@HT1 No hate from here, I appreciate the honest answers based on your many years experience. Email sent, a good opportunity for me to thank him as well.
I would not expect hate from you, But production foundries cannot tolerate the potential failures this technique will cause, and FNG's trying it and failing will say "HT1 is Full of $hit, and I have reached a level of salt where I'm not going to do something Just to show people it can be done ( OK maybe if I'm feeling particularly froggy) SHHHH! super secret, I have a project on my agenda using this exact technique . But im so insanely backed up im sure I'll be several days late for my own funeral V/r HT1 Oh P.S. in my social medias I'm doing a daily post of my pattern Library, and New Long format Youtube videos are in the works
@HT1 , looking forward to your fresh social medias! Roscoe got back to me right away. There is a small amount of draft in the pattern, the angled sides that seem parallel are drafted slightly towards the back/bottom edge. Brilliant solution as it does not make it harder to machine if you clamp to the back as shown in the machining video HT1 posted upthread.
I had cut out an incorrectly-sized version of the Roscoe bracket and follow board before I got in touch with him but decided to keep going with it. I am still on 'light duty' from some knee/back stuff so the scale of the project was good. The loose waste in the center on the follow board (blue in pic) caught the bit and caused the CNC router to dive, I should have designed in tabs or added screws. I glued up the right angle (back to shelf) added the draft with a combination disk/belt sander before gluing on the sides. The fillets are beeswax with the inexpensive dotting/mandala tools from Michaels. I have half a mind (not sure where the other half went) to cut the metal tools in half, remove the silicone covers, and bed them into dowels so each size is its own tool with a wooden handle. The fillets turned black as I got soot from the lit candle I was using for heat as I did not use the heat gun. The mating surfaces in the follow board were made by adding Bondo (per Roscoe's video) and seating the sanded pattern against them with a layer or two of 'Saran Wrap' (kitchen cling film) to keep the pattern from gluing in-place. I did not surface plane the pine to thickness so I needed to fill in some areas with Bondo and spot putty before spraying with shellac. Not the prettiest work but it kept me entertained as I could do a little and walk (shuffle, limp) away while various glues, fillers, and finishes dried. The 3D print would have taken 7+ 1/2 hours. I would have needed some more time in CAD to add the draft to the 3D model and make the follow board match.
Still not molded, but I got something, or is it nothing, to be- (bad pun alert)- upset about... 1.6" (40mm) or so added to make room for the pattern w/ follow board in the drag. Upset is attached through the 4 blind holes w/screws that are set up to only align one way, dims staggered 1/2"(12.7mm). Had I had some 'aircraft' (extra long) bits I would have considered dowel pins. Visible dowel pin is used for a match plate, similar one on other side of cope. Brings up another ?...should pins extend from cope or drag? Saw Roscoe separating a match plate setup with the pins being in the drag. Most of my mechanisms are proud/pinned from cope. On my flasks that are not 'pinned' I add pins to the cope to catch the match plates, allowing the other bits to align drag to cope.
it does not matter save when it does , and it alternates back and forth , most often you want pins facing up, so when you place the drag on the matchplate the pins index the matchplate , but if your doing a split pattern seldom matters, but if you are doing a tall cope and short drag pins up or removable pins are required to get indexing the entire length of the pattern (think bell) V/r HT1
Nice, thanks. So do what it takes to mold the part. Molded up the last 2 sets of patterns, things went pretty good as in no big tear-outs/drop-outs. I still need to mind my edges and corners better. I ran out of Petrobond after having enough for finishing flask half #3, so I did #4 the drag (runner) of the mini SOAT brackets in K-Bond. Hoping to pour later today or tomorrow, we are having a nice run of weather here in Minnesota this weekend, predicting 60 to 70 F highs (15-20C) which is a fair bit above 'normal', followed by a chance of rain and snow on Monday and a dip back to more seasonable weather.
I got to pour. Calculated 34 oz (.96kg) @ 20% over CAD, loaded 35 oz (1kg) and was still short filling one basin, by about the amount I overfilled the other one and whatever extra I took out in dross. The parts look OK, calling it a good pour. The mini SOAT brackets with the heavy middles have small shrinks and the backsides of all of those have the 'fried' look I get with my current batch of K-Bond. On the mini Roscoe there is a defect where the gate meets the part, guessing I did not skim enough and sent in some dross that hung up in the intersections of gate to part. It took me a few minutes to find the smaller pyrometer, by the time I did and took a reading I was a little over my target temp. I should really find all those things before I light the furnace but figure it will fill the time while melting...which is already taken up with putting on safety gear (spats, apron, jacket, gloves, face shield), gathering tools, making sure the work area is level (needed to shim) and carrying the molds out to the shimmed area on the bench to be poured.
