What did you do today?

[RB211]

Aligned a lathe headstock. Frustrating and slow. Got it to within 1/2 thou on 4 inches, but it suddenly bumps to 1 thou at 6. The indicator tracks zero until about 4" when it starts moving up. So I don't know what's going on there. Goon enough for now I guess.

If it's not linear, I'd say the test bar is bad. If you need better accuracy than that, turn between centers

[RB211]

Today(last night) I redid my air connections on my CNC mill to add a tap for the pneumatic drawbar and tested the actuation valve. Very cool. I also like the 5x8mm air hose and quick attach connectors enough that I am now running them from the compressor to the mill.

[Mcgyver]

Aligned a lathe headstock. Frustrating and slow. Got it to within 1/2 thou on 4 inches, but it suddenly bumps to 1 thou at 6. The indicator tracks zero until about 4" when it starts moving up. So I don't know what's going on there. Goon enough for now I guess.

How are you indicating? If you are just just running an indicator along a bar this can or is even likely to happen because you don't know that indicator has moved straight along the Z. i.e. the indicator could be slightly higher at one end or the other, and because the bar is round, etc.

imo the way to do it is to revolve a straight bar by hand and note two indicator readings 180 degrees apart closest to headstock and then at the end of the test piece. All that's needed is a true cylinder. using the method it does matter whether the cylinder/bar is held concentric or even aligned with the headstock as you deduce the spindle's true position.

For example, if you got say -.001 and + .001 at the headstock and -.003 and +.003 at the end, the spindle is perfectly aligned but the bar is slightly off from the axis (doesn't matter), if you got .006 and 0 at the end its not. When scraping in a headstock you do this in the XZ and ZY plane (remember Z is spindle axis).

Doing it this way, the ratio has to be linear, or else the bar isn't straight. I eliminates the error indicating along a bar and eliminates the need for fancy taper mounted test bars. When scraping, that imo is the best to get perfect alignment

[The Metal Butcher]

How are you indicating? If you are just just running an indicator along a bar this can or is even likely to happen because you don't know that indicator has moved straight along the Z. i.e. the indicator could be slightly higher at one end or the other, and because the bar is round, etc.

imo the way to do it is to revolve a straight bar by hand and note two indicator readings 180 degrees apart closest to headstock and then at the end of the test piece. All that's needed is a true cylinder. using the method it does matter whether the cylinder/bar is held concentric or even aligned with the headstock as you deduce the spindle's true position.

For example, if you got say -.001 and + .001 at the headstock and -.003 and +.003 at the end, the spindle is perfectly aligned but the bar is slightly off from the axis (doesn't matter), if you got .006 and 0 at the end its not. When scraping in a headstock you do this in the XZ and ZY plane (remember Z is spindle axis).

Doing it this way, the ratio has to be linear, or else the bar isn't straight. I eliminates the error indicating along a bar and eliminates the need for fancy taper mounted test bars. When scraping, that imo is the best to get perfect alignment

I wasn't scraping thankfully, I don't have that sort of knowledge.

I was turning a test bar (3" diameter with about a 1.5" through hole) with light cuts and mic'ing the ends. Then I took the delta and divided it by two and adjusted that until the large end was 1/2 that amount closer, using an indicator at the location of where the cutting tool was.

Your method is really not bad at all, maybe I should have done some reading before my attempt. I don't know if we have any substantially (actually round) stiff bar of any length, but probably.

[Hopefuldave]

Finally got around to taking off the wallowed-out 3-jaw and fitting a 4-jaw on my little rotary table, took a partial skim cut on the OD to take off some gnarly damage (it was cheap because...), milled pockets for the M8 capscrew heads.


Next I need to make a tailstock to match...

Dave H. (the other one)

[The Metal Butcher]

Finally got around to taking off the wallowed-out 3-jaw and fitting a 4-jaw on my little rotary table, took a partial skim cut on the OD to take off some gnarly damage (it was cheap because...), milled pockets for the M8 capscrew heads.


