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  1. #21
    Join Date
    Nov 2014
    Posts
    75

    Re: would you buy this machine?

    your replies are Gold! Really thank yu!This lathe i am trying to convert doest have a lead screw...it has an anthreaded bar with a slot in it that moves the carriage ...so only a feed screw if you can call it like this...The idea to make a mechanism for holding ballscrew nut would be perfect...so you could move alla the time manually and alsobe able to makhold the screw when you need it...i have a pc with a parallel port in it with the paid version of mach3 and laso with windows xp...its only for this reason...

  2. #22
    Join Date
    Mar 2015
    Posts
    409

    Re: would you buy this machine?

    Than you are almost ready to take off. Adding an index pulse sensor to the spindle is a lot easier than adding a stepper to the spindle, so I would put the spindle stepper on hold and go for a proximity switch.

  3. #23
    Join Date
    Nov 2014
    Posts
    75

    Re: would you buy this machine?

    Than could you maybe show me what sensor will i need to put ti the spindle?I can buy from www.ebay.co.uk I have built a cnc router that can mill aluminium too...but the cnc lathe is not something i know alot about and not much info on the web with how to do it with mach3 ...in a youtube video i found proposing this https://www.ebay.co.uk/itm/New-OMRON...v/121350357120 .The way you attached the spindle to the stepper motor when you need it is a great idea and i think i could maybe do this if i can make two aluminium gears in the cnc one for the stepper and one for the back of the spindle.the one on the spindle could have threads on it and screw on the threads of the spindle maybe? But if there is a more simple way to cut threads then i am all ears!!

  4. #24
    Join Date
    Mar 2015
    Posts
    409

    Re: would you buy this machine?

    I don't know if mach3 can handle this 2000 PPR encoder output for threading, the inputs on Mach3 (BOB) are a limited. Because you have a heavy motor and gearbox, your spindle speed will not change a lot at the start of a thread so i think one simple index pulse will do. For this you can use a proximity switch. They come in different output options. But just for an idea, have a look at this one on eBay. It can be used on optocoupler inputs (- side) and logical inputs. If activated, it switches the input to GND https://www.ebay.nl/itm/NJK-5002C-Pr...uETz:rk:1:pf:0

  5. #25
    Join Date
    Nov 2014
    Posts
    75

    Re: would you buy this machine?

    thanks alot!!This is very cheap and if it can work it will save me alot of money!!When i will be ready i will inform you for how its going!Thanks again for the time you spent to guide me!

  6. #26
    Join Date
    Mar 2015
    Posts
    409

    Re: would you buy this machine?

    Have fun and make this lathe a good working machine.

  7. #27
    Join Date
    Nov 2014
    Posts
    75

    Re: would you buy this machine?

    So after some cleaning i now have the lathe bed ways cleaned... Maybe someone knows can i run a 5.5 kw three phase motor with a smaller inverter i mean a 2.2 kw inverter?A friend told me i could maybe run it but it will run underpower...any thoughts/? i upload some photos of the cleaned ways too,.Also i am trying to find a way to take the motor and its gearbox out but i think that it has to come out as one piece..

  8. #28
    Join Date
    Jun 2015
    Posts
    4131

    Re: would you buy this machine?

    it is indeed a very nice looking machine, i just can't believe that you actually found it you are very lucky ...

    just kidding man, wish u all the best / kindly
    Ladyhawke - My Delirium, https://www.youtube.com/watch?v=X_bFO1SNRZg

  9. #29
    Join Date
    Dec 2013
    Posts
    5717

    Re: would you buy this machine?

    I don't think that a 2.2 KW VFD would work well with a 5.5 KW motor, the 2.2 KW VFD would barely output enough power to run that motor unloaded. You would be better to run it with the proper sized VFD if you have 3 phase power available.

    If you only have single phase available, then you would need a VFD that is rated for single phase input at 5.5KW or about a 10KW VFD that will run on single phase. Another option would be a 10KW rotary phase converter.
    Jim Dawson
    Sandy, Oregon, USA

  10. #30
    Join Date
    Nov 2014
    Posts
    75

    Re: would you buy this machine?

    Quote Originally Posted by deadlykitten View Post
    it is indeed a very nice looking machine, i just can't believe that you actually found it you are very lucky ...

    just kidding man, wish u all the best / kindly
    haha why you say this? Isnt it a beauty?? :P well for the money i gave it is ok i am an amature that does this as a hobby

  11. #31
    Join Date
    Nov 2014
    Posts
    75

    Re: would you buy this machine?

    Quote Originally Posted by Jim Dawson View Post
    I don't think that a 2.2 KW VFD would work well with a 5.5 KW motor, the 2.2 KW VFD would barely output enough power to run that motor unloaded. You would be better to run it with the proper sized VFD if you have 3 phase power available.

    If you only have single phase available, then you would need a VFD that is rated for single phase input at 5.5KW or about a 10KW VFD that will run on single phase. Another option would be a 10KW rotary phase converter.
    thanks for your answere! Yes in my workshop i have a single phase power and i dont know if the line can hold so much power i will have to test it...well i now have to dismount everything so as to clean this machine cause deadly kitten is making fun out of me hahaha

  12. #32
    Join Date
    May 2008
    Posts
    1185

    Re: would you buy this machine?

