[allesg]

Hi,

I've been lurking for a couple of years around the 8020 router build forums.

I've also read everything widgitmaster has done - several times.

I stumbled into some I Beams at $0.15 a pound. That got me thinking.

I came up with the design below. No mold required at all. I realize this
is not the optimum use of E/G, but for me it is quick and painless to do.

I have access to a large Hass to machine the Ibeam surfaces true after
they are welded.

I'm thinking of filling the left side space between the flanges in pour #1. The right side flanges in pour #2. and the void between the two I beams welded together in parallel in pour #3.

I'll be traveling for a few weeks - starting tomorrow so I won't be able to reply any time soon, but a friend or two of mine here can at least see my design and
well, probably tell me not to do it this way...

[allesg]

I found a computer to use for a few minutes. Whew! Computer withdrawal!

It came to me that if I rotate the four I Beams that form the skeleton by
90 degrees (so the H's are standing) and space the parallels with something like very strong standoffs between them, I could take advantage of E/G much better and do MUCH LESS machining.

No CAD here, or I'd do a diagram! Awk!

[allesg]

Up till now, I've been planning to do a Mill using 8020 extrusions.

I have experience with 4" steel tubing filled with cement used to support the main central floor beam running down the middle of a house. The result is a much stronger support than if the 4" tubing were left empty. Adding plain old portland cement to the columm is cheap and easy. Soooo I've sorta been looking for a similar thing to do with 8020. (focus on cheap and easy filler mix)

I had been thinking of using something premixed and available from Home
Depot or Lowes or such until I stumbled across the postings here on E/G.

Finding huge I Beams in a local scrap yard at $0.15 a pound lets me construct a very strong frame quickly and it leaves lots of room for an epoxy filler to dampen vibration. With the design posted above, the accuracy of the machine would be in the welding and machining of the parts. Since I have access to a huge CNC Mill, I'm confident things will come together well.

Soooo for this design approach, I just want a quick and easy filler mix.

What's a good inexpensive mix for this design approach?

Later posting will cover having the E/G do all the work instead of the CNC mill.

[allesg]

SolidWorks JPG file

[rowbare]

This is what Bob Warfield used to fill the base of his IH mill: http://www.cnccookbook.com/CCMillEpoxyFill.htm

bob

[allesg]

Bob,

That was exactly what I needed. I'm not ready to calculate a trajectory to the moon just yet, all I want to do is weigh this balloon down.

I'll build a rocket ship sooner or later with fancy molds and all, but I wanta start out with baby steps first. I don't care if it costs more this way.

Thanks!

FWIW the I beams are being cut and welded.

Then I'll machine them.

Gary

[snookered1ca]

Up till now, I've been planning to do a Mill using 8020 extrusions.

I have experience with 4" steel tubing filled with cement used to support the main central floor beam running down the middle of a house. The result is a much stronger support than if the 4" tubing were left empty. Adding plain old portland cement to the columm is cheap and easy. Soooo I've sorta been looking for a similar thing to do with 8020. (focus on cheap and easy filler mix)

I had been thinking of using something premixed and available from Home
Depot or Lowes or such until I stumbled across the postings here on E/G.

Finding huge I Beams in a local scrap yard at $0.15 a pound lets me construct a very strong frame quickly and it leaves lots of room for an epoxy filler to dampen vibration. With the design posted above, the accuracy of the machine would be in the welding and machining of the parts. Since I have access to a huge CNC Mill, I'm confident things will come together well.

Soooo for this design approach, I just want a quick and easy filler mix.

What's a good inexpensive mix for this design approach?

Later posting will cover having the E/G do all the work instead of the CNC mill.

Hi Allesg

I have been contemplating adding EG to the interior of 8 x 10" rectangular structural steel tubing to form the base of a lathe bed. I'm just wondering to what thickness you used and if you encountered any adhesion problems. I anticipate applying the EG to all 4 interior surfaces after the required holes are drilled and tapped in the tubing.

Thanks
Bruce

[BobWarfield]

Howdy fellas.

FWIW, adhesion can be an issue. Make sure there is no oil residue and I would roughen the surfaces before pouring. Better still would be to give the Epoxy Granite something to "bite" into. Since you're using mild steel weldments, you could just simply spot weld some pieces that will reach into the Epoxy Granite and give it something to grip onto.

You can make the material as thick as you like. Be careful on a lathe bed exactly how you set it up as the weight might warp the bed, which would be a hassle.

E/G is great fun to work with. Just be careful of the epoxy as it can cause an allergic reaction that gets worse each time. Gloves are a must, but working on a big project beware brushing up against it. You'll get a nasty belly rash that takes months to go away--DAMHIK!

Remember that while the material is somewhat strong/rigid (can be about 1/3 of cast iron), it is mostly there to dampen vibration. Make sure there's enough steel beef for the real strength. I would think your project should come out real nice.

I assume you'll use a VMC (you mention a Haas?) to machine the beds for your linear rails so they're properly aligned. I wonder if you might want to consider whether that material will move after it is machined? You might consult with a machinist on that. Many materials like that do move as stress is relieved. There may be some seasoning procedures you could do to minimize the movement.

Cheers,

BW

[castinite]

We can provide various epoxy quartz filler materials, much better quality and lower price than anyone.
~Castinite~, polymer cast, polymer castings, precisions machine grouts, polymer base pumps, base pumps

[castinite]

We have developed cast epoxy-quartz technology that allows us to cast to very precise tolerances, without secondary machining. This means delivery is much quicker and cost much lower.

[allesg]

Thanks for the suggestions guys. They're great.

My initial enthusiasm is still here, but unfortunately several everyday real life things got in the way. I have been in very intensive training for HAAS, Mastercam and machining. Well, intensive for someone over 60 anyways...
That has taken about 110% of my time.
I'm hoping this next semester will allow me to finish this project.

I decided to use 10" x 4" with 1/4" wall steel tubing instead of the two I beams butted up to each other. The advantage is no welding - no distortion.

All I'm doing to the tubing is drilling some holes to mount the rails with, so there's little stress to worry about.
I'm planning for hollow cardboard tubes to allow for through bolts.
I'm thinking about cap nuts on the inside of the tubing where the rails need to be fastened, but that's probably overkill. I think I read somewhere that someone greased anything they didn't want the epoxy to go
I'll be machining some thick end caps for mounting the servos and ball screws and that's about it.

Thanks again for the suggestions.