We did another pour today. I lowered the cooking temp on my baked core from 450F to 325F. Bad idea. The core gassed and ruined that pour. Vern has some better pics. After he went home I made another core. Added vent wire holes connecting with the bottom holes I spoke about earlier. Blind holes not quite to the top of the core but open to the bottom. I also set it up off the table so the vents could work freely. I baked this core for 30 minutes at 450F. I let it cool on its own. I warmed the mold with a hand held propane torch well in advance of the pour hoping it would encourage any wetness and gassing to be minumized. I also did not put any sand at the mold joint as we noticed the finish there was not as good as the rest of the piston when I do that. The pour went well. I did not get the core well centered as you can see. Too bad because otherwise it is a good piston. I know i said i was going to make something to do that with but I got exctied and put it on the back burner. It is up front now. I also think my baked core is a bit too high so after pour I took my core box to the saw and shortened it a bit then repainted it. The finish right out of the mold is nothing short of great. I am more than happy with it. We are making progress. It takes 8 muffins for 1 pour. Don
I am now convinced I am on the right track so I threw out my other type molds including my XXX jug clay mold. The way these pistons are coming out of the mold and by that I mean the finish as cast has convinced me that for me this is the way to go. The problems are solvable. Don
Or you could drill a hole into the bottom of the mold and make a corresponding boss on the bottom of the core that would fit into said hole. That way you don't have to make the mold any deeper or the piston skirt any shorter. It would mean that you'd need a new bottom for your core box though.
I figured he had some locating method I just was thinking maybe he could extend the register and the core a bit to stabilize the top portion of the core.
From the way his core box is made, it seems to me like he's just setting it down into the mold and eyeballing center. He said he was going to make a gage to help with the centering, but I took that to mean some piece of stock that would allow him to evenly space it from the sides, but still by hand. It occurred to me that instead of changing the core box, he could just push steel dowel pins into the core from the bottom as he's tamping it, and then let those locate into holes drilled into the bottom of the mold. All he'd need is two pins and a piece of flat stock with the right size holes drilled in it to locate the pins properly while the core is being tamped. That'd be super easy to implement, and would guarantee that every piston ends up with the core in the same place. Four holes, a random piece of flat stock, and two 1/4" x say 2" dowel pins, and he's golden. But we'll see, maybe he's got something even simpler and just as effective in mind already.
The core is not tilting. Just I didnt put it in the right place. I want a slipper skirt so round bottom is out. Besides that still will not locate it . I am making a wooden locater that will go in beside the core when I place it so it will be centred side to side. This is no big deal. Say the difference between the outside of the piston and the thickness of the core is 1/2 inch then a 1/4 inch stick will locate it perfectly side to side working from the flat part of the core. Similar end to end except it is rounded so i will have to get creative but I am used to carving wood making fiddles so it is just time and patience that will do it. I thought about the dowel idea too. I need those holes for gassing. When i poured the last pour which went well I had vented the core and it pushed smoke and hot air etc out of those holes for about 4 minutes after the pour. I will try my wooden locating sticks first. If that doesnt work I wll give these ideas a shot too. I could also carefully locate the core then mark it with a sharpie. Remove it and stamp four locating marks with my letter stamps using say the letter I. It takes a bit of fooling around to sort this all out but it is so interesting to me I dont mind it a bit. Sure beats siting in the house staring at TV. What worries me is after I get my piston blanks done I will be finished casting . I will miss doing it for sure. Don Coolhand is right by the way. I just eyeballed it. Didn't have my glassses that time and got ahead of myself. Not a design problem. I got in a hurry and I screwed up. Plain and simple. I may be cute but I am not perfect.
your core locating pins could be tubes, they would locate and let the steam out, having the core just sitting there i'm thinking it could shift.
GOT ONE !!!!!!!! I had a successful pour today. I found a piece of metal in my stack that was exact for 6 spots in the core to wall clearance of the mold. (Budd good idea for sure. I did think about straws or steel tube like brake line but I am on a roll now) This piston I am happy with. Nothing iffy anywhere. 5 to go although I will probably make 7 . Here are some pics. First baking the SAND CORE in my $18 toaster oven. 2 fifteen minute cycles at 450F. Next, inside the skirt . Way high up you can just barely see it but there is a "D" on both sides. I stamped it in the wood of my core box and it printed out in the core and survived the pour. Then there is the piston cooling away. I was cranked cause I knew it should be good. And then how the mold looks before pouring with the baked sand core . The mold is sitting on two half bricks and open underneath where the holes are. Simple as that sounds that alone seems to be a major improvement. When I pull the piston the vent holes are black and sooty and smoke comes out for a long time after the pour. I used to sit it on the pour table. Probably before the gases couldn't exit fast enough. Don
BTW. the core bakes itself to the bottom plate. I bake it already located and sitting in the plate. It is stuck quite well actually and takes some force to move it if you have to and I did once on another pour. Don.
