Thread: Bore gauges

Better deal from the Allendale store though on ebay..at that price i might get one Imperial Dial Bore Gauge 2-6 Inch Cylinder Bore Measure | eBay

Originally Posted by Ueee

They look nice.....but other than the shape of the legs, how do they differ from the normal calipers? I have a few M&W "flat" leg calipers that i use normaly to test how close i am to a finished size before i go to a mic.

On to Mikes original question, arc euro have some new dial bore gauges at pretty reasonable prices. Dial Bore Gauges - Arc Euro Trade the imperial one at the bottom of the page jumps out at me!

A couple of things I think. I own both small M&W "flat" leg and a couple of pair of Starrett round leg(they used to be, maybe still are, called toolmakers calipers) and the Starrett round leg are lighter and the adjustment knob turns more smoothly(lighter bow spring) and they just get a better feel. Have used them for years and with practice you can get good measuring results with them; you can also with the "flat" leg types but the very nice feel of the Starretts just make it easier, I feel anyway. Perhaps M&W made a similar caliper.

I very rarely use my dial bore gauge(Mercer) for machining I only use it when honing cylinder bores as it makes it quicker to measure different sections of the bore quickly. I set them(zero them) by first measuring the bore with an inside mike and if I have say .002" to come out I put the bore gauge in and set it at .002" under zero then hone to zero then recheck with micrometer, if good then gauge is good for rest of bores.

Cheers.

I don't know whether air gauging is still used out there. With CMMs and other digital gauging being more available, I suspect not.
The problem with air gauging is that that you are relying on measuring the back pressure to establish the size, so the finish of the hole is going to be important and the gauge itself has to be very close in size to the hole it is measuring (I can't remember the limits but I think it is sub thou). Pretty useless except in a production situation. It's also an indirect method (that is, you are not measuring directly what you want to know but something else which you will then relate) so probably avoided if other more direct methods can be used. These days you set up a programmable CMM and it will check your bores and at the same time check for taper, roundness, position, squareness, ...

Michael

It arrived today

Its tiny , much smaller than expected . It is the genuine made in England item. Quality is top grade.

I havent worked out how it actually goes together yet . I need a destruction manual

MIKE

Like this.

Thanks Bob

I can see the second pic, but not the first ! Dont know why


I found this while searching for info
001 : Page Numbers

OK

I've worked out that the mic head has a .250" travel .

So without the extension rod it will measure from 1 to 1.25" bore .

It measures in .25" increments by adding extensions , up to 2"

But I cannot figure out how the extension device fits into the mic head as there isn't any obvious mating fitment

Originally Posted by morrisman

OK

I've worked out that the mic head has a .250" travel .

So without the extension rod it will measure from 1 to 1.25" bore .

It measures in .25" increments by adding extensions , up to 2"

But I cannot figure out how the extension device fits into the mic head as there isn't any obvious mating fitment

Hi morrisman,
The piece with the round hole in it fits over the micrometer body at the anvil end, the slot clears the thumbscrew head, now the long handle screws into the boss and the pin end fits into a small hole in the micrometer body. Tighten it nice and tight. Be careful not to jam the inside micrometer in a bore when the handle is fitted, always carefully adjust upwards to bore size and testing until a nice easy feel on the diameter is achieved.
Nice set, same style as my 25 to 50mm Moore and Wright.

Cheers.

Originally Posted by Log

Hi morrisman,
The piece with the round hole in it fits over the micrometer body at the anvil end, the slot clears the thumbscrew head, now the long handle screws into the boss and the pin end fits into a small hole in the micrometer body. Tighten it nice and tight. Be careful not to jam the inside micrometer in a bore when the handle is fitted, always carefully adjust upwards to bore size and testing until a nice easy feel on the diameter is achieved.
Nice set, same style as my 25 to 50mm Moore and Wright.

Cheers.

I was going to add another photo Log but with that description there was no need.

Ok no worries

I understand how to attach the ring and the long arm that allows you to measure a deep bore

But I still don't get how you extend the range of the head .. e.g., how to make it measure a larger bore than 1.25" Thats my problem

Can you undo the knurled screw and remove the centre rod that is in the micrometer head now,if so then insert the longer rod this should give you 1 1/2" of length if you want 2" remove the 1 1/2" rod insert the 1/2" spacer onto the 1 1/2' rod and then re insert into micrometer head,this should then give you the ability to measure from 1 1/2" to 2".

Originally Posted by morrisman

Ok no worries

I understand how to attach the ring and the long arm that allows you to measure a deep bore

But I still don't get how you extend the range of the head .. e.g., how to make it measure a larger bore than 1.25" Thats my problem

, Undo the little thumbscrew and pull the anvil out then fit new bits as required.When I read your post 53 I thought you knew that

Cheers.

Originally Posted by Log

, Undo the little thumbscrew and pull the anvil out then fit new bits as required.When I read your post 53 I thought you knew that

Cheers.

Ah ! your a champion ... got it now