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  1. #1
    I have purchased this frame:

    http://www.mekanikacnc.com/m36.html

    However, it does not come with a 'bed'. When looking at other CNC frames, I notice that they have an aluminum bed that is able to clamp things onto it. Is this the best type of bed to go for or should I just get a piece of mdf cut to fit?

    Cheers


    ice.

  2. Ice,

    Aluminum is rather expensive for a bed if you go the solid plate with T channel route. It is still not "cheap" if you go the aluminum strap that you true and surface. MDF could be used but realize that it will warp over time and need to be checked regularly to resurface as needed. High grade plywood (marine grade will work very well) is also an option as is going with a plastic like HDPE or UHMWPE.

    It really depends on you budget and how accurate you want things to be. With that type of frame the bed, will add a good bit of rigidity to the whole structure. If on a rather tight budget I would save up and get the HDPE (15 - 20 mm thick would do), surface it and then bolt it down to the bed. As that will allow you to bolt to the bed rather easily and also give strength that will rival the aluminum bed; without the cost of the aluminum. Now saying that HDPE is not cheap either in large sheet sections so sit down and look at the budget before you jump into anything.

    Good Luck

    Michael

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  4. #3
    I use 18mm MDF on my machine bed, which is considerably larger and I think it's a good choice for your machine.
    1. You can screw directly into it
    2. You can surface it with the machine to get it precisely flat (parallel to X&Y), unlike aluminium which you can't surface as that frame is nowhere near strong enough.
    3. It looks like a cheap frame anyway, so no point spending lots on the bed.
    4. B&Q will cut it to size for you so you can get 4 (?) pieces from one sheet which is 17.48
    5. Skips are a good place to find MDF :whistling:
    A sheet of MDF will not be as strong as an aluminium or HDPE bed, but considering the strength of the gantry / rest of the machine I think that's nothing to worry about.

    It also depends on what sort of things your machining. If you're using a lot of cutting oil/coolant (probably not likely?) then HDPE is much better for obvious reasons.

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  6. #4
    Hi,

    thanks for the pointers, I was hoping to cut aluminum with this frame. The guy who sold it to me said it is capable of doing aluminum but I am starting to wonder if this is incorrect information from what you have said (this is my first foray into CNC'ing).The frame was about the same cost as the one from CNCDUdez (I found that after buying this frame and he shows milling aluminum with his frame). I have all the motors etc ready for mounting.

    I will go for the MDF bed route and see how I get on - if it is a complete waste of money then I may just opt for one of CNCDudez frames instead as he has shown some vids of that cutting alu.

    Cheers

    ice.

  7. #5
    Quote Originally Posted by icedfusion View Post
    I will go for the MDF bed route and see how I get on - if it is a complete waste of money then I may just opt for one of CNCDudez frames instead as he has shown some vids of that cutting alu.

    Cheers

    ice.
    While I hate MDF with a passion I agree with Jonathan in that I wouldn't waste any more expense on this machine than MDF cost's.!! . . . I'm also Sorry to say this but you have just as much chance of cutting concrete has you have in cutting aluminium effectively or accurately with this machine. . . Forget it.!!

    I'd also suggest if you want to cut Aluminium seriously you think about other options than the alternative you have in mind.:whistling: . . . Have considered designing or making your own machine custom to suit your needs.? It's not as difficult as you would imagine and there's plenty of good help and advice around.

    If you haven't the equipment to build it your self it's still possible to build your own custom machine by having the main components made for you, which you then basicly just assemble.
    I have helped and cut parts for loads of people who have done this with great success. It obviously works out slightly more expensive than full DIY but often it still works out cheaper or the same as buying kit's like the ones you see about.? . . Why . . .Mainly because you only build it ounce and it does exactly what you need because it's custom to your needs.! . . .. Unlike the kits which are usually a compromise or has is often the case due to 1st time CNC Inexperience, It only just border line fullfill's your needs which you then quickly out grow as your CNC knowledge and needs increase. . . . Or worse still and unfortunatly I see all too often doesn't do what the buyer thought it would or like in your case missled into beliveing it can do more than it's capable of.!!. . . Which you then end up selling or canabilizing to make another machine better suited to your needs. Either way you usually lose money and cost's more than bulding DIY ounce.

    The other route or approach which unfortunatly again I see all to often and recommend you ABSOLUTLY DO NOT TAKE is to buy the kit, then when it doesn't perform as expected try to upgrade.!! . . In my experience It nearly ALWAYS ends up costing more than cutting your lose's selling what you have and starting again.

    Like I say seriously think about your needs and building or designing your own machine, it's not as hard as you might imagine or expensive and there's good folks willing to help/advise.

    Buy MDF for this one.!!. . . . Because I don't think you'll have it long.

  8. #6
    Thanks for your honest opinion Jazz.

    I wanted a smallish CNC machine for cutting aluminum parts for my hobby (it is around A3 size).
    I believe the other parts I have should be up to the task of milling alu - but it appears that my frame is not! I was hoping to not have to build my own frame - but rather create my cnc machine from constituent parts.

    As to creating the actual frame itself, I really would not know where to start or what would be needed to create a frame stiff and accurate enough to mill aluminum, hence why I bought it from the advice I was given at that time.

    Browsing around here, this one looks like it could be up to the job:

    http://www.mycncuk.com/forums/showth...ull=1#post7002

    but I would not be able to at this stage design anything like that to give to someone to be able to cut for me.
    If someone here is able to create something like that for me then I would be very willing to discuss costs etc with them

    Cheers

    ice.

  9. #7
    Quote Originally Posted by icedfusion View Post
    but I would not be able to at this stage design anything like that to give to someone to be able to cut for me.
    If someone here is able to create something like that for me then I would be very willing to discuss costs etc with them

    Cheers

    ice.
    Can't speak for others but I would be more than willing to help if your not in a great rush.
    Also I have a machine design and actually have a half built machine sat on the bench(And has been for toooooo long now because I'm always cutting some other buggers stuff.!!) thats very similiar to Steve's just not with the 4th Axis capabilty machined into the gantry sides that will be for sale when finished.

    I will drop you a PM with contact details if you want to have a natter about this or building something smaller or more custom to your needs.

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  11. #8
    Much appreciated, look forward to having a chat!

    Cheers

    ice.

  12. Jazz,

    I have no idea about who's other stuff you could be speaking of. Ice, Jazz has a lot of experience and not helps in getting the project done but helps in getting over sections of the knowledge needed to use things to their best ability.

    Good luck and hope things go well for you.

    Michael

  13. #10
    Quote Originally Posted by JAZZCNC View Post
    Can't speak for others but I would be more than willing to help if your not in a great rush.
    I'm also willing to help, with the same criteria. I've not got enough time at the moment to make a whole machine, though I would like to, as I've already agreed to make another and can only do it at weekends due to being at University. However if you need any parts made or designed then I'm happy to help.
    If you use skype / msn then my address for both of those is in my profile should you wish to discuss things that way...or whatever.

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