spindle chucks? (and more newbie questions)

ttabbal, the gear chart is specific to the 1236/1340GT and the 1440GT models. Essential you use a spreadsheet to look at your current gear ratios, and then plug in other combinations for other change gears. Information for these have charts that have been previously posted, see the links below. The electronic VFD carriage stop system is a complete integrated control system which replace the stock machine control board, wiring, switch gear, etc. so it is not an add on device for machines with VFDs.

Most of the imported lathes for the US as far as I am aware use imperial lead screws, as such the threading dials do not work for metric and visa versa if it is a metric pitch. There are some lower priced lathes and mills that do use a metric pitch screw thread that is a close approximation to imperial thread pitch. Had that on my last mill and made it pretty much useless when using the dials, so had to install a DRO.

https://www.hobby-machinist.com/threads/pm-1440gt-change-gear-thread-pitch-calculator.60066/
https://www.hobby-machinist.com/threads/metric-thread-pitch-on-pm1340-lathe.59976/#post-494663
 
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Chipper5783 said:
Consider a machine with a metric lead screw. Yes, you can cut metric threads on a machine with an imperial lead screw - but it is a bit of a work around (you can't disingage the halfnut until you are finished).
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ttabbal said:
I forgot about the half-nut thing when threading for metric. That would be somewhat annoying. I think I would probably just buy some nice taps and dies for at least the smaller threads.

I haven't seen any tools small enough to single-point an M3 internal thread anyway... Hey Mikey, want to grind us one? :)
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Not being contentious because it is common wisdom that you cannot disengage the half nuts when cutting metric threads on an Imperial lathe ... except that you can. Conrad Hoffman (smart guy!) described the technique here: http://conradhoffman.com/metricthreading.htm, and Tom at Ox Tools did a video on it:


Most of the threads we cut in this country will be Imperial with some metric thrown in. Some lathes, like my Emco Super 11, have a thread dial indicator that does both. In my opinion, having Imperial leadscrews in the US is a good idea because we tend to think in Imperial, work in Imperial increments and many of the things we need to fit will be Imperial. I cut a lot of metric threads too and do not find it difficult to change gears if my QCGB doesn't have what I need; I have a complete set of change gears for the lathe. I work on sportbikes, too, so I understand the need for metric threading but I also work on Imperial stuff most of the time and prefer to work on an Imperial lathe.

And just for the record, internal threading in tiny holes is best done with a good carbide bar from Micro 100. Nice try though, @ttabbal! ;)
 
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You can at a later date buy better quality chucks, and assuming your spindle nose was ground in place, just swap them on and sell your older chucks. You can easily swap between chucks with a D1-X spindle. You can add various styles of collet chucks if you want to consistently mount and remount work pieces in those size ranges. You can get a run true or other chuck and mount it up. It really all depends on what you are going to do. If all you ever plan to do is single setup fully subtractive turing you might only ever use a 3 jaw. If you need to be able to turn concentric to an existing surface you will need some other chuck. 4jaw/collet/run-tru/etc. If you need to setup, concentric and swap ends a 4 jaw will work. If you need to do it fast then a run tru or a collet chuck might work better.
 
So earlier 1127's had a spindle like the 1030, but looks like new models have the D1-4 it seems. But honestly, other then the threading I was shying away from the 1127 since for a few hundred more you can get a many more gearbox options in the 1228 which seems like a huge win in terms of usability. But the 1228 seems to be missing some basic features that you see included with other machines (4 jaw check, faceplate) or is extra (QCTP). The 1236 is +400lbs heavier then anything else and basically requires only two possible change gear settings for any metric thread. Funny how easy it is to say "for a few dollars more..." and end up going $1k. :). Does either the 1127 or 1228 deserve a serious second look? Both have variable spindles which seems really nice.

I guess one disadvantage of going with an imperial lathe is that the metric markings on the 1236 dials is going to have the same issue as the metric lead screws with imperial markings- never going to be quite right. Am I making a bad decision to not go with DRO on a lathe since I'll be working significantly with metric? Probably would end up adding that on myself via eBay... the QMT option seems kinda spendy for a 2 axis deal unless I'm missing something obvious? Guess I should probably ask Matt about that too. As long as I'm not running coolant, the optical/glass ones would seem to be fine. Just haven't been able to find any decent fully metric lathe. They all seem low end/smaller machines with metric lead screws with imperial markings on the dials.

mksj, that electric stop looks pretty awesome. :) Another hobby of mine is designing electronics (PCB design/etc) and so I bet I could do something similar. The Ox Tools video showing an alternative method makes everything look really easy, but I guess it all depends on how good your hand/eye coordination is.

