Hold Down Techniques

Special Interest Groups CNC Milling
#1

I’ve been through many techniques but I’m in love with Blue Tape and CA Glue with Activator (accelerator). To this day I remember being introduced to this combo.

Howard was presenting it at a Digital Tools SIG meeting and he challenged me. “I’ll put it down and you immediately try to slide it off.” No way could it set up that quickly, I thought, so I accepted the challenge in front of everyone.

Wow, did I look the fool! That hold was not going anywhere. I pushed. I pulled. I slid the bench trying to break that hold. It was strong. Quickly. When I gave up he showed me the next best thing about this technique. It pulls up easily and pulls off cleanly. It’s not good for all hold down but for smaller wood objects it’s really good.

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#2

My fav hold downdowns a a Festool Board Morf and 3D Printed Ecentric clamps from Thingeverse.

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1 Like
#3

Lou, you probably don’t know this but when you pitched this at a General Meeting three years ago it had an important impact. Finally people could see a practical use for a 3D printer. Finally I was able to put one in the Shop.

Nice work!

#4

I would love to see a hold down like the one above at the Shop.
I feel bad drilling holes into the spoil board, and some projects you have to build a jig and drill the jig into the spoil board.

Maybe I can build this kind of spoil board and bring it in for my projects? I’d lose some Z height by adding it on top of the existing spoil board.

Susan

#5

Walt is currently the one who volunteers to plane out spoil boards.
I wonder if he’d be interested in milling the bed for this system?
The clamps can be printed; we have some in the DT room.

#6

For my personal machine I use the Axiom clamping system.

https://www.youtube.com/watch?v=eJp-H48e2AI

#7

I use this all of the time. I’ve also had success on larger pieces using kitchen cabinet shelf liner paper!

Perry

#8

Watching the trueing-up process starting at 0:30 is really cool.

#9

You use the “blue tape plus CA” all the time or one of the other techniques?

#10

Haha thanks for the clarification request Travis. Forgot people are not mind readers! I use blue tape with the CA glue. I don’t use the accelerator though as just the CA glue usually sets fast enough and allows me enough time to shift the material to be dead square on the table. I also have t-tracks on my table and if I can I put one or more clamps on to make sure that the glued tape has a little pressure to make for a good contact. I then remove the clamps after the CA sets which allows full access to the piece.

One word of caution with this technique. Lets say I am cutting a pocket, say a mortise in a 12" (or whatever length) long 2" x 2" board. If my toolpath is parallel to the 12" length the tape will likely hold. However if the toolpath is perpendicular the tape bond will likely fail and you will need to dive for the STOP button.

PC

#11

Yeah, I too have learned that with thin stock, blue tape plus CA can be a weak hold.

#12

Did you mean thick stock? :slight_smile:

#13

Yeah, that wasn’t clear.
Normally on a CNC “thin” would be in Z.
I meant narrow in the X or Y dimensions, “thin” that way. :innocent:

#14

https://lwmcnc.com/product/lowpro-t-track-clamps/ Here are the best I have seen, these force the material down, unlike any side pressure clamp that lift the material. Expensive, maybe but they work. Here’s a video https://www.youtube.com/watch?v=6Dv3qfYPlKE

#15

If we do decide to utilize hold down clamps for CNC (fantastic idea!), I would like to bring other tools into the discussion (read drill press) and others into the mix, as there is T-track holddowns already at the shop. Might as well share the love, and parts, and cost between tool groups as they would be rarely used at the same time. My $0.02.