Thread: Dial Gauge Holder !

Hi Guys,

After playing about with trying to make accurate measurements on my backplate and collet holder and then discovering that some of my collets were not all that they were said to be, I decided to make a good dial gauge holder that I could use to take accurate readings with.

I had made a similar device quite some time ago, which turned out quite good enough for centering work in the four jaw chuck, but it was flimsy and tended to float about depending upon which way you rotated the chuck.

These are the pictures of the work that I have done so far !

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These first four pictures are of the holder showing the construction of the device and the hinge. I didn't take any pictures of boring the 13 mm diameter hole for the bearings. Basically I just bored right through the 5/8" inch thick alloy offcut from a 5" inch wide plate. The spindle for the movable arm is a 5 mm dowel pin. You might notice the 1.6 mm step on each side below the hinge. After machining the bore and step, I realised that it wouldn't fit in the lathe tool holder. So I milled 1.6 mm off each side.

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This picture shows the general arrangement of the holder. The fixing for the dial gauge has yet to be done. The hinge end is the one that will be secured in the lathe tool holder.

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Next I needed a suitable probe to be able to sense external diameters. The pictures here show a 2 mm diameter steel ball from a bearing superglued into a recess in the end of a 3.75 mm diameter rod 50 mm in length. I threaded the 5 mm of the other end M4. This is so that I can secure it at the end of the 6 mm thick moving bar.

I also intend to make another probe that I can use for internal measurements. I propose to make it screw into the end of the moving bar.

That all for now, more later !

Hi Guys,

A little more done and some pictures.

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Two drillings got done here. The 6 mm diameter hole for the split collet, shown in the first picture. In the second one a measurement error, hopefully corrected with a centre drill. Then the collet shown secured in its bore. The two M4 screws holding the drilled and threaded collet in place.

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These three pictures show the drilled and threaded collet in its hole, and the screws and washers used to secure it in place.

That misplaced punch mark replaced by the drilling is where the 8 mm hole will be drilled for the dial gauge stem. The idea is that the 8 mm drilling will take a bite out of the edge of the collet causing it to fit round the gauge stem. In use the collet will be sawn in half and one end will be drilled to clear an M4 screw.

More to follow. Thanks Guys, your input is appreciated.

I can't quite picture how this is going to work, it's obviously not trying to copy the operation of a regular magnetic base designed for dial gauges, I'll have to follow this thread to the end - might be a good idea I can copy.

Hi Ozzie, Guys,

Thanks for your posts.

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You may remember this device that I made to solve the problem of centering things up in the four jaw chuck. The device is simply held in the lathe tool holder. I subsequently made various modifications to it. Whilst in this form it did the job, it lacked stability.

The new device is intended to overcome those problems.

Hi Guys,

More bits and pieces done and some more pictures. Sorry for a couple that may not be in good focus.

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Maybe I got a little too close with the holes for the collet and gauge. The first picture is just after I drilled the 8 mm hole for the gauge. I only had 1.5 mm to play with, so I ended up just cutting into the collet threads. The collet is 6 mm diameter with an M4 thread through it.

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This is after I split the collet and drilled out the threads in one half. The gap between the two half's is just the thickness of a junior hacksaw blade. Plenty wide enough to grip the dial gauge stem securely.

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These two pictures are of the back and front of the collet holding the gauge stem.
The little blob that you can see on the gauge crystal is a spot of superglue ! The crystal fell out whilst I was fitting the collet.

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These pictures show the two probes that I made screwed into the moving bar. The large ball is 6 mm diameter.

At this stage the device is nearly finished, just a few tweaks needed !

I'll take some more pictures later when I get to testing it out.

Thanks Guys !
Seasons Greetings to all, have a merry Christmas.

Hi Guys,

I hope that everybody had a nice Christmas and the presents fairy was kind.

I've finally finished the new dial gauge holder and tested it on the new collet chuck. I now get a half thou runout measurement on the inside edge of the collet taper which I think is about as good as it will get !

I've also bought a set of oversize ER32 collets 21 mm to 26 mm in 1 mm steps. It seems that the largest three are made from carbide rather than HSS. I was surprised how much shorter in length these collets are.

Now the pictures: I have not taken any of the collets, unless anybody wants me to.

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This is a picture of the two probes that I made.

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I added a light spring because I found that the spring in the gauge plunger wasn't quite enough to push the arm away. In hindsight the sensing arm could have been a little slimmer. I hadn't considered the weight of the sensor arm causing it to rub on the bearing housing, purely due to the slop in the bearings.

Thanks for your attention guys.

The pin with ball should work well as the motion is (more or less) in line with the indicator, but the longer pin I'm not so sure about. Does it work? I would have thought that the forces to move it would make it less sensitive.

I like the general idea though - may have to pinch that one...

Michael

Hi Michael,

Part of the problem originally encountered was getting close enough to the workpiece without fouling the four jaw chuck jaws with the indicator dial gauge, also at the time I was playing about trying to use the indicator to measure the crosslide travel with respect to the top slide, which was bit pointless when I thought about it.

Using the long probe doesn't cause any problems that I have found. In fact the much smaller ball is an advantage, particularly if you use the indicator from the rear.

The obvious disadvantage is that the long arm does reduce the measurement accuracy by a very tiny amount. The ball probes work very well ! There is no chatter unless the surface is bad/rough. Otherwise it works very very well.

As far as making use of the design, go ahead you are very welcome ! I would be interested in any changes you might make.
Then I could pinch yours

Originally Posted by BaronJ

Part of the problem originally encountered was getting close enough to the workpiece without fouling the four jaw chuck jaws with the indicator dial gauge.

That's the reason I am interested it in - I have the same issue at times.

Michael