Guidance requested on 8520 maintenance

[palada]

Hi all,

For context around my questions, I'm a complete newb to machining.

I picked up a Johansson/Clausing 8520 mill a few days ago and I'm going through it checking bearings, etc.

I would like some guidance/advice on these two items please.

1. The leadscrew and nut for Y travel are very worn (.052 backlash and visually the threads don't look like acme anymore). I'll call Clausing about replacement parts, but I'm concerned that the nut on my machine doesn't resemble the one in the attached drawing. Does the nut in the attached pics look standard/correct?

2. When I got it the Y travel was very tight on the ends of the travel and moved OK in the middle. I'm thinking that's because the way is worn and the gib was over-tightened to compensate. I'm hoping it's because there was gunk buildup on the ends of the travel. I cleaned a lot of gunk from it, but I'd like to know if it needs grinding/scraping before I reassemble it. Is there a way I can measure to determine this?

Thanks


BTW, some context on the general condition of the mill: the bearings were mostly worn out and the spindle had the wrong kind, so I'm replacing them all. The wiring was funky and had the power switch on the knee so I'll redo that. A previous owner cobbled up a strange motor mount to use a longer belt. The base was replaced with a homemade angle iron stand. It had a dried up hornet nest where the quill gears should be. It was painted white (not painted well).

 

[woodchucker]

I'm not familiar with the Johanson/Clausing? I have a Clausing 8520. The nut in the parts breakdown is the nut I have, not sure why your nut is different. Do you have pics of your mill? Can you show the area the nut attaches to the table saddle, since that shaft would obviously be used to join the two? Also a side shot of the nut would help..

 

[Richard King 2]

If the screw and nut were worn out then the ways are no doubt worn in the middle as all mills are used in the middle of the travel. If your not familiar with scraping I would leave it alone or hire a pro to do it. Check your gibs like this. When it is loose in the middle.

 

[G-ManBart]

I'm not familiar with the Johanson/Clausing? I have a Clausing 8520. The nut in the parts breakdown is the nut I have, not sure why your nut is different. Do you have pics of your mill? Can you show the area the nut attaches to the table saddle, since that shaft would obviously be used to join the two? Also a side shot of the nut would help..

Johansson is the original manufacturer of the 8520 line. Eventually Clausing/Atlas bought them entirely, but I think there was a fairly long period of time where Johansson was making them and they were simply badged as Clausing. Essentially, the same machine, sometimes different badges.

I don't know if the early versions had a different nut, but the OP's isn't what I would expect to see from a mass-produced part.

 

[palada]

@woodchucker I added a picture of the side of the nut and a pic of the whole machine from the day I picked it up (it's in many pieces now). It attaches to the saddle with a nut on the threaded shaft. I don't have a pic of that. Mine says Johansson on the castings and Clausing on the plate. I guess it's from shortly after Clausing acquired them.

@Richard King 2 thank you. It looks like I have to reassemble to measure. I was hoping there was a way to measure while its apart. Do you know how to find places or can you recommend one that knows how to scrape correctly in Los Angeles? Google doesn't give me much, or maybe my search terms are wrong.

 

[Richard King 2]

Call and ask these guys who they would use. They could probably grind it first and then someone would only lave to 1/2 moon it ir scrape some oil pockets. https://schaffergrinding.com/

 

[palada]

Johansson is the original manufacturer of the 8520 line. Eventually Clausing/Atlas bought them entirely, but I think there was a fairly long period of time where Johansson was making them and they were simply badged as Clausing. Essentially, the same machine, sometimes different badges.

I don't know if the early versions had a different nut, but the OP's isn't what I would expect to see from a mass-produced part.

That was my thought too. Its a casting with a bronze or brass insert with a keyway and a clip on one side and screws on the other to hold the insert in. I guess I have to cross check with Clausing.

 

[palada]

I called Clausing and they have the nut from the drawing available ($225) but they don't have the cross slide screw anymore so I'll have to get one made or figure something else out. They did share the drawing with me for the screw, which is 11/16 diameter. Doesn't look like acme threaded 11/16 is available anywhere.

I'll follow this guide and see if I can recreate it well enough on my old SB lathe. http://wentztech.com/WebDisk/Metalworking/Clausing/Leadscrew Replacement.pdf. I'm guessing I might not be able to get to the precision where the bearings are pressed on, but maybe yes. If not, I'll see if a machine shop can do that for me. I have to order 3' of rod anyway, so its OK if I waste a bit trying myself.

 

[woodchucker]

I called Clausing and they have the nut from the drawing available ($225) but they don't have the cross slide screw anymore so I'll have to get one made or figure something else out. They did share the drawing with me for the screw, which is 11/16 diameter. Doesn't look like acme threaded 11/16 is available anywhere.

I'll follow this guide and see if I can recreate it well enough on my old SB lathe. http://wentztech.com/WebDisk/Metalworking/Clausing/Leadscrew Replacement.pdf. I'm guessing I might not be able to get to the precision where the bearings are pressed on, but maybe yes. If not, I'll see if a machine shop can do that for me. I have to order 3' of rod anyway, so its OK if I waste a bit trying myself.

you know you don't have to have the same lead screw/nut. You can make your own pair or buy a pair that provide 0.100 per inch / revolution.
you can go bigger diam, Also you could go a little longer and use it for a power feed. Just turn off the threads where it needs to go into the bearing, and leave it longer for the power feed.

edit: when I added my power feed, I had to add length .. so this is based on my experience.

 

[palada]

you know you don't have to have the same lead screw/nut. You can make your own pair or buy a pair that provide 0.100 per inch / revolution.
you can go bigger diam, Also you could go a little longer and use it for a power feed. Just turn off the threads where it needs to go into the bearing, and leave it longer for the power feed.

edit: when I added my power feed, I had to add length .. so this is based on my experience.

This is the kind of thing I forget sometimes. The link I posted above is of someone making a 3/4" set out of parts from McMaster-Carr. That's what I'm going to try. I bought a SB 10K lathe a few months ago and hardly use it, then forget that I can make stuff like this.