# Clausing 8520 TouchDRO



## Briney Eye

Now that my recently-acquired mini-mill is up and running, I've started using it to make the mounting hardware for digital scales.  I'll be installing a full set of Shars scales and using Yuriy Krushelnytskiy's "TouchDRO" hardware and Android app.  I've already set up my Logan Model 200 lathe with TouchDRO, and love it.

I started with the quill scale, figuring that it would be the most difficult given the limited space.  First to go were the factory mounting brackets.  There simply wasn't room for them.  After a lot of measuring and sketching I came up with a scheme for two L-shaped brackets, and only one needed to be bent.  A flat "moving" bracket would attach the read head to the quill stop, and a "fixed" bracket  with one 90-degree bend would attach the top end of the scale to the mill's head.  The bottom end of the scale would float.  I had already successfully used a similar approach on the X axis for my lathe DRO.

I milled and bent the brackets from 1/8" mild steel, and this shot is of the initial fit check, to make sure things aligned properly and to mark the length of the top bend in the fixed bracket:




I can only use 3" of travel, so I cut the Shars 4" stainless vertical scale down using a cutoff wheel in my Dremel, then squared it up on my 6" x 48" belt sander.  Piece of cake.  After the fit check I milled the top end of the fixed bracket to align with the back face of the scale and drilled and tapped it.

So much for the easy part.  I don't own a drill bit that will touch this hardened stainless, so now I'm waiting for the cobalt and carbide to be delivered.  Once I have the tooling I will be drilling the top end of the scale to match the fixed bracket.

Marking, drilling and tapping the quill stop, in place, was a delicate hand operation, but went well.  You can see the 2-56 cap-head screws that attach the moving bracket to it.  To mount the fixed bracket the head was drilled and tapped for a single 10-24 cap head screw that you can see here just peeking out from underneath the moving bracket.  After aligning and tightening the fixed bracket I drilled for two 1/8" anti-rotation roll pins, one of which you can just barely see here.

Once everything is assembled, aligned and tight I will install 1/16" roll pins in the moving bracket/quill stop and the fixed bracket/scale so that the 2-56 screws aren't shear-loaded and to stiffen things up.

I apologize for the verbiage.  Pictures will be much easier to understand, and I'll be posting more detailed shots over the next few days if life doesn't get in the way.


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## Briney Eye

Here's a shot showing how I made the brackets.  I will be drilling and tapping a hole to relocate the thumbscrew to the left side at some point:




I'll probably "streamline" them a bit more.  I plan to give them a black oxide treatment.  I might also make a hairline indicator to attach to the left edge of the quill stop bracket.

I'm afraid that I have to wait a couple more days for some carbide drills.  Cobalt drills won't touch the scale.  I'm a little surprised by how easily I cut it with my wimpy little Dremel.


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## 34_40

Thanks for sharing the effort and the pics. maybe someday I'll get up the nerve to do this to mine.
I'll be "watching" for the next installment.


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## Briney Eye

This shows both the relocated thumbscrew and the reason that I had to move it.  I wanted to maintain access to the oiler on the fine feed:


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## Briney Eye

Z axis is installed and aligned:




I'm going to do a chip guard as a separate thing.


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## tweinke

Looks like a nice clean install so far! I added TouchDRO to my PM727 earlier this year using one of the premade boards and used the W axis combined with Z so that the head movement and quill are combined. So far I have been very happy with my choice because I can move either the head or quill and still keep position on my tool. I do not know if this is normal on a mill but it sure seems to be a nice feature to me.


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## Briney Eye

tweinke said:


> Looks like a nice clean install so far! I added TouchDRO to my PM727 earlier this year using one of the premade boards and used the W axis combined with Z so that the head movement and quill are combined. So far I have been very happy with my choice because I can move either the head or quill and still keep position on my tool. I do not know if this is normal on a mill but it sure seems to be a nice feature to me.



