# $10 Calipers To Dro



## fgduncan (Feb 21, 2015)

$10 Calipers to DRO


Having studied the workings of digital calipers, I realized that they could be trimmed to make perfectly functional DRO’s. Harbor Freight has these for sale, with a coupon, for $10. The pictures show what has to be trimmed off leaving behind the LCD Screen with the depth blade and the sliding ruler.

I used a Dremel tool with a cutoff blade and it took less than 10 minutes to finish removing the non-essentials.

I needed a DRO for the tailstock ram on my lathe, but it had a travel of about 3 inches. I trimmed off the sliding ruler to the length I needed and it continued to work just fine.When I had finished trimming, I put the sliding ruler on my mill and used a carbide mill to clean up the rough edges. The Dremel would have done a serviceable job, too.

The rulers are made of hardened steel and I had nothing that would drill through it. I used the edge of the cut-off wheel to carve half-round notches in the sides of the sliding ruler which just accepted half of a screw.  When the sliding rule was placed on the bracket, the notches lined up with the screw holes and the sliding rule was secured. The depth blade was clamped in position and everything worked just fine. The notches can be seen on the left end of the sliding rule below. 

The only other modification I would recommend is to glue a piece of transparent plastic over the LCD screen since it is a little delicate. You might also consider putting the LCD screen in a fixed location and have the sliding rule move.


----------



## dirty tools (Feb 21, 2015)

That is a great idea'
I will have to do that on my lathe.


----------



## Holescreek (Feb 22, 2015)

This one's been on for a few years now, they're pretty robust.


----------



## RJSakowski (Feb 22, 2015)

I had done this for a quill feed on a mill/drill and on some custom projects in the past.  

Be careful about buying the HF calipers  The latest version are Pittsburgh and the grinding is very poor.  The loosen the adjustment screws to provide travel over the beam but the slop introduces reading errors and if you tighten the adjusting screw to eliminate the slop, they bind.  They also have an auto shutoff feature and have to be rezeroed.  This was not true for the calipers they sold earlier.


----------



## compsurge (Feb 22, 2015)

If you can afford the extra $7, I like the Neiki brand on Amazon better than the current HF calipers. They keep their measurement after shutoff and feel a little better overall. Still not a Mitutoyo, but I don't expect it to be.


----------



## compsurge (Feb 22, 2015)

I just realized I meant Neiko* It doesn't seem like I can edit posts after someone likes them or there has been a certain time elapsed...


----------



## KMoffett (Feb 22, 2015)

Did the same.

Ken


----------



## fgduncan (Feb 22, 2015)

If anybody is interested, I show what I have done with this idea


KMoffett said:


> Did the same.
> 
> Ken
> 
> View attachment 96237


Neat job! Identical idea. Convergent evolution in action. How did you fasten the LCD to the bracket?


----------



## KMoffett (Feb 22, 2015)

There were two threaded holes on the back of the display module.  I used one to fasten it to the L-bracket.  It was not a cut-down caliper.   The single screw also acts as a pivot point to help align everything.

Ken


----------



## hman (Feb 26, 2015)

HF actually sells two different 6" digital calipers.  Item number 47257 has a black head.  It's cheaper, but forgets where zero is when shut off.  Item 68304 has a gray head, includes a fractional inch readout, is a few dollars more, and keeps track of zero when shut off.  IMHO, it's well worth the small difference in price.

As always, carefully inspect at the one you're thinking of buying.  Some slide pretty roughly, and I've seen some whose bodies are visibly bent.  You might have to go through a few of them until you find one that's smooth and straight.


----------



## ogberi (Mar 1, 2015)

The older HF digital calipers are definitely better.  I used two on my Taig lathe for digital readouts, and plan to use three on my Atlas horizontal mill in the same fashion.  I'd like to rig them to a Raspberry PI, so I can have hole patterns, center finding, etc, etc.  I used a dremel with cutoff wheels to remove un-necessary parts as well, but drilled holes using a solid carbide drill bit.  I bought several sets from an electronics surplus place.  They're generally tiny, 1/8" shank, used for drilling fiberglass circuit boards.  Razor sharp but delicate.  

Excellent work on on yours, and I'm sure you'll like the accuracy.


----------



## mksj (Mar 1, 2015)

The newer Igaging Absolutes DRO are not much more ($45) and also work well. They allow a little more flexibility and the display is a bit bigger, which is a plus for my old eyes. The older Igaging DRO units had issues with errors and accuracy. The Absolute I installed on my tail stock, tracks perfectly out to 4" of travel, and does not loose track of the origin or last reference point.  The only issue with these units is the readout display lags by about 1 second with rapid movement.


----------

