Starting Mini-Lathe Mods

[ozzie46]

Chuck, thanks for the gib write up. I've been meaning to do this for several years now but have been intimidated by it. Now I will give it a shot as soon as I can make time.
Thanks again.


Ron

 

[Twmaster]

Chuck, that has come out very well. Bravo. Applause for YOU!

 

[Blogwitch]

Very nicely done Chuck, and a very good result. It looks like you had a lot less trouble than I did.
I gather you like the smooth action and easy adjustment over the old method.

I have to agree with you on how easily it can be done, I reckoned on a good day or maybe two in the shop if everything with the machine was OK.

BTW, great fix on the adjusting screws, I had a crap time trying to make the slots strong enough for adjustment, your method completely solves that.

But if anyone is going to try this, give it a good measure up and check for squareness before you start to hack away. You must watch out for things that are out of line or bent if you have an older type of machine.

Some of those early ones were made by cavemen with flint tools.


Bogs

 

[Twmaster]

Some of those early ones were made by cavemen with flint tools.

The ones as of 2008 were as well in some instances...

Chuck, after looking over your gibs again I have to say that hands down this is way better than the route I took with shimming my old 7x10 lathe. I cannot see this taking any more time than I spent fussing with making shims.

Between your posts and Bog's thread over on MM I think anybody with a mill can make these.

One last silly question. (The tool geek in me wants to know) what milling machine do you have?

Thanks!

 

[cfellows]

Very nicely done Chuck, and a very good result. It looks like you had a lot less trouble than I did.
I gather you like the smooth action and easy adjustment over the old method.

I have to agree with you on how easily it can be done, I reckoned on a good day or maybe two in the shop if everything with the machine was OK.

BTW, great fix on the adjusting screws, I had a crap time trying to make the slots strong enough for adjustment, your method completely solves that.

But if anyone is going to try this, give it a good measure up and check for squareness before you start to hack away. You must watch out for things that are out of line or bent if you have an older type of machine.

Some of those early ones were made by cavemen with flint tools.

Bogs

Yep, Bogs, I'm definitely pleased with the results. I still have a bit of stickiness to iron out. The ways might be a smidge thicker toward the tailstock end. May not be able to do anything about that. Also, the plastic cover I installed on the inside of the carriage apron rubs a little bit against the carriage feed gears. I may just face off the gears a bit to sort that out. Seems easier than making a gasket to raise the cover off the casting. Also, the front gib may be rubbing against the rack for the carriage feed, so I need to check that out. All minor things that I should be able clean up.

Some of those early ones were made by cavemen with flint tools.

The ones as of 2008 were as well in some instances...

Chuck, after looking over your gibs again I have to say that hands down this is way better than the route I took with shimming my old 7x10 lathe. I cannot see this taking any more time than I spent fussing with making shims.

Between your posts and Bog's thread over on MM I think anybody with a mill can make these.

One last silly question. (The tool geek in me wants to know) what milling machine do you have?

Thanks!

My mill is an Enco mill/drill that I bought about 16 years ago. It works good and I can't afford / don't have room for a bigger one. Besides,it hard to sneak those really big items past the CFO.

Chuck

 

[cfellows]

One more follow up on the tapered gibs. I found a couple of problems and fixed them.

The first problem I found was a small ridge on the bottom of the rear way where it meets the vertical part of the casting. The top, inner edge of the gib was riding on that ridge. I fixed that problem by milling a groove along the edge of the gib. In woodworking, we call that a rabbet... not sure what the metalworking term is.

When I put it back together, I found that the gib was now too thin. So, to correct that without making a new gib, I skimmed about 7 thou off the top of the clamp where it meets the carriage.

The other problem was not enough clearance between the rack and the carriage feed pinion. So, after pondering that for a bit, I decided the easiest fix would be a shim between the carriage and the apron. You can see the end of the brass shim sticking out in the following picture:

Note to self: Wonder how many times I'll cut myself on that little piece of shim before I decide to trim it off? :-\

Chuck

 

[Twmaster]

Chuck,

Not bad if that's all you've had for follow-on fixups. I see a lot of folks with those older Enco Rong-Fu clone mill-drills. I'm hoping to be able to afford something similar this summer. Not a matter of getting it past the CFO. More a matter of getting it past an empty wallet.

And my guess is 6 on the number of times you knick yourself on that brass!

 

[zeeprogrammer]

I'll take 2.

First time..."Drat...I knew that was going to happen."
Second time..."Drat...Not going to let that happen again."

No one should admit to more than that. ;D

 

[cfellows]

I'll take 2.

First time..."Drat...I knew that was going to happen."
Second time..."Drat...Not going to let that happen again."

No one should admit to more than that. ;D

Actually, having already seen it and commenting on it, I would be thoroughly embarrassed to admit it if I cut myself on it now. Guess I better go trim it off!

Chuck

 

[Swarf Rat]

Chuck, I really like those big-headed gib adjustment screws. I wonder if they'll need some kind of lock to keep them from vibrating out of position.

