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Clamps, hold-downs, double-sided tape, or ...?

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  • Clamps, hold-downs, double-sided tape, or ...?

    I am struggling with the method of securing the workpiece to the platform. The clamps are fine if you don't need to get close to the edge of the piece, but they do present issues if you do, and this is especially true with the laser head, since it is pretty big and can bump the clamps even if the laser target is over an inch away from the clamp.

    I tried foam double-sided tape. BAD idea. The stuff peeled off the wood just fine, but it was a major pain to remove from the platform, and required judicious scrubbing with some mineral spirits to remove all the adhesive.

    Tried hot glue, the low-temp kind. Worked well with the platform... peeled right off. BUT it did not want to come off the wood very well... tore fibers from the wood.

    Last night I wanted to work with a small workpiece, so I hot-glued it to a larger piece with a few drops, and clamped the larger piece with the holddowns. Worked okay until I wanted to remove the small piece from the larger piece. Even the low-temp had bonded very strongly, and tore some of the wood fibers from both pieces of wood. (Actually, I did this twice, and the first time I split the smaller piece in trying to remove it.)

    I'm eager to hear any recommendations you may have, and if possible, give me a trade name for what you may be using instead of the clamps/holddowns, to make it easier for me to find it.

    Thanks in advance!

  • #2
    For the laser I found that I just need to make sure that the part that I was trying to engrave did not move with the vibration of the machine so for larger pieces all I needed was a non-slip mat like the ones you put in tool chests cut so it did not over hang the table. For small items the mat did not work so well so, I had to experiment. I found my best results was a simple jig with a sockets the size of piece I wanted to engrave that I made using the cnc router configuration. It worked awesome for engraving a batch of wooden nickels but took some time to build.

    Another trick that takes almost no time that I have used also is poster tack putty like the brand I linked below its cheap/reusable and has enough stick to hold things in place for laser engraving. My technique was to put a flat board on the table top held down with clamps or small bolts to get a flat smooth surface then used pea sized blobs around the edge of the part I wanted to engrave to hold it in place. For most projects I only needed three blobs to hold things while the laser engraved and found it cleaned of most finished surfaces easily and unfinished surfaces as long as it does not get mashed into end grain then its a bit of a pain but a little sanding can clean that up.

    Note: these tricks only for laser engraving I wouldn't attempt any of them in a cnc router configuration.

    Hope this helps
    Find product information, ratings and reviews for a Scotch Removable Mounting Putty 2-oz..

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    • #3
      Thanks, mcaron. I just went by Office Depot and picked up some different things to try. One of them is the mounting putty you have shown; the other two are stickier but removable. All made by Scotch. As you say, the putty is probably fine for laser, but not for engraving. However, I've used the scotch removable glue dots and things like that for mounting signs, and they hold remarkably well. So, I'm going to try them next.

      The CNC milling machine I used before (a few years back) had clamps that basically slid up against the sides of the material being machined, in t-slots like the ones on the Piranha. I may have to manufacture something like that to use, and if I did, I probably would make the "jaw" of the clamp out of oak, maple, or some other hard wood (instead of metal) just in case the router somehow encountered it.

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      • #4
        Tony,

        This is what I use for turning and temporary holding for templates and on the CNC. What you are looking for is a premium quality crape paper double sided tape. This is not double sided carpet tape, I don't like carpet tape but some people use it. It seems expensive but you don't need much for most applications. I use a putty knife to remover the item and then the tape just peals off, no residue. Take your time removing the item so you don't break it. The price varies and size of rolls vary, you just have to try them to make sure they are what you want because there are look a likes that don't work.

        Here are 2 links to what I use:
        http://www.ptreeusa.com/turning_accessorie_shop.htm
        http://www.rockler.com/double-sided-turners-tape

        Hope this helps

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        • #5
          Thanks, meb. I'll look into it if these things I got today don't work well. There's a Rocker store about 90 minutes from me, but I could probably order it online anyway.

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          • #6
            Tony

            I use a combination of T-Track Clamps from Rockler and some home-made, rubber, cam clamps. Here are links to the Rockler clamps. They sound similar to what you previously had on your old CNC machine

            http://www.rockler.com/rockler-inlin...t-track-system
            http://www.rockler.com/rockler-short...t-track-system

            I set the Rockler clamps up to lock in a work piece on 3 sides and then use my home made cam clamps to snug it up on the 4th side. The cam clamps are made from a rubber guard used to stick under the leg of a piece of furniture so it doesn't scratch the floor. I turn them upside down and drill a hole in it that is offset towards one edge of the rubber disc. Then I put a hex bolt through it sized so the hex head is the right side to lock into the T-Track. Finally on the top side I use a fender washer and a plastic knob. The fender washer adds some additional stiffness to the rubber. By spinning the rubber portion it acts as a cam against the work piece and locks it in place.

            I've attached a picture so you can see what I'm talking about. Hopefully this will help. Attachment sizes are pretty limited so I had to drop back significantly on resolution of the photo.

            A second method is to take a piece of, for example, 1/4" hardboard and clamp that down to the top of the CNC. Now you can use double stick tape between your work piece and the hard board. As you found, the tape won't be quite as aggressive a hold as it will be against the aluminum extrusions so it will be easier to remove.

            Finally, if you use hot melt glue to hold a work piece in place, use a hair dryer or heat gun on it before you try to pull it off your work piece. The heat will soften the glue and should allow you to pull it away for your work piece without damaging it.

            Hope this helps
            Attached Files

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            • #7
              I'm glad to see people sharing their ideas of holding items for carving and laser work. @jbasen I like the rubber disks with the angle on the edges, it should help parts down. the T-Track clamps you show work good and are quickly located where you need them.

              The double stick tape I use will hold small parts for maching if you take it easy with your feeds and speeds.

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              • #8
                I just finished doing a small piece that had a combination of engraving and laser work, and used some of these to hold it down onto a larger piece of stock, which I clamped down to the table. They worked very well, and I anticipate using them more.

                jbasen, the ones you linked to are similar, although the ones on my machine were all aluminum. I'll have to decide whether I want to order some, or make my own. :-)
                Amazon.com : Scotch Restickable Tabs, 1 x 1 Inches, 18 Squares (R100) : Mounting Tapes : Office Products

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                • #9
                  These clamps from Little Shop look good. I will have to try and make some out of aluminum
                  Bob
                  http://littlemachineshop.com/product...3758&category=

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                  • #10
                    You might check out the following links:

                    https://www.youtube.com/watch?v=RESF53ltsO0

                    https://www.youtube.com/watch?v=r4-dufCwGEA

                    You can use any hardwood to make them as well.
                     

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                    • #11
                      I purchased some of the T-track clamps from Rocker, and they work pretty well, although it is required to tap in a couple of small wedges on one side, to tighten things up.

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