Thanks everyone for the info and advice!
 
Yup, you can "just a little more money" into some serious iron. :)

I had to stop as I had a hard limit, that I pushed just a little with shipping cost added. I think it will be a great setup. There's always something better. Just like computers.

I started thinking about getting a mini-lathe. Then the 1030, then pushed to the 1127. If I had the budget, I would actually love the 1236, but I really think the 1127 is more machine than I need for a long time. I may well be eating those words later, but you never know...

At the end of the day, the only person who can decide what is good enough for you, is you.
 
synfinatic said:
I guess one disadvantage of going with an imperial lathe is that the metric markings on the 1236 dials is going to have the same issue as the metric lead screws with imperial markings- never going to be quite right. Am I making a bad decision to not go with DRO on a lathe since I'll be working significantly with metric? Probably would end up adding that on myself via eBay... the QMT option seems kinda spendy for a 2 axis deal unless I'm missing something obvious? Guess I should probably ask Matt about that too. As long as I'm not running coolant, the optical/glass ones would seem to be fine. Just haven't been able to find any decent fully metric lathe. They all seem low end/smaller machines with metric lead screws with imperial markings on the dials.
Click to expand...

It is true, the dual dials are not very useful (IMO) - my larger lathe has dual scales. If the cross slide screw is Imperial (say 10 tpi - which is pretty common) then 1 turn is 0.200" off the diameter - which is 5.08mm off the diameter - and that is a major pain to keep track of. Same idea if the cross slide screw is metric - there will be some odd value of inches per revolution.

Yes, a DRO pretty much solves that. I suspect there are fancy little handwheel gearing arrangements to shift between inch and metric advance - but not on my lathe which has the dual scales. The scale needs to match the style of screw that it is associated with (i.e. a metric dial with a metric screw). IMO there is no benefit to having dual scales.
 
I have a Chinese V356 = 14 x 40. D1-5 chuck which is a bit of an odd ball. Variable speed low 40 -400, high 220 - 2000 and could only buy metric which is a bummer as I do a lot of Imperial stuff. no biggie but does mean I have to swap a gear. Needed to make a few extra change gears but I do run into some obscure threads. Variable speed, I'm in love with it, being able to alter speed if chatter starts on a hard spot or slow down when approaching the end of a thread or fast reverse with half-nut engaged. Like everybody else says get the biggest you can especially the biggest spindle bore.
ttabbal,
 I posted this elsewhere and copped some flak from a couple of people because you need to work out a lathes gearbox ratios but it is a program I use almost daily so can recommend. It is non-specific. Bit of a fiddle to save your input, find the file and rename it but worth it.
 

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Thanks for the program. I'll check it out. I know I'll need gearbox ratios and such if I want to calculate threading for unknown settings, that's just part of the deal. I started another thread to see if anyone else already has that info out there, nothing yet, but it's only been a day. I can figure it out when I get the machine if needed, though I'll email PM next week if I don't hear anything. They might know the details without me having to count turns. :)
 
Hope you like it. You can work out the ratios from the info stated on the thread plate. Find the thread listed that is the same as the leadscrew and work the ratios from there. Remember to factor the initial ratio from the spindle. Pretty easy once started. I wrote all down on a piece of paper and saved as a TXT file on a USB along with the finished saved file which came in handy when I had a computer meltdown.
 
So I pinged QMT via email and learned a few things:

1. The 1127 does all the threads I care about.
2. Still not 100% sure on the metric threading capability of the 1228. It's probably just fine like the 1127 though.
3. There's a step up in quality from the 1030 and 1127+. But spindle run-out is going to be pretty much the same until...
4. There's another step up in quality from the 1228 and 1236. Runout on the 1236 is about half that of the 1228, 1127, etc. That said all of them seem plenty good for my needs right now.

Oh, I realized why the 2-axis DRO QMT sells is priced higher then eBay/Amazon:
1. Slimmer scale for the cross slide
2. Higher resolution scale for the cross slide
3. Includes the necessary mounting brackets, rather then having to fabricate my own.

Doesn't seem as over priced after all.
 
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