Re: [CAD_CAM_EDM_DRO] Re: Holding work down on Router

Dave wrote:

>Anyone else use a sacraficial board, then just a good quailty double
>sided tape.
>Thats what i've been using on woods, Plastics & even brass/alloy.
>Make sure the tape is a thin type with little side ways deflection
>when components are stuck down.
>I have had a few faliures when doing the metals due to heat build up,
>But if fine cuts are used & economical feedrates it can be done.
>

Hey Dave, I do that too on my Router. I have a sheet of 1/4" cast
acrylic that I can set down on the table, then use "engravers tape" to
hold the parts. I can run all the way around a part, skimming the waste
material without getting near the table top. My Acrylic sheet has holes
thru it everywhere I have a tapped hole in the table top. ( I put a
pattern of tapped 1/4-28 holes thruought the table top as I found no
other real solutions when it comes to mechanically holding something
that just can not come loose accidentally) This way, on stuff that might
come out of place, I can usually "back it up" with some non movable object.

By the way, My supplier no longer offers the "clear" engravers tape I
used to use, now selling some tan colored stuff that feels more papery.
The new stuff has a "liner" where the old stuff was a plastic tape that
wrapped right on itself. The new stuff is just a little too sticky. If
you know where I can get some of the clear stuff, please let me know.

Another real time saver is Hot Glue..... As long as you do not have any
oils on the surface of the table top or the item you are holding, a good
bead around the outside works pretty well. I found that even cutting
aluminum parts will stick pretty well and the best part is the Hot glue
comes off pretty easily when done. I keep a squirt bottle of Denatured
alcohol handy for cleanup prior to glueing.

The handiest method though is thru either part specific Vacuum jigs, or
a generic jig. Place a few holes (1/8") thru the top and run a vacuum
line to them. Then you can lay down various "jigs" and place items on
top of the jig using the incredible power of "closed system vacuum".

All you need is to place a closed cell foam weather strip around the
outer perimeter of a sheet of Acrylic, drill a hole in the center of it,
then place some of the same weatherstrip on top of the sheet in the
shape of the item you need to hold. Put the item on top of that, flip on
the vacuum and go.

I also have used acrylic tubing to hold items. Take some 1/4" wall 6"
diameter clear tubing about 2" long. Place foam tape on both ends. Set
it over the hole in the table top, set your part for cutting on top of
the acrylic, turn on the vacuum and safely cut all the way around.

If you have not played with vacuum yet, what are you waiting for ?? If
your doing "small" work, Look for a Gast type Carbon Vane pump. You
don't need lots of Horsepower, a 1/4 -1/3 hp will do, AS LONG AS you
control your leaks. No leaks ? No need for much CFM ! It can be a 50 or
60 hz unit.

. E-bay has new ones now and them for under $100. Put a checkvalve in
the suction line and run that to a tank. Get a cheap vacuum switch to
turn it all on and off automatically. With a "t" in the line somewhere,
run a length of 1/4" ID hose to your fixture or jigs. Whalla.! I stuck a
pump on an old Aircomp tank with the wheels still on it. Works great. I
also have a 3HP motor on a rather large belt drive pump for a future
Vacuum former, but I have not needed it to hold parts on my machine.

>But i have found a tape that bonds when heated to 180 C & release's
>agian when heated up to 180 C, but haven't purchased any yet to try.
>(It's not cheap).
>
>

I've got some of that and it does work very nice. I used it when I had
to cut some shapes out of thin Stainless sheetstock. I placed a layer of
thay gold "paper" between an oversize sheet of aluminum and the
stainless and heated it up. Cut the job, reheated and pulled it loose.

I used an electric frypan to get it hot, but an oven would be far better.

Chris L

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