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  1. #16
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    Quote Originally Posted by pipeclay View Post
    Do you have a choice of different gears to use on your chasing dial/ star wheel.
    Not sure - I got some bags of gears, which I assumed were for the feed, but I'll have to have a closer look.

    If so the large number 14,15 &16 correspond to the pitch of the thread being cut.
    That could make sense. I don't see why they'd call the default one "0" though - it must have some number of teeth.

    For your 1 mm pitch there is no large number there fore you can engage your half nut anywhere.
    Does it have to be the same number on each pass?

    The other pitches that don't also correspond or fall in the 1 mm pitch range or choices need to have the correct large number gear changed to engage on your leadscrew and the corresponding engagement point used.
    Cool, that all makes sense. I do wish they'd put that in the manual.

  2. #17
    jatt's Avatar
    jatt is offline Always within 10 paces from nearest stubby holder
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    My only criticism of the machine so far is that the foot "brake" is not mechanical, rather it just triggers the stop on the variable speed drive, which while having a braking resistor, still takes quite a few turns to come to a stop, and no faster than just stopping the lathe using the lever.
    That was pointed out to me when I told em lathe would be setup at business shop. Don't think the sales guy thought a lot of the variable setup either, so am curious to see how yours goes. Me, well ended up with the 336. Now that I have it going, seems capable enough for my needs. Can still run 16 mm stuff.
    Frisky wife, happy life. ​Then I woke up. Oh well it was fun while it lasted.
    From an early age my father taught me to wear welding gloves . "Its not to protect your hands son, its to put out the fire when u set yourself alight".

  3. #18
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    Quote Originally Posted by jatt View Post
    That was pointed out to me when I told em lathe would be setup at business shop. Don't think the sales guy thought a lot of the variable setup either, so am curious to see how yours goes. Me, well ended up with the 336. Now that I have it going, seems capable enough for my needs. Can still run 16 mm stuff.
    While I'm disappointed about the lack of a real brake, I do like the variable speed drive (I'm no BobL, but I do like VSDs). I can do my surface speed calculation and then just dial in the corresponding RPM. Slowest speed is 70 RPM in low range, which seems slow enough for my ventures into threading. At some point I'll pop the cover off where the VSD lives and check out what it is, and whether I can futz with the parameters.

  4. #19
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    I think my questions about the mysteries of the chasing dial have been answered by reading the relevant section of the RMIT "Fitting and Machining" book I purchased many years ago (partially in the expectation of getting lathe). It goes into very useful detail about the relationship between the lead screw and the thread being cut, with examples in good old metric

  5. #20
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    Quote Originally Posted by RustyArc View Post
    While I'm disappointed about the lack of a real brake, I do like the variable speed drive (I'm no BobL, but I do like VSDs). I can do my surface speed calculation and then just dial in the corresponding RPM. Slowest speed is 70 RPM in low range, which seems slow enough for my ventures into threading. At some point I'll pop the cover off where the VSD lives and check out what it is, and whether I can futz with the parameters.
    How are they doing speed range selection? Some of the Eastern machines some years ago were using belt swapping to get fast/slow ranges, which is not really a problem in itself, but they had a timing belt that couldn't slip as a primary belt (motor to an idler) and a standard V belt for the belt swapping secondary belt Idler to spindle gearbox). If you set up for low range, the belt was always looser than high range and the belt slipped terribly, so the machine was effectively single range 4 speed. Nowhere near as effective as the good old noisy back gear arrangement on the belt drive lathes.
    I used to be an engineer, I'm not an engineer any more, but on the really good days I can remember when I was.

  6. #21
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    Quote Originally Posted by malb View Post
    How are they doing speed range selection?
    It uses gears, with a high-low lever.

    The only trap, which they warn about, is if you've turned up the RPMs in low range, you need to make sure to turn down the speed dial before engaging high range, otherwise the work might spin up much faster than expected.

  7. #22
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    Quote Originally Posted by RustyArc View Post
    It goes into very useful detail about the relationship between the lead screw and the thread being cut, with examples in good old metric
    Used to be called "French Measure" in my younger days
    Best Regards:
    Baron J.

  8. #23
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    Probably time for an update, now I've use the machine a bit here and there for actual jobs.
    So here it is in the shed. I'd been holding off on getting a machine on the basis that I'd be replacing another shed, at which point I'd fit it out for all manner of machinery. When I realised that wasn't going to happen any time soon, I worked out I could squeeze it into my little 8x4m workshop, and it ended up slotting in quite well between my CNC router and colour laser.
    IMG_2692.jpg

    There's a shallow shelf just above the machine, which is working well for all the tool holders, centres, drill chuck etc, then above that a deeper shelf with the 4-jaw, faceplate, random stock and other things. I also use the bench to the right for collecting tools, and also there's a bench behind me.

    My conclusion is that you need a fair number (or size) of flat surfaces around the lathe.