Cool idea to shim the apron to fix the pinion clearance. Does that not affect the half-nut allignment or pinion engagement?

 

[cfellows]

Chuck, I really like those big-headed gib adjustment screws. I wonder if they'll need some kind of lock to keep them from vibrating out of position.

Cool idea to shim the apron to fix the pinion clearance. Does that not affect the half-nut allignment or pinion engagement?

I hope not. I haven't installed the lead screw after shimming up the apron. With a little luck, the .010" shim won't seriously affect leadscrew alignment. I'm not too concerned about it at this point since I doubt I will be using the leadscrew much.

One other issue I had to correct is that the tapped holes for the screws that hold the rack onto the bed aren't deep enough. The result is that 1) the rack isn't held on very tight and 2) the heads of the screws stick out proud of the rack. My quick fix was to grind off the length of the screws a little bit. The holes could be drilled deeper, but I don't have any metric taps to deepen the thread.

 

[Twmaster]

Chuck,

You may want to go ahead and replace the hardware holding the rack to the bed. On the 7x10 I had one of the screws was stripped. I drilled the hole out and tapped to the next size up. I cannot remember what size I used and the lathe is long-gone.

 

[ozzie46]

Cfelloows, How will the shim effect the mesh of the rack and the saddle gears? It seems to me you have introduced .010 free play between the gears. Maybe it won't effect anything.

Ron

 

[cfellows]

Cfelloows, How will the shim effect the mesh of the rack and the saddle gears? It seems to me you have introduced .010 free play between the gears. Maybe it won't effect anything.

Ron

The purpose of the shim was to add some clearance between the rack and the saddle gears. They were too tight before but after adding the shim, they work more smoothly now. I'm actually thinking it may need even more. It's not binding now, but I think the gears could use a little more clearance.

Chuck

 

[ozzie46]

Thats good news Chuck. Sounds like it work out very well.

Ron

 

[cfellows]

This is a picture of a 3", 3-jaw chuck I bought several years ago. I don't recall why I bought it, other than I just thought it was neat, but I haven't really found a use for it until now. Turns out it is virtually identical to the 3" chuck that came on my Mini-Lathe.

So, I chucked it up in my 8", 4-jaw in my logan and trued up the back of it. Then I bored out the recess to about .030" oversize. Didn't mean to go that far, but it kind of got away from me. Anyway, now I am going to make it into my version of an Adjust-tru chuck so I'll be able to adjust for the runout. Should be about the simplest way to get a really accurate, self centering holding device for the mini-lathe.

Chuck

 

[cfellows]

My Wilton, keyless chuck with integrated MT2 shank came in todo. This is really a nice little drill chuck, even though it was kind of pricey at $62, but shipping was free. Here's a picture compared to my 3/8" generic keyless chuck that I use on my Logan. The overall length of the chuck body on the Wilton (bottom) is almost 3/4" shorter than the generic keyless. That's going to be important on the mini-lathe. Hate to chop off the shank, but gotta shorten it to make it fit the tailstock on the mini-lathe.

 

[cfellows]

One more post for today. Here is the 3-jaw chuck with the adjusting ring added. I turned the ring out of a piece of steel pipe with a 1/4" thick wall. The ID was turned about .010" smaller than the chuck then pressed on with my (you guessed it) 20 ton hydraulic press. Really had to work that sucker to get it pressed on. Probably should have heated the ring up first. After I got the ring on, I mounted the chuck in my 8" 4-jaw chuck on the Logan, centered it up really good, then trimmed up the ring and bored out the inside to about .030" larger than the spindle flange on the mini-lathe. Tomorrow, I will drill and tap 4, equally spaced radial holes around the exposed part of the ring on the chuck to bear against the outer diameter of the spindle flange for centering the chuck. Once centered, the chuck can be tightened against the spindle flange with mounting studs and nuts. I don't expect to change chucks often if at all, so re-centering should only be an occasional effort.

Chuck

 

[cfellows]

One more post for this part of the project. I finished my version of the set-tru 3-jaw chuck and installed it on the lathe. I drilled and tapped 4, equally spaced radial holes around the outside of the adjustment ring. 8-32 setscrews were threaded into each hole after grinding the ends flat so they wouldn't dig into the lathe spindle flange. The chuck was mounted on the lathe using the usual studs and nuts provided with the lathe. These were tightened moderately, then the 4 set screws were used to center the chuck, using a DTI and a round bar chucked in the lathe. When the bar was accurately centered, the nuts holding the chuck were then further tightened. I consider this a complete success although we'll have to see how well work of different diameters stays centered.

In this picture, you can see one of the 4 setscrews.

 

[cfellows]

Don't ya just love the look of a freshly made dovetail slide?

Decided I needed the ability to cut angles on my minilathe so I decided to think outside of the box (some might say outside of the planet). Rather than attach the tool post to the compound, I decided to make a compound which attaches to the toolpost. Here is the first piece. The compound will slide horizontally on the dovetail that I've already finished. Next is the part that slides.

Chuck