Denis, I am looking for a simple I-beam construction extrusion that is about 3.5 inches tall with a 1/8" web. I do know I can get it for $35 a foot. But… Realistically I should be able to get it for $10 or less per foot.
this is a skill that Molders need to have, it is s skill, and a hard learned one , flask design(slotted Locater Bushings , Dual Pins, Adjustable V pins ETC. ) Help , and pattern designs, ( Split patterns and Patterns Plates) help to resolve the issue entirely, but if you are working from an old part or most any very tall or deep pattern, you MUST be able to lift the mold half Directly Straight up. Bells are a great example of this . One of the things many Hobbiests get to avoid, is tht in most cases, your Flask pins really should be taller then the flask half that is being lifted off of so you are sure to clear the top of the pattern with the mold, again a bell is the example that most of you will be familiar with V/r HT1
My flask tasted sand today for the first time. And, though I have yet to be able to lift my cope from the cheek perfectly, the bulb-nosed pins mentioned above, were a treat to use! ;-) Seen leaning against the bench in the upper photo is a top-board for the cope. It attaches via 1/4-20 button head screws. I have found that generous blasting of the threaded holes in the flask sides seems to clear them of sand quite well. So, no sand-jamming so far. The blue triangular band on the right in the upper pic is an aid to me to help make sure orientation of drag/cheek/cope is correct and identifies this set. There will be a red set in the not distant future. This flask set is really nice to use. Denis
The finished mold weighs about 185 pounds—-the flask set is 27 and it takes three five-gallon buckets of sand plus a few pounds for the bottom board. I am packing the the aluminum flask set and a similar-sized wooden flask set for another pour later today if the weather holds. The castings I shook out yesterday were both really nice. I’ll be pouring the rest of the pieces for a second flask set soon. Denis
Here is a link that gives a look at the lift setup I use. Before I made the drill-motor lift, I used a chainfall on the overhead trolley. The remote-controlled lift is way more convenient though the chainfall worked well enough. My heaviest mold weighs about 400 pounds. Having two hands free to guide cope and drag when splitting one from another or when assembling a mold is a big plus. http://forums.thehomefoundry.org/in...trol-foot-pedal-foundry-hoist-prototype.1016/ The lift has been working trouble-free since installation in March of this year. Denis
In retrospect I think I was making the corner joining techniques too complicated for my needs on these flasks. The flasks have worked really well and after casting into them 15 times or maore they have held up without a hint of trouble. But, I know I will be using this flask configuration over and over for a long time. SO, I cast a second set so I can do simultaneous pouyrs of the recurring pattern that fits these dimensions. This time I simply welded the corners. I used a chop saw to makew 45deg flats on the ends of the cast parts and then just fired up the tig and tacked them up square and then welded them. It was so much fasted than all the overly-fussy machining I did the first time around. And, should I ever decide the flasks need to be disassembled, that can be done by just cutting through the welds with a band saw. And I am currently making patterns for smaller aluminum flasks. In this caser I am simply going to use solid blocks at the ends of the patterns and then plan to chop saw miters and weld. Again, a much streamlined process. The welded corners are not a great option if the flasks will need frequent reconfiguring. But, for flasks likely to be used in a given size for a long time, I'd skip the fancy corners. Denis
So, I’m doing he lazy man’s filleting using epoxy resin. I masked off the flat surfaces as I did not want to coat them with epoxy. They will be covered with shellac and lacquer later. But I took advantage of the epoxy viscosity and surface tension by brushing a poured/spread layer into the recessed areas. The epoxy climbs the wall and makes a “perfect” inside radius to make the fillets. I did cut 20 degrees of draft on the inside edges of the picture frames to. I want these pattens to draw very easily and reliable. This saves hours of work otherwise needed using fillers of one sort or another—-typically Bondo or thickened epoxy.
A couple coats of shellac and a couple of lacquer and we’re ready to go. They are not perfect, but they are perfect enough for flasks. Denis
Printing a second set of Olfoundryman's smallest (150mm) flask side patterns now. Looks like I can fit two sides in a 12x12 flask but I need a couple more 12x12's to be able to pour 8 of these in one go. Planning to build those tomorrow. I may need to make several of these cast flasks if they turn out ok. Jeff
New flasks built. The top one has pins too now as of tonight, but I took the first pic before that. I built 2 boxes out of 2x8's then cut them in half on a table saw. Easy compared to building 4 boxes with 2x4's that all fit right. Flattest best parting line I have ever managed to get on wooden flasks! Both drags fit both copes perfectly at the parting line, I'll be making them that way from now on. Follow board drilled to match the pins on the new flasks... Still needs to be cut down to size and much sanding and smoothing before I pin the followers on, but I guess it will look more or less like this. I fixed an old flask that was falling apart too. Its pins don't quite fit but there's room on the other 2 sides of the board for another set of holes. I can just mold them sideways in that flask... My 4th 12x12 has no pins, just wooden blocks for alignment. I'll have to use the flask half where nothing sticks up past the parting line to mold the drag with that one, and just be careful not to let it move around while I work. A little more work to go before I can ram up the 4 molds I need, but I'm almost there. Hope I can pour all four with the #12 to get 8 sides in one shot... I may have to break into my unused petrobond stash to try. Jeff
Had to cut the follow board down so it fit through my friend's 16" planer, so no second set of pin holes is possible. The repaired flask will need new pins fitted to the new flasks's standard instead, unless I get lazy and just try to mold the drag using the flask's cope half (with the holes instead of the pins). Much depends on how many chores I can avoid to get going on this before the end of the coming weekend. Still needed some bondo and sanding after the planer. Then a bit of primer and more sanding. The followers are pinned to the board but they can come off if I want them off. Patterns got some high build primer and sanding too, still some layer lines but hopefully they'll release from the sand ok. A few other printed patterns I've been messing with have worked out ok with this treatment. Trying to follow both Olfoundryman's flask series and the examples upthread as closely as possible here. Jeff
Got the first mold rammed up, here's the drag after ramming up half the mold and removing the follow board. I forgot to take more pictures after that. I was in such a hurry I forgot to drill holes for screws to draw out the patterns with. Result: a little breakout along one of the long edges of the side with the alignment pin ears. The ears themselves pulled clean though! I figured since the first one's gonna be an ugly one, instead of starting over I'd just pour it now to make sure my gating works, before ramming up a whole flask's worth of molds the same way. I will let you guys have a look again once I shake it out. Jeff
As promised. Could be worse... Some little pits here and there I'd rather not see as usual, but I think I can use these. At least they filled. And the new flask worked great. Here's a better look at the ugly part though. Jeff
Hmmm... The 45's on the patterns are good, I checked them. But... Yikes! Not sure how they got so far off. They're like that no matter which corners I try fitting together. Jeff