Vodkaman

PoP dryer final prototype

19 posts in this topic

The pics show the final prototype of the recycling PoP dryer. The construction is self explanatory, but should anyone need more detailed information, I will make it available.

The air is drawn through two mains operated cooling fans. These are very quiet and low power consumption. The air is forced underneath the shelf and up past 3 x 100W bulbs. The bulbs serve as a source of heat. The heated air passes over the mold and back through the fans.

The mold(s) sit on wooden pins, to allow air to pass all around, with at least a 1

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Dave, Why the two fans? Could you use one larger or a higher speed? Or is there a reason you chose 2. I am asking because I have everything sitting here in my house to make one of these if it can be done with one fan. I can move 100 CFM with this one fan or use a rheostat to turn it down if needed. Thats a whole lot of air moving through a little box.

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This type of fan was cheap, readily available and easy to work with (square). It does not have to be two fans. I tried one, but the drying time was not good enough, just a bit too long, plus I had the space. But your 100CFM fan should suck the pips out of a melon and do just fine.

The heater does not have to be bulbs. Again, it was what was readily available. The vent holes are 19mm dia, because that is the size bit I had in my cave. Try a hole, if you get condensation, make it bigger. If may not even need a hole, so try without first.

Use kitchen scales to weigh the mold before drying. You are looking for a 30% weight loss. Example, if you demold weighs 700gm, the dry weight will be 490gm, eventually going as low as 455gm (35%).

Don't bother sealing the wood. As I stated, not necessary.

A thermometer would be nice, just to see what is happening.

Dave

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Well, the PoP mold still has to be sealed. If using the thinned epoxy method of sealing, I would say yes.

The dryer may help with the curing of Elmers sealing, but that has not been tested yet. The temperature may have to be reduced, but this is simply a matter of removing a bulb. I will start a test piece sealed with Elmers and see if it blisters.

Dave

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I did the elmers drying test in the PoP dryer. It seemed to work just fine.

I used 50:50 mix, soaked the first coat for a minute or so, drained, then into the dryer. I monitored the weight as the coat dried and gave it 3 hours, until the slight tacky feel all but disappeared. The tacky feel could have been exagerated due to the heat.

I then gave three more thin coats, giving each an hour in the dryer.

BUT, after drying, I noticed that I could mark the surface with my thumb nail. so I gave it a few more hours, no change. I then left the mold in the room for a couple of days, still no change.

Either force drying Elmers is a bad thing OR the thumb test is normal OR my batch of elmers has deteriorated, it is a couple of years old and was a bit thick and may have needed extra thinning.

So, the result was inconclusive. Any comments?

Dave

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Just a guess but I am leaning towards force drying elmers is a bad thing. I was kind of thinking this is how it might turn out when you said you were going to try it. If it was me I would attempt with a new batch of elmers just to find out but I think the same will happen. I am trying to figure out why I was thinking it wouldnt work when you posted it and for whatever reason, (probably because its almost 1:00am here) I cant remember what I was thinking. But who am I to question the genious of the Great and Noble Vodkaman. I think the pop dryer is a great accomplishment. I can wait for glue to dry. LOL

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Nothing noble, just searching.

I will pick up some fresh elmers on my next shopping safari. But just 'cos you pay for a new bottle, in Indonesia it does not guarantee fresh. I always have to open it and check the consistency.

Dave

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I haven't made a mould since I was in cub scouts, back when there was no "under God" in the pledge of allegiance, so I'm just thinking out loud here. :?

When I read this thread, I dropped down and reread the other thread about the dryer, and the PoP mix.

Years ago, in another life, we used milk when we mixed our fixall to smooth floor joints, because it made fixall stronger and helped it stick to the sub-floor surface.

I wonder if mixing PoP with milk might result in a pre sealed, stronger mix?

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Mark, I tried a google search for the milk idea, but came up with nothing. I did read, that milk was used to make paint.

I did another test, air drying the PoP sealer. The results were the same, easily marked with my thumb nail. So my conclusion was that speed drying made no appreciable difference.

Then thinking about your post, I did an elmers/water mix. I replaced 20% of the water with elmers. The new test piece took longer to dry, just over 3 hours to get to 30%. I continued drying for another 2 hours and got to 32.5%. I then tested it with my nail, the surface was much harder and very difficult to mark.

From this I can only conclude that the problem was the plaster and not the elmers. With the elmers in the mix, the surface strength is far superior.

Dave

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Dave,

Glad the glue worked. Seems like a logical thing.

Just watch the amount you add, because glue can cause shrinkage when it sets.

I ran out of tapping mud on a drywall job once, so I mixed carpenter's glue into the topping mud I had on hand, and it worked. But it was murder to sand, because it was hard as nail. Tapping mud has some kind of glue in it, to give it strength and adhesion to the drywall tape and board, but it also shrinks more than the topping mud, which is softer and easier to sand, and which shrinks less.

Before they started coloring them differently in the factory, we used to add latex paint, a small amount, to our topping mud, so we could tell what had been coated and what hadn't. We used to argue about what color to use (my personal favorite was blue), until we hit on yellow, because it colored the mud well in small amounts, and didn't bleed through when you primed the walls for painting. If you added too much, the mud shrank.

I even mixed fixall with carpenter's glue, when I didn't have any milk, but it didn't work as well as milk.

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A mini kiln is a good idea, I have used it to dry off some unsealed prototypes. Actually, I am finding new uses for the PoP dryer every day.

One of my favourites is to switch off the bulbs and put my dinner plate inside. Cools the food down in a minute.

Speed drying socks, when you run out. I am not admitting to trying that one, yet.

Dave

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Speed drying socks, when you run out. I am not admitting to trying that one, yet.

Dave

Dave,

That's why hair dryers were invented. :lol::lol::lol:

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Very informative post Vodakman! I was wondering if the percentages can be applied to water putty as well?

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Very informative post Vodakman! I was wondering if the percentages can be applied to water putty as well?

Easy enough to find out:

Weigh the mold once cured and write down.

weigh the mold at regular intervals.

When the weight no longer reduces, the mold is dry. Divide the final weight by the start weight and x 100.

The numbers are useful, because any mold that you make in the future, you can check the drying progress and even predict how much longer is required. As long as you record the start weight. Surprisingly, molds dry at a constant rate.

Dave

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