Quill Mounted DTI Holder?

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Quill Mounted DTI Holder?

This topic has 9 replies, 6 voices, and was last updated 26 May 2025 at 19:00 by John Purdy.

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22 May 2025 at 17:38 #799243
Bo’sun
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@bosun58570
Hello,

I have a quill mounted DTI holder bought from ARC some time ago and it works just fine. However, to establish a reading by nudging a DTI with such limited travel is far from ideal.

Has anyone come across such a holder with a fine adjust like you get with some of the mag based indicator holders?
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22 May 2025 at 18:35 #799258
Diogenes
Participant
@diogenes
Yes, there are other designs, mostly with some horizontal rail or rails that the bit that holds the indicator can slide along.

I have a home-brewed ‘dovetail’ version which is okay-ish, Mitutoyo made a nice one with a pair of round rails (based on a Starrett design maybe?), and Stefan Gotteswinter designed a really useful one – see pdf here;

https://www.patreon.com/posts/low-profile-dti-90933448
23 May 2025 at 10:54 #799339
Robin
Participant
@robin
Problem is you need one of those Hogwarts Special milling machines where you can lock the spindle or let it spin free on a whim 🙂

Robin
23 May 2025 at 18:08 #799409
Diogenes
Participant
@diogenes
I have a Hog-Warcs Major, one only has to slip the belt… Maybe you should buy the Pinnacle, Robin..?
23 May 2025 at 19:22 #799418
bernard towers
Participant
@bernardtowers37738
Try graham meeks design
24 May 2025 at 10:36 #799501
Bo’sun
Participant
@bosun58570
Thank you Bernard. Any idea where to find it? I’m assuming in one of his books.
24 May 2025 at 12:26 #799513
Clive Foster
Participant
@clivefoster55965
Noga do a universal adjustment clamp under type number FA1500.

https://en-british.desertcart.com/products/19522005-nogafa1500-universal-fine-adjustment-swivel-clamp-for-dial-test-indicators?gad_source=1&gad_campaignid=20572390682&gbraid=0AAAAAoLvBX2rEGOmIHh9d4EMiscL-sTnB&gclid=CjwKCAjw3MXBBhAzEiwA0vLXQcjyH4xeeO-N2iHKbmnI50FzIgcrWY56XUsENBXDaDQZhLkkINQmqhoCfFgQAvD_BwE

Expensive but making something similar doesn’t seem too hard. Basically the actual indicator carrier is on a pivot in a forked carrier with a sling loaded screw to adjust it through a few degrees of angle.

Clive
24 May 2025 at 18:15 #799554
John Purdy
Participant
@johnpurdy78347
This is what I use, and I find they cover all situations. The DTI has inter-changable stems of different dia. so can be used in the drill chuck or collet whichever is in the mill. The position of the point of either is adjusted with the cross slide and knee as required.

John
26 May 2025 at 11:14 #799804
Bo’sun
Participant
@bosun58570
Thanks John. I’ve tried using a plunger type dial gauge with the quill mounted holder (although mounting it was a bit challenging), hoping the longer travel might help, but it’s too heavy for the holder to support (and a little bulky). Maybe a smaller dial gauge might be worth a try.
26 May 2025 at 19:00 #799884
John Purdy
Participant
@johnpurdy78347
Bo’sun

The quill clamp I use with the dial indicator is from a commercial holder I purchased. When trying to use it I found it was next to useless.
It clamped to the quill at three points, two raised parts at 120 degrees apart and a plastic tipped screw opposite them. The two raised parts were not flat but were as cast and the screw had a soft plastic tip.
The result was that no matter much the screw was was tightened the whole assembly would wiggle.
Also when the dial indicator was attached to the arms it was a real fiddle to get it in a good position and even when it was, the whole assembly was so flexible it couldn’t be relied on to give an accurate reading.

So I got rid of all the pieces except the cast quill clamp and made some modifications to it.
I replaced the plastic tip on the screw with one made of aluminum, and using a 1″ end mill cleaned up the two cast quill contact points to make them flat (well semi circular) and at 90 degrees to the face of the clamp.
I also drilled an extra hole in the body of the clamp to mount a 1/2″ dia steel post that the dial indicator screws to.
The result is a holder that is now totally rigid when clamped to the spindle.
Hope the pictures make this all clear. The first is the original unit (but with the mods to to clamp body showing) and the other two are the modified clamp.
John
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