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Clamping method

Clamping method

Postby Awesomeness » Sat Dec 05, 2009 1:43 am

I was reading your post about clamping methods ( http://buildyourcnc.com/clamping.aspx ) where you suggest drilling through the table, and tapping epoxy filled holes.

What about T-nuts? I love these things. You could just drill through, put a T-nut on the other side, and bold through. You might have to take pliers and bend the points back flat.

See here: http://www.stafast.com/products/tnuts.html

If you don’t have time to do it right, when will you have time to do it over?
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Clamping method

Postby PHoodDaniel » Sat Dec 05, 2009 4:29 am

Along with the t-nuts, there are threaded inserts like ones seen here: http://www.ezlok.com/Home/index.html.

For the bigger machine, I like to use fence clamps. It is similar to the clamps used for electric miter saws. I personally try to stay away from clamps that have a presence above the workpiece.

Vacuum clamps are another option which can also be pretty easily done by hand. With a small MDF block and a few "o" rings (from the dollar store) and a long drill bit, you'd be 3/4s the way there.

Sounds like a good tutorial.

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Clamping method

Postby george » Mon Dec 28, 2009 9:01 pm

Slick mounting ideas:

http://www.youtube.com/user/radioshack7

I saw several and the one I like best uses a T-bar with a small piece of scrap the same size as the piece being worked on. The above video shows a trianble block that fits any size.

George

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Clamping method

Postby keith » Mon Dec 28, 2009 11:24 pm

I would suggest before anyone bend the points back on a T-nuts you test this idea on a couple using some scrap MDF first. I have tried this in the past and found that the pins are what stop the T-nots from spinning and if you bend them flat..........

I have just installed 105 on my machine working on a 6" grid and if anyone else wants to do it remember that they ALL must be counter sunk to avoid unleveling the base of the table. This can be done using a 19mm spade bit; or what ever is the outside diameter of your T-nuts.

It realy would be best to install them on the inside of your torsion box when you build it. Unfortunately I did not. This will still work however I will lose around 18mm + my sacrificial layer of MDF in my Z travel.

If anyone in the future wants to do this at the beginning of their Torsion Box build I will be happy to advise.

The Titanic was built by professionals; the Ark was built by Amateurs..........
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Clamping method

Postby philipw » Wed Dec 30, 2009 2:05 am

Eariler this year I was building a pair of subwoofers and discovered the existance of a different kind of blind nut that's commonly used in MDF by speaker builders. It's called a "hurricane nut" and though similar to t-nuts, does a better job of staying put in MDF. It's also easier to install, and can easily be glued with epoxy or polyethylene glue, just be sure and clear your threads with a tap if you get any inside them. You can search for them at parts-express.com, which is where I purchased mine.

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Clamping method

Postby george » Sun Apr 11, 2010 3:44 pm

I just discovered a slick way to hold down flexible materials, like thin plexiglas. Beanbag diving weights! Last night I was cutting some 1/16" plexi which was clamped at the edges and after cutting out the middle, there was no rigidity left and the plexi started vibrating. 5lb diving weight in the middle (where it had already been cut) did the trick.

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Clamping method

Postby mikecnc » Sun Apr 11, 2010 8:56 pm

I just finished my first cnc, the blueChick with and extended 36" table. In looking for a way to clamp parts down it seems like the 1/2" table holes with pins and wedge is an easy and effective way to go. My question is could I not use wooden dowels instead of metal or plastic pins? That way if I cut into a pin there shouldn't be any damage to my bits. Most of my parts will be wood.

Also, is this pin method enough or should I tape as well to avoid the part lifting, or does that every happen?

thanks,

Mike

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Clamping method

Postby mikecnc » Mon Apr 12, 2010 6:27 pm

Well I've tried the dowels and that works fairly well but the part stock must be cut exact or there is movement. Also I find that there is just not enough pressure on the stock. Maybe with practice I could get it to work well.

Has anybody used the Festool Clamping Element? They look like they would be super easy and steady.

http://www.youtube.com/watch?v=2q1f_lADLEg

http://www.amazon.com/Festool-488030-Clamping-Element/dp/B000JNEC1Q

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Clamping method

Postby Awesomeness » Mon Apr 12, 2010 8:34 pm

Those Festool clamps look interesting, and they are a nice low profile, but for $100/ea no thank you. haha

If you don’t have time to do it right, when will you have time to do it over?
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Clamping method

Postby mikecnc » Mon Apr 12, 2010 10:16 pm

I called about them and $100 gets you two clamps and two ends so you can clamp from four points. It's going to cost me about $75 just to get the T-nuts if I go with that setup. My only real concern is will I still need to clamp the stock down as well so it doesn't lift.

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