Clausing 8520 TouchDRO

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.
 
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
 
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.
 
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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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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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?
 
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.
 
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...
 
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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