A New Stack

Stack...thats just what I call it.  I guess in retrospect rack would work just as well.  But it just seems more apt.  I dont know if anyone else thought of this.  Most likely.  Its a simple enough idea.  I remember documenting it here on the blog when I first made it.

When I first started casting, I was using a very small pressure pot.  In fact it was a paint pot.  I had to turn it on its side to be able to make the larger molds. I could barley get my hand in and sometimes it was sloppy.  So I was pretty happy when I found the one I am using on sale for $70.00.  But it is deeper than it is wide.  And that made for alot of empty space.  So I made a small shelfing (apparently thats not a word...hmmm) system. 

I cut 3 pieces of thin paneling.  I put one on the bottom of the pot, because the pot is curved.  Then I took the other 2 and drilled some holes, used some All Thread and a few nuts/washers and made a the shelf unit to fit inside the pressure pot.  Now I could make more molds at once.  At the very least, I didnt have to keep reaching all the way into the bottom of the pressure pot. 

 It wasnt until I used it a few times that I realized I made 1 small error.  Resin sticks badly to the wood.  So the shelf unit got bumpy and uneven from spilled resin.  I had to grind it off which is alot of work/noisy and messy.  However it can be easily scraped off with a putty knife or a simple scraper were it made of acrylic or some type of plastic.

So I finally got around to making the new shelf unit.  I kinda like the look.

I had some square pieces.  I just took a grinder to the excess and than spun it by hand over a belt sander.  I still have to put some pads on the bottom of the all thread so it doesnt damage the bottom acrylic plate.

Cleaning Files

You may hear me from time to time refer to Swiss Files.  This are small hand held files of various shapes.   Some are square,  some curved.  Each one designed to help get into that hard to reach spot.  I use these Swiss Files to sand down any imperfections in a cast including cast lines.  Now its more common for larger files to get clogged with bits of steel,  but if you are like me, your 'work' area isnt far from the 'casting' area.  And occasionally I will drop some resin on a file.  While a wire brush can work if you are stuck, the best way to clean a file is with a piece of brass or aluminum bronze (cheaper facsimile).  You run the brass over the file going with the grain.  With the brass being softer than the file, the brass pushes whatever is stuck in the file out.  Steel, dried resin, last nights dried remnants of a banana split...and it doesnt hurt the file.

Modified Pressure Pot

Its one thing to explain this.  Its another to show you.  1picture = 1000 words.

Metal wear on the lid from lid clamps

The clamps that hold down the lid are made of cheap pot metal.  But they are metal.  And when you tighten the clamps, the metal against metal marks up and damages the lid.  Eventually, you will wear through the lid.  This pressure pot is normally close to $200.  I would hate to have to buy one every couple of years.

New threaded Pin for clamps

This is what I was describing earlier.  The clamps I have on my lid are a 10 mm x 1.5mm thread pitch.  So I took some aluminum bronze and machined it to 10 mm in diameter and then I machined a 1.5 thread pitch on the length of bar I just machined.  This bar will replace the threads on the lid clamps.

The threaded bar that will replace the clamp threads

Here is the length of threaded Aluminum bronze I made that will replace the threads on the lid clamps.

Clamp threads replaced with spring pin installed

First I cut the threads off  of the butterflies. Next I drill a 8.5 mm (tap drill size equals diameter minus the pitch.  It's easier in metric because in Imperial you have to convert the fraction to decimal form and then you are working with 3-4 decimal places instead of whole numbers.).  Then I put some lock tite on the threads and thread it into the butterfly.  Then I drill a 1/8" hole in the butterfly in a position that is right in the middle of both the threaded aluminum bronze bar and the butterfly.  Next I install a 1/8 spring pin.

Finished Clamp with new threads

The aluminum bronze is soft.  Its a cheaper viable option to brass.  The reason I did this is that now, the threaded aluminum bronze will mushroom.  We want this to happen.  Because it is softer it will mushroom and wear instead of the pressure pot lid.  When the threaded aluminum bronze  becomes too mushroomed and no longer works, I will punch out the spring pin and replace the threaded aluminum bronze pins and drill a hole in the same place through the new aluminum bronze threaded pin and reinstall the spring pin.

