when Riley Alfred introduced us to Printed flask alignment https://www.thingiverse.com/thing:2822255/files I thought what a good idea Problem was that design has several issues 1: tapered pins 2: pins too short 3: no lifting points 4: female hole does not go all the way through (it will get sand in it leaving a cracked open mold and cause a runout) 5: no double D shaped hole Probably more I asked if a 3D artist I know would do something better for me. He agreed, I made this model, and want you guys to look at it and point out anything I missed https://youtube.com/shorts/AHVNemRjvFs Thanks in advance V/r HT1
You dont like tapered pins? I always did for hand placed flasks because when handling it allowed for the heavy mold to be a little askew in either plane yet still easily hit the bullseye, just as long as the pins are straight and close fit at the bottom when the halves met. Usually means you need a little longer pin but nothing wrong with that IMO. As for the "double D", I always just called that the slotted bushing, and yes, for sure one end needs to be one of those because it aligns the cope/drag just as precisely but will not bind like two round holes and pins. Best, Kelly
@HT1 , will the molded ones be D's? I have printed a set of the Thingiverse ones but have not cast with them. They feel 'loose' until fully inserted, at which point there is no play.
I have never seen a Tapered pin used on flasks, core boxes yes not flasks , on molds for parts with tight tolerances ,think of a 4 inch valve with a 1/8 wall thickness around the core, the flask has to come straight down or you will scrap the core and at best have loose sand, a thin wall bell is an extreme example of this long straight pins help you close a mold perfectly from tip of pin to closed slotted Bushing is another common name, but it implies a bushing, any other part would just be a slotted(fill in the Blank) in many foundry flask I have used it is a slotted square block welded to the side of the flask or part of a weldment attached to the flask
Only one side needs a slot so technically you need three models printed to do that the thingaverse ones will have issues! to work correctly you cannot have any sand in the pin assembly or they will not close tightly, and your mold will runout that is the issue with tapered pins , now if those pins where hardened tool steel and the flasks where being clamped its less likely to be an issue. But too many hypotheticals, just going to do what i know works just wanna know if any of you see something I overlooked My design is stolen and simplified from the flasks I used in the Navy V/r HT1
@HT1 If you can give a couple of stills face on and the side with some dimension's I can get you an STL and or a fusion file. no need to hire me
I get a little 'flask envy' when I see an old Hines, Adams, Fremont, etc. online...especially if they have spring release or other extra hardware for adjusting the alignment or rotating the works. The current ones at Mifco use a long straight pin with a tapered end, but only engages on the straight part, similar to the one HT1 shows above. I messed with the design in question. The pink and peach ones are from Thingiverse. My first revision attempt printing yielded 'silly string' on the cope piece. I re-designed the failed part with a revised pin and holder, printed it flat to the table with support material, and that print turned out OK. After some sanding I got them to slide together. Not saying that it is ready for prime time but I can say I made it through the process.
Something like those, yeah. I had some problems with the pins binding, but that might have been drill press operator or flask builder error... Jeff
Jeff, did you match drill them while on the flasks or did you make each bracket as its own component and attach them to the flasks with the pieces aligned?
