4th axis as a "poor man's lathe"

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    Default 4th axis as a "poor man's lathe"

    A few months ago I bought a rotational axis with a 4 jaws chuck for my CNC. I intend to use this as both a 4th axis on my CNC, or as an independent "poor man's lathe". I know, it will be a very primitive lathe with a lot of limitations, but I intend to try it out anyway to toy with, and to learn. I am sure I will be able to use it for some sort of work, but I will see that later.

    To get the lathe function I had to design a control box. This is based on an Arduino Uno module with a 2x16 lines LCD. It is a very simple design, using only three buttons, one for clockwise rotation start, one for counter clockwise rotation start and of course, one for stop. Stepper acceleration and deceleration is also implemented, with a possibility to select acceleration in 7 steps. The chuck rotation can be adjusted between zero and 380 RPM, which is the maximum with the stepper. This corresponds to 2280 RPM on the stepper, due to the 1/6 reduction pulley the stepper drives the chuck with. So it is a respectable rotation speed for being a stepper. The rotation speed is set using a rotary encoder and that speed is saved in the EEPROM, so after a power off, the last used rotation speed is restored. The rotary encoder push button is connected to the Arduino reset and acts as an emergency stop, in case there is a need for stopping as fast as possible. Of course, this means no deceleration, just an abrupt instant stop.

    I made a short video about testing the control box functions and showing the rotations. I have not used it yet as a lathe, still waiting for some necessary tools before I can do any real tests, but I thought this can be interesting to show as well. Maybe it will give other people some ideas as well.



    For powering and control I also built a separate PSU, which provides 48V 7A DC through four individual 12V power supplies connected in series. Three of these are 9A supplies, the fourth is though only 7A, which is why the maximum is limited to 7A, but considering that the stepper is only 3A, I figure that the PSU will be good enough for the purpose. The PSU box also contains a DM542 stepper driver, which is configured to the maximum current and 2x micro stepping, which results in 400 steps per rev.

    There is also a relay inside the box. This relay decides if the 4th axis is to be driven as A axis by my CNC using UCCNC software, or independently run as a "lathe", controlled from my control box and rotated non-stop until i press the stop button. The relay can be switched from the control box and the default setting (with the relay off) is that the rotational axis is controlled by UCCNC.

    If anyone is interested to use the Arduino code, here is a link which you can use to download it:

    https://drive.google.com/file/d/1CJN...ew?usp=sharing

    It is well commented, so based on the code, the simple box can easily be built by anyone understanding the basics of Arduino.

    I hope you will enjoy watching this video. More on the way...

    By the way, "poor man's lathe" is a joke. I know that once ready, this is going to cost me at least $800, and for that money I can buy a much better real lathe, but this way it is more fun, even if the performance will not be as good as a lathe for 5-600 USD.

    Similar Threads:
    https://www.youtube.com/c/AdaptingCamera/videos
    https://adapting-camera.blogspot.com


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    Default Re: 4th axis as a "poor man's lathe"

    Interesting project. I’m doing something similar using my wood lathe. I found arduino to be too slow so I’m using Teensy 3.2. The goal is to be able to just turn the machine on and not be bothered by a pc and software. Also cutting threads seems easier using a microcomputer.

    Regarding your machine; Steppers don’t have enough torque to rough cut wood. You could spin something for sanding. You can cut wood if you add an XZ axis and a router.



    Sent from my iPhone using Tapatalk



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    Default Re: 4th axis as a "poor man's lathe"

    Quote Originally Posted by Dean448 View Post
    Interesting project.
    Thanks.

    Quote Originally Posted by Dean448 View Post
    I’m doing something similar using my wood lathe. I found arduino to be too slow so I’m using Teensy 3.2. The goal is to be able to just turn the machine on and not be bothered by a pc and software. Also cutting threads seems easier using a microcomputer.
    The Arduino is fast enough for one axis, and in fact, also for three, depending on the microstepping settings of the driver. I run only one axis (the spindle) so that's not a problem for the Uno I am using. Of course, I use the FastAccelStepper library, which I had to modify a bit because for for some reason, it has a built in upper pulsing limit of 25kHz. I removed that limit, and now I can happily run at very high speed.

