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Thread: More CNC questions

  1. #1
    Join Date
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    More CNC questions

    I know Leo made leg extenders for his machine to get the table at a height he likes. I'd like to make my cabinet the right height to begin with. And I know we had a discussion a long time ago about the composition of the table. But I still have questions.

    So the base is made up of the 8040 extrusions. I like the idea of t-slots for work hold downs but into what kind of material? I have a sheet of 3/4" HDPE that is big enough, but maybe that stuff is too slippery. Leo said his table has some sort of rubber surface. I remember that fine sawdust made the table even more slippery which can made holding work down interesting.

    And should there be a piece of say 1/2"-3/4" MDF (or BB plywood) between the extrusions and the hold down sheet for maybe rigidity's sake?

    I need to make this decision now because I have to calculate the height of the lathe table so the lathe is neither too low or too high. That surface fits into a dado on a vertical divider and needs to be milled before construction.

    Stuck here until I make a decision.

    And now I am thinking about a vacuum table inserted in here someplace.

    Thoughts, guys?
    ++++++

    Some say the land of milk and honey; others say the land of fruits and nuts. All together my sort of heaven.

    Power is not taken. It is given. Who have you given yours to? Hmmmm?

    Carol Reed

  2. #2
    Join Date
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    I have not done anything yet whereas the flatness of the table matters, so the rubbery stuff for now seems to be OK

    I have used MDF for several years on my other machine, but is has an Aluminum table under it that I surfaced flat and I bolt the MDF to it.

    The MDF is a sacrificial surface. I just resurface it and replace it as needed.

    I also polyurethaned the MDF - so slippery would be even worst, but I didn't have problems.

  3. #3
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    Other folks' pictures of their build show a sheet that butts against the side rails which seems like it would add rigidity to the whole table. So my thought was to do that with a piece of 3/4" MDF, surface flat, and seal against moisture. Then add the 3/4" HDPE with the crossed t-slots like Brent did. There would also be a grid of tee-nuts embedded from the back side for hold downs. Likely that surface would have to be surfaced flat as well. Work pieces wold be fastened to a waste board that is held down on the HDPE table. Vacuum pucks could be daisy chained for vacuum hold down when that makes sense.

    I think this is the way to go.

    Thanks.
    ++++++

    Some say the land of milk and honey; others say the land of fruits and nuts. All together my sort of heaven.

    Power is not taken. It is given. Who have you given yours to? Hmmmm?

    Carol Reed

  4. #4
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    Reno NV
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    I gotta say, as much as I like the looks of the crossed t slots, I'm starting to wonder if maybe just having a bunch of them running the long ways might be a little more practical?
    Programmer - An organism that turns coffee into software.
    If all your friends are exactly like you, What an un-interesting life it must be.
    "A door is what a dog is perpetually on the wrong side of" Ogden Nash


  5. #5
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    Wondering the same thing, Brent. Function over aesthetics. Thanks for the insight. Been browsing the web for ideas and as usual have seen I am overthinking this. Did see some some really cool nose clamps to make though!
    ++++++

    Some say the land of milk and honey; others say the land of fruits and nuts. All together my sort of heaven.

    Power is not taken. It is given. Who have you given yours to? Hmmmm?

    Carol Reed

  6. #6
    Join Date
    Aug 2007
    Location
    Reno NV
    Posts
    13,360
    Got a link?
    Programmer - An organism that turns coffee into software.
    If all your friends are exactly like you, What an un-interesting life it must be.
    "A door is what a dog is perpetually on the wrong side of" Ogden Nash


  7. #7
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    Sorry. But it is so simple I didn't think I needed one. I'll make a SU drawing and you can go from there. An evening project for me.
    ++++++

    Some say the land of milk and honey; others say the land of fruits and nuts. All together my sort of heaven.

    Power is not taken. It is given. Who have you given yours to? Hmmmm?

    Carol Reed

  8. #8
    Join Date
    Aug 2007
    Location
    Reno NV
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    13,360
    I've been wanting to come up with some lower profile clamps than what I'm currently using.
    Actually, I've switched over for the most part to using bolts and the t-track with a wastboard.
    Programmer - An organism that turns coffee into software.
    If all your friends are exactly like you, What an un-interesting life it must be.
    "A door is what a dog is perpetually on the wrong side of" Ogden Nash


  9. #9
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    OK. I got the idea off an Instructables article about tee slot tables. (I think.)

    Think low profile and no protruding hardware. Simply a 'bar' (I will use 3/4" thick Delrin because I think I have some.) about 1 1/2" wide, maybe 4-6 inches long. Mill a rabbeted through dado in the top surface for 2/3's of the length offset to one side. Mill a rabbet on the bottom side of the ends with a 1/8" tongue. Mill a slot 1/8" wide slot in your spoilboards. Insert a buttonhead machine screw and washer into the through dado. It grabs the nut in the tee slot track wherever you need for it to be. Insert the tongue into the slot on the spoilboards and fasten. Can even use a biscuit slot cutter for the spoilboards. Just make sure the nose clamp's tongue fits into it.

    Still need a picture?

    Also made a decision about the table. Because I have a sheet of 3/4" HDPE, it will be the base table directly on top of the extrusions. I will mill dadoes to receive the tee slot tracks (http://www.leevalley.com/US/hardware...76,61994,52400) 6" apart from front to back. They will be recessed 1/16".

    Now all I need is another Lee Valley free shipping event!
    Last edited by Carol Reed; 01-29-2016 at 08:15 PM.
    ++++++

    Some say the land of milk and honey; others say the land of fruits and nuts. All together my sort of heaven.

    Power is not taken. It is given. Who have you given yours to? Hmmmm?

    Carol Reed

  10. #10
    Join Date
    Aug 2007
    Location
    Reno NV
    Posts
    13,360
    makes perfect sense. Thanks!
    Programmer - An organism that turns coffee into software.
    If all your friends are exactly like you, What an un-interesting life it must be.
    "A door is what a dog is perpetually on the wrong side of" Ogden Nash


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