Telescopic Bore Gauges

Hello,

I want to buy a set of Telescopic Bore Gauges. There are scores of sub 20 quid ones from China, and those I've handled were somewhat rough and graunchy as you might expect. There are also those from Starrett, Mitutoyo, Moore & Wright, etc, starting at around 150 quid.

Kennedy have some around the 80 quid mark. Does anyone have experience of these? Or any others around this price?

Hi Bo'sun

I have a set of cheap ones double sided ones - graunchy when bought as you descibe but taken apart and all edges stoned made a remarkable improvement on their usability such that I disposed of my one side Moore and Wright ones to a friend.

I've done some pretty accurate measurement on bores with them - I find then totally acceptable now they have been tweaked

Tug

'This Old Tony' on Youtube did a video on improving a set of telescopic bore gauges, it might be useful having a look to inform your buying decision. I wouldn't personally buy this sort of thing for less than £20, it would end in tears. The Kennedy ones look OK & you can always get a refund if they are a load of rubbish but as they are mainly an industrial supplier you should be alright.

Tony

Here you go, I was just finding it when you posted your reply; from a couple of minutes in

Bill

I bought a set from Arc Euro a month or so ago for about £18 +P&P. Work well and no issues - I did take them apart for a look but did not need to "improve" them as they were quite smooth in operation. Usual disclaimer.

Telescopic bore gauges seem to be one example of where decent quality used but looked after is better than brand new. Run in rather than worn out seems to be the thing.

I have a cheap import set bought as being all I could afford on first job wages which is rough to handle and very hard to get good results from.

I also have a couple of M&W sets bought used, one with 3 gauges and one with 5 plus some odd Starrett and M&W ones obtained somehow. Probably a "I'm throwing the box out, anything you can use?" type source. The big ones in the 5 piece M&W set have very little use and are noticeably less smooth than the more used ones but still way, way better than the imports.

The nicest one is a vey well used and, when dug out of a throwaway box, somewhat rusty Starrett. I nearly didn't keep it but it filled the gap in my odd ones collection so I cleaned it up with gratifying results. Officially my tooling / measuring "odd ones" sets are loaners to ensure my good ones don't get abused but I'm not sure that I want to lend this one.

Clive

Like Marmite (Vegemite to our antipodean friends ) liked or hated, it seems; based on previous threads..

Have never had results that fill me with confidence over accuracy or repeatability. Wherever possible prefer to use bore sets or a set of M & W expanding ball type, for bores up to 0.5". Imperial or Metric is no problem since having set to the bore they are measured with a mic or calliper

Howard

Edited By Howard Lewis on 18/01/2021 15:52:13

I recall asking about the cheap (~£20) sets a while back - I don't think I got any definitive answer, and reluctant to take the risk bought a single Mitutoyo to meet my immediate need. I have since bought a couple of Kennedys and the difference in quality between those and the Mitutoyo is, at most, marginal - I doubt that I could distinguish them from 'feel' alone.

Robin

The dodgy set that This Old Tony fettled was Brown and Sharpe, so price isn't necessarily a guarantee of quality.

I have a ~£20 set and find them quite useable.

Thanks everyone for your input. I was considering the Kennedy ones because they were sort of mid-priced (and from what I found, the only mid-priced ones). All the others are very cheap or relatively expensive.

I bought a set of Draper ones at £26.99 from ebay, they seem ok for an amateur like me. Guess they will never beat the high quality ones out there.

The difference was do i but a cheap set or none at all. I did a few measurements & then did the same with my M&R calipers. They came out the same.

Steve.

Hi Bo'sun,

Just been and checked mine and they too are the Kennedy ones. They do need a bit of attention but are fine once done for quite accurate work within the remit of a telescopic gauge

Tug

I want to buy a set of Telescopic Bore Gauges.

‘I want’ or ‘I need’? I bought a set from Arc, but they are actually rarely used.

I make so few holes of any specific diameter that I could quite easily do without them. I reckon drill shanks for go-no go are often close enough or make a go - no go with a piece of scrap (or re-usable bar). If it was important, I would change the chuck (to the smallest I have) and turn a piece to the required size, then change chuck's back again.

I rarely finish-bore holes to size. Drilled, bored and reamed is generally a better way to go, I reckon (or just make a nominally sized hole and make the shaft to fit...). Most certainly I would not trust them for a shrink fit. I do have a micrometer type of bore gauges (used for checking engine bores for ovality).

At the time ( think) I bought a set of transfer punches - another item I used to happily get by without. They don’t get used often but they get more use than the bore gauges.

For a while, I have thought I might like a spin indexer. Saw a second hand one on epay recently. Watched it and it sold for more than an identical brand new one. I had decided I didn’t really need one (especially not one costing more than a new item🙂 ).

The apparent ‘easy way’ is not always the best - especially done on the cheap!

This topic has been discussed on a number of previous posts. Do a search for "telescopic bore gauges" to see the comments.

**LINK**

Paul

That's interesting Ramon. Can you be more explicit about 'within the remit of a telescopic gauge'?

When my interest in the things began I was hoping to get better accuracy than I could achieve with internal calipers, which being 'springy' rely on feel to transfer the measurement from the comparatively rough surface of an internal bore to the polished faces of a micrometer. I can get to perhaps a thou with the calipers, and it's pretty much the same with telescopic gauges - just a bit quicker. It still needs 'feel' though.

If I need to do better than that I turn go/no go plugs, or just fit the parts by turning the male half a a thou over and swiping down with with wet'n'dry.

Apologies to the OP if I've diverted the thread - I'm interested in how people achieve fits from running to push to press.

Robin

Edited By Robin Graham on 18/01/2021 23:08:56

Edited By Robin Graham on 18/01/2021 23:11:39

An experienced machinist can measure bores accurately with calipers and telescopic bore gauges but you need a good "feel" to use them. Something that I don't have and like Robin, I use go/no go gauges for small bores. For larger bores I us a gauge which has a dial indicator.

Paul

Hi Robin - tele-gauges can be a bit of an anathema but like calipers rely entirely on the users feel to transfer dimensions - from bore to the gauge and from gauge to Micrometer. As this is not direct measurement the result will only be as good as the skill of the operator.

I was taught to allow the gauge to expand inside the bore with the gauge held at at angle to the bore. The lock is then nipped and the gauge rocked - once - through the diameter. The lock is tightened and the gauge measured by holding one point of the gauge to the anvil while gently rocking the gauge through a slight arc as the mic is closed. A high degree of feel as the mic just closes on the arc is possible with care. Even this can produce varying results so several checks are made to establish a mean reading.

That's not to teach granny to anyone - just how I use them

Having made several I/C engines with the requirement for very precise bores I use these gauges as such to get close but use a precisely turned plug gauge to establish the final size required eg that for bearings.

I do have a bore gauge as Paul above but find it is limited if the bore is shallow.

Tug

Edited By Ramon Wilson on 19/01/2021 08:38:13

Good morning,

I'm still looking for some TBG's and found some Kennedy ones marked "KENNEDY ENGLAND". Might that be a little white lie, or even a big fat fib? I may be wrong, but I assumed most of this kit came from the Far East. I guess you can print what you like on stuff (or can you?), but whether it's right or wrong is another matter.

I use telescopic gauges in the same manner as Tug describes but I also use a dial caliper by measuring the caliper reading obtained in the bore with a stand mounted micrometer.

The dial gauge has 2 advantages, they can measure shallow bores and slots and also check for parallelism over the length of the bore, subject to the length of the gauge legs.

Emgee.