[jhudler]

Kids paper drinking cups are pretty strong LOL!

You are correct I wasn't wearing gloves when vibrating, I did while dispensing and stirring the epoxy. Took them off because they get pretty sweaty.

I'm going to make a vacuum vibrating mixer next.

Jack

[Eson]

jhudler

Wear gloves!
Anyway my idea sort of worked. I saw the aggregate 'bubbles' didnt mix well. Maybe if you can alter the vibration frequency you can crush the bubbles.

[jhudler]

jhudler

Wear gloves!
Anyway my idea sort of worked. I saw the aggregate 'bubbles' didnt mix well. Maybe if you can alter the vibration frequency you can crush the bubbles.

I've tried that (not on camera) it really didn't have much effect, the only effective means of removing air entrapment is vibration while under vacuum.

If you notice the epoxy never returned to its before vacuum level when I released the vacuum. This tells me air is still entrapped in the mix and when I vibrated it later, it reduced back some, and air bubles are still visible just under the surface.
What I believe is preventing it from deairing is the epoxy skinning over. Perhaps that's where BYK-A-525 comes into play.

The real test is doing both at the same time.

That's tomorrow!

Jack

[greybeard]

Cameron - what are you doing on line -you should be off taking your exams?

[jhudler]

Ok here are the pictures from the top are sample 1,2 and 3.
1200 DPI Color in PNG. (I use PNG because it's lossless)
White paint was used to highlight voids.

Too big to show in an image link:

http://www.hudler.org/pub/eg/Three Samples edge.png

The large black chucks are the quartz aggregate.

Notice the random distribution.

Jack

[greybeard]

Hi Jack. As a matter of fact I've got three vac pumps including a two stage Edwards, but as I said, I'm more interested in spinning at this moment. The beams will be from 2x1 to 4x2 inches and up to 36 inches long.
Were the three samples you've posted the ones that you gave the recipe for a couple of days back, and were they 1,2, and 3, top to bottom ?
Regards
John

[jhudler]

Were the three samples you've posted the ones that you gave the recipe for a couple of days back, and were they 1,2, and 3, top to bottom ?
Regards
John

Yes they were.

Ahh I just sussed it; you want to play!

I was looking at this to save you the effort and complication of spinning.

Jack

[greybeard]

Yes they were.

Ahh I just sussed it; you want to play!

Jack

That's my cover blown then.

[jhudler]

Ok someone checkout my thinking here:
I made a list seives to grade local aggregate to the agsco sizes in the current formula.

#10 - anything that doesn't pass is junk
#30 - anything not passing for #4 (should be 25 only I don't have a 30)
#80 - anything not passing for #2
#270 - anything not passing for #2/0
PAN for everything that passes #270, we don't use.

Here's the PDF that shows Agsco sizing.
http://agsco.thomasnet.com/Asset/Par...rain-Sizes.pdf

Can add more sieves if we create/have a more precise formula.

Thanks,
Jack

[romihs]

Jack,

Great results!! Thanks!

I was wondering where you get sieves from?
I was thinking of doing the same, but gave up on the idea when I could not find a source for sieves....

Thanks

Sandi

[jhudler]

I found all I needed on eBay.
Google sieves.
http://www.humboldtmfg.com/sieves.php
http://www.benmeadows.com
www.ascscientific.com
tons more from the looks of it... however Slovenia? Don't have a clue.

Jack

[lgalla]

Walter& Sven I had the same restrictions or limits to the 300 to 400% rise,requiring Only de gassing say 1gal in a 5 gal pot.Jacks video shows the rise is minimal due to the low resin content and the heavy weight of the fillers.
Larry

[lgalla]

Woops!Jack,didn't know you were backing off the vacuum as it rose.The vacuum bell jar is a good idea as you can monitor the rise and back off as required. Larry

[jhudler]

Larry, in the video and the 3 samples I didn't. But what I saw suggested this. During some testing today I proved it. So you would not need extra volume in the mold to capture expansion, but you will need release the vacuum to add more mix to the mold as it deairs, and then pull the vacuum again to finish.

Actually if you pull the vacuum slowly while vibrating I doubt you'd ever see it rise.