Next I need to make a tailstock to match...

Dave H. (the other one)

Does your rotary table disengage from the worm? Otherwise I feel like dialing it in would get pretty tiring. One could of course dial the table in and then use the spindle to dial it in.

[Hopefuldave]

Does your rotary table disengage from the worm? Otherwise I feel like dialing it in would get pretty tiring. One could of course dial the table in and then use the spindle to dial it in.

The worm is held in an eccentric with a lever behind the handwheel (also has the fiduciary line/vernier) and there's a T-bolt to lock that in or out of engagement, works pretty well for far-eastern. Similar setup on my big rotary, but that's German and a bit better made (and needs two of us or my pusharound hand-pumped lift to put it on the mill table...)

Dave H. (the other one)

[The Metal Butcher]

The worm is held in an eccentric with a lever behind the handwheel (also has the fiduciary line/vernier) and there's a T-bolt to lock that in or out of engagement, works pretty well for far-eastern. Similar setup on my big rotary, but that's German and a bit better made (and needs two of us or my pusharound hand-pumped lift to put it on the mill table...)

Dave H. (the other one)

Ok. Basically the same for our 12", except it uses a spring loaded pin for locking. No chuck for it yet, but that's something I would really like to have.

[Mcgyver]

I wasn't scraping thankfully, I don't have that sort of knowledge.

I was turning a test bar (3" diameter with about a 1.5" through hole) with light cuts and mic'ing the ends. Then I took the delta and divided it by two and adjusted that until the large end was 1/2 that amount closer, using an indicator at the location of where the cutting tool was.

Your method is really not bad at all, maybe I should have done some reading before my attempt. I don't know if we have any substantially (actually round) stiff bar of any length, but probably.

It has two big advantages for scraping, no power is required and its easily done in two planes. It does however assume a perfectly straight bed. In other words, the error produced by a headstock misalignment can be indistinguishable from that of wear and bed twist. To correct for a slight taper (work held by headstock only) I'll sometimes tweak the bolts at the tailstock to correct a turning to tenths for example.

There's removable HS lathes like the unimat db200, or if you're scraping.... but otherwise, unless there was a big crash, someone's been in there before or the lathe wasn't properly made in the first place I can't think how the HS would be off. Curious what you found?

[The Metal Butcher]

Big crash I'm guessing. Low speed inside and mark on the cross slide indicated at least one good crash. It's a bolted head on a flat casting so it moves pretty easily. Lagun 1440 btw. The Sidney has bigger apprentice marks and I've seen a Monarch that was totally beaver chewed but I doubt it had any broken gears.

[Cenedd]

Fixed my son's gooseneck reading light. Told him that fiddling with the gooseneck constantly would break it.....and what do you know! Li-Ion pack at one end of the gooseneck and LED driver the other. One of the wires between tested good and the other open circuit. Couldn't replace the wires as the neck was kinked in one point and it had pinched the wires. Managed to use the gooseneck itself as the ground with the one good wire as the positive. Was a race to see if the solder would wet the metal before the insulation of the one good wire melted! Worked though.

A question if I may: In these difficult times when we're all stuck at home and replacement parts are often difficult to get hold of....what's the quietest way of cutting trampoline springs in the dead of night?! (Kidding....well, mostly!)

[Dragons_fire]

I made some aluminum t-nuts for my mini mill

[Cenedd]

I made some aluminum t-nuts for my mini mill

Nice. I need to get round to making some for mine that don't require swearing at to get them to move down the slots!

[Hopefuldave]

Ok. Basically the same for our 12", except it uses a spring loaded pin for locking. No chuck for it yet, but that's something I would really like to have.

I've a few stepper motors / drivers waiting for me to use 'em, and an Arduino I'm learning to program so I may get the tuits to add one to it...? The steppers are about the size of the coffee mug in the pic.

Dave H. (the other one)

[Tom S]

Finished building a fence so I can have my evenings back now. I’ve got everything in to re-assemble my Ames headstock now, so that’s next on the list.