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DRO Display

adamsgt

Cast Iron
Joined
Nov 7, 2007
Location
Fort Worth Texas
Was looking at a used mill and am probably going to buy it. When inspecting the table I noticed a cable that had round multi-pin connectors on the end. Closer inspection revealed that scales were installed on the table for a DRO althought the DRO display was missing. The seller was unaware of this as the display was missing when he bought the mill.

Question, I don't know how much standardization there is in the DRO field to know how difficult it may be to find a display that will work with the scales already on the machine. This mill has a 10X54 table. Suggestions please.
 
Question, I don't know how much standardization there is in the DRO field

None really to speak of, if they have a make/model on them, I can probabally tell you.
Most use 5v TTL/ differential incremental output, some heidenhains use either 20µa or 1v p/p.
If 5v TTL then you may be able to hook into some of the other makes, the other stumbling block is how much the DRO unit is able to scale to the resolution of the scales you have.
If TTL it might be easier to look at the free PC DRO on the www.lindseyengraving.com site.
M.
 
Minder

It was really cold and blowing today when I looked at the mill which was under a carport. I think I remember seeing a partially obscured name on the scale on the side of the table that had h's and n's in it so they may be heidenhains as you suggested. I think the front just blew through and I might be able to get a better look tomorrow. Unfortunately it's a 45 mile drive. Nothings close in Texas.
 
Minder

I went to look at the mill again today. The y axis scale reads Heidenhain LS 603C 420mm dnr 316 559 -39 SNr614561A V5. The cable has eight pins in a circle with a center pin. I'm googling "heidenhain" and trying to see what I can find but it's more than a little confusing. With both scales and the cable on the machine is the display all that I'd need?
 
It looks like that series is sine wave output, so you would either have to have a converter box to TTL to work with most other makes, providing they will calibrate to those, or go with a Heidenhain DRO, of course you do not know the condition of the present scales?
If you are lucky, all they may need is a clean with de-natured alcohol and optical tissue.
The heads can be removed carefully and cleaned as they are aligned when mounted.
M.
 
You can get the Heidenhain nd 780 display box for less than a chinese dro package.

Take the scales someplace that sells the displays and see if they work.
 
Thanks Jim

You can get the Heidenhain nd 780 display box for less than a chinese dro package.

Take the scales someplace that sells the displays and see if they work.

I found that nd 780 box on the web and it looks neat. Haven't yet found a price for the box alone. Would there be any alignment or calibration issues with taking the scales off the table and re-installing them?:eek: I'm asking that question because I have almost no idea of how these DRO's work. I have a lot to educate myself on.
 
Many of the heidenhain scales have set screws that set the head at the right gap from the scale when everything is in place. The head itself is usually spring loaded up to the the scale when installed.
You can remove the whole scale carefully, for cleaning, the heads can be slid out of one end of the scale and cleaned with de-natured alcohol and soft tissue.
I would get hold of a copy of the head adjust sheet when you re-install them, I may have a copy somewhere.
M.
 
I forget which outfit was advertising it, but I found a place who'd sell the display for $790 or so. Google it.

Otherwise, I got my system from Tim at www.accuratemeasurementsystems.com. Extremely helpful and nice guy, and he'll beat any quote you can get in writing. Mine was 30% off list. He also has everything in stock and can measure and check stuff before you plunk down the cash.

I just bought the nd 780 with a 3 axis scale kit last week. It's all that and a bag of chips from what little probing I've done with it, and from reading the manual. If you do hole patterns much, this sucker is worth it's weight in gold. There's a wicked menu for everything right on the screen. It doesn't get any easier without cnc turning the cranks for you.

Granted, the system was about double what a chinese rig would cost, but everything about my kit is first rate. The scales add up, but you already have those - the display should be a no-brainer.

I'm hoping to have mine installed by the end of the week. I have a lot of other things going on, so it might take me a while to get around to it. I'm pumped about it though!
 
Jim

talked with a salesperson at Accurate measurement systems, They have a factory rebuilt nd 710 unit that they are sending me to see if it will work with my scales. This will cost less than half what it would be to try to add a ND 780. They will not charge my credit card until I'm satisfied. If I went with the ND 780, I'd have to buy a pair of cable adapters at $86.00 each. With the 710 I can use the cables already on the mill. As you said, very nice and helpful people to work with. I'm sure hoping the scales and display will play nice. :p
 
All of the Accurite units I have come across have used TTL (5v) scales, so you may hit a snag there, unless they have changed things for recent models.
M.
 
I am running into the same problem on the mill I just got. It has Accurite scales in questionable condition. I have access to a Pathfinder readout but the connectors are different. Does anyone have any documentation on the interface for either the Pathfinder or Accurite. The scales are from about 1990.
 
Well I hooked up the the cables to the DRO display and only the y scale had any readings. Swapped the cables with the y scale into the x port and had readings there. This means that the display is not reading from the x axis scale. I guess the next step is to remove that scale and attempt to clean it.
 
Cleaning might help but be careful. Someone with more experience with scales than myself will have to advise you on that.

But-

As I mentioned before, I have a machine that's very similar to your's and of about the same age. (mine is circa early 90's) I had the same issue you're having. I tried cleaning, adjusting etc. but it didn't help. I pulled the cover from the reader head and other than a few resistors and a cap the only electronic component was a very common quadcomparator chip. After a quick trip to Radio Shack I de-soldered the existing chip and replaced it with a new LM339 chip (less than $3), put everything back togther and it now works perfectly.

I have a pretty good vac de-soldering station but you can buy de-soldering wicking from RS or other electronics supply store or one of the vac buld irons. If the cleaning/ adjustment doesn't cure it you might consider plugging in the iron.....

Good luck
 
Cleaning might help but be careful. Someone with more experience with scales than myself will have to advise you on that.

But-

As I mentioned before, I have a machine that's very similar to your's and of about the same age. (mine is circa early 90's) I had the same issue you're having. I tried cleaning, adjusting etc. but it didn't help. I pulled the cover from the reader head and other than a few resistors and a cap the only electronic component was a very common quadcomparator chip. After a quick trip to Radio Shack I de-soldered the existing chip and replaced it with a new LM339 chip (less than $3), put everything back togther and it now works perfectly.

I have a pretty good vac de-soldering station but you can buy de-soldering wicking from RS or other electronics supply store or one of the vac buld irons. If the cleaning/ adjustment doesn't cure it you might consider plugging in the iron.....

Good luck

Thanks for the advice. I'm going to take tomorrow off and shoot a falling plate match. Supposed to be nice weather. I've taken the guard off the scale and stopped at that point. I'll call the people that sent the display on Monday for more tips. Been a long time since I picked up a soldering iron. At one time I had built neary every piece of test equipment in the Heathkit catalog. Gave all of it to my brother in law years ago and all I have left is one pencil soldering iron. You didn't say, but did you have the Heidenhain LS 303 scale? Do the scale and read head come as a matched set? Inquisitive minds want to know. ;)
 
I have purchases a replacement reading head and cable, the head is automatically aligned when you do the correct install.
M.

I don't know anything about the construction of these devices but the scale would appear to be an inert device while the read head has components that have some function that can fail. That implies that if the scale and head are clean then the read head is the most likely point of failure. Or, can the scale fail in some way other than being dirty?:confused:
 








 
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