were accurate for most purposes and quite accurate when used in conjunction with  a set of of feeler gauges to measure intermediate sizes using the flat ends of the rollers. The attitude with slip gauges was they should not be used unless absolutely necessary  to reduce wear and maintain accuracy and wo betide any one who touched and left fingerprints on the accurate faces of a slip gauge. Nowadays due the collapse of the engineering and metrication ,slip gauges have become available at very low cost,I have a good set  and due to my training I still use my rollers ,as they are useful for quick bore measurement on fractional size holes.Hoffman rollers were very accurate as I heard that they were selected from large batches of rollers.

[Michael GilliganParticipant @michaelgilligan61133]

Eminently logical on all counts, Nigel

MichaelG.

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