Today's raw casting sits beside the first one I machined up when I started pouring. You can see the revamped shape of the skirt. It gives a bit more support to the pin. The crown is extra tall . I machine well below the lowest point. The finish on this raw casting is excellant. i am very happy with it and only hope I can duplicate it at least 5 more times. Don
looking good, i hope your friend comes around and takes a few pics, i guess because your on dialup uploading large pics is pretty slow, some pics of the machine process would be nice, and a video of the first time you run the engine up to 5000 rpm's.
It has to go to at least 7000RPM or the project is not worth doing. I am losing 32 cubes with this build but believe the more conventional stroke will allow better performance albeit I will have to crank it up there to make up for the less cubes. I am currently running this motor (246 cubes) to 6000. I talked to my wife today about taking pics from the very first step to a completed piston. As for machining though with winter closing in I want to get all my cores cast before the snow hits so I wont be machining till that is done but sure I will cover it all. BTW I have tomorrows baked core cooking in the oven right now. Don Sorry not apples. Sand cores.
BTW Budd Vern takes lots of pics. Maybe he needs some encouragement to share them. You are right too. Dial up is a royal pain. Don
it is cool to see you baking the cores, you must be thinking ahead a little to baking cores for an intake, are you reusing your core clay?
You have been reading my mind. I did think about it but I have a more interesting plan what to build after i get these pistons done. Top secret for now. I have not tried reusing the core sand. It is like powder when it comes out. It is real hard but as soon as you break it it pours out. If I reuse it and it doesnt work I have wasted time and actually saved nothing. I have lots of good sand here why take the chance i thought. I am learning that in this casting there area lot of absolutes. When everything is right it works . If anything isnt it doesnt. Not much wiggle room. So on that basis I decided not to reuse the baked core sand. My wife who is an expert chocolate molder told me it is also like that. It is either pefect or it is no good. Nothing between. I am looking also for a 198 slant six crank this side of the Canadian border. If anyone knows of one please let me know. 198 was the base engine but not too common from 70 to 74 Dart Duster etc. Don BTW I also do the other baking. When i am in Germany visiting they have the worlds best breakfast buns. (Brotchen) They are hard , chewy and if you were shot with one out of a cannon it would probably kill you. Nothing i can buy here comes close so i taught myself to make them. After i finshed baking the core for tomorrows pour I came inside and started on this batch too. My misspent youth included a summer spent helping a couple of old bakers in their shop in Arnprior. I never knew it would come in so handy now baking sand cores and fuel for the foundry man as well. Don
Maybe try some of the Mopar car clubs. http://www.moparfest.com/occ_auto_club_membership.htm Probably others around. Might get lucky, and find a crank.
I did the Kijiji thing just now. We shall see. I would have to join the moparfest club to post there. I never got a warm fuzzy feeling from that group. I dont currently have a superbird or a hemi cuda (although I did have a Hemi dart.) Just a 63 MAX WEDGE and a slant six dragster plus the first V10 Ram ever ordered or sold. Somehow I just dont think i would measure up to their standards and i doubt they have any slant six folks anyway. Don
OK UnK you get the cigar! I already have an answer on Kijiji. The guy is nearby too, even in the same county. Hopefully he doesnt want too much for it. I am off to this morning's pour. If it goes well I will pour all day. I have charged my camera battteries , cleared the SD card and will film every step. Both video and still. Don
Got another!!!!!!!!!! Filmed everything start to finish. Am going to pour all day and finish if possible. It is beginning to spit rain but not enough to bother yet. Got the next "Sand cookie" baking as we speak. Don
there once was a backyarder/DIY guy from NZ who marched to the beat of his own drum, http://www.nzonscreen.com/title/britten-backyard-visionary-1993
Gotta another!!!!! Then we had lunch. Must have been getting a bit cocky because the next was a bummer. I could tell right from the first it wasnt pouring well. I think I didnt keep the mold hot enough. I think I let it go too long between warming and the pour. I have another one baking now and am trying to get back on track. It is probably just me being to anxoius to be done. If I mess this one up I will quit till I settle down and pour Monday.
The Jalopy Journal
