New Source for a "NICE" and cheap DROs

Thanks John, nice resource. Looks like with an adaptor available from the same place, the US Digital readers and strips from just about any HP bubblejet printer could be used in a dro! (I've been saving dead printers for just such a project).

Welcome back.

What kind of accuracy do the readers and strips from the printers provide? I was looking at a new HP wide format printer at a store, and the strip is not much for rugged.

Would the converters on the site allow the use of their box with "real" DRO scales? Ebay seems to usually have a pile of scales available for pretty cheap.

Cheers Trevor Jones

If there are a lot of auctions in your area you should be able to pick up a machine with a DRO installed fairly cheap.

Should be able to. Except for all the fricking morons that have a pocket full of money and desperatly want to spend it whenever a machine tool comes up. Took me 2 1/2 years to find a small mill. Drove over 8 hours each way to pick it up, and still paid more than I wanted.

Watched two guys from a shop duke it out over a twenty year old surface grinder at an auction a while back. Yeesh! it sold for about triple what I thought it should be worth it it had been complete and working. Any mill that looks sorta OK tends to be around $4000-6000 to start, and the dealers are pricing stuff as if it had to be carried over the mountains on somebodies (well paid somebody, at that) back.

Finding a DRO on a machine is effectivly a non-starter, as a result. For the prices a used one goes for, I can buy new.

But, on the other hand, this project looks like fun, would give me satisfaction, even if all I was doing was populating a board and building a box for it, and is relatively cheap. Perhaps not as cheap as trolling ebay for the various parts to build a whole system, but the size of this one fits well with my shop.

I have a very little knowledge of things electric, and can do a decent solder joint if I put some effort into it. Oh yeah. "Here" is Edmonton Alberta, Canada. Not a lot of machine tools up for grabs. Not for cheap, anyway.

Cheers Trevor Jones

Greetings Trevor, I think I'm gonna build on too. Not sure yet about the scales. I emailed Scott Schumate to see if the last digit could be made to read individual tenths instead of either 0 or 5 tenths. He said it would require some major changes but if enough requests were made he would think about doing that. So it won't be any good for my lathe work but will be close enough for most mill work. I am going to e-mail him again and ask which, if any, commercial glass scales will work with his unit. Cheers, Eric

If you have higher resolution scales, can't you just move the decimal point? pete

You live in the wrong area, I guess. Basic manual surface grinders are going for about $50. I just saw a Bridgeport with a Mitutoyo DRO setup sell for $950. An old Van Norman with a DRO went real cheap, less than 200 IIRC, the guy planned on stripping it and selling the rest of the machine for scrap.

Not as good as real glass scales. The best plastic strips from usdigital are 500 line units, with quadrature reading they yield 2000 transitions per inch. However, most (old and cheap) printers do not use these strips.

To match the coefficient of thermal expansion of the machine they are being used on, it is possible to edge clamp them full length into a rail of the same material as the rest of the machine and they maintain accuracy throughout normal temperature swings.

Their main advantage is cost. In single quantities, the reader heads are about $25 iirc and the linear strip is about $12 for the first 7 inches, longer than that it is by the inch.

Not extremely useful by themselves, but very handy for the oem or above average tinkerer. That is, though I am not familiar with standard input for dro readouts I would guess that the format does not allow simple plug and play. Hence the converter dongles for sale at the site mentioned earlier to adapt to his chosen standard.

Apparently I do live in the wrong area. If I was seeing prices like those around here, I'd need a whole lot bigger shop. :-)

Where are you?

Cheers Trevor Jones

I recently disassembled an HP ink jet printer, model 620(?), that had a rotary encoder from Rhulatec that has 1800 grads on a disc approx. 3 in dia. Rhulatec's web site says they have 1000 lines per inch strips as a standard item. You might check them out as a supplier or look for HP ink jets to salvage some high res. rotary encoders.

Richard Coke

No. He said you could do that but then the maximum reading goes from

99.9995 to 9.99995. Unless the travel you want is less than that it won't work. ERS

Long Island, and I am thinking about building a bigger shop. Truthfully at this point, I don't always know what I'm looking at, but I can see where the dealers are willing to go pricewise on stuff, and I know how much some stuff will bring on ebay. When I got my first Nichols mill recently I didn't know an arbor from an arborvitae, and I'm still ignorant but gaining some experience.