Poor Man's DRO

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olympic

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I'm not a very good machinist, I don't have a lot of money to spend, and I have a Craftex (Canadian Busy Bee equivalent of a Grizzly G4015) B2071 lathe/mill combination. With these three strikes against me I felt that it couldn't hurt to try adapting a cheap digital caliper to make a DRO for the vertical axis of my mill.

Accordingly, I found a cheap, but stainless steel 4" digital caliper to adapt to the mill. I had to have a short caliper because of the limited space available to me, and even then I had to cut a little slot out of the drive belt cover to accommodate the height of the caliper.

With the slot made, though, things became easier. I merely laid the caliper against the mill housing and tapped a 4-40 hole in the housing. The "top" part of the caliper just screwed into place, held through a hole I drilled in the plastic scale body.

I secured the bottom ear of the caliper by drilling a hole in it and threading a 4-40 screw into an aluminium bar fastened to the collar at the bottom of the quill. The bar is what I had been using till now with a dial gauge to adjust cut depth (the mill's original scale is hopeless), and I left it long in case I have to go back to it, though I hope I don't; the dial gauge is very difficult to mount there.

I now have a single-axis DRO for my cheap old mill, and I don't intend to add anything to the other two axes, as my dial gauge is easy to use.

Everything moves freely, and as for accuracy, I seem to be consistently within .001", and that's good enough for me.

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I have admired the expensive DRO's that some use on their mills and lathes, and considered purchasing a nice system.
After building a foundry, I decided I needed to conserve funds, and so I resorted to the "poor-man's DRO" system.

I fastened a 6 inch DRO to the carriage using a non-permanent grip between two washers, and let the end touch the gearbox housing.

I had my doublts about such a crude setup being useful, but it does work very well, and is great for all sorts of things such as parting off piston rings, cutting piston ring grooves in pistons, etc., or a fixed-depth counterbore as shown in the photo below for the gland.

I use mine constantly now, and save a ton of time with it.

My dad was always dead set against anything digital (he did have a mechanically-actuated rotary dial digital readout micrometer, but it was not electronic).

For $20.00, I could not be happier with my poor-man's DRO.
I intend to add one to the tailstock of the lathe, and also at least one on the mill.

The hearing aide batteries don't last long, but I did tried a DRO wired into a standard alkaline battery, or maybe batteries (I forget what the voltage was, but I matched the voltage on the button cell), and that worked well too, and gives a very long battery life.

The accuracy is surprisingly good, and I am more than pleased with the results I get with my inexpensive lathe-mounted DRO.

The mount for my DRO does not require modification of the DRO, and I can quickly release it and use it as a standard vernier caliper.

The way it is used is to get the bit into position, slide the extended end of the DRO over against the gearbox housing, and then hit the RESET button to zero the readout.

This arrangement gives me almost 6" of travel, which is as much as I generally use.

This is so much quicker than trying to read the dials, and I make far fewer errors using it too.
DRO is the only way to fly in my opinion, and you can set one up for very little money.


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the calipers you folks are using are the ones sold by harbor freight here in the US, and they have a version already adapted to be a DRO for a small mill or drill press. My problem with them is that the battery life is abysmal.
 
the calipers you folks are using are the ones sold by harbor freight here in the US, and they have a version already adapted to be a DRO for a small mill or drill press. My problem with them is that the battery life is abysmal.
The battery problem is with the ones that are on standby to retain previous information. There are more 'basic' ones which when off are really off and not on standby. The batteries (cells) on these last very much longer these are often available in the UK at Aldi or lidl as special buys but you have to switch on when zeroing your toolpost.

TerryD
 

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