Tried to match drill them together already on the flasks, but didn't get the results I was hoping for with my Soat Mon style hardware. I still have my patterns but never installed them on more than 1 wooden flask (so far) to try getting it right. Instead usually I just use blocks of wood that are easier to drill straight (enough) and can maybe flex a little unlike metal hardware if needed even if not drilled 100% perfect, rather than binding. The lazy approach in other words. Olfoundryman has similar "ears" on his metal flask patterns and he struggled with the pin holes too. I cast 7 of his 15x15cm boxes for the blacksmithing school here and one for myself. The ears on those have more draft than mine do so the bit walked off downhill even worse. The pins in mine are atrocious, shimmed with toothpicks and krazy glued just to make the flask even closable at, but just barely usable if I'm careful with it. I was really glad the owner of the school wanted to assemble his 7 so I didn't have to... He didn't spend too much time on setup to drill the holes, just banged them out real quick then drilled them a little bigger when we found nothing would fit right... We ended up with loose fitting pins that didn't even try to be fastened to either of the flask halves, they just dropped in from the top and would fall out of the bottom if you lifted the flask off the board without hanging onto them. Some would rattle around in their holes worse than others. Each cope had to stay with it's matching drag too. It worked better than it sounds but it was a bit frustrating to see after casting 64 of those flask sides. Olfoundryman shows how he got it done properly here, with drill press table supports and drill jigs and reamers and so on: Jeff
Thanks for the info and videos Jeff. I have yet to try casting flask pieces. Myfordboy seems to do well with smaller pins pushed in and out through wood blocks. Soat Mon has a rework video adding one slot per side per flask:
Myfordboy's short push-in/out pins seem to fit his blocks every bit as nice and even snugger than the fixed pins we used were meant to. It's easy to see they work great for him. I don't know how he doesn't constantly lose those pins in his sand. Maybe working on the floor helps. Students at the school were forever dropping their pins down into the sand bins beneath the molding boards at their benches. Glad they were big long easy to see pins... They worked fine. I would have liked them better if they didn't fit so sloppy. Jeff
I stuck with the KISS principle. Aluminum angle 1/8" and 5/16" bolts with the head cut off and beveled. Countersunk both sides of the holes so the pins don't bind.
I like your new design for these! Looks really good! I'd love to see how they stack up against each other in use. I dare say your version will be the better of the two. I have found another design, though I have not printed it yet. It can be found here. I'm thinking of giving this set a try as well. EDIT 1: I have also just found this file that looks possibly good, though I'm partial to the pin style ones in appearance (I have not enough experience to know if the pin style is as usable or not, but a lot of professional flasks I've seen have a pin) EDIT 2: I have also found this castable flask design...it's a lot of printing, but it looks pretty cool.
Thanks Riley. This has been a fun diversion and a great thread. I am still looking forward to what @HT1 comes up with, his will be tempered by many more years experience than what I have done. Some of the stuff on Thingiverse is very interesting visually, but sometimes lack the styling of a classic casting pattern: draft, fillets, etc. So if you are printing to use the printed part it is fine, if you are hoping to cast multiples to outfit many flasks then there may be issues pulling the patterns from the sand. In the meantime I drafted up and printed a 4-pack of small ones to be cast and drilled for pins. The design archtype is Soat Mon and the some of the cast flask pieces on Thingiverse et al. Currently my flasks have wooden guides, CNC cut plywood or simple 3/4" (19mm) sticks nailed and glued to the flasks. Other than me accidentally packing cope and drag backwards, they have not really let me down. So I would not let lack of flask hardware be a deterrent to starting to cast.
I'm looking forward to seeing what HT1 and Crazybillybob come up with. Your redesign of the file I had found and printed looks like a great improvement and I look forward to an update on that as well. This new pattern (Soat Mon style) is interesting and I think I like it! It seems to solve a bunch of issues that HT1 brings up, and they look simple to operate. My first flasks are going to have simple wooden alignment guides like the ones you show in your photo here. I'm trying to get some fun things 3D printed that I can cast to be upgrades for the foundry. For example, my initial sand ramming tool is going to be a rubber mallet, but I have 3D printed sand rammers in several styles to cast and try to see which I like best. And then there's the topic of this thread, the flask hardware. I'm hoping to get a bunch of different styles printed and then cast and see what I do and/or don't like about each of them. When I find one I like, I'll probably make a bunch so I can make all my flasks the same way for consistency.
if you need a pattern for a hand rammer I will send you mine for shipping, obviously I''l never use it again, aluminum split pattern V/r HT1
I've placed the cope on backwards before. Small registration marks contributed to the fault. I ended up painting one whole side of the flask to prevent it from happening (see above photo). For multiple flasks of the same size, each flask gets a different color. As for rammer's, they are perfect candidates for entry level lost foam. They are 'one off's' and quick, easy shaping. Here's two of mine.
