[ckelloug]

Count me in! I work for a firm that makes prototype carbon fibre parts and we would like to join the search to make a stable table.

Great. Several of us have the idea that a mold for a table could be made by casting a slick of low viscosity epoxy with a deairing agent. This will be good to about .0002 in/ft or the curvature of the earth. Precision Epoxy http://www.precisionepoxy.com/ makes epoxy commercially used for making plates on the floor for aligning car suspensions.

To make a cast plate, one will have to get a flat surface perhaps by the self leveling epoxy method and then make a mold and cast a more substantial plate against the flat surface. For a small plate, this will work but for a truly large plate, .0002 in/ft might not be accurate enough.

Could some one point me to a website or post with some info about vibe tables as i think i need to understand more about the compacting. In my limited knoloage it seems to me this is the biggest thing holding back the diy build.

What do you guys think about this idea:

build an mdf torsion box to create a flattish casting surface, skin it with a thin released al skin to make it air tight, build in any need features, fill with DRY granite, infuse, demold and fill any exposed thread/mounting holes with wax, build a small side wall and pour a very thin low viscosity slow cure epoxy and then put in our autoclave and spin up the vac pump to degass any air.

I want to do it this way as i have no access to a decent flat table to make a flat casting on. We have a 3x2.5m al plate but it is not very flat -/+ 2-3mm over its length.

also has any one tryed steel ball bearing of the right size so each fit in the gap of the lager one above? it seems this could be a solution that may need less shaking?

Is there any way to search a single thread?

I don't think anybody here knows if a fully compacted mass of powder can be vacuum infused or not. I've successfully vacuum infused a very loose packed mass of particles with epoxy but that doesn't scale to a tightly packed mass.

In general, Steel shot is more expensive than other fillers and the friction between the randomly oriented balls means that it is just as difficult to compact. It also does not achieve Face Center Cubic structure like the fitting balls into the voids of the larger balls idea would hope.

The models suggest that optimally one needs at least 4 orders of magnitude of size difference between the smallest and largest particles and for 4 orders of magnitude, and 8 carefully selected intermediate sizes between the largest and smallest.

Vibration is the most difficult part for the underequipped and from the research from several places, the part appears to need to be vibrated at at least 2g to compact fully.

The search this thread tool on the right side of the page up by the thread numbers does a passible job. If you are a linux user, I have written a couple of scripts to download the entire thread so I can search it with grep. I've also written some code that allows me to link to posts by post number which I used to make the index thread. If anybody wants to update the index, I'll share my tools with them.

Jestah, Take a look at the links on pg 301 to get a bit more idea of what's going on.

Regards all,

Cameron

P.S. Thanks to MBK for the post on optimizing the EG spindle.