guage face

[tomrux]

Hey
Anybody know an easy way to print out a new face for a dial guage.
I have a long travel guage but the face is in imperial.
It is a 2 inch guage marked in 1 ten thou divisions by one hundred divisions. so that is ten thou per rev
Most of the time I work in metric.

Tom

[Tony Wells]

i've never seen a direct reading "tenths" indicator that travels 2.000". If you have a similar face, you could copy it and laminate it. Or if not exactly what you wanted, scan it and modify it with PhotoShop or comparable

[sparky961]

To get a reasonable amount of accuracy, use a vector drawing program and lay out the gauge face using angular divisions in that program.  I tend to use CorelDraw for this sort of thing, but many would also be familiar with Adobe Illustrator, AutoCAD, DraftSight, or many other free vector drawing programs.  I would stay away from the rastor/bitmap programs to do this sort of thing as the resulting gauge face would be much less precise than with a vector graphics program - not what you need from a precision instrument like this.

I've laser-printed various things on overhead transparencies in the past instead of paper to make them waterproof (and oil-proof to an extent).  Something made from white plastic behind it would make it readable - or if you can find some thin white plastic you can put through a laser printer that would work great (and let me know what you used because I'd be interested too!)

-Sparky

[Lew_Merrick_PE]

Tom,

How valuable would the transformation be?  1 inch = 25.4 mm.  Thus, you turn the .100 inch/rev dial into a 2.54 mm/rev dial.  Thus, instead of having 10 gross divisions of .010 inch, (I assume) you want 25 gross divisions of 1 mm -- and then resolving that down with fine divisions to (say) 0.1 mm.  Is that a correct assessment?

In addition, you will want to re-identify the revolution counter scale.  Correct?

Understand that what you will end up with is going to be a kludge of significant proportions.  The problem is that you will accumulate a 0.4 mm error with each revolution away from 0.0.  Thus, the first revolution is fine traveling from 0 to 2.54 mm.  The second revolution travels from 2.54 mm to 5.08 mm.  The third revolution travels from 5.08 mm to 7.62 mm.  Etc. until you reach 50.8 mm.  Each revolution (and there will be 20) adds to the disparity of what the dial reports and what you are going to get in the real world.  It seems to me that this would not be worth the effort!

However, with that caveat, what you are doing is to replace the 100 division/revolution dial face with a 254 division/revolution dial face -- and adjust the revolution counter to match.  Right?  That is a relatively simple task using CAD tools these days -- once you know the: outside diameter of the dial insert, the radius to the top of the indicator pointer arm, the diameter of the centerhole that clears the indicator shaft, and the position and size of the revolution counter arm.  The hard part will be disassembling things such that you can (accurately) reassemble them.

The cheap solution is to take a file (PDF, most likely) of the CAD dataset to a commercial printer with a good, calibrated printer and pay to have it printed out on high-clay paper.  This could be contact cemented to the existing dial face (having painted over the face to prevent bleed-through).  You could also, depending on your skill and access to equipment, use something like a Cronite engraver to make a whole new dial.  I would be happy to create the dataset for you if you wish to pursue this.  However, I doubt you will be happy with the results.

I can't remember where I have seen them (other than the high-end Starrett and Fowler units), but digital travel indicators in the 2 inch/50 mm range have been appearing in recent years.  I seem to remember (not that I was particularly paying attention) that they were running in the $60 range.  As a comparison, the Harbor Freight 1 inch/25 mm (+/-.002 accuracy -- at best) digital travel indicator sells for (about) $30.  My good Fowler digital travel indicator (+/-.0005 accuracy) cost me about $240 in 2007.  (As a side note, my Starrett .5 inch travel, .0001 inch resolution, +/-.000025 inch accuracy mechanical travel indicator sold was listed in the McMaster-Carr catalog for $650 in 2007 -- though I bought mine in 1969.)