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  1. #1

    Question Spoil/Waste Board Questions

    I'm in the process of building a birch plywood CNC router 4x4 ft. with a 5x5 ft. 3/4" torsion box base.

    I see MDF boards with t-slots cut and can't imagine it having enough clamping force. So for a spoil board I was thinking aluminum t-slot tracks with 3/4" MDF strips in between. Something like shown in this link...

    https://discuss.inventables.com/t/fe...-board/27227/6

    Is it enough to simply screw the t-slots into the torsion box? Will there be enough clamping force without pulling out the screws? What is a good price for 48" length aluminum t-slots?

    The t-slots are ~1/2" high vs. the 3/4" MDF. Is 1/4" enough to dress out the board and have enough left over to run without nicking a t-slot?

    For the strips of MDF what spacing should the screws/bolts be?

    If you have a better spoil board ideal I'm all ears!

  2. #2
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    Re: Spoil/Waste Board Questions

    Quote Originally Posted by Project_Hopeless View Post
    I'm in the process of building a birch plywood CNC router 4x4 ft. with a 5x5 ft. 3/4" torsion box base.

    I see MDF boards with t-slots cut and can't imagine it having enough clamping force. So for a spoil board I was thinking aluminum t-slot tracks with 3/4" MDF strips in between. Something like shown in this link...

    https://discuss.inventables.com/t/fe...-board/27227/6

    Is it enough to simply screw the t-slots into the torsion box? Will there be enough clamping force without pulling out the screws? What is a good price for 48" length aluminum t-slots?

    The t-slots are ~1/2" high vs. the 3/4" MDF. Is 1/4" enough to dress out the board and have enough left over to run without nicking a t-slot?

    For the strips of MDF what spacing should the screws/bolts be?

    If you have a better spoil board ideal I'm all ears!


    Here's the best price anywhere for t-track. Order over $100 worth and shipping is free. You'll need more than $100 worth. https://www.orangealuminum.com/t-tra...es-oa7150.html''

    Most folks trust screws to hold the t-track. However, some, including me, don't trust screws when we don't have to. Lay out t-track on your torsion box. Cut strips of 1/2" MDF to go between the t-track. Glue or glue & screw the MDF in place. I use only glue. Finally, top with 3/4" MDF cut to overlap the edges of the t-track, but leaving the full width of the t-track slot open. Glue or glue & screw the 3/4" MDF in place. I use only glue. An alternative for the top is fastening the full sheet of MDF and use the CNC to cut out the slots. It's hard to get the glue spread on a 4'x4' piece of MDF and clamped in place before the glue sets too much, though.

    Descriptions are not nearly as good as photo and videos. Here's very good video showing what it looks like and explaining it:



    A nice thing about Peter's technique is you don't need screws at all. I use a few to keep the t-track from sliding back and forth, but I don't need them.

    There are a lot of good tips and tricks on Peter's YouTube Channel. Give it a look see.

    I depart from Peter when it comes to spacing the t-tracks. If I recall correctly, he has them 7" or so apart. I tried that spacing and bitterly regretted it. Seemed like the spacing was wrong for what I was cutting - time after time, after time, after time . . . . I have all sorts of wood hold downs, some way longer than they should be. I'm just finishing up my 2nd build. I'm spacing my t-track 4" OC.

    Attached is Peter Passuello's video, Don't Spoil Your Spoilboard. I use the technique. Works like a charm, but IMO, it works best with a touch plate of some sort. I have Bill Griggs' Maker's Guide. There are similar plate on EBay that are less expensive. Or, you can try cutting your own. It is vitally important that you set the the offset for the plate's thickness EXACTLY. Any error, however slight, will leave you cutting too deeply, or not deeply enough.

    I think I've about covered it. Let me know, if I failed to address a question.

    If you have some time to kill, you might want to take a look at my build thread. There may be some discussion about spoilboards in it, although I haven't yet installed mine. I have an order for more t-track coming from Orange Aluminum.

    https://www.cnczone.com/forums/diy-c...machinist.html

    Gary

  3. #3
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    Re: Spoil/Waste Board Questions

    MDF does not hold screws all that well. I put down some multi ply 1/2 inch Birch plywood first and then placed a sheet of 3/4 inch MDF on top. Screwed the entire package down to the table. Surfaced the top and then milled slots for the track. It really needs to be on 6 inch centers, mine is on 8 but 6 is better. Screwed down with short flat head screws. No issues.

    Track, best price I found was with Amazon Prime its "free" 2 day shipping, Price is for a package of 2 48 inches long so I got 4 total track pieces in addition to the ones I already had. Gary got a better deal if you order over $100 worth.

    https://www.amazon.com/gp/product/B0...0?ie=UTF8&th=1
    Retired Master Electrician, HVAC/R Commercial. FLA Saturn 2 4x4 CNC Router

  4. #4
    Community Moderator ger21's Avatar
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    Re: Spoil/Waste Board Questions

    I would never use T tracks, or any type of clamp that clamps the top of the work and is always in the way. I use T nuts in the table, and cam clamps to hold the parts against fences.
    My machine also has a torsion box table, and, I'm putting my T Nuts in a sheet of 3/4" MDF, with a layer of 1/2" MDF on top of that.
    Gerry

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    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  5. #5
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    Re: Spoil/Waste Board Questions

    My tracks are about 3/8 below the surface of the table. The clamps are aluminum and long enough to be out of the path and still hold. Never in the way, if the path goes off its aluminum the bit is hitting. Since I use a 1/4 hard board as a spacer when cutting through, no scars.
    Retired Master Electrician, HVAC/R Commercial. FLA Saturn 2 4x4 CNC Router

  6. #6
    Community Moderator ger21's Avatar
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    Re: Spoil/Waste Board Questions

    Not the tracks themselves, I mean the clamps you bolt into them.
    Gerry

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    http://www.thecncwoodworker.com/2017.html

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    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  7. #7

    Re: Spoil/Waste Board Questions

    Gerry,

    Are there pictures of your board setup? I curious how it works.

