Hold-down strategy

[revwarguy]

I have a fairly large table, (about 3x4 ft) but most work is under 10x18 inches.

I have installed a t-track and clamps as shown being used in the attached photo, taken while cutting some plastic parts. There is a 1/4 mdf spoiler under the plastic.

It seems I am always fighting with spoiler boards, clamps, trying to maintain flatness for an accurate z cut, keeping the clamps from interfering with the router path, etc, etc.

I have a fairly high z-axis, and most of my work is one inch or less, so I have room to do something in between to address this.

If anyone has a photo of their arrangement for holding work in place, I would love to see it. If anyone has a better idea, I would also love to hear it. Ideally, I would love to see pictures of an adjustable height table with some kind of integral clamps (like cams, maybe?) that don't stick up very far, but yet rapidly accommodates a variety of rectangular shapes in the range of 4x7 inches to 10x18.

I don't use upcut spirals much, so there is little need to push down on the piece, most forces are to move it across the table.

So, anyone have a better idea?

TIA,

[Pplug]

I screw my work down to the table and I normally keep a safe z height of 2" to avoid any problems.

When I work with sheet stock, I program a drilling toolpath to put a small divot in the sheet where screws can be located. Small parts are held in with tabs and large parts the sawdust from the cuts keeps them secure.


When putting in a screw, drive the screw home then back it out from the base material. Then put pressure on the screw and it should pull tight to the waist board.

So far this method has saved me a ton of cash! I don't have to make a vacuum table!

[Boots]

You can also get plastic screws and nails so if you hit them it's no big deal. We got a nail gun that fires plastic nails. Cut parts free with a sharp putty knife slid undernieth.

[Phife]

The best solution ive found is my vacuum table.

Do a search for Vacuum Table on here and you'll find a ton of info on them. Ive been using mine for a few months now and it hasnt failed me yet.

best thing about the vacuum table, it holds the material flat in all areas, not just corners/edges like with screws or clamps.

[FandZ]

I've used hot glue with good success and double sided tape too. If a vacuum table is an option, as Phife is suggesting, that would be ideal.

[louieatienza]

I'd like to implement a vacuum hold down, but I'm saving that for build 2. Tight now, I just make a grid of 1/8 holes about 3/4" apart, and use screws and washers to hold things down. Cheap, but... well... cheap....

[revwarguy]

I thank you gentlemen for your responses. I guess I thought a vacuum table to be a pretty ambitious and expensive project (are there cheap but suitable vacuum pumps?) How much of a vacuum is needed? How big a reserve tank? How muck leakage is permitted? I did a search on this site, but didn't see a real build log for a system - anyone got an address for one? Also, my wife is going to just love one more motor running while I use my table!

Pfife, do you have any pictures or can you direct me to a build log for the vacuum table?

What would be ideal is something where I can use pre-cut blank material (that doesn't allow for screw holes in the part) and would also eliminate quite a bit of waste material, so a vacuum system would do that.

More simply, perhaps something like a drill press vise in both x and y dimensions, with adjustable feet? This would just use some threaded rod (which I happen to have left over from the table build, but I can't quite figure out how to make it work in 2 dimensions.

[Pplug]

I've used offset-cam clamps pushing a part against a steel bar mounted to the machine before. Just don't expect to mill the edges of an object. It works great with the kids in school and a standard part size. I can get 25 kids through a machine with custom wording on each piece in about 45 min.