Monday, September 2, 2013

Easy to use CAM for wax carving

Imagine you have a customer with there own design/image and they want you to make a copy of it in metal.
 
You know how to carve wax... you know it will be hard to make an accurate copy but you don't want to pass up the job....
I went from the art work above...
to this...
 
It took the machine longer to cut the wax than I did making the file that created the wax.....
... since we're a casting shop, you know what comes next... yes we made a mold and cast a bunch in bronze and pewter.
The machine that did this, carve the wax from a Jpeg that I got in an email and turned into a usable wax in under an hour..... It didn't cost $30,000 and take me a year to learn the complex software to be able to use it. It does require that you have a Mac, doesn't run on a pc (sorry Bill)  I edited the Jpeg with something similar to Photo Shop. Ok, I could keep going on and on I'll save that for another time. It's call Waxcutter...

Waxcutter

...it takes up about 14" square on a table. It can cut flat parts one sided and rings. It can also cut the sides of a ring and with a little practice you can cut two sided flat pieces too. Best of all its made in the USA by people who use the machine and the software is easy to use. Oh the software is called "Easywax" and it comes with the machine.
 

I will be showing some things made by this amazing little machine soon. If any one is interested we are gearing up to teach a class about how to use the Waxcutter, email us to find out more.




Saturday, August 31, 2013

An easy way to keep your tools clean while working with injection wax...

We are testing out our new YouTube channel and making video tutorials.
In this first video tutorial we reveal an easy tech tip forr keeping your flex shaft tools clean while working injection wax. This also works great for other tools like scalpel blades while cutting sheet wax.

Wednesday, August 21, 2013

Round molds for round part

Have you ever tried to mold and reproduce a solid round cylinder? You make the perfect mold and the part still comes out slightly oval... not so good if it need to fit into something or you have to finish it....
So this was an experimental mold for polyurethane casting in our plastics shop. I was looking for a way to improve on a system we developed almost three years ago.
Our current system relies on speed, ease of use, accuracy and mold life.

This mold is used to encase an electric device in a protective polyurethane casing designed to take a beating.



The outside is the "mother mold" its made of acrylic and split down the center and drilled to create alignment marks.

The orange part is the master and the grey part is the sprue and funnel to pour the liquid polyurethane into the mold.


The mother mold was taped together with blue painters tape and becomes the mold frame. It seems to be the best tape to use because the adhesive doesn't react with the platinum cure RTV when the two touch. Maybe the lack of sulfur compounds in the adhesive, I'm not sure....

The mold has only one seam in it and it is designed to leave no mold line on the finished piece.



The blue tube  in the bottom of the mold is a peice of brass tubing wraped with that same blue tape. Its designed to hold the electric component upright in the mold so it doesn't touch the sides of the mold while casting.


Over all this mold seems to preform very well but it missed on two points of our criteria...
1 Speed
assembling the mold to cast is a four part process, our current process has only 2 steps.
2 Ease of use
the top half of the rubber mold is like a condom and is hard to remove from the casting.

We could over come the ease of use if we use a rubber with a lower durometer but we might sacrifice the accuracy if we do.

The next test in this arena will be to add a vertical parting plane... to be continued




Monday, August 19, 2013

A way to reinforce investment for casting hollow parts.

In the past we use to invest the part and treat it very gingerly with the hope that the investment doesn't let us down. Then we started using scale to measure the water and the powder, thinking it could be controlled by precise measurement and temperature. Once you learn this stuff it stays with you, like muscle memory. I'll talk more about that in another post.....
So in our shop we still use solid walled flasks and over the years we found great uses for the stainless steel welding rods we use to provide vacuum vents is the investment. The one use I will be focusing on is using it as "reed bar" in the investment.

I was commissioned to make a sword handle for a very expensive hand made blade.
the original 300 year old handle
I was given this handle as a starting point to make the new handle for the new blade. So began the process...


I made an RTV mold of the original and an RTV mold of the tang of the blade ( the part where the handle is attached ) so that I did need to keep the blade ( $150K )...

the wax model

 So here is where the reed bar trick comes in. This handle had to be cast in one piece with an 11 inch by 1/4 by 2 inch hole. The tang of the blade had to fit inside perfectly because my teacher was going to mount it on the blade the same way the original 300 year old handle was mounted. Just like a katana with one pin through the center of the handle. In the picture of the original handle the red dot on it is wax covering the hole where the mounting pin went. It was covered because I didn't want RTV inside the handle, it was going to be put back on the Ken blade it came off of. Back to the investment story....
This handle was all most 14 inches long and had a diamond shaped tapered hole that was at least 11 inches deep. we had to wait to drill the hole side ways through the handle until it was finished and ready to mount. So the solution, I invested the wax in the picture with the open end facing away from the base so all the air could get out of the space. I also inserted three 13 inch long pieces of that stainless steel welding rod into the empty space inside the wax. The three rod stuck about a half inch out of the investment and the end of the handle was about 2 inches under the investment.

The finished handle was the proof that it worked. I ended up making two, the first was a test cast to figure out if there was anything i didn't think about or needed to watch out for.