That's what I intend, and I'm assuming that the quill readout puts out a compatible format.  I need a Micro-to-Micro USB cable to test it with one of the read heads, though.  On my list.  (UPDATE: The digital output from the quill works with a display from one of the other scales, and is ALWAYS ON even if the quill display has turned itself off.  This is good.)

I believe that I can make a nicely-sealed Z-axis chip guard using some aluminum angle and door sweep weatherstripping.  Also on my list.  I should be able to pick up something that will work at the hardware store.  Maybe I can get a picture up today.  If I'm not happy with it I'll order a brush-type sweep from McMaster-Carr.  (UPDATE: I bought the brush type and it looks like it will work well.  Eventually I will post a picture.)


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## Briney Eye

I was wondering why the Y axis wouldn't lock up:




I don't remember it, but I just went through the bits and pieces again to make sure.  At some point in this machine's life, the "645-012 Rod" went missing.  So I made a new one.  Right behind it you can see the 1/16" spacer (UPDATE: actually needed 1/8") under the mounting plate to provide some clearance when I install the chip guard:




... and now the Y Axis scale is installed.  Shimmed up the outboard end 0.023" to get it aligned:




Hey, what's one more hole under there, anyway?  I made the mounting plate 1.125" wide, and it butts up tight against the underside of the cross slide.  I don't know how to make it any stiffer.  There's just enough clearance for a box end wrench on that gib screw locking nut to the right.


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## Briney Eye

All the scales are installed, with just the Z axis cover to go.

I made some Y-axis cover mounting blocks to replace the temporary washers:





Laid flat in the front, I can still use the 1/4" t-slot, and I don't lose travel on the Y axis (where there's not that much to begin with):







I had to order some 2-1/2" aluminum angle from McMaster-Carr and cut it down:




Looks pretty clean, I think:




Also from McMaster-Carr, to keep the chips out of the Z-axis scale:


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## Briney Eye

Hooked all the scales up:




Everything works!




Just have to button up, mount the box, make the Z axis cover, do some cable management, and calibrate!


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## tweinke

That looks mighty fine! Have you calibrated your scales yet? I remember reading something about the W needing to be done separately but no info how to do that. I decided to just plug it into x and figure the correct counts. If I may ask, what are you using for a tablet mount?


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## Briney Eye

I figure this ought to work:

1. mount a test indicator in the spindle
2. extend the quill fully and lock it
3. lay a 1-2-3 block flat on the table to provide a good reference surface (or just use a good spot on the table)
4. zero the test indicator on the top of the 1-2-3 block using the knee, and lock the knee
5. zero the DRO Z axis
6. stand a second 1-2-3 block on top of the first one
7. unlock the quill, zero the test indicator on the top of the second block, and re-lock the quill
8. scale the W axis CPI so the DRO says 3.000 inches (I suppose I should measure the block and use that number)
9. remove the standing 1-2-3 block
10. unlock the knee and crank it up to zero the test indicator on the flat 1-2-3 block
11. set the Z axis CPI so the DRO reads 0.000

The articulated arm is a CAMVATE camera mount, and the tablet holder is an ASICS.


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## tweinke

Sounds like a plan to me. Thank you for the info on the tablet mount. It might sound silly but I have been putting my tablet on the mount I made for the lathe and having to look over at it which is not very handy or even possibly unsafe as I now think of it. Never thought of looking at camera gear.


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## Briney Eye

Mounted the Big Box O'Lectronics on the column today.  I wound up switching to a normal USB connector for the W axis.  There must be somebody online who carries cables with micro connectors on both ends, but I couldn't find them (Argh!  Digi-Key has them, and I've been ordering from them for 30 years!).

The power consumption of the Mixed Scale board is so low I didn't bother with ventilation.  It might get a little warm in there, but it won't get hot enough to be an issue.  I simply notched the edge of the enclosure with a rat tail file for the cables:




Buttoned up:




I just bent some 1/16" aluminum from the hardware store to make the brackets, and drilled and tapped the column for 10-24 button head screws.