Jack

Jack

[jhudler]

Oh tested mixing with the System 2000 Epoxy Laminating Resin from
http://www.fibreglast.com/documents/345.pdf

I have the 2060 version at 950 Cps (37-127 is 600) and could not tell the difference in mixing between the two.
The 2060 shows a tensile strength of 45,170 psi while EPOTUF 37-127 shows 10,000.

Should be an interesting set of D-790 tests.

Jack

BTW I remember someone buying the thicker stuff from US Composites.
If your not using it.... could have it... or a sample of it?

[greybeard]

Hi Harryn.
I, too, am looking at using this approach to "true" up the surface of component pieces.
The only idea I can offer is along the same lines as yours, of multiple pours, but how about doing a quick brush coat on one side of the component, then turn it over, drop it onto whatever jig you've set up to get it level, then do the "table-top pour" on the other side.
While this reduces the warping stress, familiar to people veneering panels, what I can't figure out is what happens when you do the second pour over the brushed coated side to true that one up ?
Perhaps the only answer is to always fabricate anything that needs two opposed but true faces from two layers with their bad sides inwards.

On second thoughts, is this really a problem, given the difference in bulk of Larry's channel and that of the resin coating ?
John

[jhudler]

Harry,
Three steps are (if I remember)
1. seal the floor to prevent it from out gassing bubbles, and perhaps add color and/or decals.
2. Apply intermediate layer to level the system, and repair imperfections from seal coat
3. Final level coat to achieve desired results.

If you want to test the straightness or flatness of something you can use a laser interferometer (measures the angle of two parallel beams that are 90 degrees out of phase), an autocollimator (essentially a telescope with cross-hairs, light source, and very flat mirror), or....
Hook up your high MegPIX digital camera on a level and steady tripod and take pictures of a fixed target (90 deg block with a line inscribed on it) at precise intervals (say and inch) along the surface. Then count the pixels of deviation of the scribed line. This gives you the displacement in pixels (which have to be adjusted for distance). (note: huge amount details left out here, but I'll leave it to the reader to fill in)

You measure the whole surface to find the low spot, then polish down the high spot... this assumes it's pretty close to flat already, otherwise it's sandpaper time!

I use a laser interferometer only because I have one. I've used this to take a B Grade Starrett granite surface plate and lap it with Cerium oxide to +-.000015 or 15 millions of an inch.
Has to be done in a constant temperature environment and takes a long time.

[lgalla]

Thanks for the input guys.
The floor plate requires 3 coats as the concrete surface is sanded and may have cracks or expansion joints which may have air which would expand and rise ruining the surface.This applies to table tops also as you need a prime coat.Steel is non absorbing which would only require one coat or a first brush coat then pour as John suggested.An1/8 " of epoxy is not going to warp a steel plate.If this works we could build accurate machines with minimum tools and no trips to a machine shop$$$.
Harry have think a bit on the Al angle.
I have THK HRW-21's for the Z axis.These are low profile wide blocks making it necessary to use spacer blocks to raise them up to fit the ballscrew between the rails.Possibly I could pour some E/G into the channel under the rails as the spacer and leave the centre clear for the ballscrew.Any ideas?
Thankyou
Larry

[greybeard]

I have THK HRW-21's for the Z axis.These are low profile wide blocks making it necessary to use spacer blocks to raise them up to fit the ballscrew between the rails.Possibly I could pour some E/G into the channel under the rails as the spacer and leave the centre clear for the ballscrew.Any ideas?
Thankyou
Larry

Thin wall plastic pipe down the center, back fill 3/4 deep with resin, remove pipe with big heave ?
John

[walter]

Jack,

Thank you for that awesome movie. Seeing is believing!

Which pump did you use? Like this http://www.cnczone.com/forums/showpo...postcount=1365 ?

On the subject of laser flatness. Will you be able to investigate the epoxy surface plate meniscus? There was a discussion about whether it will cause any problems http://www.cnczone.com/forums/showpo...postcount=2037
This seems like a serious concern.

Once again thank you for an excellent job. You're officially admitted to Mad Scientists' Club!