Another obligatory New PM-833TV and PM-1340GT Ordered!

I do not get it either, unless your chuck mount was out. I would check that when you have the test bar in and rotate the spindle that the reading TIR should be nil, check the spindle mount that it is also running true. End of the day is that it cuts true over at least 6-8" unsupported with larger diameter stock. I am not sure about using a test indicator for this application as any change in height when sweeping the bar would have a large impact on the reading.

Getting a good precision level sure helps with setting everything up, lots of crap out there and anything decent is 2-3X prices from several years ago. This one popped up when I did a search, VIS are quite good for the price. Know nothing about this listing service.
www.lsn.com

Precision Machinist Level - $100 In Baxter TN - LSN

VIS 12" Precision/Machinist Level-0.0005"/10"-Made in Poland
www.lsn.com www.lsn.com
 
mksj said:
I do not get it either, unless your chuck mount was out. I would check that when you have the test bar in and rotate the spindle that the reading TIR should be nil, check the spindle mount that it is also running true. End of the day is that it cuts true over at least 6-8" unsupported with larger diameter stock. I am not sure about using a test indicator for this application as any change in height when sweeping the bar would have a large impact on the reading.

Getting a good precision level sure helps with setting everything up, lots of crap out there and anything decent is 2-3X prices from several years ago. This one popped up when I did a search, VIS are quite good for the price. Know nothing about this listing service.
www.lsn.com

Precision Machinist Level - $100 In Baxter TN - LSN

VIS 12" Precision/Machinist Level-0.0005"/10"-Made in Poland
www.lsn.com www.lsn.com
Click to expand...
Just spoke to the seller. He is figuring out shipping and will be buying that level. Starting from scratch, my plan is to level the lathe, align the head stock using a normal Dial indicator (or 2) with flat nosed tips, and then Rollies dad the rest of the way by shimming the bed (instead of adjusting the leveling feet).

Shimming the bed was the suggested way of doing this per John at PM support.

A few other changes would be to cut and hone a sharp HSS blank for the 2 ring job, I was using carbide, albeit the honed carbide for aluminum as that also cuts steel well with light cuts. PM said to use HSS.

The saga shall continue!
 
I’m starting to wonder if the MT5 taper inside the spindle is out of alignment with the surfaces that the chuck registers against when it’s tightened down. Maybe you’ve already tested that and I’m not picking it up in your workflow of tests. I had the headstock completely off the bed of my 1340 for repainting. So I had no choice but to realign it. But I first got the bedways completely level and confirmed no twist or dips, then aligned the head with the MT5 test bar, then confirmed everything with Rollie’s dad method using a 3” diameter x 16” bar of 1018 found on eBay. Then I set about dialing in the tailstock. The headstock alignment was the most frustrating because of the crude adjustment points. Having a reliable and sensitive level (pristine Starrett 199 I found for $400 on eBay in 2004) was paramount for me getting my lathe dialed in.
 
Just some interesting measurements I took recently to see if I can level the machine using the ways, or the apron/cross slide. Look how off the apron is to the ways. Is this normal? I ensured on blocks. were resting on anything like a ball oiler, and I ensured all 1-2-3 blocks gave the same readings with level flipped 180.

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davidpbest said:
I’m starting to wonder if the MT5 taper inside the spindle is out of alignment with the surfaces that the chuck registers against when it’s tightened down. Maybe you’ve already tested that and I’m not picking it up in your workflow of tests. I had the headstock completely off the bed of my 1340 for repainting. So I had no choice but to realign it. But I first got the bedways completely level and confirmed no twist or dips, then aligned the head with the MT5 test bar, then confirmed everything with Rollie’s dad method using a 3” diameter x 16” bar of 1018 found on eBay. Then I set about dialing in the tailstock. The headstock alignment was the most frustrating because of the crude adjustment points. Having a reliable and sensitive level (pristine Starrett 199 I found for $400 on eBay in 2004) was paramount for me getting my lathe dialed in.
Click to expand...
I spun the spindle by hand with the test bar. less than a .001" wobble at the end, and it shrinks as you get closer to the chuck. I would think if the MT5 was off axially or off center to rotation that would be picked up at some point. I must be doing something wrong, but the plan is to start fresh with leveling --> Head --> twist --> tail as soon as I get back from the holidays, and as soon as I have the new to me master precision level Mark linked above.

All this being said, I have not been methodical with my work flows, and have been proceeding with an unusable level what loses calibration by just looking at it wrong. Once I get the new level, I will be much more methodical and will document it better in case I am doing something wrong...which I HAVE to be because I can not in my wildest dreams imagine what would cause what I have measured. Slowing down, and keeping it simple moving forward.
 
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Have you put an indicator on the carriage - reaching out about 10" and down to the bedways, and run the carriage back and forth? I have seen situations where a badly adjusted gib on the back of the carriage or the handwheel that engages the rack along from front of the bedway casting has caused the carriage to lift. And have you checked the bedways for flatness with a straight edge and feeler gages to ensure it isn't shaped like a banana?
 
Christianstark said:
I spun the spindle by hand with the test bar. less than a .001" wobble at the end, and it shrinks as you get closer to the chuck. I would think if the MT5 was off axially or off center to rotation that would be picked up at some point. I must be doing something wrong, but the plan is to start fresh with leveling --> Head --> twist --> tail as soon as I get back from the holidays, and as soon as I have the new to me master precision level Mark linked above.
Click to expand...
I can imagine a scenario where the mounting taper for the chuck alignment was machined out of axial concentricity from the internal taper. Not likely, but certainly possible. That would put your chuck axis out of alignment from the test bar in the MT5 internal taper. Is your chuck/backplate configured such that you could mount the chuck and the test bar at the same time? If so, you could check the alignment of them both in one setup and see if they agree by indicating to the chuck jaw internal faces.
 
I think I know what is going on. My spindle/ways are NOT perpendicular with my apron/cross slide, nor are they level either.

The taper is likely a combination of twisted bed ways, but the apron and cross slide thing is measurable. I will document everything when I get back to it with reliable tools.
 
Christianstark said:
I think I know what is going on. My spindle/ways are NOT perpendicular with my apron/cross slide, nor are they level either.
Click to expand...
This recently came up in another posting, they are not parallel to each other, it makes no difference as long as you use the same method/position to measure if there is any bed twist. I prefer to use 123 blocks on the flats of the ways, in particular when using a longer level that will not fit on the cross slide.
www.hobby-machinist.com

New PM-1236T Lathe has arrived

It is probably alright for most lathe work. But I have a milling vise that I want to use on the lathe as a backup milling option. I can't do accurate milling with a vise that runs downhill with respect to the spindle. I have reached out to P.M. for a solution. They are contacting the factory. I...
www.hobby-machinist.com www.hobby-machinist.com
 
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