Mystery to me, Moore and Wright

[Paul BarterParticipant @paulbarter66156]

Hello all, Back again to acess the knowledge

These rods are marked with sizes, yet the tduplicate wo inch and one inch are consistently two thou over ie 1.002 and 2.002.The two micrometer heads have domed ends and are graduated for tenths.The rods have flat ends on truncated cones.Can anyone identify the name and use of these please?

Thanks paul

[Paul BarterParticipant @paulbarter66156]

Help in identifying thuis set of tools please

[Paul BarterParticipant @paulbarter66156]

Just to add to my post the two adjustable heads measure 3.625 when set to zero on the barrels were these for some very particular measuring process like go no go gauges?

Thanks again for any suggestions Paul

[Howard LewisParticipant @howardlewis46836]

Most probably an internal micrometer set, possibly with the heads in need of resetting to remove the 0.002 error.

Which raises the question, before making ANY adjustments, of how accurate are the devices used to measure the overall length?

Have they been checked against length standards or slip gauges, to confirm their accuracy?

Do any, or all of the other extension rods show the same +0.002" ?

If adjustment is required, the spanners with which to do it are there

Howard

[Nick HughesParticipant @nickhughes97026]

They are End Measuring Rods, used on a Jig Boring Machine.

[Paul BarterParticipant @paulbarter66156]

Thanks to you both or the swift response, the rods are not adjustable and were measured with Mitutoyo micrometers set to to slip gauges so I am surprised at the consistency of the apparent error. also the rods marked 8 and 4 inch are also duplicated. A Jig boring machine is beyond my skill set, but how would these be used please Nick? is 3.5/8 of particular significance and why two?

Thanks again to you both Paul

[Nick HughesParticipant @nickhughes97026]

Have a look from page 10 and on of this Pratt and Whitney brochure :- Pratt & Whitney Jig Borers Circular 513

If the link fails, PM me and I'll send you the PDF

Nick

Edited By Nick Hughes on 26/04/2021 16:01:40

[Paul BarterParticipant @paulbarter66156]

Thank you very much Nick, the link worked perfectly and I shall enjoy reading all of it. The penny has dropped! I doubt that I will ever use these as intended but they were too interesting to be left at the car boot! In any event I now have a set of standards up to 12Inches

Thanks Paul

[Clive FosterParticipant @clivefoster55965]

As Nick says these are used in jig borers to accurately set distances. Often toolroom class milling machines had a trough on the front of the table to carry them when doing accurate work. Even Bridgeports had an accessory to enable their use.

The adjustable heads are nominal 3.625" long. They should be set to read 3.625" on zero by the usual method of turning the micrometer sleeve. However some firms preferred to leave the sleeve in a fixed poistion and note the error. My set, obtained for a specific maybe job but never used, has calibration labels for the two heads. One says 3.6258 an one 3.6250. If I ever use them I shall sort that so both are calibrated to 3.6250

The length bars should be accurate to ± 0.00005" at standard temperature. That equates to less than 0.0001 error band. No idea why you are measuring one or 2 thou over. That said out in the real world you'd expect regular calibration with last time details to be in the box

These would normally be used with a tenths thou indicator. See the picture half way down this page :-

**LINK** , http://www.lathes.co.uk/bridgeport/page3.html for the Bridgeport accessory set up.

Clive

PS Nick sent a very interesting link whilst I was typing making the above post pretty much redundant! I've grabbed the P&W information from Nicks link too.

 

Edited By Clive Foster on 26/04/2021 16:18:49

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Nick Hughes on 26/04/2021 15:52:58:

Have a look from page 10 and on of this Pratt and Whitney brochure :-

.

Clever use of the dial indicator :

.

MichaelG.

[bernard towersParticipant @bernardtowers37738]

Dropped on my doorstep this morning, its brand new but actual M&W information is scant to say the least. Cant think of a use for it in the average model makers workshop can you

[Speedy Builder5Participant @speedybuilder5]

We called them “stick mikes” and had sets measuring 5 foot long. Used them for making the jigs of the TSR2 forward fuselage. Hell of a problem with trying to make accurate measurements in “fan heated” open workshops!

[Neil WyattModerator @neilwyatt]

Family resemblance to my M&W Bore Micrometer.

[DiogenesParticipant @diogenes]

..you could set stops on a mill table or lathe saddle with them..

..might come in handy when the price of electricity makes you think twice about turning the DRO on..

Just realised my redundancy – that’s what happens when you arrive at the bottom of a thread and scroll up – apologies.

[bernard towers]

On bernard towers Said:

Dropped on my doorstep this morning, its brand new

The original post in this thread notes that two of the length standards appear to be oversize by 0.002″. Could you check your one and see if the mystery from 2021 could be advanced.

[Chris CrewParticipant @chriscrew66644]

This has got me thinking. I acquired a M&W bore micrometer in box of ‘odds and sods’ years ago at the British Timken works closure auction in Northampton. I think it extends to about 18″, possibly, and has been lying a tool cupboard since as I have had no practical use for it. Now having read the P&W brochure and seen how a jig borer is used, I am thinking could suitable cradles and stops be made and fitted to the milling machine to lay the bore micrometer in? Obviously, this would not approach the accuracy of a jig borer but it may just be a quick way of indexing holes and edges etc. rather than just relying on marking out lines. Anyway, just a brain fart at the moment until I get down to the workshop in the morning and have another think about it.

[Chris CrewParticipant @chriscrew66644]

Yes, it was just a brain fart. Having looked at the Mill there would be no real practical way of using the bore gauge to index. A DRO, which I do not have fitted, would be a far better proposition.

 

[Chris CrewParticipant @chriscrew66644]

BTW, I have just noticed it’s Johanssen bore gauge, not M&W as I previously thought. It came in a box full of bits and pieces and I seem to recall bidding £2 for the lot.

[bernard towersParticipant @bernardtowers37738]

DC31k, The red one is on the money at 3.625″ and the green one is 3.6255. Does this help?

[bernard towersParticipant @bernardtowers37738]

DC31k, The red one is on the money at 3.625″ and the green one is 3.6255. Does this help?. The 1 inch pieces measure 0.99976″ and 0.9999″ and the 2 inch ones are 1.995″ and 1.996″. This all done with non certified measuring gear!.

[bernard towers]

On bernard towers Said:

DC31k, The red one is on the money at 3.625″ and the green one is 3.6255. Does this help?

On Chris Crew Said:

BTW, I have just noticed it’s Johanssen bore gauge, not M&W as I previously thought. It came in a box full of bits and pieces and I seem to recall bidding £2 for the lot.

Would you like to double your money, on just that item, Chris ?

MichaelG.

🙂

[Mark RandParticipant @markrand96270]

Red and green are Go/no-go calibrations.

[JohnFParticipant @johnf59703]

A wee bit late but foe interest here’s a copy of the M & W cataloge page from my archives —

[bernard towersParticipant @bernardtowers37738]

Thanks for that John I now know that I hve set 788/C for all the good that it will do me as they seem to be a little used tool any more, so its under the bench for now!

[Mark RandParticipant @markrand96270]

Same here:-

I was also wrong in my assumption about go/no-go calibrations 🙂 . They were an impulse buy a number of years ago and help to stop the other little used metrology tools getting lonely.

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