what does dial indicator use to measure?

[cnc2k]

Hello all,
I have see poeple use dial indicator to measure something when building machines. Can anyone explane what this tool does?

Thank you
EZ

[Al_The_Man]

It can measure/indicate to less than .001" axis backlash, spindle run-out, used when centering a part in a four jaw chuck for a few.
Al

[HuFlungDung]

The dial indicator is most often used as a comparator, as Al described in his various sample applications. That means that it is really only used to indicate some degree of change in relative position, the actual amount it "says" is not necessarily a useful "measurement quantity".

Suppose you had the dial indicator body fastened onto a sliding bushing on a rail. You could then position another rail nearby, and place the indicator stylus upon it, and push the sliding bushing. If the shafts were not parallel, then you would notice a change in position of the indicator hand relative to the dial scale. You could then reposition the second bar and keep testing the parallelism by sliding the dial indicator along it, fastened as described, on the first rail.

Most often, multiple planes of reference must be checked to truly achieve a truly parallel setup of two parts. Machinists do this all the time, with their vises, relative to the table slides, too.

[Splint]

It can have a wide variety of general uses. Really all it is, is a device used to measure using a plunging style probe. It can be used to measure end float, run out, really any type of movement where the measurement needs to be linear. It could also be used in a situation where you may want to measure how paralell the guides are by a bar a bit wider than the rails with a stop which locates against one rail and the probe mounted against the opposite rail. Keep the tool square to the rails and check the reading in different positions along the rails.

[ViperTX]

Hu basically nailed it.

Following Hu's lead, you can attach an indicator to the spindle of your mill.....lower the quill until you the indicator barely touches the mill's table....rotate the spindle and with the relative indicator readings you can determine if your spindle (mill head) is square (orthogonal) or Tram to the table surface.

[MBG]

I use mine to square the mill everyday
you can also use it to square up your work piece. It is the most valuabe tool besides my caliper

[RJT]

The Dial Indicator its the machinist's best friend. You can clock a hole , find position's , check for flatness , true vices, use it as a read out on a lathe , : chuck it at your buddy...lol, it's all about improvising .

[cnc2k]

Are there any accessories i need to measure the parallelism of my linear rails and how straight the gantries are. I attached the picture of my desgin. the rails are 48" apart.

thank you

[Mat-C]

Add some triangles in there dude The top rails might be strong enough by themselves, but those uprights look mighty thin. You know this of course.

I don't know much about truing things up skew-wise, I am hoping with my lil' cnc that I can get it working and then have it move around with a dti as its workpiece, measuring itself and then I'll correct it. You might be able to do the same. Failing that, get a long stick and put the dti on the end, between the rails?

Thanks for the tramming tip ViperTX.

[OCNC]

Add some triangles in there dude The top rails might be strong enough by themselves, but those uprights look mighty thin.

..or make the gantry uprights out of a box section so you can maintain the max. length of spindle travel.

Chris