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Very nice project.
I like the bow roller feet too!
I've been using old hockey pucks for my machine feet. They machine very nicely on the lathe, but don't have that sylish profile.
Cheers,
BW
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Well, as I mentioned in another thread here, I have begun building my spin casting machine and thought I'd go ahead and post some pictures of the progress so far.
I'm waiting on a 4 digit LED display to arrive so I can build the tachometer and then I'll be able to finish the control panel. It is all working (spinning) now and is pretty well balanced.
The frame is heavy to help dampen vibrations and I have been looking for an inexpensive way to add some good rubber feet. I've seen where guys have used hockey pucks for this but living in Florida those are of course nowhere to be found and with shipping they're not "that" inexpensive.
The solution came to me yesterday. I was walking through Walmart in the boating section and passed some boat bow rollers, they are only $2.96 each and 1 roller makes 2 feet ! You can see the pics of these below. I used 3/8 x 1-3/4 bolts because that's what I have allot of and these give good enough adjustment travel. Also put some feet on one of my drill presses.
I'm in the process of building a resistance furnace for melting the zinc also.
Anyway, here's some pics so far...
Last edited by SScnc; 01-24-2009 at 03:41 PM.
Very nice project.
I like the bow roller feet too!
I've been using old hockey pucks for my machine feet. They machine very nicely on the lathe, but don't have that sylish profile.
Cheers,
BW
Nice looking !
Could you tell us what kind of rubber will you use ? (and from where are you getting it ?)
Regards
Daniel
Originally Posted by dandumit
Thanks, good question. I plan to use This RTV to begin with then build a vulcanizing press and order rubber or silicone discs.
That is unless someone informs me of a better product to use for this application.
Thanks,
Steve
I am impressed Sam, looks very professional.
Thanks Joe, And thanks to all your work and help on the code, I can install the tachometer and finish the control panel.
I still need to decide the best method of clamping the discs together before spinning. I'm thinking I will just drill and tap the lower plate on the outer perimeter and screw in threaded rods then use knobs with threads to tighten the top plate down. Suggestions, ideas anyone ?
Pics to follow soon.
Steve (or Sam, hence the "SS")
Hi Steve, What are you going to spin cast, Wax or Metal ?
I ask because I am a little concerned as to how the material will enter the mold. On the metal casters I have seen, the crucible spins with the mold, whereas on the wax casters, you pour through a hole in the center of the lid.
I'll be casting zinc mainly. As for how the molten metal will get into the mold, if you look at the third pic from the left on the second row you can see a + marked on the inside of the lid. This is where I'll drill a hole about 2-1/8" in dia. and I may or may not use a funnel when pouring, depending on what works best. I think Harryman said that he never uses a funnel on his spincaster. That + mark lines up perfectly with the exact center of the spinning disc below.
You can also see I've incorporated a locking lever that securely locks the lid closed. I don't have a safety interlock switch on the lid, I don't think it's needed.
I've seen the type that the crucible spins with the mold too but mine will be the spinning mold type. I posted a link to a youtube video of one of these types in action using what I think is molten zinc, I'll find it and post it here too.
The best way to clamp the mold is via air pressure. I think the plans that Jeff posted indicate the basic setup. There's a rotary air fitting at the bottom of a hollow drive shaft forming a cylinder which moves the bottom plate up against the bottom of the mold.
You will find that to get quality castings, you will need to quickly, easily and evenly adjust the pressure and once you figure out the correct rpm and clamping pressure, it will have to be repeatable from pour to pour. Removing the mold, pulling the pieces and loading it back in the machine will have to be completed in the same amount of time, each time as well. The total cycle time both in the machine and out controls how warm the mold is when run which can be critical.
I used an old spin caster years ago that had weighted arms that clamped down on the top plate when spinning because of centrifugal force. Hardly effective, you could change the force either by moving the weights on the arms or adding weight, I forget, but it was junk.
I've cast waxes and resins and although it works, IMHO, it's less than ideal. Besides being a real mess, the materials are so light that to develop much pressure, you have to run the machine at really, really high rpms. There's better ways to cast them then spinning.
www.harryhamilldesigns.com
CAD sculpting and services
Hi Harryman,
Jeff's plans were helpful and I appreciate them but I could not determine just how the air clamping system worked. Your description has helped me get a better picture of it. I'm glad you mentioned the weighted arms because I had considered that but ruled it out because it seems that at the start of the spin cycle there would be no or very little pressure on the plates and that could allow the molds to shift.
I am concerned about repeatability and "hassle" of using bolts to clamp the plates. I wish there were a spincaster locally I could go and examine to better understand just exactly how the air clamping system works in regards to the relationship of the moving up and down of the bottom plate and the shaft, pulleys and bearings. But your description has really helped, I have a couple of methods in mind now that I will explore.
Thanks for your help !
Well, getting your hands on one would be the best way, I don't own any any longer or I'd post pics.
To the best of my recollection, the drive shaft is hollow and fixed in place on the frame so it won't ride up. There's a rotary fitting at the bottom of the shaft that allows the shaft to spin and pressurized air to be introduced.
http://www.mcmaster.com/#rotating-jo...ittings/=hrzfq
The bottom plate of the casting chamber is made up of 2 slabs of AL, the bottom most one is bolted to the top of the hollow drive shaft and has a recessed cylindrical pocket machined into it to the required stroke depth. The top slab of the bottom assembly has a corresponding male shaped cylinder with an big O ring acting like a piston ring. Air flows into the shaft, up through the bottom plate and acts against the upper plate of the bottom assembly, compressing it and the mold sitting on it up against the very top plate in the casting chamber. There are springs and sholder bolts on the bottom of the bottom assembly that pull the plate back down when the air is released, freeing the mold. The very top plate is held in a fixed position by interlocking tabs on it against notches or pins in arms bolted to the very lowermost plate of the bottom assembly. This might not be a very clear discription, but it'd all make sense the minute you saw it.
If you need it, I can create some simple drawings. I'm away from my computer ATM, but I could do it next week if it'd help.
www.harryhamilldesigns.com
CAD sculpting and services
Harryman, That's an excellent description ! It's a very clear description, I can fully visualize it now. THANK YOU. That's the way I'll do it on mine, I'll change the solid shaft to a hollow one and start making some new lower discs.
No need to take time making drawings if you don't want to but, do you recall the approximate diameter of the cylinder/piston ?
And thanks for the link re: the rotary fitting too.
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