My little 7x14 is now ready to be cleaned, fettled and the rest

[OTmachine]

Now, there you go. Sounds Good!

 

[RaisedByWolves]

Now that's an interesting idea that has made me realise what an idiot I am.

I negotiated a milling attachment and ER40 collet chuck with a few collets thrown into the deal with my lathe. I cleaned them up (they were covered in the usual anti-rust gunk) and put them in a drawer for later.

Turns out they might come in handy earlier than I thought.

If I have the right collet (not sure I have, will check tomorrow) I could use the slightly messy spindle with the collet chuck mounted to lengthen the keyway in the good spindle.

I can't believe I forgot the milling accessories. I pushed for those to be included because I knew I wouldn't be able to afford a mill for a good while and then just plain forgot I had them

Just remember to keep the cutting forces going down into the lathe ways and not lifting it up.

 

[Larry$]

I've watched this entire series of trials and and learning experiences. I got most of my "learning experiences" before computers. Turns out computers can be useful.

 

[SouthernChap]

[sigh]

Well a couple of steps forward and one and a half a step back...

Spent most of yesterday trying to get the carriage to run smoothly on the bed. I'd already stoned the surfaces where the plates engage with the underside of the bed at the front and back so it was just a case of getting the 6 screws at the right level of 'barely tight' which created no drag but also allowed no up and down play.

Finally got the hang of this utterly non-orthogonal adjustment technique, and got a good smooth motion up and down the bed.

Attached the apron and wheeled the carriage up and down the bed: it felt awful; notchy with a few places where there was definite binding.

Took the apron back off and checked the carriage and it ran smoothly.

Put the apron back on without the pinion installed and the carriage also ran smoothly.

So, it's the engagement of the pinion with the rack.

Checked the teeth on the rack and the pinion visually: nothing untoward.

Checked the pinion for being off-square: all's fine.

Checked the rotation of the pinion within the apron: rotates smoothly and I can free spin the handwheel. Visually, the pinion looks to be rotating with the teeth moving concentrically to the axis.

Put the apron back on the carriage and getting my head in the most uncomfortable position and using a torch, I can just about see the engagement of the pinion teeth with the rack; looks a bit deep.

Put a small square on the rack: oh, there's a bit of rock and roll going on in a couple of places. That, combined with the possibly over-deep engagement might explain the ugly notchiness and binding.

I might be able to solve this by shimming the apron but of course that's going to push the top half-nut closer to the lead screw so I'll have to be careful there to make sure there's enough clearance when the half nuts aren't engaged and avoid any binding on the leadscrew when it is; also doing this will likely increase the backlash on the handwheel.

One other possibility is the the rack's deviation from true is not vertical, but actually front to back, due to the surface of the bed where it is attached not being true. The rear top angle of the rack is reasonably radiused and the flatness of the racks rear surface looks good so that's fine; just need to check the flatness of the front of the bed where the rack us attached (no overspray of paint there; the factory at least managed that ).

Or, I suppose, it might be a combination of both vertical and front to back deviation from true. I guess this creeping lack of trust in anything being true is an occupational hazard of fettling these mini-lathes.

I've also ordered a new rack, just in case. If I need to use that, it'll mean getting everything off the bed, transfer punching the new hole locations and sticking the bed on the drill press...delightful.

Eh, all this might sound like I'm getting fed up a bit, but despite the frustration, I am kind of enjoying this.

By the time I've got this thing running smoothly I might have saved up enough for a Myford or a Colchester

Haven't added any pics because I was in 'focused debugging' mode yesterday . If anyone's interested enough to want pictures of specific problem areas then feel free to ask.

 

[Firstram]

[sigh]

Well a couple of steps forward and one and a half a step back...

Spent most of yesterday trying to get the carriage to run smoothly on the bed. I'd already stoned the surfaces where the plates engage with the underside of the bed at the front and back so it was just a case of getting the 6 screws at the right level of 'barely tight' which created no drag but also allowed no up and down play.

Finally got the hang of this utterly non-orthogonal adjustment technique, and got a good smooth motion up and down the bed.

Attached the apron and wheeled the carriage up and down the bed: it felt awful; notchy with a few places where there was definite binding.

Took the apron back off and checked the carriage and it ran smoothly.

Put the apron back on without the pinion installed and the carriage also ran smoothly.

So, it's the engagement of the pinion with the rack.

Checked the teeth on the rack and the pinion visually: nothing untoward.

Checked the pinion for being off-square: all's fine.

Checked the rotation of the pinion within the apron: rotates smoothly and I can free spin the handwheel. Visually, the pinion looks to be rotating with the teeth moving concentrically to the axis.

Put the apron back on the carriage and getting my head in the most uncomfortable position and using a torch, I can just about see the engagement of the pinion teeth with the rack; looks a bit deep.

Put a small square on the rack: oh, there's a bit of rock and roll going on in a couple of places. That, combined with the possibly over-deep engagement might explain the ugly notchiness and binding.

I might be able to solve this by shimming the apron but of course that's going to push the top half-nut closer to the lead screw so I'll have to be careful there to make sure there's enough clearance when the half nuts aren't engaged and avoid any binding on the leadscrew when it is; also doing this will likely increase the backlash on the handwheel.

One other possibility is the the rack's deviation from true is not vertical, but actually front to back, due to the surface of the bed where it is attached not being true. The rear top angle of the rack is reasonably radiused and the flatness of the racks rear surface looks good so that's fine; just need to check the flatness of the front of the bed where the rack us attached (no overspray of paint there; the factory at least managed that ).

Or, I suppose, it might be a combination of both vertical and front to back deviation from true. I guess this creeping lack of trust in anything being true is an occupational hazard of fettling these mini-lathes.

