PDA

View Full Version : Dial Test Indicator Trouble - Please help!



Rtldan
02-05-2015, 06:28 PM
Hello,
I recently bought a dial test indicator off of Amazon. It had good reviews, and it wasn't the cheapest one, but certainly no Starett, etc..
(I know you get what you pay for, but I am a hobbyist just trying to make sure my vise is square while learning to mill on my TAIG.)

Anyhow, I have been struggling for a couple months to get it to work successfully.
Today, I simply took my finger and pressed lightly on the stylus to see how it would react. That's when I noticed, it doesn't seem to be returning to it's starting position. No wonder I can't seem to accurately square a vise with it!

I opened the cover and applied a drop of synthetic oil to the gears (the same oil I use on my mill) as I had read it could be "sticking". That did not solve the problem.

I created a video to help show what I mean. I may have applied slightly more torque than was necessary in the video, but in my tests before the video, even a small amount of torque would drift and not return to it's starting point after a few repetitions.

So I'm basically clueless, asking is this thing a lemon? Is it out of calibration? Am I using it incorrectly? Is there anything I can do to fix it?

Thanks in advance for your time!


https://www.youtube.com/watch?v=8j-0mC5vsHM

Bob Fisher
02-05-2015, 06:40 PM
I think the internal stop is not a reliable test. Put it up against the fixed jaw on your vise and zero it. Slide a shim, say .050 in between the indicator and vise and let it return to zero. If the zero changes then, you have a problem. The hand may be loose and I'd send it back. Bob"

iMisspell
02-05-2015, 06:53 PM
.. Slide a shim, say .050 ...That sounds like a good test, but i would not use a .050 (50 thousands) shim.
Most of them indicator's are only .015/.020 (.030 both ways) of travel.
If you where to zero out the indicator after a couple thousands of movement, then tried a .010 or .015 shim it might be a little safer.


_

boslab
02-05-2015, 07:01 PM
Letting it snap back and expecting it to arrive in the same spot isn't really a feature of an indicator, it only really works under load, I just sited a starret and it doesn't snap to the same spot, what you need to do is press the tip against something like a diameter in a lathe , zero it with dial or by adjusting the position of the stand and then measure the total indicator reading.
It's pretty much the same for plunger types too, I think the only one that actually goes to zero unloaded is a digital.
As long as it's smooth then it's not an issue.
I don't know if yours has a turn switch thing on the side for direction but watch it's in the right place.
The verdict one I have requires you to just grab hold of the stylus and push it on a ratchet hinge to the position you need, first time I did it years ago I thought I'd broken it!
I think yours will be ok.
Mark

Rtldan
02-05-2015, 07:13 PM
Thank you all for your quick replies!
I will do a test shortly and see what the result is on the actual machine against the vise jaw and report back the results.
Once again, thanks for the fast replies!
-Daniel

SGW
02-05-2015, 11:00 PM
It may do better with no lubrication at all.

J Tiers
02-06-2015, 08:32 AM
A good one should return to the same place, but maybe not if snapped-back.

Instead, set it up against a smooth surface and see if it will always give the same readings when a variety of feeler gages are slipped under the tip. A 6thou may not indicate 6 thou difference, but it should always give the SAME READING with the same gage slip if the indicator and surface have not changed.

The consistent readout for a rotating shaft is a similar test, if your setup is solid

If it will not even do that, send it back and get a refund.

Rtldan
02-07-2015, 06:25 PM
Well,
Thank you all for your help. I was probably a little bit over worried because of my limited knowledge of these tools!
I did the test that you suggested using a feeler gauge against the vise jaw. It seemed to be working well. I notice that although my dial test indicator has a decent range on the display, the stylus itself can only be pushed maybe 10 thousands before it will deflect and take on a new position. Realizing this, I made sure to give it as little as possible -- something like 4 thousands from 0 was my working point.

Squaring of the vise ended in a result within 1-2 thousandths difference from end to end, which I thought was acceptable for my purposes and tools (the vise is the cheapie that came with the TAIG mill).

Thank you for your help with this issue!
-Daniel

iMisspell
02-07-2015, 06:49 PM
I notice that although my dial test indicator has a decent range on the display, the stylus itself can only be pushed maybe 10 thousands before it will deflect and take on a new position.Hummm.. are you saying you can slide a .008 feeler between the indicator tip and vice and the needle does not move ? it takes a feeler of .010 or more to move the needle ?
Or
If you slide a .010+ feeler then the indicator as a whole unit moves, kind of like you ran out of travel ?

If the first: then your indicator is not working correctly.
If the second: then that would be "normal", you've reached the limit of travel.

_

JoeLee
02-07-2015, 07:11 PM
I tend to agree with J Tiers, the dial should always return back to zero, even when snapped all my Starrett dials do and so does my Mitutoyo that reads in .0001.
All the dials I've taken apart have a clock spring wound gear that always keeps the gears loaded in one direction to eliminate lash and there should be some sort of stop built in. Struggling for a couple months to get it to work successfully in my book would be totally unacceptable. I would have returned it within a few days of struggling. We shouldn't have to struggle with our tools !!! especially precision ones.

JL...................

Hopefuldave
02-07-2015, 09:32 PM
Hummm.. are you saying you can slide a .008 feeler between the indicator tip and vice and the needle does not move ? it takes a feeler of .010 or more to move the needle ?
Or
If you slide a .010+ feeler then the indicator as a whole unit moves, kind of like you ran out of travel ?

If the first: then your indicator is not working correctly.
If the second: then that would be "normal", you've reached the limit of travel.

_

I think he means that he can only get 10 thou" movement before the friction joint between stylus (tip) and mechanism slips - which is what it should do, to a) save damage if it gets over-deflected and b) allow the stylus to be positioned at various angles to the body of the DTI - every one I've ever used has had this feature, and I've used a lot of different makers' products. That DTI would only have a 0.030" range anyway, as it shows -15 to +15 in half-thou" increments (and many of the far eastern ones don't cover the full range on the dial face, rather like cars with 160mph speedos don't neccessarly do 160mph...)

Regarding returning to zero - umm, the dial face rotates so the zero is completely arbitrary, and should be set against the needle in use, perhaps "snapping back" to zero is returning to the same point each time, not neccessarily zero on the dial? Which the OP's DTI appears to be doing in the video...

duckman
02-07-2015, 09:37 PM
Is this an auto reversal indicator or do you have to switch a lever on the side, if lever type is lever all the way to the stop