    Probably a key feature of the machine is the variable speed drive, the manifestation of which is this:
    IMG_2693.jpg

    Unlike most VFDs where you pre-select a frequency (and that is displayed), on this one it's a closed loop selection of RPM, and that only displays once it's running, as it has a sensor on the spindle to detect actual RPM. That's good, as when you load down the machine, it maintains the RPM. The downside is that when it's not running, you don't know what it's going to fire up to. So you could be on the upper end of the speed range in low gear, change to high gear, and have it winding up to a much higher RPM than expected. So it's advised that you set the pot to minimum whenever you turn it on.

    Apart from that minor downside, it's a great feature. You can effortlessly change RPM to suit the task at hand, including increasing the speed as you face or part off to maintain the surface speed, or kind of fast-forward then slow down to sneak up on a long feed.

    One of my reasons for thinking this was the ideal machine was the appearance of a foot brake.
    IMG_2700.jpg

    I liked the idea of being able to pull up the machine quickly, partly for operations like threading, but also in general use, jut to speed things up rather than waiting for the chuck to spin down. Turns out this is one thing I got wrong. In the range of these lathes, as they step in size, there's a model with a variable-speed motor, and a model with a fixed-speed motors (with more gears to select speeds). They both appear to have foot brakes, but it's only the fixed-speed motor units that have the linkages and brake assembly on the drive shaft, the variable-speed units use "electronic" braking. This works on the principle that when the motor is spinning down with the momentum of the chuck, it's acting as a generator. By more-or-less shorting its output with a resistor, that load serves to slow the motor. However, while quicker than just letting it idle to a stop, it's nothing like stomping on a brake.

    So the pedal is kind of pointless - there's no linkages inside, just a microswitch to send a signal to the VFD. At best it's a safety feature, being an extra option to stop the machine.


    IMG_2701.jpg

    The machine came with a DRO in a bag. So far it's been awesome - I typically just zero an axis when I start to care about depth of cut or position. I'm sure it has a heap of other features, and tool offsets is one I should investigate at some point.

    In addition to the machine, I got a bunch of tooling and accessories to get me started. Hare and Forbes "TM" brand "made in Taiwan" tooling does seem to be decent quality. Their basic insert kit (left, right turning and RH boring bar) seems to do the job, also unlike what I was lead to believe, there's pretty much no choice of profile when it comes to the triangular 110204 inserts.

    IMG_2694.jpg

    The QCTP tool holders seem to work well enough, except some of the adjustment nuts seem to be almost at the end of their threads. I bought some cheaper 250-201 holders off Ebay, but they seem to be a looser fit on the dovetail. Not sure if this affects performance though.

    IMG_2698.jpgIMG_2697.jpg

    The most annoying thing about the tool post and the holders is the random mix of metric and imperial, both with the nuts and hex head grub screws.

    I bought this live centre set thinking "this will be handy". It has been.

    IMG_2696.jpgIMG_2695.jpg

    So for someone who, like many, only ever used a lathe back at school, and whose only education since has been YouTube, this machine was bought with the idea that it would exceed my requirements, rather than have me wanting more. So far that's proved to be the case - it's reasonably heavy (~600kg) with a solid feel to it. While I haven't pushed it to where it feels like it's really working, it'll happily take a 1mm DOC in 25mm dia mild steel at 800RPM at a reasonable feed rate (haven't quite worked out the numbers on that bit yet).

    It's been as precise as I've needed - the DRO being a big help. I've made a few bronze bushes, and have come out to within 0.05mm of what I was shooting for, but I still need to work on sneaking up on a diameter or fit (and learning how, say 0.05 of a mm relates to fit). Parting off has been fine, except for a bit of gouging on bronze (still cut off fine though) my first try at knurling came out fine too. I've also done a bit of milling as per this pic:
    IMG_2586.jpg

    Which seemed kind of sketchy at the time, but milled perfectly.

    And I've tried a bit of 4-jaw action, turning down a dog to fit the narrower slots in my faceplate:
    IMG_2674.jpg

    Again, seemed sketchy, dialled in the oval-shaped drive leg as best I could on 2 axes, and it turned down just fine.

    So, while this machine, with tooling, cost a fair bit so far I'm really happy. Apart from the lack of a proper brake. But that's not proving to be much of an issue.

  9. #24
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    Quote Originally Posted by RustyArc View Post
    The QCTP tool holders seem to work well enough, except some of the adjustment nuts seem to be almost at the end of their threads. I bought some cheaper 250-201 holders off Ebay, but they seem to be a looser fit on the dovetail. Not sure if this affects performance though.
    Provided you can snug up the tool holder so that it does not move, it should be fine. It would be nice to have everything lock when the lever is in the same position but sometimes they don't.