Close up of finished clamp

Now I realize not everyone has a lathe to machine the 10 mm x 1.5 pitch or whatever thread pitch your lid clamps may be.  You might be able to get some brass  bolts or cap screws.  You can use these just as well.  You just need to cut off the head of the cap screw or bolt. It took me 1 hour to drill and tap the holes, install the new threaded pins and drill and install the spring pins.  All in all a couple of hours and our pressure pot should now live longer than we will.  :~)

And if worst comes to worst, you cant find the parts or you don't feel comfortable doing this...drop me a line at gold_dober@yahoo.com   I'll do it for you for a VERY reasonable price. 

Now the only thing on our pot that will need replacing is the seal every so often.

Washing LEGO

After using the LEGO a few times to make molds, they do get dirty.  Some of the clay sticks.  Some of the silicone gets into the inside.  Plus you have the sealer mold release that leave traces as well.  How do you clean it up?

In regards to the silicone, you basically rub and pick it out.  For the clay, sealer and mold release,  your best bet is to just wash it. 

I have heard stories from others about various methods of washing LEGO.  The one that sticks out the most is when someone put their LEGO through the dishwasher.  Even tho LEGO is injection molded, it is still plastic.  At about 170 F it starts to melt.   212 F is the boiling point of water.  And if steam is achieved, it can get reach even higher temperatures.  If you use boiling hot water, you will warp all your LEGO. 

The best way is to hand wash them in warm soapy water.

Modifying The Pressure Pot

I'm cheap.  I wear a $35 pair of runners till they fall apart.  I got a great deal on the pressure pot.  And I know things don't last.  I guess its a matter of personal position where you stand on this post.

Before you do something, you have to ask...Is it worth it?  Do I spend the time/effort to make something last or do I just go out and buy another one and throw the old one out?  I prefer to milk what I have till it turns to dust.

So I modify my pressure pot.  Not the design, I basically replace certain parts.  If you rub steel on steel, eventually it will wear.  That's why I put coppercote on the threads that lock down the lid.  To keep the threads from binding.  But when you lock down the lid, the lid top gets marked up.  So we replace the thread.  Drill out the handles.  Tap them the same size as the threads that lock down the lid.  We use Aluminum Ready rod.  Cut it to length.  Thread it into the handle.  Then you drill through the handle AND the screwed in Aluminum Ready Rod and in that hole you install a spring pin.  This allows for 2 things.  It secures the Ready Rod from coming out and it also allows for you to be able to simply knock the pin out and install a new Threaded bar when this one gives out.  We use Aluminum because then it wears and doesn't gall the lid.  This helps the lid to last longer.  Coppercote the new threads and you're ready to go.

Now like I said, I paid $ 70 on sale for my pressure pot.  Its regularly closer to about $150-$200.  And in just over a year I have had to do maintenance.  So I figure 2-3 years to the pressure pot without preventative maintenance. 

Some of you might choose to just buy a new one.  I'm cheap.

Pressure Pot Maintenance Advice

Im known for over tightening things.  Everything from pop bottles to nuts and bolts.  Its something I have to be careful of.  Its a natural habit for me to make sure things are snug. 

When you overtighten things, as with metal fasteners, you are creating stresses and strains.  You are squishing the threads together.  Eventually the metal will tear a little bit and start to gall up and tear in the thread.  This makes it harder and harder to turn till eventually it siezes up.

If you have the same issue as I do and even if you dont, I recommend putting some anti-sieze compound of some type on your lid clamp down threads of your pressure pot.  I use a nickel based antisieze.  There are lots out there all of them just as good as the other.  You have metal turning against metal.  You wouldnt run your engine without motor oil.  This is exactly the same.  They sieze.  Just the results of not using anti sieze are alot less traumatic and costly than running a motor without oil.

You'll be extending the life of your pressure pot substantially.