    So with your board the 1/2" MDF is the spoil board, the 3/4" just holds the t-nuts. No issue with pull-out or distortion of the 3/4 MDF?

  8. #8
    Community Moderator ger21's Avatar
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    Re: Spoil/Waste Board Questions

    The T nuts are mounted under the 3/4", so they can't pull out.
    Yes, the 1/2" is the spoilboard. It's glued down.

    I'll see if I can find some pics.

    Note that there's no perfect system for every situation.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  9. #9

    Re: Spoil/Waste Board Questions

    Quote Originally Posted by ger21 View Post
    Note that there's no perfect system for every situation.
    Understood. Really just looking for a low cost yet effective solution.

  10. #10
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    Re: Spoil/Waste Board Questions

    Quote Originally Posted by Project_Hopeless View Post
    Understood. Really just looking for a low cost yet effective solution.
    I took some photos to depict what my t-track clamps look like, and what using them looks like. Since I don't have my spoilboard installed yet, I had to show them off like models.



    This is a side view. Note the rabbits at the ends. The rabbit captures the part being cut. You can just see a slot at the bottom. The slot adds to the versatility - you can slide the claim back and forth as needed

    The screw/t-nut arrangement is homemade. I bought 1/4-20 ready bolt and oval nuts with a 1/4-20 threaded hole (oval nuts come with various thread configuration, e.g., 10-24, 10-32). I use all sizes for various projects, but use only 1/4-20 for my hold downs.

    I cut the ready bolt to the length I want. I then use super glue to glue it into the oval nut. Just a drop and it holds. If you don't glue the screw to the nut, the screw will turn and bottom out in the t-track, as you tighten down the clamp, Then, you have to fool around getting it to unscrew when you want to remove the clamp. IMO, an unnecessary PIA. The super glue turns it into something like a toilet bole mounting screw.

    The wooden part is cut from hard maple. I keep unplanned Maple around the shop pretty much all the time. I had some 8 quarters on hand, so I made the blanks by cutting 3/4" strips off the edges. I drew up the claims in CAD and created a cad file. My CAD drawing was for a 48" long piece, broken up into a number of separate pieces. It is noteworthy that ONE SIZE DOES NOT FIT ALL when it comes to length. This is especially true when you have t-tracks spaced too far apart. I've made some pretty long ones to clamp down stock.





    This is a photo showing how not to use these clamps. You can see that the clamp sits cockeyed on the adjacent piece. Actually, you can get away with slight angles like this, but If I was trying to clamp 1.5" thick stock, it would be a problem.



    This photo shows the right way to do it. You use a spacer block at the opposite end. Now, the clamp sits level. The technique is borrowed from metal milling, where there are stepped blocks to keep the clamping force perpendicular to face of the part being cut

    Note the part being clamped. It too is a clamp, only much longer. Also, note the wood acting as a spacer. It's cut just like the clamp, except it has a square face. It come in handy, when you want to duplicate several pieces and want to set the origin at the same place for each. Saves setup time. You zero the axes ones and you're good to go for the entire run.



    Here is an aluminum clamp. I seen several videos where people use them. I have a few, but don't like them. there is a slot under the knob. They can, and do, slip. After ruining a few pieces, I stopped using them. My wood clamps have never slipped - not once - even with the long ones.



    Here is another called a Knuckle Clamp. Woodpeckers (woodpeck.com) sells them. I've not used them, but Woodpeckers makes/sells top-of-line stuff and would take it on faith that they work well. However, I am unwilling to part with $18 each for them, when I can make perfectly serviceable clamps for a couple of bucks.

    Speaking of cost, you can get 1/4-20 star knobs for about $1.20 each. If you really want to go on the cheap, use wing nuts or even a regular hex bolt instead of the knob. The knobs are way more convenient, though. You can get the oval nuts on Amazon. A 3rd part seller sells 80/20 nuts, 25 for $9.95 with free shipping. A great price. Here's a link: https://www.amazon.com/80-20-Slide-E...gateway&sr=8-2. Woodpeckers sell 10 for $5, but also charges $5 for shipping, or $1 each. The ones on Amazon are only $0.40 each. The wood? A few cents each.

    Hopes this helps with your decision-making process.

    Gary

  11. #11
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    Re: Spoil/Waste Board Questions

    I have never had a aluminum clamp slip, ever in all the years I've been using them. You need to make sure you have them positioned correctly, in the right places and double check before starting the job.
    Retired Master Electrician, HVAC/R Commercial. FLA Saturn 2 4x4 CNC Router

  12. #12

    Re: Spoil/Waste Board Questions

    What I'm trying to decide is whether to use 6-8 t-tracks and MDF strips, or a single 4x4' board and a whole lot of t-nuts.

    If I go t-nuts in a 4x4' 3/4" MDF is it enough to use only 4 bolts at the corners to hold the spoil board to the torsion box frame? Or should it be secured at more positions?

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