Dial indicators

[Rob Keeble]

I spent a great deal of time in the past two days getting my table saw aligned using a dial indicator.

I am not convinced i know how to use these things properly given the way the one i have was jumping around. So please feel free to pile in and chime in here and let me know what i am doing wrong.

I made sure to set up my indicator such that it was "loaded" as in point pressed in to around mid way. I was looking for relative reading after having set the dial to zero at one location.

I even changed from a dome shaped point to a pointy shaped point to ensure pin point measurement.

Is that the correct way to use them.

Mine seems to jump around all over the show.

The other thing i found is most are in inches and while i grew up with imperial system I have full grasp of fractions but not when it comes to working in thousands of an inch. 1/64 is where i call halt in understanding imperial system.

SO Mathias Wandel of Woodgears was informed and got me searching for a source for a metric dial indicator and i found one pretty good price on Aliexpress

Then i noticed while searching around on that site they have digital dial indicators and i wondered just how effective they were given i prefer the analog indication of movement over precise digital readout. But on the other hand if one is after a actual measurement this will give it to one without the issue of determining the reading off a fine line markings on a normal dial indicator.

Has anyone tried a digital or worked with one that can add to the merits or benefit of using one over the other.


BTW i see for anyone interested this measuring company also makes the digital scales for using on say a router table or planner at good prices US $25 inc delivery to Canada for a 6 inch or 150 mm digital readout is not bad in my view. The IGaging on Amazon is $35 looks like they come from same stable.

 

[Bill Arnold]

Rob, I bought a dial indicator 20 years ago because I read that was the right way to calibrate a table saw and other tools. Then, I started heeding what others with more experience than I were doing and that did not involve anything other than normal shop tools. Check this video by The Wood Whisperer.

 

[John Coloccia]

Without seeing your setup, I can't help you with the "jumping around." They're pretty sensitive, so what might look like jumping around to you may only be a couple thousandths of an inch. For most measurements, I prefer the bearing...that's a good general purpose contract point.

Digital indicators are nice in some situations, but I think most people that have experience using them (especially for machine alignment) would prefer mechanical. The instant feedback is very useful, and being able to see the indicator swing back and forth also gives you a very quick indication of just how straight you are. I don't even bother setting the '0' point half the time.

If you post some more details of your setup and what you're doing, it may help. One hint I'll give you is to measure on the same spot of the blade every time. Make a little mark with a sharpie and rotate the blade as you measure at the front and back of the slot. This will help eliminate any tail chasing due to run out or a slightly bent blade.

 

[Leo Voisine]

I have been using dial indicators of all sorts for the past 40 years - including today.

At the company I work for we manufacture dial, as well as digital indicators along with all sorts of other measuring instruments.

The dome shaped point is fine for what you are doing.

The indicator is jumping around because you are moving is across the face of the saw blade I am assuming?
The jumping is because the saw face is rough and making the spindle bounce. That is common.

All you want to do is "compare" one side to the other side when the indicator and saw blade are still.

I prefer analog.

Metric indicators are not at all uncommon.

Can you post a couple of pics of what you are doing?

 

[John Coloccia]

Oh, hey...here's something to watch. If you are dragging it along, especially at an angle, the tip will sometimes unscrew and drive you nuts, especially if you drag it back and screw it back in!

Er...not that it's ever happened to me, of course.