    I cant tell if your lathe has a hydraulic pump on it or not. If so it will have a lot of drag on it and the smaller 2.2K VFD might be a problem.

    I have been running my 3 phase lathe on a VFD for some time and it works fine.

    For the price I would get a 5K VFD or the 3.2K from China and it will work fine. I have a 2.2K a 3.2K and a 5.5K. The 5.5K is almost twice the size of the 2.2 or 3.2K units. The 3.2K is the same size as the 2.2K but the heat sink is larger.

    All the AC motors have good efficiency so what to look at is power in and power out and start up current. 3.2K power output is good enough for most work so that leaves startup current. This is where a VFD is so good. You just ramp up the motor so start up is really easy and has low peak current.

    Most VFD's will also give you more current for a short time before faulting.

    With the low start up current and knowing that you can only do a 3K cut you lathe will work fine with most VFD's. I would grab a 3.2K and it will be fine for $149.

    My only problem with the China drives is the noisy fans. I just replaced the 5.5K unit with a much slower fan and its SOOOO much quieter. I like it this way. I can get all the peak power I need and I never need continuous 5.5K of power so it does not over heat.

    I have a new fan for the 3.2K too, the stock fan is really whinny.

    BTW it looks lie a really nice Lathe. Cant wait to see the finished product.
    youtube videos of the G0704 under the name arizonavideo99

  13. #33
    Join Date
    Nov 2014
    Posts
    75

    Re: would you buy this machine?

    Quote Originally Posted by arizonavideo View Post
    I cant tell if your lathe has a hydraulic pump on it or not. If so it will have a lot of drag on it and the smaller 2.2K VFD might be a problem.

    I have been running my 3 phase lathe on a VFD for some time and it works fine.

    For the price I would get a 5K VFD or the 3.2K from China and it will work fine. I have a 2.2K a 3.2K and a 5.5K. The 5.5K is almost twice the size of the 2.2 or 3.2K units. The 3.2K is the same size as the 2.2K but the heat sink is larger.

    All the AC motors have good efficiency so what to look at is power in and power out and start up current. 3.2K power output is good enough for most work so that leaves startup current. This is where a VFD is so good. You just ramp up the motor so start up is really easy and has low peak current.

    Most VFD's will also give you more current for a short time before faulting.

    With the low start up current and knowing that you can only do a 3K cut you lathe will work fine with most VFD's. I would grab a 3.2K and it will be fine for $149.

    My only problem with the China drives is the noisy fans. I just replaced the 5.5K unit with a much slower fan and its SOOOO much quieter. I like it this way. I can get all the peak power I need and I never need continuous 5.5K of power so it does not over heat.

    I have a new fan for the 3.2K too, the stock fan is really whinny.

    BTW it looks lie a really nice Lathe. Cant wait to see the finished product.

    Hi there!It doesnt have a pump on it ....with the motors and the vfds i am a little bit confused i will try to read it better maybe i am missing something..i really like te procedure too...i will definately keep you informed!!

  14. #34
    Join Date
    Nov 2014
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    75
    Quote Originally Posted by pikolo View Post
    hello! Some days ago i went to tha jank jard so as to buy cheap metal...there was a lathe there the one shown in the picture and the guy told me that he would give it ot me for 400 euros...
    so would you buy it ? is it worth it trying to clean it and make it work? Is the price good for what it is?thanks alot for your time .
    Progress so far

  15. #35
    Join Date
    Nov 2014
    Posts
    75

    Re: would you buy this machine?

    The machine is almost done and i am trying to convert it to an electronic gearbox so as to be alble to cut threads....Some questions that i would like to be answered if it is possible
    Would a 8 Nm closed loop servo motor have enough power to drive the carriage? I am also thinking of connectng a ballscrew to the carriage and wondering will it be possible to move the carriage by the handwheel if a ballscrew is attached to it ?I mean i would like to use it as a manual lathe too

  16. #36
    Join Date
    Mar 2015
    Posts
    409

    Re: would you buy this machine?

    Quote Originally Posted by pikolo View Post
    The machine is almost done and i am trying to convert it to an electronic gearbox so as to be alble to cut threads....Some questions that i would like to be answered if it is possible
    Would a 8 Nm closed loop servo motor have enough power to drive the carriage? I am also thinking of connectng a ballscrew to the carriage and wondering will it be possible to move the carriage by the handwheel if a ballscrew is attached to it ?I mean i would like to use it as a manual lathe too
    I have both my lathes converted to CNC and can still do manual threading. This is because I use the original spindles. If you mount a ball screw, you can't move the carriage by hand because there are no (two) half nuts any more.

    The faster you will like to accelerate, the more torque you need because there is al lot of mass (carriage) that has to be moved. However, a lathe is not a milling machine and there are not so many direction changes in a turning pass. If it is just for fun, you don't need the speed. The stronger the steppers, the more damage there is if something goes wrong.

