Bore Gauges / Dial Gauge for ML7 Measurements?

All,

I'd like a better way of measuring bores than digital callipers.

I notice ARC have a set of telescopic bore gauges for about £20. They appear to be spring-loaded against the bore, and can then be locked, removed, and a measurement taken with a micrometer or callipers.

Are they any good or are there better options? Don't want to spend a fortune.

Also, I've been puzzling over mounting DROs on the ML7, but they all look a bit clunky, and look like they could easily damaged in use. I'm wondering if a simple 3D printed Dial Gauge holder that clamps to the bed would suffice for saddle movement measurement, and an adapter for the tailstock so that the DTI could be mounted quickly for drilling depths. These are the two measurements I'd need most - the cross slide re-settable dials are fine for the other axes.

Can anyone therefore recommend a decent metric dial gauge with perhaps a 50mm travel? Digital would be ideal, but a needle is also fine. Again, I don't want to spend a fortune.

Thanks.

You can 3D print a dial indicator holder and mount them with magnets embodied into the body and these can be used on any axis to tel you saddle movements and cross slide movements you dont have to have a large plunger movement as these are more expensive and more liable to damage. You may want to make one with a policarbonate cover to keep off swarf and coolant. I have seen one used with slip gauges to set tool depth to zero.

David

All telescopic bore gauges work better if the action is smooth and the locking mechanism retains the setting.
There is a known method to set the gauge within the bore, tilt the tool slightly and then apply light locking to the gauge before tilting the measuring piece to vertical and locking the gauge dimension, measure directly over the gauge for the bore dimension with your vernier or micrometer.

Several videos on youtube from well known engineers showing how to use the gauge.

I have a pair of dial verniers for bore measuring, note the reading with the legs inserted, remove and then measure over the end points at the reading obtained to confirm dimension.
These will also indicate if the bore is parallel.

Emgee

Edited By Emgee on 01/03/2021 10:43:53 https://youtu.be/zv6NUyFbWEQ

Edited By Emgee on 01/03/2021 10:51:06

If you want to measure carriage travel you don't need to go digital. Graham Meek's resettable carriage handwheel dial integrates perfectly with the lathe, covers the full travel of the carriage, and provides adequate accuracy for most tasks. Interesting project to make, or you can buy ready made. Photo of my example attached:

Hi Doc - I've been using the double ended teleguages for years now without any problems. I bought a set of them similar to those at Arc Euro - all I found was that the sliding surfaces need to be smoothed with a small fine stone to improve the slidability as Emgee states. The change was considerable such that I passed on my single ended Moore and Wright ones!

I also use the method of tilting the guage, tightening it slightly then swing it through an arc across the bore to close the gauge to dimension. do this movement only once ie don't rock back and forth. When measuring rock the gauge slightly on a short arc as you close the mic until it just touches. I have other means as Emgee's guages above plus a bore gauge and inside mics - still turn to the teleguage at first though.

Use them all the time - only yesterday infact

Ramon

PS Re the digi readout on the lathe - I have them on both mills but have never felt the need to fit them to the Myford. I do have a fixed stop set up and use slips for accurate X measurement if needed. I do have the resettable dials fitted and metric leadscrews on cross and compound slides.

Edited By Ramon Wilson on 01/03/2021 11:16:31

Thanks all.

I'll get a set of ARC bore gauges then.

I do like the handwheel scale, but it still leaves the other main measurement - tailstock drill depth - without a solution.

I wonder if a set of drill collars would be a good solution? Are they available like collets - so that each can be tightened to a small range of diameters? My range of drills goes from 1 - 10mm in various increments.

Regarding the tailstock, Gray also designed a very nice resettable tailstock dial. Unfortunately it is for a Super7, not an ML7, so unless you are prepared to obtain a Super 7 tailstock it’s not a solution.

regards

Mike

Doc,

A means of tailstock depth measurement beyond the scale marked on the tailstock spindle is a desirable and useful asset. For years I had considered making something but never got round to it. For the main part the accurate drilling to depth is not that often encountered but if it is then I have taken to using slips again to give me a 'degree' of control.

I bring the drill up to the work and 'zero' the the tailstock scale to a specific line eg the 1" mark. I then hold a slip or make up of slips onto the spindle and drill until the line is level with the end of the slips. Accurate - well not exactly but 99.9% of the time far better than the scale itself and of course infinitely variable. You may not have slips but a simple piece of material milled to the dimension required will serve just as well.

If it had to be 'accurate' in depth then it would have to be bored again using slips to control the depth.

Just a thought - certainly works for me

IIRC Steviegtr posted here a few days ago about adapting a digital caliper to a Myford tailstock.

OK great - plenty to think about.

Shame the myford castings are curved where they'd be more use flat (topslide/tailstock etc).

I suppose I could have milled the topslide flat when it was stripped the other day. Would have been useful for mounting a magnetic base.

Thanks.

Standard/optional Myford graduated handwheel for the main leadscrew is a cheap way to measure carriage movement.

Tailstock, I never need to know depth with that much accuracy that a DRO would be needed. Only drilling holes so to the nearest 10 thou would be close enough, which is easily achieved by either the graduations on the barrel, or by making an index mark on the tailstock handwheel and remembering that if one turn is .125" of movement, quarter of turn is .032 and eighth of aturn is .015" etc.

You could machine a flat around the OD of the tailstock handwheel and inscribe 125 graduations and and stamp on the numbers and you would have one-thou accuracy. I just have never found the need though. Tend to use a felt pen mark on the drill as much as anything.

And bore gauges: ball gauges are easier to use and thus more accurate below about half an inch diameter.

T gauges: the more expensive ones give smoother feel and thus greater accuracy. I have a used set of Mitutoyos that are very nice.

Edited By Hopper on 02/03/2021 08:36:54

Yes, I've been using a felt-tip mark on the drill, but it's a bit naff. It's true I don't need anything like dial gauge accuracy. I think drill collars might be ok instead of the pen. The graduations on the ram are very widely spaced and not too easy to read.

I've already got a graduated leadscrew handwheel, but never use it for moving the carriage. I either use the saddle wheel, power feed or the top slide.

The wheel is too stiff to turn with the gear setup I've got for fine feed. I suppose there's an obvious way of rapidly disconnecting the leadscrew from the rest of the gear train, which I'll feel daft about when you point it out!

Thanks.

Hello Doc, You have a PM

Ramon