How to hold this down?

[knight_toolworks]

I have made a lot of jigs to do these aluminum parts. but so far I have only engraved them and marked where to drill them. but these I need to drill on the cnc. I made a jig that they pocket into so they can't really move side to side. and I will use vacuum when I engrave them. but these are small only 2.1" long and .9" tall and the holes take a fair amount of room. I just don't know if there is enough vac space to really hold them down. thse will be in strips of 7 at a time. there are pre drilled holes on each end too

7317

[thewoodcrafter]

Double sided tape.

[knight_toolworks]

thats how I will do the samples. but when you have to take them in and how maybe 50 pairs at a time the tape may get a bit slow. Plus there will be vac foam in there when I use vacuum and engrave them.
I will engrave them all then I will make the holes this batch I will be doing 7 batches. thats 7 of this one pictured and 7 of the back with only 2 holes. so 100 plates in all.

[harryball]

I think I'd try to design a vac mask to use with my high vac pump.

/RB

[sawdust535]

I never tried this, but I wonder if you coated a spoil board, like MDF, with rubber cement. After machining, it rubs off easily.

[Brady Watson]

A single Fein with a well constructed BradyVac II, and reasonably well thought out toolpaths will hold this down - no problem. Sometimes figuring out what works & what doesn't means doing some experimentation with the payoff being knowledge & know how for the next job.

-B

[knight_toolworks]

here is the jig I made for all the parts I cut this way http://i154.photobucket.com/albums/s266/knighttoolworks/posting/P1000534.jpg

but just now I was thinking the problem with this jig is getting it all lined up when you use it again. the laser helps quite a bit bit it is still a pain.
what I just thought of is if I just sue a piece of mdf and cut the pockets in it use spray adhesive to hold the pieces in place. engrave them and drill them pop them out and I am done. no worry about getting it re aligned or screwing up the jig or really storing it. I could also set it up to use your vac setup but it may not be needed.

[stevem]

A very shallow pocket with a toggle clamp at each end would be the fastest and most secure way to hold small parts, as long as your spindle can clear the clamp.

7318
If you want to be really efficient, you would use pneumatic toggle clamps that open when the machine stops cutting.

[Brady Watson]

Acrylic is awfully pricey...Home Depot composite lumber works VERY well for smaller vac jigs (larger ones too) - plane both sides & you're in biz.

-B

[knight_toolworks]

I tired the toggle clamp but they were a pain and they got in the way.
I got the plastic in a trade for 5 minutes of work so it was a good deal.
it's nice for a strong permanent fixture. but in this case single use ones or one batch jigs will be easier to deal with. so I guess I wasted it. but it is nice for high vac jigs. thats what I had it setup for.
I was cutting holes to check size using my onsrud 1/8" O flute bit. a bit disappointed about the burrs on the top of the hole and lack of smoothness.
here are the small plates. the lettering looks better in person. I just used a 90 v with no power. I should have the spring loaded diamond drag tomorrow it will do a better job. but I sure like the look of the cut without power over running the spindle it is far smoother and cleaner.
http://i154.photobucket.com/albums/s266/knighttoolworks/ALO/P1000536.jpg

[erik_f]

I used carpet tape in strips and made sure there was a strip of tape every so many inches so it would line up with the back of the piece's first edge and last edge. It was a bit of a pain in the butt...but it worked really well, and once I got going it got easier and easier. The nice thing about the carpet tape is you can get it at the local hardware store and its pretty cheap.

[gabepari]

Steve, we engrave anodized plates for our trailer. I haven't played around too much with different bits, but what works for now is I run the first pass with a 90-degree v-bit at about 18K, then run the same file again, but blast the plate with a little WD40 before the second cut. It cleans out the letters real nice and I don't have to deburr anything.

Not a perfect solution, but it works good enough.

Gabe

[khaos]

Gabe, thats a great tip. I wonder if that will clean up AL as well. I will have to check it out after my non-crispy bot is back in play.

Joe