Anilam DRO scale reassembly Q

When I took apart the table for my Bridgeport mill to clean out 30 years of crud, I had to remove the DRO's scale and inadvertantly
pulled the sender / reader apart. The reader had a springy wire with a ball on it that held the electronics etc that actually read the glass scale. It was easy enough to put that back together and nothing appeared to be broken.
When I reassemble the reader and scale, what do I do to position the sender correctly with regard to the scale? Do I just get it close enough to read or should it ride on the glass scale? Should it touch the glass at all? The "adjustments" are pretty crude, so I'm guessing the little flat square reader should ride on the glass, but with the price of these things, it's better to wait and ask first. Should I clean the scale and sender while I have it apart? What to clean it with - Windex? Alcohol?
RWL
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On Tue, 13 Jan 2009 22:07:09 -0500, GeoLane at PTD dot NET <GeoLane at PTD dot NET> wrote:

I think some Anilam scales have pair of machine screws in the aluminum extrusion that don't appear to have any function other than plugging a couple holes or fastening a label. If you remove them and position the reader head under the holes, there are tapped holes in the head that line up with the holes in the extrusion. With the proper screws and spacers installed the reader head is held in alignment and you can adjust the brackets to mate with the mounting surface of the head. The seals should give you some idea of the proper location of the head in the axis perpendicular to the face of the scale glass, and thus the length of the spacers.
Take this with a grain of salt as I'm going by memory of the scales on a BP I sold several years ago.
Alcohol is good for cleaning the glass.
--
Ned Simmons

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wrote:

Thanks. Mine does have those two screws on the scale that made me wonder what they were for. I didn't spot the mounting holes in the reader head that they'd mate with, but I did upload a pdf of pictures of my Anilam scale to the dropbox.
Look for the file Anilam scale from Bridgeport milling machine.pdf
RWL
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GeoLane at PTD dot NET wrote:

I'm guessing this one doesn't have tiny instrument bearings used as rollers or it would be obvious. So, it most likely has teflon-coated pads that ride on the glass. The cheaper scales are built like this, and when the pads eventually wear down due to swarf getting past the seals, the read head starts to rub the glass scale and wipe the grating off. Then the scale is trash.
Examine it to see how the head is supposed to ride on something that keeps it in close proximity to the grating on the glass. I've never heard of onw that was just supposed to float on the spring, I suspect the spring is supposed to gently hold it against the glass. But, only the sliders are supposed to touch the glass (or something else in the housing that serves as a slide rail).
I'd clean with alcohol, then wipe with a soft cloth to remove any haze left behind.
Jon
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It sounds like Jon also described what my reader head may look like. I uploaded photos in a pdf file to the drop box for anyone who cares to look and comment on how to adjust this reader head to the scale. After looking at my photos I'm beginning to wonder if you just put the scale in place and adjust the mounting bracket up or down a little until the scale reads and just tighten the screws in place. On the other hand, scales are expensive, so I thought I'd ask the voice of experinence before I ruined something.
Look for the file labled
Anilam scale from Bridgeport milling machine.pdf in the drop box. I uploaded it late Wed evening.
RWL

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I uploaded photos in a pdf file to the drop box for anyone who cares to look and comment on how to adjust this reader head to the scale.
Look for the file labled "Anilam scale from Bridgeport milling machine.pdf" in the drop box.
or use the tiny URL
http://tinyurl.com/8pzunw
After looking at my photos I'm beginning to wonder if you just put the scale in place and adjust the mounting bracket up or down a little until the scale reads and just tighten the screws in place. Does this look familiar to anyone? Are there things to watch out for when mounting the reader in the scale housing?
RWL
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GeoLane at PTD dot NET wrote:

The last picture tells me the read head rides on the brown plastic piece, but it looks like the slider pads may be worn down a bit. When they wear down until the analyzer grating rubs on the scale grating, the whole scale is destroyed. This is how the cheaper scales are made, designed to self destruct. You might want to put a very thin strip of teflon on the slider pads to maintain clearance between the two glass parts. It doesn't want much clearance, just a few thousandths of an inch. Once that is attended to, then the spring applies a gentle force to hold the plastic slider against the glass. If the spacing between the two glass parts is not tightly controlled, the scale will not work repeatably, ie. it will lose counts when you reverse.
Jon
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On Thu, 15 Jan 2009 22:49:36 -0500, GeoLane at PTD dot NET <GeoLane at PTD dot NET> wrote:

The encoder and scale are not made by Anilam. This is a Acu-rite AR-5 model scale and encoder. The manual for the scale/encoder can be downloaded at the Acu-rite web site. Acu-rite sold these scales to Anilam with the custom cover plate until Anilam made a deal with RSF Electronics to have custom scales and encoders made.
Regards, Tim Barnard LMSC 877-376-4373 www.digitalreadoutsystem.com
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Tim, thanks for that bit of information. Things are beginning to make more sense now. I didn't realize this reader head had adjustable standoffs. I only had time to download and scan the manual, but it looks very helpful. I talked to "Betty" at Accu-Rite on Friday afternoon and got some general advice. I did flick some chips off the glass scale when I took it apart, but I want to clean the glass before I reassemble it. Betty said they used acetone to clean scales at the factory, but said that alcohol would work fine. The important things she said were to use a lint free cloth and get no streaks. Getting the scale reassembled will be next weekend's project unless something comes up.
RWL
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