The machinists at work took pity upon me and helped me drill out the mini-SOAT brackets. One is pinned 1/4"(6.4mm) and the other 3/8"(9.5mm) with standard, low-cost bolts with the factory head removed. The bolts are not dead round like a shoulder bolt or anything else that is turned-ground-polished. I regret making 2 of the 4 'chunky' and may eventually recast them or see if the guys will cut out the middles to make them more like the 'skinny' ones . I also hope to make 2 more mini-Roscoe brackets and assemble those.
The Roscoes look more like pictures of "pro" flasks I've seen, but they also look like better sand catchers than the Soats... Jeff
You've done a fine job of casting those up. One of the drawbacks I see is they are only 'two finger' lifters. They would be okay for small flasks but for a large flask I need 'four fingers' to lift a heavy cope. Also the wider the better to control the lift. More CAD work?
ive never seen a pro flask tha t was not a bit of a sand catcher, Mifco's current being the absolute worse https://mifco.com/foundry-accessories/steel-flasks/ you need a place to grab, but that is just silly V/r HT1
Thanks. Yes, more CAD for sure! I am working on a new pattern with better finger room between the installed brackets and two tabs for the pin. If I can get my confounded 3D printer to make a couple pieces without failing (on my third attempt, one end keeps peeling off the bed) I should be able to assemble then and give them a try.
I installed the ones that were just finished. I like the larger pin (as pictured) better than the smaller one, I am wondering if they'd work smoother not having the 'chunky' receiver with less metal to drag against. I ended up drilling the blocks out 1/64" [.015"/.4mm] over the nominal pin size. They slide well but have a couple spots where there is a catch, guessing it is the partially the bolts not being dead round and whatever alignment issues I caused during install. The third set of prints worked, I am still assembling and filleting, neither which would have been needed if the original prints worked. I think I'll wait to see if they cast, then drill and install, before having a 'reveal'.
Reveal-schmeveal, here is an in-process update! Here is the intent as designed: The latest patterns are hybrid construction: wood for the base plate and 3D printing for the more 'swoopy' features, Bondo fillets, putty touchups, and coated in epoxy. The starting thickness is 1/4" (6.4mm) and the draft angle is 3 degrees. Patterns were designed to be 'flat backed'. I molded the first set in the drag. I did get some sand wash and a small shrink in the back, will try part in the cope next time. My guy at worked helped me get the 3/8" holes for the bolts in place. For the Roscoe patterns we drilled them stacked per Roscoe's Youtube video setup and for my new ones we drilled one up and then the other down, with stops on the vice, to assemble them mirror image. Theses sets already slide better than the ones from last week. I will drill the mounting holes shortly. Looking forward to seeing what others are using or scheming to use. PS: I was pretty excited that the hollow cavity in the new patterns molded well at 1" (25mm) deep, I did add a small air hole 1/16"(1.5mm) to each pattern before molding.
I really like that "Cleat Design" it still has the issue of needing a pretty good Drill press and an Angle plate to finish them, but I cannot think of a better option ( I need a better drill press) BZ V/r HT1
Olfoundryman worked out a pretty good drill jig setup for his drill press to get the pin holes right on his metal flasks. Something similar might work well for this hardware. Too late for me though. The one Olfoundryman flask I built for myself, the pins are horrible, I used a neighbour's really nice drill press but the bit still walked downhill on the drafted surface and the holes went oval, so when I tried to use the set screws to fix the pins in place, it pushed them out of square so I had to stuff shims and glue in there. Embarrassing really. And the 7 flasks I cast for the school that I didn't have to assemble never had the pins working quite right either - the owner had trouble too, and he had a machine shop so you'd think it would have been pretty easy. His compromise was to drill them pretty loose and not attach the pins to either flask half, they just dropped in and rested on the molding board, would fall out and get lost in the sand bin half the time when you'd lift the finished mold up to move it. We managed ok since students were only having to use the flasks once, and since the only patterns we had with any significant depth to them were molded all in the drag anyway, but that would be a no go for my home foundry. I wish Olfoundryman had been able to put this video out a year and a half sooner. Jeff
I wish he had kept that video private , he has the same Drill press as me, which sort of blows my trepidation out of the water .... save as a Machine operator , I know if I tried to set up a wood Jig like that the Boss would have a heart attack or fire me ... Ok he would not fire me, but he would defiantly loose his cool... I know if it works it works, But we gotta set the limit somewhere. Oh hold it a pour molten metal in my driveway V/r HT1
I made a big flask with fun laser motifs for Saint Patrick's Day and mounted the last two assemblies.I am thinking I will need to shorten the pin on one side so they engage the brackets at the same Z height...or make another half set of each and actually use matching pairs.
I like pic 2's best...if it was wider. Why are your drags so deep? All but one of mine are 2 1/2". Less sand, less weight.
