# Eccentric clamp thickness



## Ripthorn (Aug 27, 2014)

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?


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## chips&more (Aug 27, 2014)

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.


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## Don B (Aug 27, 2014)

chips&more said:


> 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.


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## John Hasler (Aug 27, 2014)

chips&more said:


> 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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Don B said:


> 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.


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## Don B (Aug 27, 2014)

John Hasler said:


> 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.


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## John Hasler (Aug 27, 2014)

Don B said:


> 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.


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## billdeme (Aug 27, 2014)

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


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## Ripthorn (Aug 27, 2014)

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?


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## Ebel440 (Aug 27, 2014)

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.


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## John Hasler (Aug 27, 2014)

Ripthorn said:


> 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.


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## Ripthorn (Aug 28, 2014)

John Hasler said:


> 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.



So is this why the t slot clamps have a set screw in the t-nut?  You would then position the t-nut, tighten the setscrew so that the t-nut doesn't move, then tighten the cam screw to secure the work, correct?  I was wondering what that set screw was for...


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## John Hasler (Aug 28, 2014)

Ripthorn said:


> So is this why the t slot clamps have a set screw in the t-nut?  You would then position the t-nut, tighten the setscrew so that the t-nut doesn't move, then tighten the cam screw to secure the work, correct?  I was wondering what that set screw was for...



I assume that's how they work.  I don't have any.  It would be more convenient and elegant to only have to turn one screw but I haven't figured out how to make it work yet.


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## Ripthorn (Aug 29, 2014)

I just thought of a way that it could be done with a single screw.  I may have to try it out first to test it, but it would be pretty simple and like you said, very convenient.


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## John Hasler (Aug 29, 2014)

Ripthorn said:


> I just thought of a way that it could be done with a single screw.  I may have to try it out first to test it, but it would be pretty simple and like you said, very convenient.



Can you post an explanation or better yet a sketch?


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## Ripthorn (Aug 29, 2014)

John Hasler said:


> Can you post an explanation or better yet a sketch?



Sure thing, Let me work up a neater sketch and then I will explain.


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## Ripthorn (Aug 29, 2014)

*T Slot Eccentric Clamp with Single Screw*

Here is a sketch of my idea for a t-slot clamp that locks down with a single screw.  The key to this is the eccentric screw has the last little bit turned down to act as a piston on a spring loaded pin.  As the eccentric gets tightened, it pushes down on the pin, which then locks the t-nut.  As I am typing this out, I don't know just how well it will work.  This is an idea that I have spent all of 10-15 minutes on.  If you successfully amke one, let me know.  It will be a little while before I am able to get in the shop to try it out.  Sorry if the sketch is small.


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