    Quote Originally Posted by Dean448 View Post
    Regarding your machine; Steppers don’t have enough torque to rough cut wood. You could spin something for sanding. You can cut wood if you add an XZ axis and a router.
    I think the problem is not torque but the speed. Wood, plastic and aluminium needs much higher rpm than the 380 rpm I can get from this stepper. I mean, the torque here is actually multiplied by 6 due to the gearing, so I guess that's not the issue and should be more than enough for wood. This stepper can actually used for drilling in a steel rod, which I tested in my initial test.



    I have a CNC router already, which is also my own design and build.

    https://www.youtube.com/c/AdaptingCamera/videos
    https://adapting-camera.blogspot.com


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    Default Re: 4th axis as a "poor man's lathe"

    Still not a fan of arduino for stepper control. Check this out

    https://www.pjrc.com/teensystep-fast...ntrol-library/


    Sent from my iPhone using Tapatalk



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    Default Re: 4th axis as a "poor man's lathe"

    Quote Originally Posted by Dean448 View Post
    Still not a fan of arduino for stepper control. Check this out

    https://www.pjrc.com/teensystep-fast...ntrol-library/


    Sent from my iPhone using Tapatalk
    That's OK. Anyway, I am a fan of anything that works and for a single stepper or servo Arduino definitely works. I am not saying that there is nothing better and of course I would not chose it for my CNC, but for a single motor it is good enough. At least for now.

    https://www.youtube.com/c/AdaptingCamera/videos
    https://adapting-camera.blogspot.com


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    Default Re: 4th axis as a "poor man's lathe"

    If anyone ever removed the motor holder from a fourth axis then please share how you did it.



    I can not for my life understand why it is been done this way and how they installed the whole thing. Is the spindle just pressed into the housing or is it glued also?

    https://www.youtube.com/c/AdaptingCamera/videos
    https://adapting-camera.blogspot.com


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    Default Re: 4th axis as a "poor man's lathe"

    i can't help, just here to wish you good luck with your projects

    we are merely at the start of " Internet of Things / Industrial Revolution 4.0 " era : a mix of AI, plastics, human estrangement, powerful non-state actors ...


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    Default Re: 4th axis as a "poor man's lathe"

    Quote Originally Posted by deadlykitten View Post
    i can't help, just here to wish you good luck with your projects
    Thanks.

    https://www.youtube.com/c/AdaptingCamera/videos
    https://adapting-camera.blogspot.com


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    Default Re: 4th axis as a "poor man's lathe"

    I made a severe update, basically changed everything. This was planned from the start, but it was a major update. Everything is changed, except the control box, but even there the Arduino code had to be updated for enabling the use of servo. Made a video regarding the current status.



    I have also made two machine hand wheels which will be used for initial testing. I am not sure I will install steppers later on, probably I will, but in the meantime, these wheels will enable using the lathe while the steppers are installed. Of course, without a proper cross slide, the use will be limited, but still, for testing it will work.



    The hand wheel is 3D printed, it took a total of about 7.5 hours to print the three parts necessary for each, but that's because my extruder has a 0.4 mm nozzle and I printed with 0.2 mm layer height and 65% density. The material in my case is PLA, and I think for me that will be good enough. I chose to print in three parts, not just two, because I want the coupler part to be exchangeable and the wheel usable for other purposes also. Anyway, if you are interested in printing it, in the video there are instructions on where to download the stl files from.

    https://www.youtube.com/c/AdaptingCamera/videos
    https://adapting-camera.blogspot.com


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    Default

    A lot of that noise is servo tuning, if you are able to on your controller, it would be worth going through the manufacturer recommended servo tuning procedure.

    The servo may also be highly salient, that is electromagnetic lingo for it has really distinct non-sinusoidal poles and a sharp waveform, trapezoidal likely. That typically is also exacerbating motor cogging and the noise can be a combination of cogging frequency, drive frequency due to drive waveform to motor waveform mismatch, and oscillation in the PID loops.


    You can only (maybe) control the PID loop tuning, so it's a good place to start. That will be with the controller manufacturer. If it's an integrated controller, then the servo manufacturer would be the place to start.



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    Default Re: 4th axis as a "poor man's lathe"

    Actually, most of the noise comes from the belt and that weird motor holder I had to make for this quick test installation.

    Btw, I did go through all the parameters and tuned the motor, but not aimed at silencing it, but to get the highest power and holding torque out of it.

    https://www.youtube.com/c/AdaptingCamera/videos
    https://adapting-camera.blogspot.com


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    Quote Originally Posted by A_Camera View Post
    Actually, most of the noise comes from the belt and that weird motor holder I had to make for this quick test installation.

