[jhudler]

Jack,

...
Is there anything interesting about barium sulphate other than its density?
...

Just density, though if you want to get exotic I suppose BaU2O7 (Barium Uranium Oxide) would it's almost 4 times as dense!

Need to find out what the Lead Oxide stuff goes for.

Jack

[jhudler]

You know with E/G in the hands of amateurs, it opens up the use of Hydrostatic and Aerostatic ways. It moves that precision decimal point one or two places to the left and makes the damping effect just that more sweeter!

Aerostatic bearings from New Way seem to offer the best solution for the money. They’re practically crash proof which is good for the pocketbook.

Talked with Professor Slocum of MIT once about using his self compensating hydrostatic bearings on E/G, but he sold the patent off to Hardinge and the data necessary to reproduce the effect is in an excel spreadsheet that’s probably locked in a safe. Too bad, E/G makes it easy to route hydraulics without much fuss.

If your a precision nut like me (why do you think I own 2 laser interferometers), his book is worth the read Precision Machine Design.

Jack

[ckelloug]

Jack,

You had specified nanoparticles and I found the following today which lists cost for almost every imaginable nanoparticle except lead oxide.

http://www.nanoamor.com/

If you're trying to increase mass, you don't likely want nanoparticles anyway since the nanoparticles can actually degrade properties if they are over a couple percent by weight of epoxy.

For regularly sized particles of lead compounds, I looked in the thomas register and found:

http://www.hammondleadproducts.com/

Jack and Walter, It sounds like the RF45 project would be awesome. Jack's drawings are pretty remarkable.

Walter, It's completely generous of you to cast that base for testing purposes!

Regards all,
Cameron

[Xerxes]

Walter, I wouldn't worry about damping. You probably get always very good damping because both epoxy and granite have good damping properties. To measure it, you just need a sound card, a hammer, and some suitable sensor (i.e. accelerometer) + possibly signal amplifier.


jhudler: aerostatic bearings are precise but not as stiff as metal rails. I have read some university research papers about this.

[lgalla]

Walter it was the PS fan.WD-40 solved the problem.
Epoxy Nuts:Originally posted in linear motion,but I think the Epoxy Nuts are here.I had read elsewhere on the Zone to cast nuts.Quite frankly, I thought they were nuts.Here is an interesting link.
http://www.trantekdrivesystems.com/d...iderations.htm
Larry

[jhudler]

Here's a PDF that talk about using ITW PHILADELPHIA RESINS 1500LFH to repair a lead screw nut. You could just as easily drill out the nut and make a new one with this process.

Jack

[ckelloug]

Jack,

I know that you were interested in building an optical grinding machine. The idea of running those new way air bearings on an epoxy granite chassis is intriguing. What types of machines do you think this kind of technology would be good for? I'd love to think about building something but all of my theoretical research lately has been on making strong flawless epoxy granite so my ideas for machines that need this technology are limited. I get the feeling that a microinch accurate x2 mill might not be the most needed product.


The E/G combined with the air bearings is neat because you can cast a surface that is probably flat to within .0001 over a couple feet by using low viscosity epoxy probably with some ultrahard nanoreinforcement like 20nm silicon carbide.

Interesting PDF about nut casting. I bet that this material can be replicated with chemically treated teflon powder (makes epoxy stick to it) and a thick epoxy along with a thixotrope like carbon black.

Finally, thanks for the info about Slocum's book. I'm going to have to get a copy.

Regards all,

Cameron

[lgalla]

Just for interest,Moglice:
The approximate percentage ingredients of Moglice are: epoxy resin 40-80, molybdenum disulphide 15-30, graphite: 10-15, aluminum: 5-10, copper: 5-10, alumosilicate: 8-15. Our club's Joe Williams found the Moglice patent on the web at United States Patent 4,329,238

[RICHARD ZASTROW]

Cameron, E/G type material has been in use for years in combination with air bearings for Co-ordinate Measuring Machines, Measuring microscope stages, super-precision lathes etc. All are historically not DIY projects and also quite high $$$$. You and cohorts on this thread could change that really soon. Keep it up, you're doing us all a favor.

