Tuesday, April 10, 2012

Plasma Scooter, Clamps, Umbrella And A Chair Leg

Fixing a whole bunch of things:

1. Nate broke his plasma scooter
2. Nate broke a chair leg
3. The wind broke the sun screen umbrella
4. I broke two clamps
5. I accidentally melted a clamp during aluminum pouring

1. Fiberglass is my friend
2. Polyurethane glue is my friend
3-5. The foundry DOES have a purpose, MELANIE! :)

Plasma Scooter (aka Nate's "Zoomer")
Lining the underside with fiberglass mesh and resin

Nate also managed to break the support arm so the plasma scooter doesn't tip over when steering hard left or right so the fiberglass mesh and resin got thoroughly applied
Another view of the fixed support leg

This is what it looked like from the outside once it was fixed. I think it's acceptable. Not pretty, but acceptable and Nate doesn't care, as long as he can zoom around with his "zoomer"
Chair Leg

Yep, Nate managed to break another leg! At least it wasn't his own this time. This was an easy fix: Apply some polyurethane glue and put it in the vise for an hour and we're good as new
And, because it is all hidden underneath the chair, nobody will ever know that it was fixed

During the molten aluminum pour for another project, some of the aluminum spilled over onto my clamp and because the bracket was also aluminum it melted it completely

I took a good clamp to make an imprint, then used the original screwy handle thing (you can see how the paint was burned during the "accident") as a core around the new part. I also used a custom cut piece of metal as a core for where the actual clamp goes afterwards

Here's what it looked like when it came out. The left vertical column is the sprue and the right one is the riser

After hammering out the metal core, cleaning up the fins/edges and loosening up the screwy handle I put it on the clamp that it originally came off. I only saved about 5 bucks, but it was worth gaining the experience on how to do it

More Clamps
About a year ago I broke the handles off of two clamps because I was a bit too forceful. I kept them just in case any of the others broke so that I could use these parts to fix the others, but then I thought why not make new handles out of aluminum. In the above picture you can see the triangular part that tightens the clamp that used to be connected to the handle that broke off
I took off the handles of the other two clamps that I had managed NOT to break yet and used them to create a mold for the replicates

Here they are in the drag to make one half of the mold cavity

After they cooled down enough to take out of the flasks

After they were broken off the feeder but still with all the fins and sharp edges on them

After they were cleaned out and drilled for the metal pin

Putting them on the broken clamp

Both clamps fixed. They were each about $20 bucks so it was worth doing it and they most certainly won't ever break again!

Patio Umbrella Pivot Part
We bought a swingable patio shade umbrella but during a very windy day it actually snapped right off. Since this was an injection molding created part it couldn't be glued or plastic welded so I put it aside to make a duplicate out of aluminum. However, because the injection molding process used three movable molds I had to improvise somehow to make the ribs at the bottom

First I had to drill a 1" hole at the bottom of the part and fit a piece of dowel into it. This dowel was then mounted on a piece of wood
I bent a piece of flashing around the dowel to allow enough room to make a negative imprint of the ribs

Here is the old (broken) part and the form for making the ribs

I put the original part over the dowel and filled the space with reo-flex two component polyurethane rubber and let it cure for 24 hours

This is what it looked like after I removed the original broken part

Now I could fill up the new cavity that the old part left with another batch of rubber and let it cure for another 24 hours

After I removed the created rubber replica of the ribs, I cut the original ribs off, stuck a dowel into the hole and put the rubber replica onto the dowel. I also cut the original part in half with the band saw so that I could have my split pattern for making the mold. The reason I created the rubber ribs was so that once I pulled the hard part out of the sand I could bend the rubber ribs inwards and gently pull them straight out without damaging the impressions these rubber ribs left in the sand

After the cast was pulled out of the flask and cleaned up

Add a little bit of paint

And there it is. Now, instead of throwing out a completely useless umbrella we can either use it again or sell it for $50 bucks. And, this time the part will certainly never break again
Scissors, grinder, drill press, metal file, foundry, vise, band saw

Green sand, aluminum, polyurethane glue, dowel, fiberglass, 2-componenet reo-flex polyurethane (shore hardness: A60)






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