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## tweinke

Nice install, clean and functional.


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## rlschow

Hi Jon, I watched your YouTube about this also. Your DRO installation looks great, Thank you for posting this. I am seriously thinking about using the same system on my 8520. I have a few questions.

1. What are your thoughts about the TouchDRO-bluetooth-to-tablet setup now that you've (presumably) had some time to use it? 
2. Are you happy with the accuracy and consistency of the readout? 
3. Any bugs or problems to report?
4. Does it ever lose the BT connection?
5. Are you fully satisfied with the Fire tablet for this application?
6. What length scales did you purchase for your X and Y? Did you cut them down to final length?
7. Did you maintain full travel of your table?
8. Anything else that you'd do differently if you did it again?

It looks like you installed everything so not to lose access to original locking handles or gib screws on the table and carriage, which is nice.
If I install this system I want to try to replace the USB cables from the reader heads with metal armored cable to make the installation more durable. Who knows, it might help with electro-magnetic shielding too.

Roger


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## Briney Eye

rlschow said:


> Hi Jon, I watched your YouTube about this also. Your DRO installation looks great, Thank you for posting this. I am seriously thinking about using the same system on my 8520. I have a few questions.
> 
> 1. What are your thoughts about the TouchDRO-bluetooth-to-tablet setup now that you've (presumably) had some time to use it?
> 2. Are you happy with the accuracy and consistency of the readout?
> 3. Any bugs or problems to report?
> 4. Does it ever lose the BT connection?
> 5. Are you fully satisfied with the Fire tablet for this application?
> 6. What length scales did you purchase for your X and Y? Did you cut them down to final length?
> 7. Did you maintain full travel of your table?
> 8. Anything else that you'd do differently if you did it again?
> 
> It looks like you installed everything so not to lose access to original locking handles or gib screws on the table and carriage, which is nice.
> If I install this system I want to try to replace the USB cables from the reader heads with metal armored cable to make the installation more durable. Who knows, it might help with electro-magnetic shielding too.
> 
> Roger



1.  I've used it much more on the lathe at this point.  Love it.  Now that the holidays (and a family funeral) are past, I hope to get back on the mill and finish up some things there.  I highly recommend adding decoupling capacitors in the read heads.  I still haven't gotten to it on the mill, and it's flickering in the least-significant digit.  On the lathe it didn't work at all without them.
2.  Accuracy-wise, the aluminum scales are good enough for what I'm doing, and had maybe 0.001" of hysteresis when I checked with a test indicator.
3.  No actual bugs, but I wish the Preference Banks could be named and were "smart" enough to remember which Bluetooth connection to use.
4.  The connection on the lathe started out finicky.  It was particular about which wall wart I powered it from.  Luckily, I've saved a big box of them over the years.  Adding the decoupling capacitors in the heads also seemed to make it more stable in that respect.  It's rock solid now, and only loses the connection when we lose power.  I used an old transformer-based supply for the mill, and it seems happy other than that last-digit flicker which I expect to go away when I add the decoupling.
5.  The Fire works great.  It just requires some finagling to get the Google Store installed on it first.  PITA in that respect.
6.  I cut the 4" stainless scale that I installed on the quill and the 24" aluminum scale for the X axis.  As I say above, you will need carbide if you want to drill stainless scales, but a cutoff wheel in your Dremel will hack through it.  Try not to get them too hot, since the scale is just glued to the beam.  I could have left the X scale longer and shifted the mounting blocks out flush with the ends of the table and it might have looked a little better.  I had a reason for making it shorter, but I can't remember what it was now.  Old age .
7.  I have full travel on all four scales.
8.  I keep wondering if I could have figured out a way to mount the X axis inside the table.  I've seen it done with magnetic "tape" scales, where people have buried all of them inside the machine.  You have to have a second mill to make the modifications, though.  Other than that, it's made for a great setup.