    Quote Originally Posted by RustyArc View Post
    The most annoying thing about the tool post and the holders is the random mix of metric and imperial, both with the nuts and hex head grub screws.
    It might be worth checking what you really have. My first QCTP was made for the US market, so the sockets in the grub screws were imperial, but the threads were metric. If you have a fastener place near by, replacements are not expensive and probably worth while in case the 'high strength alloy steel' fails. I was able to replace all the grub screws with better quality ones while making sure I did not have mixed systems. I also bought a couple of hex keys (the ones with the plastic overmoulded handles) so that the right size was always to hand.

    Michael

  10. #25
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    That foot brake is probably incase your hands get tied up literally and u cant stop the machine in an emergency u can with your foot

    That beast is quiet a lathe for the home, you must have done the dishes for a few months to impress the wife that much haha

  11. #26
    BobL is offline Member: Blue and white apron brigade
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    Quote Originally Posted by RustyArc View Post
    I liked the idea of being able to pull up the machine quickly, partly for operations like threading, but also in general use, jut to speed things up rather than waiting for the chuck to spin down. Turns out this is one thing I got wrong. In the range of these lathes, as they step in size, there's a model with a variable-speed motor, and a model with a fixed-speed motors (with more gears to select speeds). They both appear to have foot brakes, but it's only the fixed-speed motor units that have the linkages and brake assembly on the drive shaft, the variable-speed units use "electronic" braking. This works on the principle that when the motor is spinning down with the momentum of the chuck, it's acting as a generator. By more-or-less shorting its output with a resistor, that load serves to slow the motor. However, while quicker than just letting it idle to a stop, it's nothing like stomping on a brake.

    So the pedal is kind of pointless - there's no linkages inside, just a microswitch to send a signal to the VFD. At best it's a safety feature, being an extra option to stop the machine.
    All that means is that the VFD stop/braking times have not been programmed as fast as they could be. One reason could be that unless constrained the chuck/work might spin off. If the chuck has a locking mechanism the VFD with brake could stop it around 0.1s I think Jo Hovel has done this on one of his machines.

    When I installed the VFD brake on the Radial Arm saw at the mens shed I experimented with brake times and found I could easily get the blade to stop within ~2 seconds but the motor complained loudly plus there was always the risk that the blade could loosen so I didn't try any less time than the 2s. In the end I selected 4 seconds which is a massive improvement on the 120+ seconds it took to coast to stop. The most danger time was the last 90s or so when it ran without making any noise. This setup is not for emergencies emergency with but for day to day use.

    BTW it's not standard resistor that does the braking, conventional resistors will change resistance with all that back current running through them - it's a special resistor that does not change its resistance much with current so it produces a smooth even stop. I've tried using 150W light globes as resistors, it sure does stop the motor but there's a great BANG and flash of light from the globes and the motor moans and groans under the uneven forces generate during the stop. Can't imagine it's any good for the motor.

    My small Hercus does not run at high speeds and I have just the VFD (no braking resistor) programmed to stop in 3s which it does easily.

    The footbrake on my WW bandsaw can stop the blade in about a second but
    a) I have to move around to the side of the saw to access it
    and
    b) the entire rotating mechanism fairly groans and moans when I do that.
    Instead I typically apply the brake for about 3 seconds which brings it to a stop - its gentler on the mechanism, and far shorter than the 90s it takes to free coast if I don't use the brake.

  12. #27
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    Quote Originally Posted by BobL View Post
    All that means is that the VFD stop/braking times have not been programmed as fast as they could be. One reason could be that unless constrained the chuck/work might spin off. If the chuck has a locking mechanism the VFD with brake could stop it around 0.1s .
    Hmm. I haven't timed it, but it takes a couple of revolutions to come to a stop. The chuck is a cam-lock style, so I can't see it undoing itself.

    I'll have to crawl around the back and check out the drive some time, and see what scope there is for changing parameters. If it could be made to stop quicker, that would be good, as today I was threading up to a shoulder and wanting to keep the half-nuts engaged between passes, and on one pass I didn't stop in time, causing the tool to gouge into the shoulder.

  13. #28
    BobL is offline Member: Blue and white apron brigade
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    Quote Originally Posted by RustyArc View Post
    Hmm. I haven't timed it, but it takes a couple of revolutions to come to a stop. The chuck is a cam-lock style, so I can't see it undoing itself.
    Humm, At 1000 rpm 2 revolutions is 0.12s, at 100 rpm that's 1.2s.
    Not to mention reaction time.

  14. #29
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    Rusty i was playing with the auto feed on my little lathe and done the same thing but i wasnt threading i have since watched videos on youtube and when the guys reach the start of the job they turn off the machine than disingauge the feed than turn the.lathe back on and continue

  15. #30
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    Quote Originally Posted by BobL View Post
    Humm, At 1000 rpm 2 revolutions is 0.12s, at 100 rpm that's 1.2s.
    Not to mention reaction time.
    I think I'll try videoing stopping at different RPMs. That should get me within 1/25th of a second.

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