Favorite hold downs?

[Michael Burnside]

I use “Gator” and “Tiger Claw” clamps from Carbide 3D. The “Tiger Claw” is when I need surfacing clearance. It’s an investment but they work incredibly well and have never slipped on me. My ShopSabre also has a vacuum table, but I use these a lot for all sorts of holding.

[George Yetka]

This is a great topic. I have been using 2 or 3 armor tool inline auto clamps against x and y fence for anything that doesn't need clearance. They are awesome. and I have a piece of 1/2" mdf I CA glue small stuff too and I use the auto clamps to hold that. I tried the oops clamps but Im wall mounted and I cant get my threaded inserts to stay in they kept falling out the back.

[Ronald Blue]

Carl I tried those Kreg clamps. They have plenty of clamping force but tend to lift the work piece a little. I have done a variety of things and often end up with screws into the spoil board through the work if there is waste area. I'm toying with a DIY vacuum table myself and even purchase a sheet of MDF for it but haven't proceeded yet.

[ChrisA Edwards]

One of my first CNC projects, 1/2" PVC Sheet

[Wes Grass]

I profiled a number of parts on dedicated vacuum fixtures with weatherstripping for seals, using only a ShopVac. Curved and flat parts that had to be machined with respect to how they'd be assembled. Some were multiple layers of Urethane foam and carbon cloth, close to an inch thick. The tougher ones were a couple layers of 16th BB, Urethane foam, and carbon about 1/2" thick.

The trick was locating dowels, which match the ones in the 'molds' for the parts. And milling a shallow pocket inside the weatherstripping. Not sure if that actually did anything, but it made me feel good. And I left tabs wherever possible, mainly so the 'rem's' wouldn't be floating around once they were cut thru.

Flat parts would be significantly easier with respect to doweling them. Or even a couple nails or screws in the corners. I think Jim noted a possible height variation depending on gasket compression. So that requires some thinking/experimenting if you need to pocket to consistent depths. I don't remember exactly what the stuff I used was, other than white, multi ribbed in some way, from HD.

Of course, most of this is rather impractical for one-off stuff. But a box with a socket for a shop-vac hose, and a grid of holes in the top can be pretty handy.

[Kevin Jenness]

With vacuum fixtures I mount sticky back neoprene gasket tape in a groove half the tape's thickness so the workpiece bottoms out on the fixture and the tape's compressed thickness is not an issue.

[David Falkner]

When I began my CNC journey about 6 years ago I cobbled together some quick makeshift clamps out of Maple and Walnut thinking that I would go back and make some really cool hold downs later; the temporary ones are still being used because they just work. They aren't pretty but they do work.

[Bruce Page]

I mainly use the Incra hold down clamps. As much as I would love a vacuum setup, I haven’t found one that #1, won’t break the bank, and #2 won’t break my ears.

[Carl Beckett]

I tried a couple home made cam designs and havent found one that works well.

Purchased a couple of these Veritas cams - they work well. In fact the trick is not over tightening and causing my reference block to shift. They are metal, but low profile. My own attempt at an all ABS version was not successful.

https://www.leevalley.com/en-us/shop...SABEgIhz_D_BwE

[Michael Burnside]

Those look nice. I wish the dog was shorter and I’d probably get 4. I actually use something similar to their planing stops. The key to clamping is to keep the piece from shifting side to side. It doesn’t take much downward pressure if the piece can’t shift. I just milled 1-3/16” white oak today without issue using dogs, TSO dog stops and 4 tiny aluminum clamps.

[Carl Beckett]

What does 'dog' mean? They have a 1/4" screw that goes through (recessed) for a T-track. I had to put a longer screw in it. The body is fairly small

Wait - now I see your question. I did not purchase the version that goes into a dog hole. I purchased the version that has a t-nut type retainer that rides in your T-slot. You might have to adjust the length of your screw if you want it flush, although I used it with one of my regular 1/4" t bolts and a wing nut - depending how flush you want everything.

I think the key to this type of thing working is the friction on the camming surface. Plastic compressed (hertz stress) and they creeps back. These are cast and the mating surface is a little rough which keeps them cammed in place.

So far my fav camming clamp.

You are right about the shifting. On the vertical part of my CNC (drawer dovetails) I pasted sandpaper. Made a huge difference preventing the workpiece from slipping. Not inclined to do that on the horizontal surface.

Those look nice. I wish the dog was shorter and I’d probably get 4. I actually use something similar to their planing stops. The key to clamping is to keep the piece from shifting side to side. It doesn’t take much downward pressure if the piece can’t shift. I just milled 1-3/16” white oak today without issue using dogs, TSO dog stops and 4 tiny aluminum clamps.

[Michael Burnside]

I went a head and ordered 2 of the t-slot versions for testing. I like the idea of the low profile with some caming force. Thanks for the link Carl.