-Jon


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## rlschow

Thanks for the information. Good to know about putting bypass caps in the reader head. Putting the x scale under the table is a neat trick for protecting it, but for me more work than I want to budget for the task.


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## Briney Eye

rlschow said:


> Thanks for the information. Good to know about putting bypass caps in the reader head. Putting the x scale under the table is a neat trick for protecting it, but for me more work than I want to budget for the task.



Here's a head with a 0.1uf ceramic decoupling cap installed between VDD and GND.  I could have trimmed the leads a bit :


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## rlschow

Leaving them long means they're still usable for something else if they don't work out there. I think I'll install them in preemptively, because once I get the scales aligned on the machine I won't want to take them off to make mods to the boards


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## Zertsman

I hate to just wake up an old thread, but this is an awesome install.  I have all the lower scales on my 8520 and will be attempting the quill axis as soon as it comes in.

I'm nervous about drilling and tapping such a fine thread in steel on the quill stop.  This will be my first time going that small.  I wish it was easier to get off.

Funny thing.  I had it off when I replaced all the bearings in the head.  I hate getting old.

I already have the bluetooth setup on a fire tablet on my round column mill which I'll move to the 8520.  It's too fantastic not to have.


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## Briney Eye

Hi, Z.  Use a high-quality tap, not something from a Chinesium set, and a good small tap handle.  I will testify that it can be extremely difficult and expensive (though I didn't have to pay for it, the company did) to get a small broken tap removed.  And use lubricant.  Just be thankful that it's not stainless steel.

-Jon


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## Zertsman

I've got some taps coming from amazon, however I'm just a hobbyist and don't have the nice expensive tools and taps professionals have.  I'm a little chicken to use the amazon taps on parts I have no extras of.  I can test me doing it on other material, but it may not compare at all to the quill stop's material on the mill.  If I screw it up, I guess I can make another as it's a pretty simple part.

I just got it back together with new bearings.  I'd rather not tear it back down just yet.

Well dang it. I guess my best bet is to tear it down, take the part out and drill 2 holes all the way through pressing in 2 threaded studs for attachment saving the agony of breaking little, tiny taps.  Better to be safe and do it right, I guess.  Talked myself into it.

Also, if the studs get damaged, I can press them out from the back.


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## gard

I did one a little different awhile back. Its a head that is similar to a caliper. I removed the quill stop and made a new one that left a lot more space for screws for attaching a piece of sheet metal that holds the head. If I remember correctly I had to remove the top pulley but not the spindle. I also had to machine a pocket into the pulley guard for the sliding head of the DRO. The scale is attached to the bottom with a clamp. I made a flat spot on the bottom of the mill head by mounting an angle grinder in the vise then running the table back and forth. Then I mounted a right angle drill in the vise to drill the 2 holes in the bottom. It has worked well for years.

 This mill has never had a working brake, I just let it coast to a stop and grab the belt when I need to replace a tool in the spindle.


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## Zertsman

Well look at that!   Great idea thinking outside the box.  The extra real-estate is worth it.

This has been my evening.   Both Taps broken.  Wanted to get just one more turn before backing it out the second hole.  Now I have some digging to do.

Image is the first one I broke.  Second one is flush with the top.  Live and learn.


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## Zertsman

Back to your method..  are you holding the scale at the top or just the bottom?  You have pics from the other side of the head?


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## Zertsman

I got it..   Looks like a good plan.


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## Zertsman

Mine doesn't have a working brake either but it does have a push/pull drawbar.  If you move the wrench quickly, you can get anything out.  I have so far.  It doesn't take all that much torque to hold things in it, but it's still new to me and I've only cut a few chips on it.