    Btw, I did go through all the parameters and tuned the motor, but not aimed at silencing it, but to get the highest power and holding torque out of it.
    Fair enough, I've honestly never worked with timing belts like this before, so good to know about the noise.



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    Default Re: 4th axis as a "poor man's lathe"

    Quote Originally Posted by StrawberryBoi View Post
    Fair enough, I've honestly never worked with timing belts like this before, so good to know about the noise.
    It is the rubber hitting and releasing the grooves and rubbing against the sides of the pulleys, plus the motor holder which I think is not rigid enough, so there is some resonance. In this video I am also running the motor at maximum speed, and here it is very silent.



    I believe with tuning it can be made more silent also, but after playing quite some time with the parameters, I think that silence has a price on performance also.

    https://www.youtube.com/c/AdaptingCamera/videos
    https://adapting-camera.blogspot.com


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    Default Re: 4th axis as a "poor man's lathe"

    I don't know how interesting this thread is, but here are some updates regarding my "poor man's lathe". I am now ready with the actual basic design and first version of my DIY micro lathe. So far it's only for manual drive, and not really did any test run yet, but the machine is ready and usable as a manual lathe. Not tested yet, because I want some safety features before I make a real test cut, so it is still only cutting air, but any day from now, I'll see if it works or not, but I am quite confident that it will work as I planned and designed it for, mainly small aluminium and plastic parts. If I manage to cut steel also then that will be bonus. Will probably also use for grinding and some threading.

    Anyway, here is my latest video, showing the current status.



    https://www.youtube.com/c/AdaptingCamera/videos
    https://adapting-camera.blogspot.com


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    Default Re: 4th axis as a "poor man's lathe"

    Really cool mini lathe, nicely done. If you were to upgrade it in the future I suggest building it on top of a precision granite slab. Best price/stiffness/precision ratio for this type of build.



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    Default Re: 4th axis as a "poor man's lathe"

    Quote Originally Posted by ardenum View Post
    Really cool mini lathe, nicely done. If you were to upgrade it in the future I suggest building it on top of a precision granite slab. Best price/stiffness/precision ratio for this type of build.
    Thank you. I understand that rigidity is one of the keys to success, but for me it is also about portability. I also have no intentions to run any heavy duty jobs, just want to play around with it. Right now it weights about 30kg (66lb) without the PSU. Obviously, it is getting heavier as I change and add things but my target is to keep it around 50kg (110lb) or less for movability. Anyway, next step is to add some personal safety protection and after that it's time for a test run. If it works well then I'll digitize it and run using Mach3 or UCCNC. Maybe in the end I will also replace the fairly weak servo with a considerably more powerful one, but that will come later when I really see a use or need of that investment.

    https://www.youtube.com/c/AdaptingCamera/videos
    https://adapting-camera.blogspot.com


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    Default Re: 4th axis as a "poor man's lathe"

    The last video of 2021, before popping the Champagne...

    I am finally ready enough to use my lathe manually, and in fact have even used for more than just testing, in this video I am making parts for my lathe, but I even made some parts on order, which are not in this video. Of course, free of charge since the order was made by my son who needed two adapters and some aluminium plugs for his own DIY Christmas present project.



    Anyway, I am very happy with the results so far, and will continue improving and digitizing it.

    Happy New Year everyone.

    https://www.youtube.com/c/AdaptingCamera/videos
    https://adapting-camera.blogspot.com


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    Default Re: 4th axis as a "poor man's lathe"

    This is what I have been working on the last two weeks, it's a huge power supply, providing 50V 82A (4kW) to supply DC power which is enough for all my DC driven machines if I'd want to connect everything to the same. It is based on four HP server PSUs, each giving 12.4V 82A, and those are all connected in series. Have a look at the details if you are interested. The primary reason why I made it this big and powerful was the fact that I have more than enough server PSUs to make it. The second reason was that I needed something more powerful for my lathe. Then I realized that I could connect my CNC to this one as well. So now I have connections for both my CNC and the lathe, and also for a desk motor which will be made for my lathe to be placed on.



    https://www.youtube.com/c/AdaptingCamera/videos
    https://adapting-camera.blogspot.com


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    Default Re: 4th axis as a "poor man's lathe"

    That is an awesome project.

    I have a few questions...

