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  1. #1
    My machine is nowhere near as nice or heavy as many others here, but I don't feel I have to be ashamed of it, I built it completely on my own, cut and drilled, threaded every bit of it, so all in all, I am pretty proud of it, especially since I am an "office rat" engineer since the last 30-ish years. At work I never have to use any other machine than a computer, and even that only through the keyboard. Never the less, I miss my first 20 years of working life, not only because I was MUCH younger, but also because I do like to use my hands and brains in many ways, so at home and as a hobby, I take every opportunity to get my hands "dirty".

    So, this is how my CNC looked like a few weeks ago.

    Click image for larger version. 

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    I built this a few years ago and use it mainly for plastics and PCB, but also mill aluminium pretty well on it, so for my needs the machine is definitely good enough. From the start I kept track of the weight, but as time went by, the machine got heavier and heavier after all the modifications I constantly make. I knew it was more than 100kg, but not more exactly. The other day I managed to check it more precisely by placing two ordinary bathroom scales under it, just for fun, to check the exact weight. One showed 60kg, the other showed 65kg, so now I know that the total weight was 125kg, which explains why it was more and more difficult to move it around. I noticed this "problem" some months ago when I moved to another, larger room in my house. This is the way I had to do it:

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    I had to lower the round black feet on all four corners to lift the machine, remove the wooden blocks the machine normally resting on, raising the black plastic feet to lower the machine on the four castors, move it to the new place, lift it again, place the wooden blocks under it and lower the machine on those. It was a complicated operation, which actually put me off from doing any improvements and modifications, so I decided to do something about it.

    What I did was I ordered four linear actuators, installed castors on them and installed on the four feet.



    After installing the actuators, my CNC looks like this if I take look in an upskirt view...

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    Each linear actuator can lift 152kg, so I knew I had good margin. The only thing I am not that happy about is that they extend to three different lengths, only two are the same, but in this application that is not critical.

    I made a control box with some relays, a switch and three LEDs to control the actuators.

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    Of course, simplest would have been to use a 3-way two pole switch, but I had no such thing in my boxes and drawers. I had however more than enough relays to make it, so I went for a relay based solution.

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    The box isn't as nice as I wished for, but it does what I wanted it to do. This was the first time I made this sort of engraving, so it's OK for now, but I will make a new box top with better polished surface another time. Now it is easy to move my machine around, just flipping a switch and that lifts the machine with the wooden blocks permanently attached under it's feet. No more crawling on floor for a simple move.

    Anyway, the subject of moving around heavy machines is often discussed, also if CNC can be permanently on castors or should rest with better stability. Initially, my CNC was on large, heavy duty castors placed under its four feet (not like you see in the top picture), but even though each had a lock, preventing rolling, the CNC was shaking because of the rubber wheels and the fact that they are wheels. So my conclusion was that castors are good for moving the machine, but using it resting on castors is not a good idea at all. I considered fixing it the wall, but then I concluded that it will shake the walls and it would be better to let it rest on wooden blocks on my floor. Under the teak parquet I have concrete floor, so there is no floor vibration, and the CNC is resting firmly on the soft-ish wooden blocks, which are soft enough to dampen the machine vibration, but hard enough to provide very good stability. Actually, my CNC works much better, with higher speed, acceleration and accuracy than it had when it was resting on castors.

    I feel that my solution with the linear actuators can be used on many other machines as well, and is not adding much to the price of those 400kg + machines, so I don't understand why we don't see any of those. I have seen people building hydraulic systems, which may be needed to machinces which are REALLY heavy, but for the few hundreds of kg our machines weight, I think a pure electric linear actuator is more than enough, simple to implement and can lift quite a lot. Even if a machine weights more than 600kg, it is possible to use the type of cheap actuators I am using, but of course, it may need more than four. In general, I think it ia a good idea to leave some margin, personally I'd feel comfortable to use it up to 400kg, which would leave a 200kg in that case.

    In short, I don't think it is a good idea to build CNC which rests only on castors, it is much better to lower the castors when the machine needs to be moved.

  2. #2
    Hi, thanks for sharing this experience and your solution. My first reaction was that it was rather an over engineered solution, as I am rather more used to small workshop solutions like these or these. However a quick check on eBay suggests those actuators are only around 30 each and work for machines in the 200-500 kg range. Plus as you say simple switches and power supply is all you need. Now I have definitely stored this idea away should I need to move my machine regularly for pass through jobs. The satisfaction each time you flip the switch rather than lie on the floor winding up machine castors like these would hasten the pay back!

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  4. #3
    Quote Originally Posted by Andrewg View Post
    Hi, thanks for sharing this experience and your solution. My first reaction was that it was rather an over engineered solution, as I am rather more used to small workshop solutions like these or these. However a quick check on eBay suggests those actuators are only around 30 each and work for machines in the 200-500 kg range. Plus as you say simple switches and power supply is all you need. Now I have definitely stored this idea away should I need to move my machine regularly for pass through jobs. The satisfaction each time you flip the switch rather than lie on the floor winding up machine castors like these would hasten the pay back!
    Thank you for the comments and the additional ideas of how to move machines.

    I will have to keep this idea:

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    which I think is very good for lighter machines, but lifting a 100kg + machine is something else. I may make one for my table saw, which I also need to move in and out whenever I want to use it. Right now, I can lift it, as it weights only about 40kg, but it is not a comfortable lift because it is fixed to a stand, so to move it, I have to stretch my arms and lift it. As I am getting older, things do feel heavier...

