Does a tool exist for deep bore measuring?

My boss has asked me to find a measuring tool for reaching up deep inside cylinder and accumulator tubes for measuring clearances. All I have found soo far is your typical dial bore gauges, but I'd like to know if something like that exist with long extensions. Something with 1-6' range would be great, cause some cylinders have blind ends. Bore range is typically 2"-12". Price and brand is not a concern, but any help would be appreciated. Thanks.


Adam

You do mean up to 6' deep in a blind hole?

Extensions are available for regular bore micrometers. These add about 6" and can be stacked. However, I suspect accuracy would be an issue once you start using more than two or three of these (i.e. not going to reach 6').

The better precision tool makers do specials all the time. I'd think that if a regular 2 point bore gage (with a +/- dial and set by rings or a fixture) will do for you -- that the long extensions would be pretty easy to make. Could do it yourself and have it calibrated, if price becomes a consideration. An electronic one with a remote output could be attached to a long handle for the wider bores.

You could probably get extra long extensions for a bore micrometer made (e.g. 1', 2', 3' etc.) -- but I'd expect them to be $$$ compared to extending a bore gage.

One issue you'll face with such a long extension is sensitivity to changes in temperature. You'll want to keep your hands off the extensions and set and use them in a temperature controlled environment.

Something like a regular inside mic on a long arm would be less susceptible and able to handle bores as small as 1.5"; but likely very hard to manipulate at the end of a 6' blind hole. I doubt you'd get any sort of precision.

Perhaps a better suggestion to modify a stock instrument would be to get a digital gage with moveable/settable arms for ID and OD measurements. Put the thing on a pole and run an SPC cable out to where you can read it. This would only work for the larger bores.

I suspect your bores will tend to be somewhat standard and more likely to get smaller the deeper you get? If so, it might be possible to make up a set of the world's longest pin gages -- basically precision cylinders on a stick? Would need to be used with care, though. Be a bummer, though to jam one in and have it stick.

There are fancier methods -- what precision do you need?

Starrett used to be the go-to place in the US for specials. I must have seen hundreds of Starrett items made and marked special. Today, someone like Mitutoyo would be starting with better base instruments; but I don't know how they are for specials.

depending on your tolerance I'd look into air gaging.

I would try to use a standard dial bore gauge but replace the dial with a digital indicator so you could use a separate display. Put the digital bore gauge on a stick and poke it down the bore.

Thanks to you who have made suggestions for me. As for Starrett, we are a distributor for them and can buy direct. Most every machinist tool I have at work is Starrett, and Ive always loved there quality. We will be calling them and talking about what our needs are and see if they can help.
Bill, Im going to get with bossman and check out the links you provided.
As long as someone can build us what we need then Im not worried what the price is. We have customers asking us for inspection reports which include accurate measurements down inside cylinder tubes. Abviously I can only reach soo far with my arms and measure with an inside mic, but They want measurments documented all the way through.
They keep asking me who makes a tool that we can use to measure way down in these cylinders and all i know of is dial bore gages, but never seen any in person or in a book thats specifically made for going deep.
Ill be reserching the links, and if anyone has anymore info Im all ears.

Hey, this looks like what I need!!

Extra Length Bore Gage Extensions

As others suggested it might be better to have the reading head remote from the display. That way you can use standard bore gage components and make the handle any length you need it to be. Of course you probably dont have any more time than I do but there are electronic pickups with separate displays and I will bet some of them can fit directly in the gage socket.

Using the gages with such a long rod as you have shown might induce some error and I think would be hard to set. I mean can you see yourself putting the head in a gage ring and seeing the display at the same time when it is 6ft away? I am sure there is a way to do it but I think it would be hard.

Charles

I have done this successfully to measure extruder bores in injection moulding machines and film extruders. As others have said, a precision transducer connected by wire to a remote display. We mounted it on handles out of aluminum tube to suit the length of bore being measured.

Check Sunnen Products. I have seen their bore gages that long. I do not know if they were stock or specials.

Bruce

I worked at a plastic injection molding company and had to take bore measurements on the barrels of our machines. We had a Mititoyo bore gage and I made an extension, copying the supplied extension. It was 8 feet long! I remember using some approx. .500 OD aluminum tubing, .125 music wire, some nylon bushings that slid over the wire at 12" intervals to prevent flex inside the tube and a spring to help it all return to "0". It screwed onto the head of the gage and worked very well!

Call Sunnen they have made them a lot longer

Can be made to any length

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Abom79 said:

My boss has asked me to find a measuring tool for reaching up deep inside cylinder and accumulator tubes for measuring clearances. All I have found soo far is your typical dial bore gauges, but I'd like to know if something like that exist with long extensions. Something with 1-6' range would be great, cause some cylinders have blind ends. Bore range is typically 2"-12". Price and brand is not a concern, but any help would be appreciated. Thanks.

Adam

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Maybe things are done differently in the USA but if I were you I'd phone or email a few measuring equipment suppliers and ask them.

Not too long ago I saw something at an exhibition that was new and could do exactly what you are looking for. Neither cheap or expensive.

I've no idea who made it or who sells it or I'd tell you. Ask those that sell items like that.

most tri mics and some bore indicators can take extensions (they come in different lengths). got to remember to check calibration with a ring gage. many extension works ok but might need .001 to .003" adjustment and when you take extension off calibration needs to be checked again.
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most guys tape rags to insulate if they going to hang on to where hands touch cause heat will effect gage too. most extensions dont have permanent hand heat insulators attached cause they might get in the way.

Call Sunnen with the diameter you need to measure and the length. They can make gages for deep holes but there are limitations. The limitations are you have to be able to peak the gage (see the needle reverse directions). Bottom line the larger the diameter hole the longer the gage can be.

Mitutoyo sells 1 meter extensions for their bore gage sets. With digital indicators that can put out SPC data to a printer with a foot switch. I used that setup while honing plastic injection barrels up to 9' long. Printed out a report for every inch and held .002" throughout.
That was in the 90's!

This is a 6 year old thread resurrected by a spammer.

kenton said:

This is a 6 year old thread resurrected by a spammer.

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