Telescopic bore gauges

For checking bores for taper or ovality I use these dial calipers, any out of truth can be immediately seen, if you need to know the dimension measure over the legs with a mic or caliper at the reading indicated in the bore, I normally use a digital caliper.
This pair were bought off ebay at very low cost ages ago.

Emgee

… 'Also, I believe Starrett make a set with 2 sliding bars. Maybe someone could confirm this'?

I have a set; as previously mentioned I have not had any bother using them ...

George.

Thanks for replies. The probability of a set of used Starret/Mitutoyo/MW turning up for a fiver in the next week or so is vanishingly small I think, though that would be nice!

I have a set of ARC ball gauges going up to 1/2 inch which, I'm sorry to say, weren't that great as supplied - the cones were rough and sticky, but after some remedial work they're usable. I'll probably take a punt on the ARC telescopic gauges as JasonB has had experience of these particular tools and finds them adequate. I'm not expecting to make eg a sliding fit without fitting, but would like to get nearer to final fit by pure measurement than I can do now.

I'll look at the other styles of gauges recommended as well.

Robin

Hi Robin,

What did you end up buying?

I have the same dilemma,

kind regards

Geoff

This misnomer is unfortunately too well-established to be suppressed.

I have a range of telescope gauges,one is by m&w and the rest are mitutoyo,the M&W one has the best feel,I also have a set of M & W small hole gauges using two balls max capacity is half an inch, again it depends on an operators feel and regular use. one advantage with these is that they can be used well down into bore,all can be read with practice to better than a thou , in good conditions ,down to half a thou. During my apprenticeship telescope gauges were always know as "tele " gauges,and used when boring holes for ball races etc ,and you had to get skilled with them ,bosses dont like scrap.My favourite tool for bores is my swiss roche etalon vernier which is a proper vernier and needs an eyeglass to take a reading, A company present when I finished my apprenticeship. this has curved jaws when taking internal measurements, to get a measurement in a bore I set the jaws so that they are a perfect sliding fit in the bore ,lock the jaws,and then measure over the jaws with a micrometer.This allows me to measure the shaft and bore with the same measuring device to achieve more accurate readings for running and press fits. I never use the knife type digital vernier jaws on measuring precision fits.

telescopic gauges need a bit of getting used to, to have a consistent "feel"

Have to admit that I am more confident with a set of M & W ball gauges, or for larger bores a Baty Bore Set. A bit fiddly to set up, but repeatable, which is the name of the game, in my book!

Howard

The set with tapered sliding bars was made by Brown & Sharpe. I have set. Great for checking cylindrical bores. Useless if there is taper.

Buying cheap telescoping gauges is a mistake. Buy the best quality you can find. M&W, Mitu, NSK,...

The set with tapered sliding bars was made by Brown & Sharpe. I have set. Great for checking cylindrical bores. Useless if there is taper.

I have the two sets of Arc bore gauges but have only so far used the telescopic ones in anger.

My experience with them is that they do work but can be a bit fiddly. I am sure that part of that was my own lack of experience (and possibly patience) but I was getting a better 'feel' as I progressed. I cannot offer any comparative review because they are the only bore gauges I have ever used.

I think my view would be that they are better than having nothing - and at the price (they are not that expensive) good value for the number of times I really need them - given that as a Hobbyist - I generally make things 'to-fit' (by offering them up) - sometimes making a test gauge for the purpose. But for larger holes it's not always possible to 'offer-up' and I don't always have a lump of stock suitable as a gauge (or don't want to use it for such).

I've found that I can feel a degree of taper (if it's there) with the gauges that might be harder to detect otherwise, although I still use inside calipers occasionally. Measuring a bore further in is better than at the mouth (all you can do with a Vernier gauge) and helps to remind me to take more spring passes if needed - again patience (or lack of it) can be a problem..

So unless some of those nice looking caliper gauges show up at a car boot (at a silly price) - I think for most folk the Arc products may be the only reasonable solution - albeit they are not an essential and somehow I managed to survive many years without them.

Regards,

IanT

Edited By IanT on 10/10/2019 10:02:48

I have a set of the cheap ones and three old Moore & Wright ones. The M & W get used if they cover the size, and 0.001" is easy to get and repeat. The cheap ones are rough feeling, I should take them apart and smooth them and add a little oil, that might improve their feel.

Anyone who has just bought their first set should practice with some decent holes in materials, to get the feel and repeatability which is possible.

Edited By old mart on 10/10/2019 22:27:20

I see Chronos list them by the mysterious Dasqua, does anyone have experience of this brand?

Mike

Dasqua Tools appears to be an Italian company. That does not mean, of course, that these items are actually manufactured there.

I too bought a set of Chinese telescopic bore gauges and found them horrible. They came in a blue plastic wallet thingy (on Banggood). I have thrown them away and bought a second hand set of Mitutoyo's on Ebay.

What do people mean when they are saying things like "practice to get the feel of them". I must be using them wrong. How are you actually using these telescoping gauges then. I have a cheap set in the blue plastic and have never had any problem with them whatsoever. I hold it in the bore with the handle pointing up about 20 degrees tighten it slightly so it's too big then push the handle down to about -20 degrees and take it out. What is the correct technique? Thanks.

Hi Richard, I use very similar method to you but perhaps not as much angle, you have clearly attained the "feel" and your gauges must be working correctly if you get consistent results.

Emgee

A slight side-to-side rocking motion as you bring the handle down to the 0-degree position is usually added to the above action to ensure measurement is across the largest possible diameter line. That's where the "feel" comes in at the final stages for that last few thou.

Edited By Hopper on 16/10/2019 09:17:09

I found the tricky bits were eyeing up things so the gauge was exactly across the diameter and nipping up the lock screw without disturbing things.

The domed ends on the spring loaded bars reduce any errors due to the gauge not being exactly across the diameter. If working to the usually accepted ± a thou (ish) accuracy you have to be pretty sloppy to be out of range. Being short sighted in one eye and long sighted in the other I have an excellent eye for level at a yard or more but it doesn't work so well close up. Visual alignment with the lathe bed got me going but, having got the knack, I now just do it.

Nipping up the lock without disturbing the setting is another knack. Try to do it too tight and the gauge will almost certainly move. Too loose and it will spring out as you withdraw it or shift under the micrometer. The first, cheap and rather rough, set I had didn't help. Over strong springing and rough turning threads made it hard. The well used, well cared for, M&W set I now use are silky smooth and so much easier. Nicely run in I think and almost certainly better than new. Was given a set of three that appear to be almost unused and they aren't quite as nice, just really smooth rather than silky.

Holding the gauge and micrometer freehand to make the measurement is another knack. Especially with the big ones. I frequently cheat and use a micrometer stand.

I'm confident to within half a thou error band if need be. But the care and concentration isn't routine.

Clive

Clive

If you put the spring loaded bars vertical but hold the handle up about 20 degrees then snug up the lock. The bars are lightly clamped too big for the bore then push the handle down to about -20 and take it out. They have then been squashed down to the bore size and wont be disturbed whilst withdrawing from the bore. I get good measurements like this with no skill needed.