My observation in the process is no noticeable cracking around the rods where they stuck out of the investment. Inside the investment there was no visible distortion or cracking around the rods. There was discoloration in the rods but they held the investment in place through the casting process. The stainless doesn't stick to bronze, brass or sterling. I don't ever file the end of the welding rod flat, I leave the sharp little pinched end the bolt cutters leave. I believe it helps prevent the steel from sticking to the casting. when ever we use this form of reinforcement in investment we always use 316L welding rod we also lower the water ratio of the investment to 38% ( our investment manufacturer recommends 40% water ratio ) to make its cured strength a little stronger.

So think about this the next time you need to do something the your investment might not want to do...









Wednesday, June 26, 2013

Casting fine silver...

So we had a production run of fine silver parts to cast for an enamel artist. Anyone who has tried, will know that casting fine silver is difficult to say the least. Also clean fine silver ".9999" is hard to find. Most of the time you can find .999 pure and most of the time that .0009 % can be a problem. I have seen it wreck large runs of casting when mixing with germanium based alloys....
We have been using mullite crucibles for vacuum casting gold alloys and fine silver, the small white ceramic ones you can find at pottery supply shops.
That turned out to be problem #1... It is an aluminum silicate oxide..... I'm not a chemist but I think it could have an issue with the dissolved oxygen hungry silver.






 Hmmm... Oxide.... we noticed an interesting effect happening on the bottom of the silver if allowed to cool in the crucible. Looks like the crucible is off gassing while the metal cools. What you see in the picture is not what the inside bottom of the crucible looks like...
The first run yielded surface and flow issues, second run we used a more accurate way to measure the temperature and threw a chunk of charcoal block in the melt.

 The other thing that really helped was to raise the flask temperature a couple of hundred degrees above what we would cast the same parts in deox or sterling. Because of the fast chill rate of fine silver.







 Lastly quicker quench time for the flask after casting gave us much smaller grain formation.....
 And in closing we will be changing out the crucible for a clay graphite one...



Friday, May 10, 2013

Test grid for casting

Have you ever wanted to know just what's happening in a flask when your casting? I have and still do all the time.
A long while ago there was a disagreement about flask temperature for a high nickel content 14k white gold....
...so I pulled out my trusty grid mold made some waxes.... 700 800 900 1000 degree f.... we ran them through the burn out....
It would seem by our results that the lower the flask temperature the better the grid filled. The best casting was at 700° F with a complete fill... I'll post the test pictures here when I figure out which machine they are on.
In the mean time if you would like some grid waxes to test with email me here info@outcastandcompany.com you will have to share your results....

Sunday, April 21, 2013

working with customers platinum

Today I got an email from a talented friend named Sarah Loertscher



 She was looking for some information about working with platinum her email and my response is below....


 I have a quick question for you about platinum - I have a client that wants to reuse her grandmother's rings into small post earrings. I've found that using the rings in a casting situation is prohibitively expensive, because of the contamination and subsequent refining of the extra metal. I was then thinking about melting down the bits of platinum into little lumps, which I would then lightly facet and solder a post onto. Have you ever worked with platinum like this? I know it had an extraordinarily high melting temperature. I have an oxyacetylene torch… I was thinking maybe a rosebud tip would be appropriate. Anyway, any thoughts would be awesome, Just let me know!

Sarah
   So working with platinum, your torch should be totally fine you just need to make sure that the flame you are using is Oxidizing.... and NO carbon near the metal while you are melting it. Platinum is a serious carbon scavenger so use a clean ceramic block. If you don't have one I have some dead platinum crucibles that have a very pronounced groove on the side that I sometimes use to melt bits of platinum on they are made of "alumina and fused silica.
The other things to pay attention to is alloy type, which is sometimes hard to determine and if there is any solder in the ring you are going to melt.
The most important part is eye protection, I use #10 welders lenses. You can safely go as low as #8's but it will be hard to look at the molten platinum for very long.
Alloy..... does it look like a store bought ring or a custom made ring? Does it have a stamp ( PLAT, Pt 900, Pt 950) and a makers mark? If it has a makers mark that you can find usually you can also find out what alloy they use in their rings. Of all of the alloys a cobalt/platinum alloy is the only one to be overly concerned with, they are great for casting but a not so easy to fabricate or size without a laser welder.
Solder... a lot of times if a ring has been sized or repaired solder is used, sometimes jewelers use white gold solder to repair platinum because of the lower melting temperature. So the trick to finding that out is to heat the ring up with a torch till you get a little glow from the metal (use an oxidizing flame) don't get it too hot. Then let it cool down, if there is any solder it will turn black and the platinum wont. The you can avoid the solder if you know where it is and just don't use it.
As far as your oxyacetylene torch it's hot enough, platinum alloys have an average melting temp of around 3100° F and your torch can run up near 6000° F and is usually considered to be the best for torch work on platinum as long as you keep the carbon down by using an oxidizing flame.  

James M...

Thursday, March 28, 2013

just a little silver

And a ring.....
... oh yes and a pendant too.

Wednesday, March 27, 2013

Casting

So this is a little trick I learned a long time ago...
... An easy way to hold a carbon rod

A walk around....





My card.....

A new look for our cards...

Wednesday, March 6, 2013

Inside....

Another look...

The new!!!

A little peek inside.....

Old #3...

Fired up old number three the first time in two years.....