Bench Mill choices

[palada]

I just picked up an 8520[?] yesterday so I’ll be re-reading this thread. Mine doesn’t have the model number on it anywhere so I’m not certain it’s an 8520, but I assume it is since they were more common. It needs some TLC, but it was only $700, so it’s ok.

Did you find an instruction manual for the tear down, or did you just figure it out as you go? If there’s a step by step somewhere, I’d like to know. I like to tinker, but I don’t really know what I’m doing.

 

[Oldseabee]

I just picked up an 8520[?] yesterday so I’ll be re-reading this thread. Mine doesn’t have the model number on it anywhere so I’m not certain it’s an 8520, but I assume it is since they were more common. It needs some TLC, but it was only $700, so it’s ok.

Did you find an instruction manual for the tear down, or did you just figure it out as you go? If there’s a step by step somewhere, I’d like to know. I like to tinker, but I don’t really know what I’m doing.

You need the manual.you van call Clausing and they will email one to you. Model differences between 8520 and 8530. The 8530 has a 2 speed table feed on the right side. And the table is a bit larger. Post some pictures and then I can tell which model. It might be a Johansson model. The only thing that really goes south on these are motor failure or bearings. Only the 2 lower head bearings are expensive. I got all of mine on ebay. Read up on selection of bearings by quality. All bearings are not made equal.
When you call Clausing you need the tech department but you also need a serial number as they did have some changes in each model. But any operating instructions and part manual will help. There is also a model 8535 that's almost the same as the 8530. Maybe these couple of pictures will help.

 

[palada]

Thanks @Oldseabee. I found that mine's definitely an 8520. I'll ask Clausing about a manual.

I didn't hear any noise from the head so I thought it might be OK, then I opened the cover on the right side and found an old hornet nest where the quill gears should be. There's old nest material even under the shaft, so I'm going to pull the quill to clean it up and check it out. I'll check bearings when I do and decide if they're OK or not. Who knows how long the nest was in there or how long it ran after stuff got in there. The bugs and nest are very dry, so presumably a few years old. I'm glad the hornets were dead

Mine is a Johansson model, that's on the casting and it says Clausing on the name plate.

The things I know that need attention:

• The Y-axis has .052 of backlash and the movement is tight at the ends, so I'm guessing the gib is tight to compensate for wear in the middle of the ways. I'll look into scraping/grinding after I take it apart to make sure it isn't just gunk buildup.
• I can see the threads on the leadscrew are worn. I haven't taken that apart yet though. That's next after the head. Oddly, the X-axis is in much better shape. Maybe it was replaced recently, or they only ever used Y.
• It looks like the previous owner used grease on the shafts, ways, etc. I'll take the table and knee off to clean it all off. With any luck, cleaning is all it needs beyond the items noted above.

It didn't come with a proper base, so there's a homemade angle iron base now, but it looks functional, if ugly, so not an immediate concern. I'll see if I can get an original base from a parted-out machine eventually.

I'm sure I'll be messaging you - I haven't dug in yet, but I expect to find things and your experience will be helpful.

 

[Oldseabee]

That main shaft and gear are available from Clausing, I think all the gears are. They changed the deminsion of the shaft where it enters the back of the casting. I used a caliper measured it and drilled it out to fit. I also ordered a new oiler for that location as yhe old oiler was a smaller diameter to match the old shaft diameter. Easy fix.

 

[Oldseabee]

Work on my mill has slowed down as I was waiting for a tap and repaired table nut. A friend who is a great machinst bored the old nut out and pressed in a new section of bronze. Then he drilled it out keeping to the size limits on the blueprint. Then tapped it. So far so good. I still need to finish the nut install and the the table. And add my DRO scales to the back side of the table.
And I'm still working on getting 220 into my garage.
Attached is a picture and you can just make out the bushing curvature on the bottom.
Mike

 

[Oldseabee]

Talk about problems. I installed the rebuilt saddle nut, with the screw. Installed the table and then the left hand bearing cap. Then I added a key and the handle. Screw is very hard to turn, I noticed that I had to force the bearing cap up while installing it. I pulled it apart but left the table on the mill. The machinist has the new threads set at about 0.20 to 0.40 above the old centerline. So now I have to shave the bottom of the bronze nut to bring it back into alignment. I'll let you know how that goes. Also the new bushing with threads was backing out so now I'm going to silver solder it in place.

 

[twhite]

May I make a suggestion. After you reposition the the bushing drill and tap a small hole say 10-32 so it bisects the bushing slightly. Then locktite a set screw in. That will give a locking action.


Cutting oil is my blood.

 

[Oldseabee]

Great idea. Thanks Tom.
I found out that there is a foundry in Oxnard that casts bronze. Just in case this nut is not salvageable then I can see about getting some cast. Clausing had the original ones cast and the nut has the part number cast into it. And they look like sand casting. If I go that route I'll have extra ones cast. Now I think it would have been cheaper to just convert to cnc, at least for the X & Y . There is a lot of room under that table for a ball screw assembly.

 

[Oldseabee]

Progress. The nut as repaired was salvaged. Table moves smoothly. Now I'm getting ready to install the table dro. I'm installing it behind the table not in the front. But there is a table oiler dead center in the middle of the back side. So I popped out the oiler and there Is a long oil passage. So i used a square and marked dead center on the top of the table and drilled down into the shallow channel and hit the passage. Then used a larger bit to drill it a bit larger. Then used a magnet to remove all the cast iron from drilling. It was easy to drill. I have a new oiler ordered that will be placed in the new location.

 

[twhite]

Nice job Mike. Make sure to plug the old hole


Cutting oil is my blood.