Eccentric clamp thickness

[Ripthorn]

I need to fly cut some thin plate, so it seems an ideal time to make some eccentric clamps a la Rick Sparber. However, I would like to make a few that are as thin as possible. Is a 1/8" thick cup washer too thin if I make them from O1 and heat treat them? I really just need enough for the cutting lip and clearance, as far as I can tell. Has anyone made really thin ones? Do they still provide adequate clamping pressure? I suppose double stick tape is still an option, but why turn down an excuse for making some quick and easy tools, right?

 

[chips&more]

Holding and machining thin stuff can be challenging. I have had good luck with using super glue and then boiling water to remove. And also have a vacuum table that has worked. Both methods can put you in the scariest shop environment if something should come loose though! Your enemy is warping, heat, bad clamping and tool pressure. You will need to overcome those little gremlins to machine thin projects…Good Luck.

 

[Don B]

Holding and machining thin stuff can be challenging.

Very true......!

One option with thin stuff as well if room allows is to clamp across the work and shift the clamps as you go, I find this works well when using CA glue just for the extra security/safety factor.

 

[John Hasler]

Holding and machining thin stuff can be challenging. I have had good luck with using super glue and then boiling water to remove. And also have a vacuum table that has worked. Both methods can put you in the scariest shop environment if something should come loose though! Your enemy is warping, heat, bad clamping and tool pressure. You will need to overcome those little gremlins to machine thin projects…Good Luck.

I have done this by making up a couple of plates thinner than the work and notched to match a corner or end of the work. I use them as backup for tape or glue. Just clamp them down fitted to opposite corners or ends and tap them in until firm. The tape holds the work down and the plates prevent it from rotating. The plates can be as thick as or thicker than the work if you are willing to cut into them.

I'm going to make some of those eccentric clamps some day. They're cool. I want ones that use the T-slots, though.

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Very true......!

One option with thin stuff as well if room allows is to clamp across the work and shift the clamps as you go, I find this works well when using CA glue just for the extra security/safety factor.

When I do this the spot where I made the change always shows in the finish.

 

[Don B]

When I do this the spot where I made the change always shows in the finish.

I find it does as well if I overdo the clamping pressure, I use a piece of wood between the work and the clamp and don't do the clamp much more than hand tight, I just us it to aid the holding power of the CA.

 

[John Hasler]

I find it does as well if I overdo the clamping pressure, I use a piece of wood between the work and the clamp and don't do the clamp much more than hand tight, I just us it to aid the holding power of the CA.

I'll try that next time I need this. I hadn't thought about the fact that the CA or tape will compress a bit if I clamp hard and then rebound when I move the clamp.

 

[billdeme]

What about a mag chuck, like the kind you would find on a surface grinder?

 

[Ripthorn]

My machine is too wimpy for a magnetic chuck.

Related question: what is the difference between the eccentrics that use t-slots and not. I just figured a shorter screw into a t nut with appropriate threads. Is there more to it than that?

 

[Ebel440]

The thinnest clamp I found was .110 made by mitee-bite if you look them up they have a lot of different types and the dimensions. I have used their fixture clamps and they held well.

 

[John Hasler]

My machine is too wimpy for a magnetic chuck.

Related question: what is the difference between the eccentrics that use t-slots and not. I just figured a shorter screw into a t nut with appropriate threads. Is there more to it than that?

You'd have to get the T-nut to bind up and the cam to rotate against the work at exactly the same time. Otherwise either the nut will just move in the slot or you won't be able to turn the screw far enough to engage the cam because it will tight in the nut.