Machine base (aka table)

New Home Forum Mostly Printed CNC – MPCNC Troubleshooting – MPCNC Machine base (aka table)

This topic contains 49 replies, has 10 voices, and was last updated by  Ulli 2 months, 2 weeks ago.

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  • #6773

    Ulli
    Participant

    Hi all,
    what is the most practical yet technically optimal suggestion for the base of the machine, the table or structure that the MPCNC will rest on? MDF, plywood, a timber frame, aluminium extruded profile frame, … ?

    Of course, it depends, as always, on the demands and goals. This ranges, in my case, from 2D-milling of MDF, PVC, various woods and alumimium, 3D from polyurethane foam to wood, and moreover a somewhat open construction to also make mortises and tenons. 4D milling not excluded for the future.

    I’ve seen many examples of your working machines, what would you reommend as an optimal solution, if there is any? Also keeping in mind that the leveling should be easy, and that a sacrificial board should be easily placed and replaced. –

    Side-requests: The machine should be mobile, yet have a solid standing, maybe even stowable in an upright position. Oh yes, I opted for a 20″ by 30″ size.
    Sorry for my non-native English terminology!

    Thanks and cheers!

    Ulli

    #6799

    Ryan
    Keymaster

    This is what I keep using, https://www.vicious1.com/table/, but it is far form “ideal”. I Think I will end up welding together as a removable leg type base for this. I do like the 2×4 wood top and once it is built (to keep it square I build the top as one piece), I cut it so I can replace the center section easily.

    It would be nice to have wheels, or removable legs. There are some smaller gorrila racks at my local hardware store for $40 that would make a great base for these. Or if you want to spend a little extra there are the flat top rolling toolboxes with 1-2 drawers and a tool storage area.

    I am always looking for a better solution, but 2×4’s are so cheap and easy to work with it is hard to beat.

    #6808

    Ulli
    Participant

    Thanks, of course I had seen that before. My carpenter’s skills still have some headroom, my work would probably rather resemble a Picasso drawing. But it gives me some ideas. First pictures in the neighbourhood of this,

    #7315

    Tyler Smith
    Participant

    So I have actually put a lot of thought into this because i live in a small apartment and can’t have my table out an about so I found this table. http://www.woodworkerssource.com/blog/woodworking-projects/how-to-build-a-folding-workshop-table-with-many-uses/ I like this table because it is made to be very stable (its a router table) but folds up. On thing I also liked is the exchangeable top. obviously I’ll need to work out a top that will work just right for the MPCNC but i think the potential for this will be great.

    #7320

    Ryan
    Keymaster

    I like that table. I want to make these on just a flat top an be able to either stack them on gorilla racks or put them on a base, this looks like it would work great for that.

    Cool

    #7321

    Ulli
    Participant

    Had the idea of folding the table up (around an axis through the cog, more or less) too. Folding the rails is not so promising, but the whole table could be swept up. Or lifted and stacked in a rack (Ryan, pls design a mostly printed fork lift!). I got a simple large plywood board now that I enforced (not really necessary for 21 mm thick birch playwood) with 40 by 80 (mm²) timber beams. But that frame is a good base for legs or hinges or… If the room is high enough, one could also winch up the whole affair to the ceiling.

    More on my table real soon.

    Cheers,
    Ulli

    #7322

    Ryan
    Keymaster

    I drove a forklift For more years than I care to admit to pay for school…..I really don’t want anything to do with them. Even though it never stopped feeling like I was getting paid to drive a go-cart.

    The ideal of an angled mill seems promising, it even pretty much handles the cutting debris without a vacuum! Maybe even mounted on the wall (why not)???

    #7347

    Jon
    Participant

    My MPCNC is vertical. Well….almost. the cnc is built, I am now in the process of building the “table”. My table has a vacuum built in to hold down the work piece. It will be at 70 degrees. My milling dimensions are 48×48. This puts my table with extensions at 54×60. I want my table a little long for a possible add on later.

    #7352

    Ulli
    Participant

    Basically, it’s a matter of renaming two axes. Plus some remedies to keep things at their place. You have to do that anyway, but the added asymmetric influence of gravity has to be regarded. As Ryan remarked, getting rid of the debris is potentially a bit simpler.

