PDA

View Full Version : pic happy tonite



darryl
03-24-2007, 01:09 AM
Here's a pic of a balance I made to accurately meter out epoxy components, etc.
http://img.photobucket.com/albums/v136/heinrich/balance.jpg
Along the back you can see the different balance weights, going from 60 grams down to a half gram. There are two custom weights, matched to two of the common mixing cups I use. This makes it fast and easy to cancel out the weight of the cup. With the series of weights, I can balance to within half gram increments up to about 350 grams or so.
The brass thingy at the top is the zeroing weight, and two of the setscrews are ground to knife edges for it to balance on. The upright posts have vees' on them for these edges to rock in. The trays are- could it be- stainless egg turners. Yep. To the right are two bottles of epoxy components, the apple juice and the root beer. :) Actually, that's a very fast molding compound, which pours like water. You'd better have it poured within two minutes or it goes in the garbage.

Back to the weights- once I have the correct mixture added together, I'll just remove the custom weight from the pile on the second tray, them pour the rest of the weights from it into another mixing cup. That cup goes in one side of the centrifuge, and the mixture goes in the other side (once mixed). That automatically balances the centrifuge. I need to do some homework on that now, since the cup with the weights has a tendency to crack at the bottom when spun up.

It was interesting making the weights. I looked up the weights of brass and aluminum, took an educated guess at the alloy (for the brass, anyway) , and made up what should have been very close to 1 gram, 10 grams, and 50 grams. Then I took these to several drug stores and asked to have them weighed. One place got the weight almost exactly right, according to what I thought they should be from the data I found, and the sizes I made them. All the other places had them weighing more than they were, with the exception of one which said they were lighter. I'm talking about drug stores and pharmacies, which are using nice looking electronic scales. Hmm.

Mike W
03-24-2007, 01:52 AM
Nice job on that.

Tinkerer
03-24-2007, 02:25 AM
What the... have you seen the new stainless steel spatulas that I just bought.

Nicely done... :)

Your Old Dog
03-24-2007, 05:11 AM
damn neat job. Are the weights calibrated to a standard or do they only have to represent relationships of part A to part B?

Evan
03-24-2007, 07:36 AM
I looked at that and said to myself "Hey! that's cool". Then I thought "waitaminute, those are spatulas! Hey! that's cool."

I would be highly tempted to build one but I already have a triple beam balance.

Maybe there is a masscon under those stores?

BTW, you can use shiny new pennies and nickles to calibrate. A new Lincoln penny is exactly 2.5 grams and a nickel is 5 grams.

Oh, a dollar bill is 1.000 gram ( all bills weigh 1 gram)

C - ROSS
03-24-2007, 08:29 AM
Nice. Great job of thinking out of the box. It's plain for all to see that your mind is in the kitchen.

Ross

IOWOLF
03-24-2007, 10:12 AM
I looked at that and said to myself "Hey! that's cool". Then I thought "waitaminute, those are spatulas! Hey! that's cool."

I would be highly tempted to build one but I already have a triple beam balance.

Maybe there is a masscon under those stores?

BTW, you can use shiny new pennies and nickles to calibrate. A new Lincoln penny is exactly 2.5 grams and a nickel is 5 grams.

Oh, a dollar bill is 1.000 gram ( all bills weigh 1 gram)

Canuk or good old U.S. money?

Lew Hartswick
03-24-2007, 10:20 AM
WHAT?? No lift to keep the weight of the knife edges off the agate plates??
:-)
...lew...

Evan
03-24-2007, 10:26 AM
Canuk or good old U.S. money?

Seeing as Lincoln isn't a Canadian historical figure and we don't have dollar bills it must be US.

Alistair Hosie
03-24-2007, 10:33 AM
all bills weigh 1 gram



Evan Some of the bills I know weigh considerably more

fixxit
03-24-2007, 11:07 AM
I have been using the Nickel = 5 grams for many years.

The coins consistency is amazing, typically within one percent of 5 grams.

ProGunOne
03-24-2007, 11:26 AM
Evan Some of the bills I know weigh considerably more

:D :D

Same here

darryl
03-24-2007, 03:09 PM
Actually, I did use coins at the start for precise weight comparisons. At that point I was trying to verify the figures for weight of materials of particular shapes and lengths, round rod being the most workable. I found charts with this info on the net, and doing some math I could find what length exactly of certain diameter rod would give me the precise weights I wanted.

'maybe there's a masscon under those stores' - I don't understand

The weights are precise, but they are used as comparisons for part a, part b, mostly. Some of the mixtures are 1 to 1, some are 5 to 1, some are 10 to 1. Knowing how much to mix is handy also, once I fill one mold I can figure out how much to mix next time for that mold. That's where the actual weights can come in. No point in mixing 25 grams total when all I need is 18-

Sorry, no supports to keep weight off the knife edges. I'll have to put up with premature stickage and friction issues, etc :) So far it resolves well enough that one drop of liquid is enough to tilt it from one extreme to the other. I felt I could be happy with that :)

Elninio
03-24-2007, 04:08 PM
how did you drill granite?

darryl
03-24-2007, 04:42 PM
Elninio, you must be talking about the base. It looks like granite, but it's actually mdf with laminate put on it.

Evan
03-24-2007, 04:51 PM
Sorry. Masscon=Mass concentration. While a balance isn't affected by variations in local gravity a spring scale or equivalent is. That includes electronic force sensor scales.

ProGunOne
03-24-2007, 08:17 PM
Did you get a new camera too?

darryl
03-24-2007, 11:56 PM
New camera- No, the camera is the same Casio QV-R40 I've had for a few years now. I just got it working with the computer again, and now of course I have to make all the settings again and re-learn how to use it. Because my eyes aren't keeping up with my youthful vitality (what is that) I've had to make a magnifying contraption in front of the viewscreen in order to see things well enough. I'll post some pix of that soon.

At any rate, I laid up some laminate and fiberglass as an experiment. Here's a pic of the resin after mixing, and I purposely stirred it vigorously to entrap air-
http://img.photobucket.com/albums/v136/heinrich/beforede-air.jpg
and after 15-20 seconds of de-airing in the centrifuge-
http://img.photobucket.com/albums/v136/heinrich/afterde-air.jpg
The pic doesn't show that well how clear the body of the epoxy really is. There's a film of bubbles on the top, but the resin looks completely devoid of air bubbles. This is a 75 gram mix, the largest I've de-aired to date.

I learned a few things along the way- on the minus side, the centrifuge should not be operated on carpet-spilled epoxy is not fun to clean out of carpet- one shouldn't stand on any spots of spilled epoxy-and I'll probably learn this one later, one shouldn't sit too long with one's feet in one position on the carpet. Oh, and I learned that the ceiling in the living room is dripping water.

On the plus side, I learned that old phone books are handy to put gooey cups and spatulas on- paper towels are a godsend- fast orange does an ok job of getting epoxy off your hands-and the roof has stopped leaking, though water is still coming through the ceiling. Looks like this could be the year for me to redo the shingles.

I also learned that my research on resin coverage was accurate. The 75 grams, minus maybe 5 or so for spillage, was just about right to saturate the nearly 1 sq ft of 6 oz glass cloth.