    My HBM 300 mini lathe (0.5 kW spindle) has a Nema 17 (0.56 Nm) stepper on the carriage. I need my full weight (90 kg) to stop the carriage moving. My small lathe HBM290 Vario (1.5 kW) has Nema23 1.26 Nm steppers. I can't stop the carriage by hand and I would never turn the manual controls that hard. For me it is more than enough and I even don't run them on max current (torque).

    Closed loop can correct for missing steps when you operate outside machine limits. Never the less, it is always better if you don't stretch the limits of your machine. In that case, you could do with normally open loop steppers and save money.

  17. #37
    Join Date
    Nov 2014
    Posts
    75

    Re: would you buy this machine?

    the problem i have is that my lathe has only a feed screw with a slot in it and not a leadscrew so i am thinking of all the ways that it can be done...i found a closed loop stepper driver with a 8 NM moter and a power supply for the price of 190 euros i think it is fair price....so the ballscrew as an option is out i guess....

    Quote Originally Posted by hfjbuis View Post
    I have both my lathes converted to CNC and can still do manual threading. This is because I use the original spindles. If you mount a ball screw, you can't move the carriage by hand because there are no (two) half nuts any more.

    The faster you will like to accelerate, the more torque you need because there is al lot of mass (carriage) that has to be moved. However, a lathe is not a milling machine and there are not so many direction changes in a turning pass. If it is just for fun, you don't need the speed. The stronger the steppers, the more damage there is if something goes wrong.

    My HBM 300 mini lathe (0.5 kW spindle) has a Nema 17 (0.56 Nm) stepper on the carriage. I need my full weight (90 K=kg) to stop the carriage moving. My small lathe HBM290 Vario (1.5 kw) has Nema23 1.26 Nm steppers. I can't stop by hand and I would never turn the manual controls that hard. For me it is more than enough and I even don't run them on max current (torque).

    Closed loop can correct for missing steps when you operate outside machine limits. Never the less, it is always better if you don't stretch the limits of your machine. In that case, you could do with normally open loop steppers and save money.

  18. #38
    Join Date
    Mar 2015
    Posts
    409

    Re: would you buy this machine?

    the problem i have is that my lathe has only a feed screw with a slot in it and not a leadscrew so i am thinking of all the ways that it can be done...i found a closed loop stepper driver with a 8 NM moter and a power supply for the price of 190 euros i think it is fair price....so the ballscrew as an option is out i guess....
    I converted my mini lathe X, Z and spindle stepper (without computer) for $100. I did the small lathe for about $120. My small lathe has a lead screw for threading and a second (slotted) one for all other things. The slotted screw is a bit less accurate but always more accurate than turning by hand. Give it a try, just for a proof of concept. Doit the cheap way (24V 350W power supply, TB6600 drivers and BOB for Mach3 or an Arduino Mega running GRBL, keep the manual controls). When it is done, you have learned a lot, have a CNC controlled lathe and probably won't need more.
    I have documented the CNC conversion of my mini lathe Mini lathe 100 $ CNC conversion and modifications - Metal Worker Tools. The Z and X axis are easy to do. The stepper on the spindle for threading takes more effort. Next month I will release a GRBL-L-Mega version that supports spindle synchronization (G33). This will make implementing threading easy.

  19. #39
    Join Date
    Dec 2013
    Posts
    5717

    Re: would you buy this machine?

    Quote Originally Posted by pikolo View Post
    The machine is almost done and i am trying to convert it to an electronic gearbox so as to be alble to cut threads....Some questions that i would like to be answered if it is possible
    Would a 8 Nm closed loop servo motor have enough power to drive the carriage?
    That should be enough torque. I am using 11.2Nm (29Nm peak) servos on my lathe, and the carriage masses about 600Kg. Acceleration is very good with 400 IPM rapids. My lathe is a medium sized slant bed with a 10 tool turret, 7.5 KW spindle.

    I am also thinking of connectng a ballscrew to the carriage and wondering will it be possible to move the carriage by the handwheel if a ballscrew is attached to it ?I mean i would like to use it as a manual lathe too
    Rather than use a ball screw, it is possible to use the original carriage drive (not the lead screw) if you use linear encoders and an air spring to control the backlash. This way you can use the lathe as both manual and CNC with an instant change over. I designed this system for my manual lathe, but never built it because I bought a CNC lathe. I designed this system because I wanted both manual and CNC capability. I know the air spring works because I am using a similar system to control the backlash on the Z axis of my mill.

    To use in manual mode, just de-couple the servo from the normal lathe drive, shift it into neutral when using in CNC mode. An automotive air conditioner clutch would work well for this, they will transmit a lot of torque.
    Jim Dawson
    Sandy, Oregon, USA

  20. #40
    Join Date
    Nov 2014
    Posts
    75

    Re: would you buy this machine?

    sorry for taking too long to reply but i didnt see the replies till now!Thanks alot ! right now i have completed the tailstock and it is fanctional but a little bit low...as i see it the machine needs scraping especialy in the cross slide...dont have the equipment yet and it is too expensive for me ...maybe i could use the mini lathe bed as a straight edge?It is not worn from what i know...another pic for you to see
    Attached Thumbnails Attached Thumbnails update.jpg  

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