TANKS

[the4thseal]

how do those percentages work for the moglice.... they do not seem to add up. Seems interesting though.

[jhudler]

For those that may be following the discussion, E/G and its recipe are not a one mix fits all solution. There can be many blends of aggregates, resins, hardeners, and other agents to achieve the desired effect; not to mention the process itself. This is why you don't see any recent patents on E/G because they don't hold up when challenged. So the recipes and process are relegated to Trade Secret status.

This is why we don't have to worry about lawyers enjoining us and cnczone from talking about it. In effect we are not reverse engineering anything nor violating anyone’s patents, we are taking common knowledge and using it.

Moglice's primary application is way bearing repair.

Its resin to aggregate ratio is designed to be variable and thus can be injected, poured or knifed. It doesn't require any heat curing or vibrating. I’ve seen this used before and it’s quite miraculous to see a machine tool restored to its factory condition.

A Moglice like recipe would make a perfect liner for aerostatic or hydrostatic ways.

[the4thseal]

i understand now what you were doing with the ratios. That makes sense and that is what i thought those numbers meant. i just wanted to make sure that i was not misunderstanding you. i just wanted to make sure that those ratios were not parts or units off some kind that i missed, otherwise i agree with you 100%

[HelicalCut]

JHudler

I wasn't advocating casting new parts in cast iron, the stuff takes years to become reasonably dimensionally stable unless it can be cooled a lot, I was advocating cruising the scrap yards looking for suitable machines to aquire strip and adapt to suit your application.

About hydrostatic ways, the self compensating type that MIT did some work on. I have quite a few of those papers, the principle is fairly simple you can do the math yourself. It is 2 variable disc type orifices in series with the intermediate pressure balancing the load, the metering valve on one side of the way supplies the load pad on the opposite side and vice versa, the "picture frame" introduces considerable viscous dampening to movement perpendicular to the travel axis. I wouldn't advocate making the metering edges of the hydrorail type way in epoxy composites of any type the detail required is very fine and a hard material is required to resist wear from the fluid, the load bearing part could be epoxy composite though. You might be able to make the self compensating box ways in epoxy composites though, at least the part containing the metering passages, and use a precision ground steel or cast iron box as the element it runs on which can also serve as the mating face mould.

[jhudler]

HelicalCut,
I did understand your point; it’s just there aren't scrap machines out there with my requirements.

On the Hydrorail subject: I agree, I don't see a bearing of polymer composite having the strength to maintain a 10 micron gap at 3000 psi. Perhaps it could if it was massively reinforced, but then you’re loosing focus on the goal.
My thoughts were directed at the bearing rail, there polymer composites possess very high compressive strength and could easily handle the job. Though fluid wear was something I had not considered, but given enough time…

Good idea about making the loading and compensation pads out of polymer composite, which could make experimenting fun.

At any rate I’ve read all his papers and I do understand the math, it just the empirical data he once eluded to concerns me… but that’s in the details. I wouldn’t attempt hydrostatics at this time for the simple reason that I’ve already go too much on my plate.

Got to admit though… it is intriguing!!!

[lgalla]

Jack thanks for the Philly resins PDF's.Good info.
Moglice newer epoxy has teflon in the formula.
From the PDF,it is hard to believe removing the balls and return tubes from a ballnut and injecting moglice or Philly and increasing the load capacity and performance.From other sources;claims:Increased screw life,increased load.80% efficiency.Hard to imagine taking a $300 nut and replacing the balls with epoxy.
Experiments are in order.How about some Acme rod and oversized cheap steel nuts with the polymer injected thread.E/N...epoxy nuts.
This talk of nuts,hydrostatic and air bearings is leading to wards accuracy without welding,grinding,stress relief etc.Possibly a near total epoxy based machine is in the works.
Larry

[ckelloug]

I'm relatively clueless about bearings but I've found two things on the web that folks may find interesting.

