Foundry, Robotics, And Casting Video
idbruce
Posts: 6,197
Add it to next years Christmas wish list. For those of you who may be into backyard casting, this video will make you drool. I foresee the plans of a new CNC machine, in the near future.
http://www.youtube.com/watch?feature=player_embedded&v=jeofu_52qEc
Bruce
http://www.youtube.com/watch?feature=player_embedded&v=jeofu_52qEc
Bruce
Comments
Ken Gracey
I truly love the idea of 3D printers, but this video is just too cool for metal casting. When the machine is done carving the casting sand, just add molten metal. Similar concept, but instead of adding material with the tool path, you carve the mold, and then add material.
The forum has not heard the last of me and CNC. I have not given up! There is a lot in the works that has been on the burner for way too long.
I don't know if you read my last post about the wood lathe modification, but at the current time, I can now machine the ends of 36" long threaded rod, with that modification. There are still some problems to overcome with workpiece deflection and properly supporting the drive end, but when I conquer them, I can start making my design of inexpensive linear actuators, which means CNC galore for me.
Lots of projects laying around that just need drive screws.
Bruce
In many cases, you can take the molds to an existing foundry near you and they will do the casting. That eliminates the need to have a heavy industry site for your hobby work.
I have done such with lost wax bronze castings for art work. But there is no reason why the same approach would not apply to mechanical project. As long as the foundry can be assured that your mold is strong and stable enough to not explode, you can establish a good working relationship.
And you can likely choose between aluminum, brass, bronze, and copper rather easily. Steel might be more demanding and more costly as it has a higher melting point... and the higher temperature increases the hazards if gases backup in the mold.
One can do smaller molds at home and cast with silver and gold as well. Dentist and jewellers have been working out of small shops for ages.
Jim
That is a very good question! Between the two concepts, just think of the possibilities.
Dental and jewellers wax comes in a range of hardnesses and various properties. But you might just be able to use plastic currently available for 3D printers to construct a mold.
After the positive is constructed and attached vents and a sprue are inplace, the investment in an appropriate plaster is done. After that, you burn the wax (or any plastic) out of the mold to leave it ready for pouring metal. This is usually done by firing the mold in a kiln at a high temperature.
The only requirement of the plastic would be that it doesn't leave significant residues to interfere with the casting's details or to general gases that would cause bubbles during the pour.
Aluminum is easily cast from positive styrofoam parts without the burnout process. The styrofoam is merely buried in sand and the metal replaces the foam while the pour occurs. The only drawback is the surface texture is that of the styrofoam. If one wants to set up their own foundry, starting with aluminum is likely the easiest place to begin. But there are a lot of safety issues, and you need a good source of fuel, either gas or oil. The energy costs are quite high. Of course, there are fire brick, a good crucible, and a few tools required as well. It wouldn't hurt to have a fire retardant suit to work in.
I watched a video yesterday of a guy making a pour in blue jeans. While making the pour, he accidentally spilled a significant amount of the pour, which narrowly missed his leg and foot. I must say that his videos were pretty cool, but if that molten aluminum had reach his body, I am sure he would have been screaming.
I also did sand casting of aluminum in metal shop class in junior high school. Lighting the oven for the soldering iron was where I really caused an explosion.
-Phil
I truly appreciate that link. Thank you. I like the entire concept... a lot.
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The investment formula shown for that aluminum was 50% sand / 50% Plaster of Paris. I used something different for bronze and can't recall exactly. We did use vermiculite, maybe Plaster of Paris, and maybe sand. The main point is to consider carefully that your formula is right for the material you want to cast. Bronze is a higher temperature than aluminum. Steel is even higher and may not work with a lost wax casting type mold.
I believe that the mold I built included some stell wire to assure that it would not crack or burst.
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Steel is most often seen cast in sand in foundry work. There have been a lot of additives (traditional and new technology) created to stabilize the sand. The video at the beginning of the thread appears to be a stabilized sand that is being machined out to create a mold. If you can add the code for vents and sprue, there is no reason to not do this approach as I suspect there is no limit to the final casting material used.
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Regarding a fireproof suit..
You don't really need such a suit unless you are working in a steel mill. As long as your casting set up provides enough distance - headgear, apron, and gloves may be enough. You only get into trouble if you work too close to the molten metal and the pour. I was 'pivot man' and our scuplture teacher was the 'pour man' on a device that carried the crucible and it was about 20 feet long with the crucible in the center. Having an overhead crane pick up the crucible and doing the pour remotely is even better. Only the foolish get close to molds being poured as they may squirt molten metal, suddenly outgas, or completely burst in an explosive manner.
http://www.youtube.com/watch?v=IGJ2jMZ-gaI
:surprise:
Simply amazing. I cannot believe the sculpture that resulted from that pour. I am sure that is so much more effective than grandmas bottle of "Ant Be gone".
Bruce
It brings new meaning to "fire" ant!
I did notice that he stopped pouring when the metal began to backup and the soil began to steam.
Ants just may be the most numerous life form on dry land. And there are some claims that they do more to make soil than earthworms. It is likely that the trio of bees, ants, and earthworms are all critical to soil creation... more so that erosion.
Got my CNC almost ready.
Long time no see or hear. It looks good. Is it for routing PCBs?
Bruce
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Ya...Its a 12" by 18"
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I have run a bunch of simulations from DipTrace...I'll try it out this week-end.
http://www.youtube.com/watch?v=JB0DmVtvICI
Pretty cool video... Industrial settings are always very interesting and that is one place I would like to visit, just to see all the different processing.
You might be interested in the NAMES exhibit in the Detroit area. They have a lot of DIY casting, model engineering etc. They have a couple of vendors selling CNC plans and things like that.
http://www.namesexposition.com/
This prolly isn't the right thread, but for your lead-screws, you might want to go with Kerk motion. That's what I use. They have zero-backlash and are expensive, but that's just the nature of leadscrews.
I'm working on my own CNC right now, and so far I've got it drawn up on SketchUp. It's meant to hold a Dremel.
Thanks for the link and I am sure it would be interesting, but I will not be going.
After looking at your sketch, I would suggest that you consider using flatbar aluminum, and if necessary, drill extra holes in the flatbar to access coupling setscrews. In the past, I have had to bend angle aluminum just to make it a true right angle (90 degrees), unless of course you mill your mounts to be true. Additionally, the motor mount should also be thought of as a heat sink. I assume you will be using stepper motors and stepper motors can get quite warm. By using thick aluminum (1/2" or greater), you will preserve motor life.
I'll be using brushed DC because they are very strong and the ones I have come with integral encoders (Pittman brand). I hope I don't run into too many problems regulating speed, etc.
I understand that
If you are using rigid couplings and since you are using angle stock for your motor mounts, you must ensure that your motor mounts are square, instead of angling the output shaft upward or downward, otherwise you may break an output shaft or wear out the motor bearings prematurely.
(It looks like a lot more than designs like the ShapeOko I'm building has)
How will you combat wobble?
Brushed DC is really overkill.
NEMA17 or NEMA23 steppers are plenty enough when the spindle is a Dremel.
(Even Dewalt DW611 can be moved with the NEMA23 motors)
Most, if not all, already available control boards(Uno with GShield, Smoothieboard and so on) are designed to handle steppers, too.
You mean wobble of the Dremel bit? Or just looseness of the structure?
If you mean Dremel bit wobble, I'm accepting inherent wobble of the Dremel. If you mean looseness of the structure, I'm just trying to keep everything as solid as possible with steel and tight tolerances.