    How did you separate the negative from the chassis & earth ground.

    I believe there is a sense signal that has to see a small load to turn the PS on. How did you signal them to turn on.

    Did you make or purchase the plug on the low voltage side of those power supplies.

    Those appear to be the hot swap variety found in many of the Proliant Gen5 and newer servers. I probably have a few dozen of those in bins as spares before we got rid of that server line. This would be a great project those are designed to run 24x7x365 for several years pushing close to max load. We had some pushing 1100-1200 watts (shared across 2 power supplies) for close to 7 years without breaking a sweat. They came in 460, 700, and 1000 watt versions if I recall correctly. There were failures within a data center full of those, so it would be a good idea to have a spare or two on hand. However, the big issue with this HP servers was the backplane between the power supply and the motherboard. HP cheaped out of the caps, and they were on the motherboard! We had an 80% failure rate of those in one data center. But that should also mean that tons of the power supplies should be on the market for dirt cheap for projects like this.

    I am very curious how you interfaced with those power supplies.

    Thanks, John Z

    Sent from my SM-G991U using Tapatalk



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    Default Re: 4th axis as a "poor man's lathe"

    Quote Originally Posted by JohnZ View Post
    That is an awesome project.
    Thank you.

    Quote Originally Posted by JohnZ View Post
    I have a few questions...

    How did you separate the negative from the chassis & earth ground.

    I believe there is a sense signal that has to see a small load to turn the PS on. How did you signal them to turn on.
    It is quite easy, but you must be handy and know what you are doing. Don't just cut the earth, as some internet heroes are doing, because that makes your PSU extremely dangerous to use. The protective earth must be kept on the mains side and the case. This is how I did it. Of course, you must remove the electronics from the case, which is a bit fiddly, but easily can be done if you are handy and not violent.





    Quote Originally Posted by JohnZ View Post
    Did you make or purchase the plug on the low voltage side of those power supplies.
    I purchased a bunch of these AMP connectors from Digi-key.



    https://www.digikey.com/en/products/...xoCxYE4QBdAXyA

    I think it is better to use connectors than soldering wires to the PCB. For initial experimenting I offered one PSU because I could not wait for the long delivery time from USA to Sweden, so I soldered for testing, but the four used for my project are connected through the connector. Whatever you do, DON'T drill through holes because the PCB is a four layer PCB and you don't know what you are drilling through. Some internet heroes drill holes, but in case you want to save the connectors, it is much better to solder the wires.

    Quote Originally Posted by JohnZ View Post
    Those appear to be the hot swap variety found in many of the Proliant Gen5 and newer servers. I probably have a few dozen of those in bins as spares before we got rid of that server line. This would be a great project those are designed to run 24x7x365 for several years pushing close to max load. We had some pushing 1100-1200 watts (shared across 2 power supplies) for close to 7 years without breaking a sweat. They came in 460, 700, and 1000 watt versions if I recall correctly. There were failures within a data center full of those, so it would be a good idea to have a spare or two on hand. However, the big issue with this HP servers was the backplane between the power supply and the motherboard. HP cheaped out of the caps, and they were on the motherboard! We had an 80% failure rate of those in one data center. But that should also mean that tons of the power supplies should be on the market for dirt cheap for projects like this.

    I am very curious how you interfaced with those power supplies.

    Thanks, John Z
    Yes, they are from G5 Proliant serves and yes, they are hot swapable, so they have all the necessary protection built into them. The fans are also fairly quiet, unless the load is very high. We used a few hundred at work in a safety critical environment, and when all the servers were replaced due to planned modernisation, the servers were binned and I saved a few for my own use. During the years we used those servers a few of these failed, but never really cause any problems. The servers were running H24/7, and the PSUs were rotated, which means that the running ones got replaced with stored ones on a regular basis, so they were all used. We believe this is the best way of keeping them alive. Our PSUs were all 1kW type. Due to the application the servers were used, these never been sold only binned. We apply a maintenance replacement schedule and replace the servers all at the same time. Funny that we have so different experiences, we have had very few failures but OK, we did not use them for 7 years. I also think that the early series were a bit more prone to failures than the later ones and we never buy the most modern, latest and greatest hardware, only after they have been tested by others...

    https://www.youtube.com/c/AdaptingCamera/videos
    https://adapting-camera.blogspot.com


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4th axis as a "poor man's lathe"

4th axis as a "poor man's lathe"