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## gard

The DRO scale is held only at the bottom with the clamp. With the grinder in the vise I was able to get the clamp surfaces vertical front to back. Using a clamp instead of bolts allows some adjustment in vertical location and angle right to left. The head is attached with a piece of sheet metal, slightly Z shaped so it has a little compliance in X and Y directions and is stiff in Z direction. There was 2 mounting holes on the head when I salvaged it from the junk bin.
The X and Y DRO was on the machine when I purchased it so I have no experience mounting bigger ones but I have been thinking about one for the SB lathe...


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## Zertsman

I've put them on 2 mills so far.  I did one from scratch on my Round Column mill and rebuild the one on my little Clausing.  Just need to add the quil and then set up TouchDro to sum the z scales.

I like your method for the quill as there is more material that allows a larger tap to be used.  This little 2.56 sucker, while a challenge is broke off and stuck in my second hole.  I'll just leave it.

I like your clamp at the bottom as I think it'll be a little easier to make and not require drilling holes over the quill.

I'm thinking of drilling the hole under the quill stop through the bottom and holding it in with this DRO bracket.  This will negate taking the top pulley off to get to these components.  Shoulda been this way from the factory.


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## Zertsman

Well, I made a Z stop with larger threads (sort of) and I got the flat spot on the bottom of the head, drilled and tapped and added a bracket.  Holding the new igaging scale up, there isn't enough room for the full 3" of z travel without also modifying the top cover.  The igaging reader is tool tall.

Very sad.  I really do not want to modify the top cover as I'd like to keep it original.

Also, maybe this is too much around the bottom of the quill.  Could be in the way of installing collets, gages and no telling what.  Second guessing the whole install now.

I have it on all the other axis with TouchDRO.  I may hold off for now or modify a cheap caliper like I did on the Round Column mill.

Very sad.

Anyone have any thoughts or suggestions?


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## woodchucker

gard said:


> I did one a little different awhile back. Its a head that is similar to a caliper. I removed the quill stop and made a new one that left a lot more space for screws for attaching a piece of sheet metal that holds the head. If I remember correctly I had to remove the top pulley but not the spindle. I also had to machine a pocket into the pulley guard for the sliding head of the DRO. The scale is attached to the bottom with a clamp. I made a flat spot on the bottom of the mill head by mounting an angle grinder in the vise then running the table back and forth. Then I mounted a right angle drill in the vise to drill the 2 holes in the bottom. It has worked well for years.
> 
> This mill has never had a working brake, I just let it coast to a stop and grab the belt when I need to replace a tool in the spindle.
> 
> View attachment 392823
> 
> 
> 
> 
> 
> 
> 
> 
> View attachment 392822


The brake is not to slow it to stop it.
it's only there for locking up while changing the endmills.


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## gard

Nice job on the Z stop, looks very similar to what I did except mine is squared off at the top. Were you able to remove the adjustment screw from the bottom?

Not sure if It was clear from my photos but with the bottom clamp I made, nothing really sticks below the bottom of the spindle housing so I have never found it to be in the way of any operation.  I did have to cut a hole in the belt cover, then I added some aluminum in there so the DRO head and bar would be protected in case the belt ever came off the bottom of the pulley. I use this DRO almost every time I use the mill. I was also a little nervous about cutting into the cover but have never regretted it. You do need proper lighting to be able to see the DRO easily, I found small "sewing machine light" on amazon, it is 110V LED with magnet base was cheep and works well.
I think the spindle DRO is a little more accurate than a Z axis on the table because the table always moves a little in Z and Y when it is clamped in place.

I think I could repair and reinstall a brake on my mill but it seems to get further and further down the list. I guess it makes sense to not use the spindle brake to slow down the mill, that would probably wear things out quickly.  Just grabbing ahold of the 2 belts with one hand has worked fine for me.


