New cross slide dial and bearings

[bhusted]

I managed to find a 12" lathe locally for very cheap. It needed a bunch of work and cleaning up. Now that I've gotten it working properly, I decided to tackle my first real improvement. I find the dial on the cross slide to be pretty terrible. The 1" dial just sort of slides around on the screw and I could never be confident that it hadn't slipped when dialing in a cut. The dial also only having 100 marks got frustrating because every other lathe that I've used didn't require diving every cut in 2. Being a well used example of the 12", my lathe also came with a healthy amount of slop in the bearing assembly of the cross slide. Tightening the nut behind the handle to reduce the free-play made it impossible to turn the handle. So I set out to make a new one.

I had seen the video of tubalcain on YouTube making a dial and liked his method. The rest of it was just laying out the parts needed. New bronze bushings were used to support the lead screw and thrust bearings were added at the ends to eliminate play. I also wanted the ability to zero out the dial, but didn't like the thumb screw approach. I designed a bushing and collar that allow the dial to spin freely and then be locked into place.

I started out with a chunk of 1.75" 1144 steel and turned it down for the main part.

Things were progressing nicely until the threading dial jumped and I double cut part of my thread. I backed out of the cut and managed to pickup the thread again to save the part. I wish the threads were better and I may remake the part someday, but at least it works. Any suggestions for ensuring that the thread dial doesn't jump?

The bore on the other end is for the thrust bearing.

Here it is with the other components. I didn't stop to take pictures of turning the others. Sorry.

Indexing for the graduations was achieved using a 200 tooth saw blade. All 200 marks are scribed and then cleaned up.

I couldn't be happier with the results. The action is smooth with no more end play on the screw. The dial came out better than I thought it would. I still need to stamp the numbers on it. Most importantly, the toolpost now only moves half as much as the change on the dial! Anyway, thanks for letting me share my small success. If anyone is interested in my drawings for this project, I'm happy to share.

 

[wa5cab]

That does look nice. But none of your photos show the locking thumbscrew . I'm just curious as to how you did it.

 

[DiscoDan]

Craftsman lathe? I hate my dials.

 

[bhusted]

That does look nice. But none of your photos show the locking thumbscrew . I'm just curious as to how you did it.

Instead of a thumbscrew sticking out, I modeled it after the knee dial on a vertical mill. The inner bushing is locked to the lead screw with a jam nut. The dial rides on the bushing and is free to rotate. It becomes locked to the bushing by tightening the knurled locking ring just behind the handle. Here's a cross sectional view of what's going on. The bushing is purple, the dial is blue, and the locking ring is pink.

 

[wa5cab]

OK. I remember wondering what the knurled part was, but forgot to ask. The final version of the Atlas and Craftsman 12" that Sears called the "Commercial" has a similar arrangement except that the dial has a knurled head thumb screw that locks the dial to the internal threaded shoulder bushing. That's what I thought that you had done, except that I couldn't find the thumb screw. Cross feed screw end float is adjusted in a similar manner.

 

[bhusted]

Good to know. Are the dials on the commercial version graduated for the radius or diameter? Do they also use thrust bearings? This was a fun project, but maybe I should have just gotten the screw from a commercial version.

 

[chippermat]

Very nice. What thrust bearing did you use, and what cutter did you use to cut the graduation marks? Are you going to figure out a way to roll numbers onto it somehow? Did you rig up your saw blade identical to how tubalcain did it - that was kind of interesting, or did you come up with a different method? I'd like to see a picture of that. Thanks for sharing.

 

[bhusted]

The thrust bearings and washers are from McMaster-Carr.
Bearings: 5909K25
Washers: 5909K251

For the graduation marks I used a carbide threading tool turned on its side. I considered grinding a piece of HSS to a sharper point, but worried that the tip would break down too much before I finished scribing. I plan to stamp the numbers. I ordered a set of 3/32" number stamps. Still thinking about some sort of fixture to align the numbers and marks. I will update with progress on this part.

The the indexing, I decided it would be easier if the blade and dial were next to each other. I turned a piece of bar stock to fit the 5/8 arbor of the blade and then a smaller diameter to be a close fit with the dial and tapped the end. This way I could sandwich the dial and blade together and index from the chuck side of things. For the actual indexing, I cut a couple of pieces of 1x3 to fit between the ways and used a section of old hacksaw blade to engage the teeth. I don't have a carrage stop for the lathe (probably another project at some point), so I used a mill vise stop.

Another thing I forgot to mention is that like tubalcain, I found that the oil hole from the cross slide was no where near lined up on the original. To drill the hole in the new piece, I tightened it down in the cross slide and then marked where the oil hole and graduation mark would go. This way the oil drips into the space between the two bronze bushings.

 

[wa5cab]

bhusted,

They are graduated to read actual movement of the slide that they are on. So in the case of the cross-slide dial they read DOC (Depth Of Cut), not 2 times the DOC. Which is to say that they are made the normal way that many newcomers to the lathe think is wrong until later they try to do threading, facing, knurling, milling or some other operation that they hadn't thought about before. However, this subject is one of those personal preferences that maybe should be added to the banned subjects list with politics, etc. Anyway, it all looks quite well done, which is to say much better than some of my early work!

No, the factory parts don't include a factory ball or roller thrust bearing. That part did not change.

 

[chippermat]

Very nice, thanks.