    #19262

    Guys, how do you stick the material to the table? My ideas are:
    1. Drill some holes in the MDF which i use as table with some thread. Then use some fixators, screwed into this thread. But, making thread in the wood does not look reliable.
    2. Drill some holes and use something like a metal threaded collars, glued or fixed in the table holes. (i’ve seen something of that kind somewhere)

    are there any better/simplier ideas?

    #19281

    Barry
    Participant

    I just use screws and clamps. I use the plastic printed hold downs where I think the router might go, the metal ones I use where I know the router will not get close, or where the dust shoe has to pass over.

    https://goo.gl/photos/rsGdFYbYgv94LM8j8

    I have also used superglue and painter’s tape. Put tape on your spoil board and on your material being cut. Then a bunch of superglue on one piece of tape and spray quickset on the other. Press the two pieces of tape together and hold for a second. So far nothing has come off, and even if your tabs get cut off, inside cut out pieces will stay attached.

    This is how I attached the piece of acrylic in this video.

    #19288

    Thanks Barry! Thats an interesting method using glue, need to try this also 🙂
    Regarding the metal fixings – how do you mount them to your board? I suppose there are no nuts underneath, or ?

    Forgot to tell one important argument – in my case I assembled the CNC on the MDF board, which is supposed to be put on the other table, so it is supposed to be flat on the bottom. That’s why nuts on the bottom side do not suit me. I need something that will not increase height of my board… Mmm, maybe thats my problem, but I wanted to make CNC as portable as possible…

    #19291

    Barry
    Participant

    No nuts, I just use screws wherever. I’m sure eventually it will mess up my table too much, but the spoilboard takes the brunt of it. When it comes to that, I’ll just use the router to surface off the table top and glue a new piece in place. You’re going to have a hard time keeping your machine flat without a sturdy table underneath your mdf. Not sure where you live, but some hardware stores sell slatwall that you could cut to fit your cut area. This would give you basically a row of t-tracks that you could use for hold downs.

    #19350

    Derek P
    Participant

    I have a couple of posts in the hardware section that might be useful. The first is a folding plywood table built using pocket hole joinery. The second is a U shaped tub, machine base of MDF and a spoil board.

    #20622

    David
    Participant

    Is there any reason not to simply fix everything to a 3/4″ MDF sheet and place it on the floor to use it? I can’t think of a mode stable surface than a concrete floor…

    #20623

    Barry
    Participant

    @david, but is the concrete floor flat? Most aren’t.

    #20626

    David
    Participant

    I assumed it was flat.. it looks like it, but I guess I should go do a level test.

    #38762

    Benjamin Shaw
    Participant
    You’re going to have a hard time keeping your machine flat without a sturdy table underneath your mdf.

    I’m trying to find out more info on tables, but didn’t want to start another thread so I dug up this one.

    Barry, you mention having a table underneath the MDF, are you referring to a tabletop? As in the top having two layers, a top and then the MDF?

    Also, the main page instruction set for a table says to screw down the top (does not specify if this is MDF) and then “cut the center out” so that everything stays square and you end up with a removable portion. How is this cut achieved? A skill saw?

    Also, I see no mention in the instruction for any workpiece hold down features. In a lot of videos, and even the main table image you see evenly spaced holes that look to be about 3/4″. I’ve seen videos of pipes being inserted into holes like this. Where would I find specifications for this layout, and a description of how to use it?

    Thanks.

    #38768

    Ryan
    Keymaster

    Skill saw is what I used.

    Hold downs depend on what you are doing. I just screw to the table or clamp to the edges. I have drilled 9 large holes before so I could put clamps in the middle of the table, but screws are way easier.

    I suggest not inserting nuts into the table, you will eventually need to replace your table so that is a lot of wasted time and space, maybe drill the holes for it and only insert a nut if you need it and only from the bottom, not the top. It is a sacrificial board and will get cut into, you do not want to hit a steel nut.

    For some things I just but a weight on top, others just double sided tape. The method depends on your use and expectations.

    I would say do not over think it and just start using it. You will figure out what you need and can CNC a new table for yourself.

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    #38769

    David
    Participant

    The build in the image isn’t a MPCNC (well, it is a mostly printed CNC in progress, but not *the* MPCNC), but I built the table with a miter saw and a bunch of Simpson strong ties for about $120. This table is 9.5×5.5ft, so for something the size of a typical MPCNC you could probably do the same for around $80 (half the cost was the strong ties). Don’t wuss out on building a table — it’s by far the most important part of the build.