I've also ordered a new rack, just in case. If I need to use that, it'll mean getting everything off the bed, transfer punching the new hole locations and sticking the bed on the drill press...delightful.

Eh, all this might sound like I'm getting fed up a bit, but despite the frustration, I am kind of enjoying this.

By the time I've got this thing running smoothly I might have saved up enough for a Myford or a Colchester

Haven't added any pics because I was in 'focused debugging' mode yesterday . If anyone's interested enough to want pictures of specific problem areas then feel free to ask.

I bought my mini 3rd hand and it was terrible on all fronts as well. The rack engagement was so loose there was about 120° of handle backlash.

I repaired it by machining flanged eccentric bushings for the pinion and the carriage hand wheel shaft. The bushing OD was determined by drilling a test hole in a piece of scrap with an annular cutter, they make nice round holes! I placed a spacer on one jaw in the 3 Jaw to offset the stock for the eccentric bore. I think it was offset by .060" or so.

I used two cheap low profile sealed bearings on each shaft and held everything together with Loctite. Once the bushings were finished, I disassembled the apron and opened up the bores with the annular cutter. I also drilled and tapped set screw holes to lock the bushings in position once adjusted.

Install the pinion first, rotate the bushing with pliers to get the best gear mesh and lock it down. Same thing with the hand wheel, adjust your clearance to the pinion gear and lock it down.

I don't remember any of the dimensions but, I worked backwards from the bearing size and used what we had. If annular cutters aren't an option, step drills are cheap and make a decent hole if you push it all the way through. You can remove the larger steps with a bench grinder if it's too big.


Overlook the mess!


Set screws on the bottom


My wife couldn't understand why was spending so much time on a crappy little lathe. She always asked what I was going to make with it. My answer was always the same, " I'm making a killer little lathe"!

 

[SouthernChap]

there was about 120° of handle backlash

Blimey!

I think if I have to shim the apron so much that it leads that kind of backlash, I think I might have to reconsider my approach and definitely fit a new rack!

In your case (and in my general fettling of this thing) though, I reckon the work itself becomes its own virtue, so to speak.

I mean, as hobbyists, the difference between doing the work necessary to fettle a suboptimally adjusted/manufacturered lathe on the one hand, and doing the work to say, make a steam engine on the other, is only one of type.

If we make progress (however we define that) then it's worth it.

 

[Firstram]

Blimey!

I think if I have to shim the apron so much that it leads that kind of backlash, I think I might have to reconsider my approach and definitely fit a new rack!

Fitting a rack to the pinion could lead to mistakes and many extra holes in the lathe. My rack was tight to underside of the front way and would have needed to be shimmed down. The bushing thing allowed me to dial in the mesh there, as well as the backlash between the 2 shafts. Besides, who doesn't like bearings!

In your case (and in my general fettling of this thing) though, I reckon the work itself becomes its own virtue, so to speak.

Absolutely!

I also moved the electronics to the backside of the headstock (where they should have been from the factory)!
There's a KB motor controller powering a "2hp" treadmill motor through a speed reduction jackshaft.

I upgraded to tapered roller bearings and a larger spindle so I could direct mount 4" chucks. While torn down, I also moved the speed selector and feed direction lever to the front and made a more conventional locking lever handle.

The cross slide got a 20 tpi lead screw and the 1" additional travel mod.

The lathe was the project at the time and I had a blast doing it. It has been trouble free for the last 12 years!

 

[Firstram]

Forgot to add a picture.
The ring on the spindle was shrunk fit and machined in place with .020" clearance for the chuck. Eventually I'll get around to adding 4 set screws to dial in the 3 jaw runout.

 

[SouthernChap]

Fitting a rack to the pinion could lead to mistakes and many extra holes in the lathe. My rack was tight to underside of the front way and would have needed to be shimmed down. The bushing thing allowed me to dial in the mesh there, as well as the backlash between the 2 shafts. Besides, who doesn't like bearings!

Absolutely!

I also moved the electronics to the backside of the headstock (where they should have been from the factory)!
There's a KB motor controller powering a "2hp" treadmill motor through a speed reduction jackshaft.

I upgraded to tapered roller bearings and a larger spindle so I could direct mount 4" chucks. While torn down, I also moved the speed selector and feed direction lever to the front and made a more conventional locking lever handle.

The cross slide got a 20 tpi lead screw and the 1" additional travel mod.

The lathe was the project at the time and I had a blast doing it. It has been trouble free for the last 12 years!

Oh, for your scenario, it sounds like shifting the pinion via the offset bushings makes sense.

In my case I think I just need the engagement of the pinion to the rack to be a teensy bit less deep and so hopefully I can just put shim between the carriage and the top surface of the apron to lower the position of the pinion by maybe just a few thou. I've got steel shim in 0.004", 0.003", 0.002" and 0.00" so I should be able to get the thickness dialled in close enough.

Hopefully I'll not get much or any extra backlash and maintain enough clearance between the bottom half-nut and the lead screw.

I love your hi-lo and forward-reverse levers. They're proper old-iron looking

 

[Firstram]

Oh, for your scenario, it sounds like shifting the pinion via the offset bushings makes sense.

In my case I think I just need the engagement of the pinion to the rack to be a teensy bit less deep and so hopefully I can just put shim between the carriage and the top surface of the apron to lower the position of the pinion by maybe just a few thou. I've got steel shim in 0.004", 0.003", 0.002" and 0.00" so I should be able to get the thickness dialled in close enough.

Hopefully I'll not get much or any extra backlash and maintain enough clearance between the bottom half-nut and the lead screw.

I love your hi-lo and forward-reverse levers. They're proper old-iron looking

Thanks. Sorry for the highjack, just showing some additional mods to keep you fettling for the next few months!

You can slot the lead screw bearing block screw holes with a file and gain some adjustment, if you need to.