Automotive Rear Upright/Wheel Carrier

Discussion in 'Lost foam casting' started by Al2O3, Nov 25, 2018.

  1. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    As the title suggests, it’s an upright for a midengined car. The original is cast malleable steel. It weighs 14.5lbs. This would be cast from A356. I could elect for a stronger alloy but the person I’m making them for desired a weldable alloy, and I have ingot. I’m targeting ~8lbs for the cast version. That’s ambitious but if that can be achieved, it will save 6.5lbs of unsprung weight on each rear wheel.

    1 upright build up.jpg 1.JPG 2.JPG 3.JPG 4.JPG 5.JPG

    The foam pattern shown is a development piece. I made it with minimal jigs and fixtures and hand assembled the individual pieces. The features are not precise, but they are close and it’s a reasonable facsimile of the part. I’ll need to make assembly fixtures for the actual castings. The wall is ¼” in most places. I didn’t have the details for the two wings for mounting the brake calipers. As shown, they’d contribute more than a pound of weight. I’ll probably lighten those up to about half that before casting. There are a few other areas that can be lighter that I passed over for the sake of geometric simplicity on this trial part.

    I’m yet to add the coring features. Most sand cast uprights of this design have a 1” hole in the center of each side of the cored cavity for hanging cores. I haven’t decided on the gating but for the cores I'm very tempted to use two very small holes at the top and bottom of each cored cavity and vibrate the sand in similar to the approach I used in this experiment.

    Something like this. Gate in centrally through the four eared flange. There would be a pair of small holes in each location shown in yellow. Pretty aggressive…….high chance of failure but very cool way to exploit the lost foam process.

    6 Gating It.jpg

    This will be a good part for the maiden voyage of my new lost foam casting rig (discussed here: )……when I get the chance. Supposed to be on the receiving end of a Winter storm today…..bummer. No casting today.

    joe yard and Tobho Mott like this.
  2. DavidF

    DavidF Administrator Staff Member Banner Member

    Very cool part. Happy to see you boxed the whole thing in for strength .
    Are you going to heat treat it???
  3. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Yes, trying to get the greatest polar moment of inertia/stiffness possible for given material placement.

    Yes, may take a shot at something that approximates a ~T6, but T5 for sure. Also will shot peen and burnish the casting surfaces.

  4. PatJ

    PatJ Silver Banner Member

    It will be quite a bit stronger if tempered.
    That is a very nice design.
    I was going to say if you cast it exactly like the original, but use aluminum, that may not work too well, but you are way ahead of the game (as usual).

    I am seeing more and more of the lost foam casting in industry.
    I thought lost foam would be a flash in the pan sort of thing, and it would all revert back to sand castings, but it looks like the method is here to stay, and after seeing what can be done with it, I can see why.

  5. cojo98v6

    cojo98v6 Copper

    Great work as usual Kelly. This really has my interest as I've been really wanting to build a Locost USA and was considering casting parts like this. My only worry was the strength of the part, so I'll be following this one closely.
    On a side note I was going to give my first lost foam castings this weekend, but not feeling good and mother nature put that on hold.

    How bad is the storm hitting you Kelly, I'm in the middle of blizzed warning down here right now, fun.
  6. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    I'm gonna give it my best. We'll see how it comes together.

    Terrible; about as bad as I've seen it in recent memory. I have a lot of driveway and sidewalk, and a 20hp garden tractor with a snow blower mounted on it. It's a decent machine but can't throw a foot of heavy wet packing snow so I got after it when there was about 4" or so on the ground. The snow was so wet it was just bunching up in front of the auger and then would load and stall the beast. When I went slow, it was so wet it would clog in the shoot opening about every 5 minutes. Most of the time I didn't run the blower and just plowed/pushed the snow across the street. It was coming at +3-4"/hr but hard to tell because it was blowing and drifting so bad. I was out there for 3 hours but it was coming so fast I couldn't keep up. I was suited up but soaked and finally said F'it, went inside and retired to a beer and watching football. Haven't seen a county snow plow all day....which is very unusual.

    Gonna put a crimp on my casting for a while.

  7. cojo98v6

    cojo98v6 Copper

    Its gonna put a delay in my castings as well. Was going to break the new furnace in, but will have to wait now.

    We had a storm several years ago that was about this bad, hit during the day and I drove home in it, my 2wd Ranger almost didn't make it home. Got me a F-150 4x4 now, so I should have a better chance. I was afraid it would be the heavy wet snow, that's the worst to clear. I got an old '68 Deere garden tractor with a hydraulic blade, its only 14hp, but that all iron Kohler cranks out diesel torque. It clangs like a diesel too. I'll find out in the morning how bad it is to clear, not looking forward as it will probably just spin the whole time. Plows have been down the highway I live off, but not down my road which is also unusual, since the station is just down the road from me. Did have a large lightening flash and rumble a several hours ago, thought it was a branch on a powerline at first, lol.
  8. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    14" of heavy, wet, packing snow here. 2-3ft drifts. Plow just now making its way through my neighborhood for the first time 6:30 AM. I'm sure it'll leave a 2-3ft wake in front of my driveway entrance.....ugh.

    I can melt inside. I could even mold inside. But with LF, the pour needs to be outside. I could even do that but can't demold by dumping on a snow/ice covered driveway. Well, I could do it once but once the sand got wet it wouldn't be useful for LF any more. It would stink to high heaven if I tried to demold inside on the shop floor and standing at the beginning of Winter, that isn't gonna happen. The shop is my Winter sanctuary. This is a pretty good sized pattern and it will need my new rig with a couple hundred pounds of sand. I have a 30"x40" steel drip pan from my automotive lift but it wouldn't handle a dump from my larger flask.

