[strandbygaard]

Hi,

I just got an SX3, and I need to add 2-axis DRO (no plans on CNC). The choice seems to be between (expensive) glass scales and (dedicated I assume) DRO units, or cheap digital scales with generic (and rather expensive for what it is) consoles.

I've been trying unsuccessfully to determine pro/con for the two kinds of scales.

Glass scales seem to offer slightly better repeatability and they are probably more accurate, though specs are often the same. Other than that what are the advantages of glass scales to justify the significantly higher cost? and does the slight differences in precision and repeatability actually make a difference?

The "cheap scales" only provide 3 reliable readings per second - is this an issue in real life? (though I know that ShumaTech consoles does filtering to support FAST mode with reliable 50Hz sample rate).

[irving2008]

It is possible to use the cheap chinese scales with 50 samples/sec. Not all support this mode but many do (and I can't tell you which do or dont... all of mine do, but they have different sequencing to get there)... the readings are reliable if you digitally filter them... And there are lot of ways of doing cheap DRO displays... as long as you don't expect to buy one off the shelf...

Here is mine (or the breadboard set up for it) under development, using a cheap VFD display from a POS terminal (5GBP off eBay!)

[Jaime128]

After I saw your post I went to ebay to check and see what was out there...hope this helps a bit. I don't own one, but thought it was interesting. You can probably shoot them an email and ask about what you're trying to do.
http://www.wildhorse-innovations.com...iewCat&catId=1

[ninefinger]

If I was to do it again I'd go for the glass scales and readout from a discount tool store like shars http://www.shars.com/products/view/7...System_Package. $470 for 2 scales and the readout, plus what looks to be a bunch of stuff to mount it. Thats a great deal.

I have built the Shumatech DRO and have it on my lathe (used to be a 3-in-1 machine). The jitter I'm getting out of the scales is driving me crazy, +/- 1 thou. I know I can spend some time working out why its doing it but at this point I'm going CNC on the lathe and the dro will become redundant.

Theres not much savings in the "cheap" DRO and scales by the time all the seperate parts are added up too. (dro, cables, scales, mounts, power supply, etc). Also - those cheap scales aren't designed to be in a milling environment so you need to add protection there as well. Lastly, how much is your time worth? The cheap route will use much of your time - it did for me...

Just my 2 cents.

Mike

PS - want to buy a Shumatech DRO?