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  1. #11
    Wow, some heavy-duty ideas there:)

    I was also advised never to weld the thing 100% and i am not doing so now.

    The base frame will hopefully be welded and gusseted/triangulated as one piece, right up to the support pads for the motion beams.

    The beams for the Y-axis will then be bolted on so they can be adjusted, paralleled and shimmed level to each other and the bed area. Once they are set, the X-axis/gantry will be easy to fit.

    That is my plan but my machine is far smaller at only 1250x1250mm cut area. I am thinking of using 50x50x5mm for the whole build including the single gantry beam.

  2. #12
    Here is another idea. You will need a torch height control. Once you accept that as a design feature it becomes obvious that the torch needs to be raised and lowered by a DC motor driven by a power op-amp. This hugely simplifies the THC and greatly reduces the weight of the torch assembly which, in turn, greatly reduces the weight of the gantry needed to accelerate it. It also reduces the wiring and without electronics at the torch head it makes you immune to interference from the arc.
    If you think of torch height as an obvious job for a DC motor it is not hard to get cut and pierce heights using micro-switches rather than using a computer and vast hardware to do something absurdly simple. There are more ways to kill a cat than building an Arnold Schwartznegger, terminator look alike, cat stomping machine.

  3. Yes I was thinking of an adjustable 'Z axis', the diagram of the table was only a rough idea.

    I'm thinking a basic frame 75x75x5 with the braces out of 50x50x5. I'm looking to cut 6 and 10mm mostly maybe some 12mm sheets so I need to build a table braced to support a 12ftx6ft x15mm sheet if need be I will increase the sizes or just make it all outta 75x75x5???

    The image of the table I attached had a .dxf file of the slat support designs I must redesign these to suit the size of table I go for and I will price them for cutting in a local engineering shop.

    My biggest problem of the whole build is the motors and the rails setup. The fabrication of the table and the separate supports for the gantry is the reasonably easy part?

    Do I have to buy the rails as a one piece or can they be joined?? Also how many do I need??

    https://youtu.be/vETkf1sqo3M
    This lad used angle irons and rollers like a roller gate set up for the liner rails will this system work?? is it a cheaper method??

    Thanks again for the replies its great seeing that people are willing to talk and share there views.
    Gavin,

    F1 Transportation & Engineering Services
    f1transportationservices@gmail.com
    We Move, Repair & Fabricate.

    Facebook - https://www.facebook.com/f1transport
    LinkedIn - https://www.linkedin.com/pub/f1-tran...ces/61/783/a06

  4. #14
    You can say 75x75x5 until the cows come home but it still won't mean anything. It isn't what you use it is how you use it. At the moment you are trying to build a bridge without appreciating how a bridge works. More James May, less Jeremy Clarkson please.

    It might be worth mentioning that all your problems are down to the idea that it will look really neat if you lift it off the floor. If you sit it down on the floor all your problems evaporate, well, so long as the floor isn't flammable

  5. #15
    Quote Originally Posted by F1transportationserv View Post
    Yes I was thinking of an adjustable 'Z axis', the diagram of the table was only a rough idea.
    If by adjustable, you mean a torch height control, then I would say for a build of your size it would be essential, not just a thought ;)

    Quote Originally Posted by F1transportationserv View Post
    My biggest problem of the whole build is the motors and the rails setup. The fabrication of the table and the separate supports for the gantry is the reasonably easy part?
    One thing I have learnt so far is to take it all into consideration, but build it in parts.

    Quote Originally Posted by F1transportationserv View Post
    Do I have to buy the rails as a one piece or can they be joined?? Also how many do I need??
    Liner rail like HiWin can be butt-joined if carefully aligned, longest bit in one length I think is 3m. As to how many, if you take a look at the specs, they can take a massive load, the 15mm section am looking at can roll a 1500kg load! It must be fitted correctly though with side support etc.

    Quote Originally Posted by F1transportationserv View Post
    This lad used angle irons and rollers like a roller gate set up for the liner rails will this system work?? is it a cheaper method??
    Cheaper, yes, better, no.