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## Zertsman

z stop is very ugly.  On a round column mill, you always have to plan on how much working height you need in the Z direction.  So my spindle is either over extended or too short for a tool change.  (the reason for the nice little knee mill)  Found I did not tighten the drawbar for one of the center drilling operations and the hole was miss placed.  Grrr.  Also my stock is only 1" OD.  1.25 would be much better.  Broke a tap in the first one and could not extract as the hole is partially in the .6875 OD of the quill stop.  But, the second one is always faster to make.   Needs a flat spot on the top though.  I wanted to post some pics of it, but it is just atrocious.  It's way uglier from the other side.

I see the clamp isn't in the way of the work, it's more of a visual thing being able to see what I'm doing.  The bracket as shown is over length, as I haven't' determined how to short to make it, so it's a bit misleading.  It's just with the reader being so long, it limits travel.  I'm at a good point to pause and can continue later without tearing the machine down.  Still thinking on it.  Just hate to put a hole in the cover.  So far I can take all this stuff off and get it back to stock.  A few tapped holes never hurt anything.  Some larger holes?  They worry me is all.

I did not drill out below the adjustment screw.  I still think it's a good idea, but will take more disassembly, setting it up in the other mill, longer drill bit (which I don't have) and making another fully threaded part.  Maybe will do this later.  If you ever need to access the quill stop, that pulley on the top has to be pulled off the bearings which I find ridiculous.  The Z stop was lose on mine when I got it.  I'll loctite it all when it goes back together.  But if it loosens again, it comes apart.   Allowing for easier removal would be just awesome and with the removable bracket under, it'd be very easy.

My brake is in 2 pieces.  I may try making one out of something besides ductile cast iron (clausing spec).  The pulley is expensive and long winded to make so I'd rather not damage it by putting something under it of the wrong material as the brake grabbs the ID of the pulley when you twist the brake lever.  If you only use it once the mill has finished turning, maybe there is no issue.  It'd be nice to have, although with a push pull drawbar and the small time I've had the mill, I've not really needed a brake.  Although you do not know to miss what you've never had.


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## Zertsman

Have found a Wixey Drill Press Depth Gauge.   Looks like the head may be small enough to fit.  Anyone have one and can get some dimensions of the reader?  Can't find that sort of detail online

I only see them for wood tools though.


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## Zertsman

Thought about this all day while at work.  There is room under the upper pulley and over the cover.  It may be pretty easy to make an adapter that just raises the cover giving room for the igaging reader and scale.  Since I do not have a brake, I can get away with this.  If you have a functioning brake, this may not work.  Depending on how far up it needs to move, maybe just make a new shorter cam that operates the brake.  Never give up.


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## Zertsman

Finally got the cover raised up.  Made some brackets that both hold in the original holes as well as clamp to the head.  Raised it up enough to get the reader in there.  Only lost about .03 of vertical.  Not too bad.  And I can put it back stock.  

I still need to make a bracket to attach the reader.  The Brass I had laying around isn't quite up to the task.

Remember I have no brake, so I can raise the cover.


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## Zertsman

Was having lots of noise and my Z axis was climbing.

The scale was turned around in the reader and the ground contact in the reader was not making reliable contact.

If you look at the edges, one is smooth and the other textured from the finish on the aluminum.  The smooth one is the ground contact.

Opened it up to check the solder joint and do a continuity check.  Turned the scale around and all is good.

Recommendations on the site are good ones as I figured they were.


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## gard

nice job, if I had thought about raising the cover I would if probably of done it that way instead of cutting a hole in the cover


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## Zertsman

There are many ways to skin the cat.  You look around long enough and can find inspiration.

I took the cover off, put the 4 mounting screws back in and then sat the cover on top of those threads and noticed I had about all the height I needed.  I was just trying to visualize where there was room and where there was not.

There was some light sanding and Dremel work, but no holes or openings were created.

They are nice old machines..  the more stock we can keep them the longer they will live.


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## wa5cab

That's probably true.  It's sort of like the surplus radio market.  Most of us tend to consider any set with obvious modifications as nothing but a parts unit.  Of course, quality of workmanship (or lack thereof) can enter into it as well.


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