[wizard]

There is a huge thread on Epoxy Granites that you can look into. Some people have used concretes and even sand.

There is a very good PDF that floats around the net called: "The Principles of Rapid Machine Design" by Eberhard Bamberg that is well worth a read. It has more information than you might want though, but it USA very good read none the less.

I read somewhere here that you can fill the square tubes with some type of gap filler to help with reducing vibration. Any recommendation on any particular type to use?
I saw a couple of gap fillers in the local home depot store. One cures to a hard solid mass: Here
The other cures to a flexible mass: Here

Any recommendation is appreciated. Also let me know if I should be looking at something else other than thse.

I haven't actually filled anything myself so I can't suggest anything based on experience. What I would or may do in the future is go the epoxy fill route. That is epoxy mixed with aggregate to make a plastic concrete.

As to the gap fillers I wouldn't waste my time! I've used many cans of that stuff to insulate my house, as such I have a hard time believing it could do a lot for you. Maybe others could chime in here with actual experience and objective tests. While I'm not one to throw the "add mass" dogma around putting the right materials in the right places can be very useful. This material adds no mass to speak of but could possibly change resonance.

[007CNC]

There is a huge thread on Epoxy Granites that you can look into. Some people have used concretes and even sand.

There is a very good PDF that floats around the net called: "The Principles of Rapid Machine Design" by Eberhard Bamberg that is well worth a read. It has more information than you might want though, but it USA very good read none the less.



I haven't actually filled anything myself so I can't suggest anything based on experience. What I would or may do in the future is go the epoxy fill route. That is epoxy mixed with aggregate to make a plastic concrete.

As to the gap fillers I wouldn't waste my time! I've used many cans of that stuff to insulate my house, as such I have a hard time believing it could do a lot for you. Maybe others could chime in here with actual experience and objective tests. While I'm not one to throw the "add mass" dogma around putting the right materials in the right places can be very useful. This material adds no mass to speak of but could possibly change resonance.

Thanks for the input.
I am kind of on the fence on this one.
hoping someone who has actually done this will chime in and say that it worked or didnt work.
I am not really looking to add any more mass. The machine is very heavy and appears very ridgid as it stands now.

This material adds no mass to speak of but could possibly change resonance.

Something along those lines...
Just wondering if the filler plays any other role as it couldnt possibly add meaningful mass like you pointed out.

[wizard]

It is interesting to note that the A10 used a foam fill to make it more resistant to damage when taking a hit. So I don't want to discount the ability of foam to do useful things in a structure.

Thanks for the input.
I am kind of on the fence on this one.

Well this wouldn't be a lot of money, so experimenting isn't going to hurt ones budget. It would be nice if you could instrument the frame to see if there is any real benefit.

hoping someone who has actually done this will chime in and say that it worked or didnt work.

That would be nice. I would imagine there is some impact especially on thinner walled tubes.

I am not really looking to add any more mass. The machine is very heavy and appears very ridgid as it stands now.

More rigidity is always an advantage as is the ability to reduce vibration in a frame. Heavier, it the right areas, just means more capability.

Something along those lines...
Just wondering if the filler plays any other role as it couldnt possibly add meaningful mass like you pointed out.

As noted above, foam has been used in Aircraft to make them more fault tolerant. It is often used in boat construction too, though that is often as sheets.

[JohnZ]

My only experience with that spray foam was to coat a sheat metal bathtub prior to install to reduce the noise when filling. It worked great btw.

on my machine, I filled the tubes with epoxy granite, but used fiberglass resin to save cost since it was just filling a steel tube. Then I started using a concrete product also sold at home depot called rapid set. It is a high strength very rapid setting, non shrinking, concrete with a high bond strength. The formula uses water in the chemical process and actually consumes the water instead of just as a catalyst. Ie, the water dissapears chemically and is no longer present in the cured product to cause rust etc. After one hour set time, it is stronger than 3500 psi, in other words, you do not need to wait for a couple of days for it to set up. I ended up using this to fill in between the steel tubes for additional mass and vibration reduction on the base frame. Before the addition, the base was spindly when the machine was under cnc control. After the addition of the concrete, it was rock solid.

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[louieatienza]

A long time ago, I filled a thin-wall Easton softball bat with Great Stuff spray foam. I would say that there was a damping of vibration, that did translate to more distance! The downside is that the bat would "thud" instead of "ping." During games, our team would scream real loud when someone was up at bat with it, and whoever was on deck would remove it!

[007CNC]

Thanks for your inputs guys on the spray foam...
I think I will go ahead and try it. Dont think it will hurt anything.
Once I am done building, I will run the machine before and after filling just to see if I can record the difference.
It might help someone else out down the road.