Thread: Clamping advice?

Bypass the wedges - they are OK but apply sideways pressure to hold something down is not ideal. Also it can buckle up your workpiece if your wedge is too firm.

This is what I use for clamping on a T slot table - see photo
It's quick to clamp and clamping forces are where they should be.

Eventually for your small pieces you can use a vacuum table. You can also use double sided tape for those - the thin film type and not the thicker foam type.

There are other solutions but I'll leave that for somebody else to comment about.


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Thanks for the picture Rod. Those bar clamps, in a much more primitive form using wood, were what i was trying to do, but my first attempt was too thin and the wood actually bent and didn't hold properly. Unfortunately at the moment I don't have longer bolts to use for thicker board, and don't have metal bar to use instead.

Russell.

Yeah I gave up on timber as it requires 19mm thick to have enough force to hold the job. That thick means the collet nut will hit the timber on a deep cut close to the clamp. The steel on mine is 25 by 8 flat bar.

I've been using this method with excellent results.
Vectric Forum • View topic - Keystone for arched casing

Originally Posted by Ger21

I've been using this method with excellent results.
Vectric Forum • View topic - Keystone for arched casing

I've never seen anhing like those threaded inserts available around here. Also, aren't they a problem then the bit hits them if going through a workpiece? He also mentions issues with the workpiece lifting, which is where I started having problems.

Any suggestions on an easy way to find metal bar, for someone living in a supply-challenged area?

Russell.

I just used T nuts in my table, with a bolt through the cam clamp.

Mine creates a tremendous amount of force (enough to push the bolted down fence out of position), and I've never had any lifting. It's also very fast, especially when running multiple parts.

Something you'd think is relatively easy is causing me problems. How to clamp my workpiece to the spoilboard.

Clamping can be one of the most difficult parts of CNC. Programming and unning a CNC router has been my day job for almost 15 years, and I still struggle regularly with work holding. Fortunately, the two 25HP vacuum pumps are pretty helpful.

Ger21 is absolutely right.. fixtures and clamping methods are half the battle when making parts.

I dissagree that side clamping is a bad idea... depends on the job and the material. I made myself a bunch of these ecentrics Mitee-Bite Products Co. for the metal jobs I've been doing and they work very well. Pins as stops are also great but need to be vertical and solid... personally wouldn't trust holes in MDF.. too soft.

I'd suggest yopu make a peg board plate out of either alloy or steel with threaded holes every couple of inches and then clamp that down to your spoil board.

I use the T slots that are machined into the bed blow the spoil board (which is sloted) to hold various sheet work of clamping fixtures down.

double sided tap is also very good but won't hold to HDPE... stuffs sliperier than snot! If the part has hols in it then cut those first thru bolt to table/fixture then cut profile...

No one technique is going to be perfect for every job and sometime it will take several techniques to get a satifactory setup.

Cheers

Mark

Yeah I guess I'm being hopeful for a One-size-fits-all solution.

I've found some meter long lengths of aluminum at Bunning this morning. The plain flat stuff is too flexible, but the have various folded shapes. So I got a piece of 3 sides 'U' shaped stuff that I'm going to try putting together like Rod's suggestion.

I also saw some silicon edged, bent teardrop shaped doorstops in BigW that I thought might act better as sideways cams. I figured my last solution failed as it was only wedged on one side, as the wedge didn't have enough grip. If I had two of these, one for each side, they may provide the grip and balance to side wedge better. But at $7 each, I'll try other things first.

PerhaPs I also need to make multi-sized spoil boards as well, and then use the T-slot base to clamp both the work and spoilboard at the same time.

You guys have given me some new ideas at least Thanks for the suggestions.
Russell

How about gluing strips of spoil board down and using the existing T-slots?

I used a gel based contact adhesive on my machine with MDF, and it holds very strong. I have yet to find out how fun it is to remove but I don't plan to do that any time soon, when it gets too thin you just glue a new piece on top of the old.

For wedges you may like to try either the large spacers that are used for tiling, or the even better ones used for sheet flooring. The latter have steps and can lock together.

Originally Posted by Ch4iS

How about gluing strips of spoil board down and using the existing T-slots?

I used a gel based contact adhesive on my machine with MDF, and it holds very strong. I have yet to find out how fun it is to remove but I don't plan to do that any time soon, when it gets too thin you just glue a new piece on top of the old.

Yes I had that thought, and for the exact ungluing reason you mention, decided against it. I had a subsequent thought out routing the tracks but not all the way through, leaving the last inch or so solid, but I didn't know whether that would provide enough support to the rest of the structure. You could leave both ends solid, but that's more of a bather if you need to move the bolts outside for anything.

Russell.

Originally Posted by BoomerangInfo

Secondly, I am using 12mm particle board wedges.

Hi Russell,
Maybe you could try some hardwood wedges if you have some scrap lying around?
I started off with particle board, but found them too soft. I switched to jarrah and had much better results.

Paul