Thread: MDF or ply?

  1. #1
    What do people tend to use for the routers bed for general wood machining / profiling?

    Max working area on mine will be 1250 x 1250.

    Cheers
    Dan

  2. #2
    For mine I'm thinking 25mm Birch Plywood with sacrificial MDF tops. If this proves not so good I'll probably move to a T slot bed with MDF sacrificial tops.
    I was planning on screwing down my work pieces to the top but I may drill the birch at regular intervals and use bench holdfasts such as these Buy Axminster Bench Clamp from Axminster, fast delivery for the UK but they may not hold the piece well enough.
    For some work I plan to use a small vacuum bed that will clamp onto the main bed, I was also need some raised beds to bring thin stock up to the cutter so that the Z axis is not way down when cutting.
    So my thoughts are that the main bed would be more for support than work piece fixing. One good thing about the bed is that it can be changed later with minimal disruption.

  3. #3
    I used to use a sabre 404, and the bed was aluminium slotted 200mm wide. On top of that was 5 mm sign board (foamex), and on top of that was 10mm foamex. They were bonded on with double sided carpet tape. Once the 10mm was worn, we cleaned it off by machining it of (table self cleaning option), then reapplied new 10mm foamex. Finishing with levelling the new bed. I'm ready to build a machine at the moment and looking at this way of doing it. The foamex doesn't distort like woods. I would steer clear of mdf, it has aims of its own and isn't healthy either.
    Last edited by alex wight; 21-10-2013 at 02:24 PM. Reason: Spelling

  4. #4
    Hi

    MDF has a bad tendency to sag over time, Just place a scrap length say a metre long between two supports and leave it for a few days it will sag by its own weight and stay bent. If you do use it use plenty of supports under the sheet

    Concrete form ply is worth looking at. (Not the cheap home hardware store kind) I went to an engineering exhibition recently and found a product called Doka Xlife Plywood the sample I have is 20mm thick and is made up of about 15 ply's including a plastic wear surface on one side.

    I have it on my list as a Router bed material. I plan to drill the bed (With the CNC router) with a 50mm spaced hole pattern for threaded M8 metal inserts, available from cabinet hardware suppliers. This ply is extremely dense. I am sure other competing form ply suppliers will have similar product.

    I have no connection at all to the company.

    Regards
    John

  5. #5
    John,
    Funny how you overlook things you've used before, the M8 inserts is a great idea, I'd recommend these too, Toolstation > Screws & Fixings > Nuts & Washers > Pronged Tee Nut
    It's true that MDF is iffy stuff and I normally avoid because of dust and Urea-formaldehyde release but for a sub-bed that is fully supported it's relatively cheap and flat.
    For now I'm sticking with Birch Ply for the main bed + M8 pronged nuts and I'm going to investigate foamex.
    alex, does the foamex compress much ? I imagine that over a large area it will not.
    Last edited by EddyCurrent; 21-10-2013 at 03:05 PM.

  6. #6
    The foamex is a relatively strong material when supported. It's lightweight which is why it's used for shop signs ect I used a scrap piece to just scratch the surface when doing jobs, to let me see what I was ready to do on the real material. It saves making errors on the real job. It's non porous as well so is very good for a vacuum bed, and if fluid is used, it doesn't swell either.

  7. The Following User Says Thank You to alex wight For This Useful Post:


  8. #7
    Hi Eddy C

    T Nuts are OK but they tend to work loose and fall out after they have been used a bit unless you put another sheet behind them.

    These are better....

    Click image for larger version. 

Name:	Insert.jpg 
Views:	308 
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ID:	10483

    https://www.google.com.au/?gfe_rd=cr...serts+for+wood

    You just drill a hole and screw them in with an Allan key (or see video below for another type). Very strong.

    http://www.youtube.com/watch?v=tIhEqoKE8Dc

    Regards
    John
    Last edited by John McNamara; 21-10-2013 at 03:42 PM.

  9. #8
    Funny, but i use one by one as sacrificial beads the plastic doors of a McDonald restaurant i found near the trash Hard plastic filled with paper or fabric.

    I tried aluminum bead and slowly i started f^^^ing it up. MDF did not work. But bolting sacrificial plastic layer/10mm in my case/ and fixing all the jobs except aluminum, with hot melt glue gun works best for me. Fast, cheap, easy to fix, reliable and easy to scratch and clean from the plastic bed, wood or plastic part.

  10. #9
    Quote Originally Posted by John McNamara View Post
    Hi Eddy C

    T Nuts are OK but they tend to work loose and fall out after they have been used a bit unless you put another sheet behind them.

    These are better....

    Click image for larger version. 

Name:	Insert.jpg 
Views:	308 
Size:	39.8 KB 
ID:	10483

    https://www.google.com.au/?gfe_rd=cr...serts+for+wood

    You just drill a hole and screw them in with an Allan key (or see video below for another type). Very strong.

    Installing Metal Threaded Inserts For Wood - YouTube

    Regards
    John
    Thanks John, I've used similar to those before, I see what you mean about the T Nuts with vibration about. Do you think he's correct when he says it's not a screwdriver slot ?

  11. #10
    Quote Originally Posted by EddyCurrent View Post
    John,
    Funny how you overlook things you've used before, the M8 inserts is a great idea, I'd recommend these too, Toolstation > Screws & Fixings > Nuts & Washers > Pronged Tee Nut
    If anyone wants to buy some of those for a good price let me know as bought a box of 1000 for my router bed and never used them.

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