  5. #4
    BTW, yes, my control box is definitely over-engineered, but as I said, I had no switch for the high current and I like to use what I have when it is possible, so I had to use relays. In fact, I am using four relays, two for one side two for the other, because the relays I have can't handle all that current (around 12A) so I use two relays for one side and two for the other. The 12A is just a guess, but my PSU to the acuators is a 12V 8A PSU which is OK for now, but if I stop the motion half way in the lifting process then the PSU stalls and the actuators won't continue the pushing. The rated current is 3A for each, but I haven't measured what is the current needed to start with load. Anyway, on my to do list is the replacement of the PSU with a 12V 82A version. Yes, eighty two amps. Once again, it is over-engineering, but I have many PSUs like these:

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    So I will use one of them.
    Last edited by A_Camera; 17-02-2021 at 02:45 PM.

  6. #5
    You have got me wondering whether a combination of your linear actuators and a lever system like on that bandsaw stand might be ideal for a mobility solution if one need to build a steel frame anyway. Maybe one for each side, as with the additional leverage two 1500N actuators would be good for weights up to 500kg easily.

    Is that a server PSU? I have been told they are a cost effective solution if bought refurbished off eBay.

  7. #6
    Quote Originally Posted by Andrewg View Post
    You have got me wondering whether a combination of your linear actuators and a lever system like on that bandsaw stand might be ideal for a mobility solution if one need to build a steel frame anyway. Maybe one for each side, as with the additional leverage two 1500N actuators would be good for weights up to 500kg easily.
    I had a similar idea as well, using two actuators, but did not do it because I need the space under my CNC for the vac. Also, the one in that link is I think too weak, but I can be wrong about it. It is however definitely good enough for a band saw or similar.

    Also, beware, these are cheap actuators, only a motor with gear box, a stainless steel threaded rod, and an aluminium tube driven in and out with a Delrin nut inside the aluminium tube, so I would take that 1500N with a pinch of salt. I did a test lift with an unmodified actuator, and that worked well, it could lift one end of my CNC, so the actuator seems to be good for at least 60kg. Not sure I'd trust it for repeatedly lifting the specified 1500N, which is 152kg, but I definitely trust them for 100kg each, so a 400kg machine should not be a big issue with the proper PSU.

    Quote Originally Posted by Andrewg View Post
    Is that a server PSU? I have been told they are a cost effective solution if bought refurbished off eBay.
    Yes, it is from HP G7 servers. We threw away quite a few last year and I saved a few PSU. They are excellent and easy to use, but beware in case you want to buy a few, the 12V GND is connected to the earth, so connecting these in series is a bit tricky. Of course, the problem is solvable, but you have to be aware of it

  8. #7
    Quote Originally Posted by Andrewg View Post
    rather than lie on the floor winding up machine castors like these would hasten the pay back!

    Ah, I've been there - brilliant machine feet, but a complete bugger when you've got a bench & mill weighing in at over 200kg and you're trying to get to the foot at the back. We need someone to design a wrench for the cog for these - my thumbs ain't what they used to be.

    A_Camera - like your idea, but over complicated. Why not build a multi-purpose jack-plate (basically what you have... but you can place it under any machine to lift it)

  9. #8
    Quote Originally Posted by Doddy View Post
    Ah, I've been there - brilliant machine feet, but a complete bugger when you've got a bench & mill weighing in at over 200kg and you're trying to get to the foot at the back. We need someone to design a wrench for the cog for these - my thumbs ain't what they used to be.
    Exactly what I got tired of, crawling on the floor, reaching the rear two was never an easy task with my previous solution. Doable in case I had to do it, but was not very comfortable and took some time to lift all four corners and pull out the machine. Now I do it with the flip of the switch, standing on my feet, and the machine is moved out in less than a minute.

    Quote Originally Posted by Doddy View Post
    A_Camera - like your idea, but over complicated. Why not build a multi-purpose jack-plate (basically what you have... but you can place it under any machine to lift it)
    Thank you. Yes, it might look complicated, but I think actually that to build a multi purpose jack plate is worse and would take as muck time as this one. Once I figured out how to do it, it took only about one day (8-10 hours of work) to complete the work, from start to complete installation. Not included the time it took to make the control box, that was a few hours extra. Now to make a jack plate would have been more complicated, especially since I don't have a welder or any material which could be used for that. I also wanted a permanent installation, not something I have to store elsewhere. I think it is better this way, it is always available and ready for use. As I said before, using a simple two pole ON - OFF - ON switch would make it a lot simpler, but in my case, it was a choice I made to use things I had at home readily available.

    It's a hobby for me, so the extra time is no big deal and the complexity thing is really nothing for me. But yes, definitely over-engineered for one who wants to keep it simple. As it is a hobby, I don't have to think about failure, or that some solutions take more time than others.

  10. #9
    In the meantime, this evening I released the second part of my video series about this project, it is about the control box and the design of it.



    Welcome to watch it, in case you are interested.

  11. #10
    Kitwn's Avatar
    Lives in Don, Tasmania, Australia. Last Activity: 2 Hours Ago Has been a member for 3-4 years. Has a total post count of 814. Received thanks 97 times, giving thanks to others 37 times. Referred 1 members to the community.
    Quote Originally Posted by A_Camera View Post
    Actually, my CNC works much better, with higher speed, acceleration and accuracy than it had when it was resting on castors.
    That's very interesting. I've just re-built my own machine onto a base with castors and in spite of checking the alignment of rails and ballscrews I have had to reduce the max speed from 9.0m/min to 7.8m/min after a couple of stalls. I had not thought that a small amount of rocking of the whole machine would have a negative effect on it's operation but may have to think again.
    Engineering is the art of doing for ten shillings what any fool can do for a pound.
    Wellington.

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