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    #38777

    Benjamin Shaw
    Participant
    I would say do not over think it and just start using it. You will figure out what you need and can CNC a new table for yourself.

    Sounds like a plan. Just going to do a good strong simple table like you have in the instructions and go from there. Thanks!

    #38778

    Benjamin Shaw
    Participant
    Don’t wuss out on building a table — it’s by far the most important part of the build.

    What size lumber are you using here? You happen to have any better pics?

    #38779

    Barry
    Participant

    @david Level and flat are two different things. A floor can be level, but have enough surface features to throw off your table. It can also be flat, but not level, which if you’re using a level on your rails, will make your table top not perpendicular to the z carriage. My living room floor is dead flat, but not level. I have to shim one side of some shelves almost an inch to make them level. Room was originally going to be the garage, so the concrete slopes to one side. My 4 foot level doesn’t rock on the floor though.
    Table = Legs and frame holding the top.

    #38780

    David
    Participant

    I can post a few later when I get home, but they’re not really all that necessary. In my pic I’m using a mix of 2×6 for the outer pieces and 2×4 for the inner and vertical pieces. But that’s overkill for a MPCNC, since you shouldn’t build it this big (and believe me, I tried).

    Just head down to Home Depot and get:
    – some 2×4’s
    – 8 of these (http://www.homedepot.com/p/Simpson-Strong-Tie-18-Gauge-ZMAX-Galvanized-2X-Rigid-Tie-Connector-RTC2Z/204834336)
    – 8 of these (http://www.homedepot.com/p/Simpson-Strong-Tie-ZMAX-Galvanized-16-Gauge-2X-Rigid-Tie-Connector-RTA2Z/100375168)
    – Some pan head screws
    – some wood screws for the cross members

    From there the table design should be pretty obvious, and the Simpson ties should let you test fit it all together before screwing anything down. When you actually screw it down though, make sure you have it all clamped and straight. If you don’t any clamps long enough, just get ratcheting tie-downs (http://www.homedepot.com/p/Husky-1-in-x-12-ft-Ratchet-Tie-Down-4-Pack-FH0829/206802316). That’s what I used, and it worked wonderfully.

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    #38781

    Benjamin Shaw
    Participant

    Would a decent way to ensure the top frame of the table is flat, be to construct it on top of the MDF, screwing it together while it’s on it? I’m picturing constructing the table upside down, using the MDF to make everything flat.

    How flat is 3/4″ MDF in general?

    #38783

    David
    Participant

    I used lumber largely because it was cheap and thick, but I concede it’s not going to be perfectly flat. I used shims to make it as flat as I possibly could for the pieces that hold the rail supports though.

    MDF on its own is extremely flat, but it will adhere to the surface if you screw it down and will no longer be flat. I had grand plans to build an interlocking plywood torsion box table, but got impatient (it was going to be a *lot* of cuts). That would be the best possible option, though.

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    #38784

    David
    Participant

    Also, remember that most of what you’re cutting isn’t going to be perfectly flat either. You’ll have to either surface the cutting area or correct it in software. I’ll be experimenting with the latter in the next few weeks.

    #38785

    Benjamin Shaw
    Participant
    MDF on its own is extremely flat, but it will adhere to the surface if you screw it down and will no longer be flat.

    Ahh. So even if I built the table upside down on MDF, it will still conform to the lumber as soon as I screw it down, unless the lumber is perfectly flat. So I guess at this point the lumber would have to be selected and possibly be machined somehow to be as flat as possible or use shims.

    #38786

    Benjamin Shaw
    Participant
    I’m using a mix of 2×6 for the outer pieces and 2×4 for the inner and vertical pieces. But that’s overkill for a MPCNC, since you shouldn’t build it this big (and believe me, I tried).

    I’m looking at expanding my 2’x 2′ existing MPCNC to be more like 52″ x 26″. You say “you shouldn’t build it this big, I tried” Do you think ill fail at the 52″ x 26″

    Thanks so much for the detailed list!

    #38788

    Benjamin Shaw
    Participant
    From there the table design should be pretty obvious

    @David. Would the reinforced design be constructed like this?

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