Needs some way of joining all the pieces together solidly while you make the mould. Could have a shoulder on the middle piece and matching steps on the outers, so you can use countersunk screws?
Semi-Lost-PLA Casting Method
- Thread starter GreenTwin
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Slicer software should be able to handle locating the parts OK, if not do it in CAD in a few seconds, jigsaw style or dovetail
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Most hobby FDM printers are notorious for needing a little extra "clearance" when printing parts that need to mate together. It's just the way the plastic-pooping robots work, those Lincoln-logs that are used to build the part do not leave a smooth consistent edge. I typically have to leave about a 0.3mm tolerance or more between parts that need to slip together, and more importantly slip apart again. Since you are casting a gear that may not make any difference, but just sayin'....
We've got a couple of industrial lab quality printers at work that are amazing for the quality of parts they poop out. But, I think the little one was about $50K and the BIG one was closer to $200K. That's way deeper than my pockets go.
We've got a couple of industrial lab quality printers at work that are amazing for the quality of parts they poop out. But, I think the little one was about $50K and the BIG one was closer to $200K. That's way deeper than my pockets go.
That is interesting, but I will have to play around a bit with bound sand and the 3D printed helical gears to get a better feel for what is possible before I try that.
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When my Canadian buddy and I were making patterns for the green twin steam engine, he offered to have the flywheel commercially 3D printed.
My 3D printer at the time was low quality, so I took him up on the offer, and he had a company print the flywheel halves.
The patterns were fantastic quality, but fragile, and I ended up breaking one pattern, and had to carefully repair it.
It is not out of the question to farm things out to high quality printers, but I do like to find hobby-level solutions, and solutions that are as simple as possible.
I am not sure exactly what this material is, but it seems like a super fine granular material.
And I don't know what type 3D printer made these, but suffice it to say it was not a cheap machine.
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These gears are not that large, perhaps 1.5" diameter, and I have found that to get gear-grade casting accuracy, you need to have as few pieces as possible, and make a very accurate mold.
Resin-bound sand is very accurate, and it can give surface finish as good as Petrobond (but with gray iron), if you use a ceramic mold coat.
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"if you use a ceramic mold coat"
You've mentioned the mold coat before, what is it that you use? (You've probably answered that question before, but right now I'm too lazy to go searching.)
Don
You've mentioned the mold coat before, what is it that you use? (You've probably answered that question before, but right now I'm too lazy to go searching.)
Don
The product I use is called "VelaCoat" (tm), by Ask Chemical.
It is alcohol-based.
The proceedure is to first lightly propane flame the bound mold, to burn off any residual resin and/or moisture, then spray on the ceramic mold coat, then burn the alcohol off of the coating.
I use a slurry sprayer, but I have seen folks use paint sprayers too.
This product totally stops the molten meltal from burning into and adhering to the sand mold.
This eliminates all post-casting cleanup work, as far as cleaning the sand off the casting, since you can just use a dry paintbrush to dust off any slight residual sand on the casting.
Below are a couple of open-faced molds, and the resulting gray iron casting straight out of the mold with no cleanup.
It is alcohol-based.
The proceedure is to first lightly propane flame the bound mold, to burn off any residual resin and/or moisture, then spray on the ceramic mold coat, then burn the alcohol off of the coating.
I use a slurry sprayer, but I have seen folks use paint sprayers too.
This product totally stops the molten meltal from burning into and adhering to the sand mold.
This eliminates all post-casting cleanup work, as far as cleaning the sand off the casting, since you can just use a dry paintbrush to dust off any slight residual sand on the casting.
Below are a couple of open-faced molds, and the resulting gray iron casting straight out of the mold with no cleanup.
This is a flywheel in gray iron cast in resin-bound sand, without mold coat.
While it is a respectable casting, you can see that there is some sand burn-in, and so the surface needs to be buffed out to get a better finish.
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While it is a respectable casting, you can see that there is some sand burn-in, and so the surface needs to be buffed out to get a better finish.
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Pat, you posted a link to this video the other day in another thread. The way the use loose pieces for the fluted column is very much what I was describing for the windmill gear as the flutes and gear teeth are essentially the same sort of detail.
I think there are a number of ways the gears can be cast, and no doubt many ways will work, but I really want to use the most simple method I can find, and save the more complex methods for situations where there is no other way to do it.
I will start simple, and if that does not work, then ratchet the complexity up from there.
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I will start simple, and if that does not work, then ratchet the complexity up from there.
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I went out to the shed, to change the oil in the car, and later to work on some bound molds.
I have seen a rather large racoon in the yard, and unfortunately he wiggled his way through a hole that developed in the floor, due to a leak at the door.
That big fellow chewed into my 5 gallon buckets full of corn cob blasting media, and then climbed up on the shelf, and walked all the way down behind the boxes, knocking things off the shelf as he went, for about 16 feet.
Then he chewed up an entire roll of paper towels, and scattered them all over the floor.
You can't make this stuff up.
I got the oil changed, but then could not locate the two JasonB helical gears that I 3D printed.
I may have taken them to work, so I will check tomorrow.
If I don't find them tomorrow, I will print some new ones.
The show must go on, so everything got put back on the shelf, the floor got cleaned up, and the hole in the floor is repaired.
If my racoon friend finds his way in again, I will have to trap him and relocate him out to the country somewhere.
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I have seen a rather large racoon in the yard, and unfortunately he wiggled his way through a hole that developed in the floor, due to a leak at the door.
That big fellow chewed into my 5 gallon buckets full of corn cob blasting media, and then climbed up on the shelf, and walked all the way down behind the boxes, knocking things off the shelf as he went, for about 16 feet.
Then he chewed up an entire roll of paper towels, and scattered them all over the floor.
You can't make this stuff up.
I got the oil changed, but then could not locate the two JasonB helical gears that I 3D printed.
I may have taken them to work, so I will check tomorrow.
If I don't find them tomorrow, I will print some new ones.
The show must go on, so everything got put back on the shelf, the floor got cleaned up, and the hole in the floor is repaired.
If my racoon friend finds his way in again, I will have to trap him and relocate him out to the country somewhere.
.
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20 some years ago when my parents were still living and on their acreage, a female woodchuck burrowed under the wall and into one of Dad's sheds. She was building a nest to have her litter, made a helluva mess. I feel your pain.
Don
Don