    I would look at proper linear rails, one per side probably 25mm size, but thats just a guess. Get the carriages fitted with wipers and scrapers.

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  7. #16
    What i said in the long post before is still valid, so maybe read it a couple of times more, cause you will get there if you think more and more deeply

    for example:

    -Hiwin 20 size rail/ or MGW15/

    If it was ok Hiwin 15 size rail, i would have told you that. The savings from HGR15 to HGR20 are very small if none, but with the small blocks on the 15 size rail you will have much more problems designing the thing.

    I was talking that if you design it properly you could even use 4 rails and only 4 blocks in the whole machine. Using the long HA blocks, where each block is 90mm long. And for sure 4 rails and 8 blocks if you dont feel like minimalist design is for you. After all if you buy from China 4 bearing blocks more, it will be only 120 euro more in the whole build.

    As you were told, there is no problem connecting Hiwin Rails, especially in plasma build.


    -While on a small table speed is no problem, on such a size you need things to be really fast. I would go as far as to say that you need 800ipm real life speeds with serious acceleration there . Cause bad things happen on plasma when deccelerates and you have crappy THC . You will need to cut thin stuff something like more than 10000mm/min

    -Again - THC is a must


    So , make the machine separate from table. Forget the stupid table for now. Invest money and effort in the actual machine. Later having THC you can support and cut the shit on a basic frame, which once you start earning money can upgrade as per your desires.

    How hard could be to sit down and design a modular sides design from that 75x75x5 or whatever. Like at the photo bellow. As i said personally will use at least 100x100x3 . You are talking about 3.6meters long+ 4 legs 1m high each side. But size really it does not matter if you use THC and simply is strong enough not rack the gantry.





    -simple 1 beam gantry with one rail. Similar to the video before. Forget about the monstrous machines from pictures. they are made to route and drill also, driven by powerful servos, etc...
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    project 1 , 2, Dust Shoe ...

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  9. yes brilliant thanks the previous massive machines (first images i found of the type of design) were only generating ideas ie separate table and rails of that type design.

    so whats my next step start drawing? or what do I need to do?

    something similar to the image above is what I'm looking to put together.

    Also sorry if I seem eager I'm just unsure what way to go with things :)
    Last edited by F1transportationserv; 29-06-2015 at 12:15 AM.
    Gavin,

    F1 Transportation & Engineering Services
    f1transportationservices@gmail.com
    We Move, Repair & Fabricate.

    Facebook - https://www.facebook.com/f1transport
    LinkedIn - https://www.linkedin.com/pub/f1-tran...ces/61/783/a06

  10. #18
    Quote Originally Posted by F1transportationserv View Post
    so whats my next step start drawing? or what do I need to do?
    I think that first you have to understand the problem

    Your problem is the change of direction on thin sheet and is all to do with accelerations.

    For a first machine you will probably build your gantry out of 75x75x5 and fit enormously powerful motors to overcome the inertia. Strangely you might use the same motor for the Z as you do for the other axes. You might even use 2 motors for the long axis and try to connect them electrically

    1 Newton force will accelerate 1 kg mass at 1 m/s/s

  11. The Following User Says Thank You to Robin Hewitt For This Useful Post:


  12. #19
    Quote Originally Posted by Robin Hewitt View Post
    Strangely you might use the same motor for the Z as you do for the other axes. You might even use 2 motors for the long axis and try to connect them electrically
    I can see that a plasma machine won't need heavy lifting capability on the Z axis but why does slaving 2 motors for the long axis merit a ROFL, unless you mean connecting two motors with a choc block
    Last edited by cropwell; 03-07-2015 at 10:22 AM.

  13. #20
    I find lots of things funny, especially since the blood supply to my brain failed last year. In fact I find it difficult to take most anything seriously

    We must remember that the decision to use 2 motors usually follows a failed Google search for extra long timing belts. You have to be oblivious to the problems it can cause or you would not give up that easily.

    How many people check the driver initial step pattern on power up before they shop for this? Do they fit a stall detect system to ensure that both sides fail at the same time? Do they fit one location sensor and pray or two sensors and then decide prayer was the easy option?

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