<A href="http://pergatory.mit.edu/2.75/2_75%20Lectures/PMD%20Topic%2016%20Rolling%20linear.pdf"> Lecture notes on bearings by Alexander Slocum from MIT</A>

<A href="http://www.designnews.com/article/CA151212.html">A design news article on future machine tool technologies from 1996 describing hydrostatic bearings</A>

Kudos to Jack et. al for posting this interesting hydrodynamic bearing discussion.

As for the problem of cast hydrodynamic bearing parts, it may be possible to make the surfaces from epoxy reinforced with Al2O3 (corundum) nanoparticles as these have a hardness greater than metals. This technology is described in the datasheets over at www.nanobyk.com for use in automotive paints.

Finally, what E/G properties are folks interested in optimizing? My work here has focused on maximizing strength and modulus by maximizing filler percentage via the rule of mixtures equation and then selecting bonding, deairing additives etc. I have written software that computes the filler percentage obtainable via Francois de Larrard's compressible packing model.

Regards all,

Cameron

[jhudler]

Walter, If you haven't yet done this (by this I mean your 100 lbs test base), look at adding a 1 inch radius where the column meets the base.

[jhudler]

<A href="http://pergatory.mit.edu/2.75/2_75%20Lectures/PMD%20Topic%2016%20Rolling%20linear.pdf"> Lecture notes on bearings by Alexander Slocum from MIT</A>

Just a taste of what's in the big red book Sorry don't mean to sound like a salesman but I really like this book, even though dated in places its very apropos.

<A href="http://www.designnews.com/article/CA151212.html">A design news article on future machine tool technologies from 1996 describing hydrostatic bearings</A>

Hmm... hexapod... wonder what you can do with casting lead screws into and E/G tube that's then injected with an E/T (Epoxy Teflon to steal a acronym) mixture to form the screw bearing. Talk about rigid!

As for the problem of cast hydrodynamic bearing parts, it may be possible to make the surfaces from epoxy reinforced with Al2O3 (corundum) nanoparticles as these have a hardness greater than metals. This technology is described in the datasheets over at www.nanobyk.com for use in automotive paints.

That could be the solution to surface quality and fluid wear! The real issue with E/G and hydrostatic bearings are the forces applied by hydraulic pressure. If you can imagine a ‘C’ shaped bearing with pads on the top and bottom; you’ll see that the middle part of the bearing in under great tension. As Helical pointed out the top and bottom pad can be some polymer composite and rest steel.

Finally, what E/G properties are folks interested in optimizing? My work here has focused on maximizing strength and modulus by maximizing filler percentage via the rule of mixtures equation and then selecting bonding, deairing additives etc. I have written software that computes the filler percentage obtainable via Francois de Larrard's compressible packing model.

Yes strength is key element in practically all the mixtures however as noted we have to be able to create other mixtures to satisfy other areas of a machine tool.

For example; I hope the end results of my research will yield a vertical lathe that will have the precision and accuracy of 10’s of nanometers. So not only are we going to need E/G for the major members, but other Epoxy mixtures for things like Rolling elements, Hydrostatic and Areostatic ways.
I know technologically I’m capable of engineering this, but I can’t build this if I’m required to haul around huge steel weldments. Of course I’m going to start off small and make a few small machine tools to gain experience before I start dropping what I’m sure will be in excess of $150K for the lathe and the temperature controlled room to run it in.

Jack

[jhudler]

Need something to handle outgassing that 1000 lbs E/G cast!

http://cgi.govliquidation.com/auctio...tionId=1342671

[ckelloug]

Jack,

Degassing may be more easily achieved for that kind of volume with dearing agent like BYK A525. Walter has had good luck with the stuff but we don't have a surfeit of hard data on whether it is as good as vacuum or whether there are any deleterious effects. I also think that siloxanes like DOW Z6040 or Dow Z6020, or some fo the Kenrich Titanates may also help deairing although strength is the primary motivation. I've got sampls of the dow and Kenrich agents but haven't started testing yet.