Newbie Question about Schumatech DRO

Wanting to add a DRO to my mill/drill (RF30 clone) and am considering theSchumatech DIY DRO. My question is do you have to be concerned about
backlash when using a DRO or does the scale compensate for it. Seems as though the DRO gives actual position and Backlash is no longer a problem?
Fo those of you who have built this DRO before, is this a project someone with little electronics experience can do?
Thanks all
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Dan wrote:

i bought Chinese DRO's as shown in: http://www.shumatech.com/support/chinese_scales.htm I bought them as a kit with the readout and all I had to do was install and plug in the wires. As far as I can tell the accuracy is OK, with a resolution of .0005" and it compensates for backlash in the machine. There is a button that will rezero the reading at any point but I have had a lot of trouble with the scales losing synchronization with the readout due to the flimsy nature of the electrical connection. When this happens you must take out the batteries and leave them out for 1 minute, then replace. Someone has suggested soldering the connections together but this would be difficult as they are encased in plastic. The battery covers and the contacts are very poorly made and have given
me much trouble. The contacts that the battery touches are .005" thick and I had one break off when replacing the battery. It was replaced by the vendor but I feel that These Chinese scales arev too pooly made to bother with. Engineman
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snipped-for-privacy@aol.com wrote:

There's no reason to use batteries, when one can supply the power via the connector.. The connector pins are :
1. - power 2. clock 3. data out 4. + power
So, in my setup, I supply the power through this connection and don't use any batteries. I have soldered wires of a cable directly to the connector of the caliper - it is easy when one takes away the plastic cover of the electronics of the caliper. I couldn't find connectors anyway, so soldering was only option.
"Losing syncronization" is weird, as the scales (calipers) send their position syncronously - about 10 times per seconds in slow mode - the display electronics just wait for a new reading, convert it to displayable number, and start waiting for next reading.. So if there is connection problem, just reconnecting should make it work again. I can't understand why one would need to switch off for 1 minute - definitely not because of calipers.
Of course, I have no experience with the product mentioned above - I have my own electronics for reading the calipers. But the principle of operation has to be the same.
Kristian Ukkonen.
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You've got it right. One of the great things about a dro is that backlash goes away. The backlash is in the screw/handwheel, moving back and forth in relation to the table. The dro measures the table directly. So if the table doesn't move (while you're taking up the backlash), the dro doesn't measure any motion.
Steve
Dan wrote:

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IMHO for the cost of most decent DROs you can almost convert the machine to CNC. Of course depending on skill level, bargains found, and current machine.
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Chris

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Dan wrote:

Maybe I didn't understand what you were asking about backlash, but I still think that for side milling you should approach the reading you want from a direction the mill will "push against" when you start cutting. To do otherwise invites dimensional disaster, particularly if you can't or don't lock the slide before starting the pass.
Jeff
Jeff
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Jeff Wisnia wrote:

Good point, Jeff. When I had a mill-drill, I remember the experience having a lot stronger words attached to it than 'dimensional disaster'. I didn't break an end mill, but things were pretty exciting for a brief moment.
Steve
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Dan wrote:

Yes, If you run into a problem just go on the web site & someone will walk you through your problem. Mine works great. I soldered the wires on HF units. Total cost with 3 scales $225.00

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Hi Dan,
I built one, was my first electronics project, actually purchased a soldering iron just for the Shumatech Dro. Now, that said, it worked, was not a fan of the "Chinese scale thing", Had a house fire, ruined it, went out and purchased a 3-axis DRO (JENIX) with glass scales, couldn't be more happy. It is much more sturdy than the Shumatech model (no did intender, great product for those with the time and a low budget). Now, that said, Scott Shumatech is a good guy, will help you through the construction (as well as yahoo group fellows) and it is a very powerful (from a software point of view) little unit. From what I last read, he is expanding the PIC Basic chip memory to allow more steps and, obviously, more features.
In a nut shell, ya get what ya pay for, cheap case, your time, but cost only a few hundred bucks....
Hint, if you are going to do the Shumatech thing, go to MyLittleMachineShop web site and order the scale to controller cables now, they are usually backordered...they made the whole job alot easier. I started off trying to make them and destroyed my first scale in the process.
John
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Hello John,
Aside from the flimsy case and Chinese scales, is there anything else you don't like about the Shumatech design? I've just ordered a couple of boards, am planning on installing them with JENIX scales. Might as well consider suggestions for improvements while I'm at it.
Nobody on the yahoo group ever has anything but praise for the design, so criticism is interesting/useful.
Thanks,
Adam Smith Midland, ON, Canada

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No criticism here either, great product...just more of a "toy" like feel to it, a bit flimsy of a box, Chinese scales are, well, Chinese scales. The box is something like 2.5"x4"x7" or something like that, about 1/5th of the size(volume) and 1/10 the mass of the Jenix box.....The software is great though, a lot of functionality, more than the Jenix that I purchased.
If you are $$$$$ conscience, go for it, it's by far the cheapest way to go as long as you don't bill your time out as part of the $$$$. Personally, I used it as a reason to buy a Panavise, Soldering station, static pad, etc.....
Go for it, you won't be unhappy, just not quite the "industrial/heavy duty" feel to it.....
John
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