[azsigns]

I've been thinking about filling aluminum extrusions with concrete in order to add mass and stiffness.

I figure a strong mix with high ratio of portland & very little water, rammed in hard would minimize shrinkage & warping.

You could even add rebar and/or steel mesh for extra measure.

Got the idea when I poured the footings for my new shop a couple of summers back.

I'm going to run a test on a 40" long section of 2"x6"x0.125" commercial aluminum door frame.

Has anyone else given it a try?

Chris

[kong]

Isfoils is working on one over here

[Boros]

Hi azsigns

I work for a CNC machine tool manufacturer who makes the whole base from a polymer concrete mix. It has great vibration damping properties.

it could be worth a try in a router. It would add mass.

Boros

[biomed_eng]

How about filling it with sand? This is what the speaker guys do to reduce (damp) vibrations and add mass.

Since the sand is removable...it'll be easier to move your router if you ever need to, just drain the sand out.

You won't have to worry about the stress caused by differing expansion ratios of concrete vs aluminum.

[samualt]

azsigns:
Why bother with that? Just build it out of steel like the CadCut CNC Router. 500 lbs of steel is better than aluminum no matter what you do with it. 2" square steel is cheaper than aluminum T-slots, it gives much more weight and is very rigid. Plus, it's fun to weld together! Of course, I'm currently using aluminum T-slots on my current machine but it is because I want it to be light, portable, and storable. But if you just want to add weight to somthing already made, I like biomed_eng's idea about sand. That would work well and it is reversable!

[DJ Morrow]

When I'm not learning about CNC stuff, I ride motorcycles long distance and long hours. 1000 - 1200 mile days are not uncommon. Handlebar vibration can be an issue so dampening becomes a topic of conversation. Some riders fill their handlebars with really small lead shot. I've never used it but I think they get it from places where you get shotgun shell reloading supplies. I've been thinking about using aluminum extrusions for a CNC frame and if you buy the larger extrusions, they sometimes have a decent size center cavity. I figured I'd use shot for that. Some riders mix it with some kind of resin or a bit of RTV to keep it from rattling.

[Mr.Chips]

I red an article about dampening viberation and sound and they used sand mixed with oil. You wouldn't be able to get it out but it would do the job.
Hager

[azsigns]

Thanks for the feedback.

I like the sand idea. I'll try it in my existing tables frame.

The way I see it a machine can't have to much power or weight!

I was also thinking concrete would make a good strong base for the smaller machine I'm building for engraving aluminum.

Thanks Kong for the link to Isfoils machine.
That's just what I was thinking of doing.

Chris

[lsfoils]

HI Chris,

Keep posting your ideas. Even those of us who are doin' it would benifit from some new perspectives. Good luck with your rig!

Doug

[yukonho]

I have access to ground up recycled tire rubber. I am going to fill the cavities in my X and Y axis torsion boxes with it. I hope it will do the trick. It is quite heavy and rather dense.
co

[svenakela]

As for me, I went to my local hand gun club and asked if I could take a couple of buckets with lead from the shooting range. And they were just happy to get rid of it since it cost them money to send it for recycling.
I can tell you, a bucket with lead is heavy!

Regards,
Sven

[h3ndrix]

Hey,

I would go with polymer Concrete like Boros said, it not only is a better vibration dampener than cast iron, it is also self-leveling and relatively cheap. It is what most gantry type CNC manufacturers use nowadays. Unlike sand, it wont move and settle either. It will make a great bed also

H3ndriX

[azsigns]

I just found some great info on polymer concrete.

http://irc.nrc-cnrc.gc.ca/cbd/cbd242e.html

Now I just need a price & supplier.

Thanks!

Chris

[h3ndrix]

Hey,

If you are going to use polymer concrete, be sure to go with epoxy polymer. Epoxy is much more durable and has better characteristics than polyester in almost any way except price. It might be a little more costly, but the pay-off is big, also it smells alot less (polyester will smell like mad) . Good luck.

H3ndriX

edit: oh, check out these guyz as a source for a quote
http://www.epoxysystems.com/682.html

[jcoats]

I've been thinking about doing concrete in a router base too. It has been 6 years since this thread was alive, so is anyone out there still interested?

[svenakela]

It's 2010, E/G table is the future.
http://www.cnczone.com/forums/mechan...out_stuff.html
http://www.cnczone.com/forums/epoxy_...es_thread.html