    Looks like I'll be relegated to making foam patterns for the forseeable future.....sighhhhh.

  9. PatJ

    PatJ Silver Banner Member

    In order to get anything done, I really need to operate through the cold weather this winter (we don't really have cold weather like up farther north, but often a lot of rain).
    I am contemplating some sort of low rolling sheet metal cover; something that won't melt if the furnace exhaust hits it.
    In the past, I put a cardboard box over the mold, and used a hair dryer into the side of the box, with a vent out the top, to keep the mold at about 70 F.
    Not sure what I would do if I had multiple molds.
    I need an open pole barn, but that is not going to happen.
  10. cojo98v6

    cojo98v6 Copper

    I got lucky, my driveway is exposed to the north pretty good and the wind blew most of the snow out of it, only about an inch, so not worth clearing. 14", you win for snow amount and I'm happy to lose, lol.

    Being I have not done the lost foam yet, I'm not sure what to expect for smell, I've seen it mentioned several times, so a bit worried.

    Being I can just work on patterns when I cannot cast actually appealed to me about the LF.

    I've been greatly considering putting some kind of sheet metal hood/roof over my foundry area that I bricked in, I prefer to cast in the winter as its much cooler out, I'm a natural born sweater.
  11. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    My business is 30 miles North of my residence and did not get any measurable accumulation. 10 miles South and you were in a Blizzard. -Go figure.

    It does stink, no doubt about it. Think of the smell of burnt Bakelite when you smoke electrical power components. Of course so do a lot of resin based sand/core binders.

    Outdoors the smoke and smell is very short lived; a minute or less depending upon wind, but you'll want to pour on the upwind side. Your neighbors might get a wiff depending upon wind direction but that's about it. There are pouring videos in some of my casting posts in this subforum.

    Indoor LF casts are out of the question for me on any scale. I would not want to breath the byproducts, certainly not at indoor concentrations, nor foul the air in my shop for days or weeks. The sand will (strongly) retain the residual smell of burnt polystyrene. I store mine in 5-gal buckets with snap lids. -No odor at all. If you left the lid off you're shop would wreak of it. At $4/bag of sand at the big box stores you could just throw it on the lawn and call it a day.

  12. Peedee

    Peedee Silver

    That was my only beef with lost foam, the damn smell! I buried a load of sand just to get rid.
  13. cojo98v6

    cojo98v6 Copper

    What you got to love about Midwest weather, a few miles one way its totally different.

    Bakelite, super, I do not like that smell at all. I figured I'll wait till a breezy day to try my LF so the smoke/smell will be gone fast.

    I'll definitely pick up some sealable buckets to store the sand after use.
  14. Tobho Mott

    Tobho Mott Silver Banner Member

    I love the smell of lost foam in the morning... Smells like victory!

    You'll learn to love it too, or at least not hate it so much, once you pull a few sweet castings out of that stinky sand. A good thing too, since your buckets will hang onto that smell even if you ditch the sand someday and leave the buckets uncovered to air out for (checks calendar) a couple years.

    Good luck!

  15. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    I added the gate, sprue, and a pair of embossed entry and exit holes to each core cavity. Each hole is 3/8” diameter. I still have a hard time accepting an unsupported loose sand core even stands a chance of working, but from the experimenting I did in the link in the first post of this thread, and experience since then, if I can get sand to flow through the cavity, entering at the highest point and exiting at the lowest point, as shown with the yellow arrows below, it packs well and remains stable…….we’ll see. -Still freaks me out though.

    7.jpg 8.JPG

    It's coated and ready to cast.

    9 in Mud.JPG

    Last weekend we got 14” of wet snow and after I plowed, about 25% of my driveway still had 1” of ice on it including the area where I cast. This weekend it’s 40F and raining hard so I chiseled a bunch of the ice loose with a coal shovel, broke it into smaller pieces, and let Mother Nature take away what she brought last week. I'm hoping to have a dry driveway next weekend. Hopefully no more snow. -Fingers crossed.


  16. PatJ

    PatJ Silver Banner Member

    That will be interesting to see how it turns out.
    Its a fairly complex piece.

    Seems like people would use electric deicing cables under their driveways up north, but I never see them.
  17. cojo98v6

    cojo98v6 Copper

    Wonder if just lightly coating some sand in SS would work, not sure if it would still be too sticky to fill the cavity. I curious on how it will turn out with your method as I have some future patterns that will have cavities too, but I'll be able to fill with sand easier.

    The snow was not the bad part, that layer of ice from rain prior to switching to snow really sucked. The parking lot at work was horrible, we had to have the snow plow business come out twice to salt it all.
  18. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    SS will work if the cavity is accessible enough to pack it in with your fingers. It won't flow and self pack through small holes and if it did, not sure you'd ever get it out. People have also successfully used green sand in cavities and undercuts and then used the typical LF routine for the rest of the mold. On the approach I've taken above, several folks have indicated they've had success by filling the cavity with sand and then taping the entry hole shut. I haven't had much luck with that because I always get additional settling in the cavity when I vibe the rest of the mold. I've had best results when I can actually make sand flow through the cavity as shown. Even with the small holes the interior cavity eventually reaches the same packing density as the rest of the mold. Now, how it stays put after that is some strange voodoo though.

  19. cojo98v6

    cojo98v6 Copper

    Ah, good point, I have not used SS in a long time and forgot how much of a pain it can be to remove. I like the green sand idea, I have about 12 5gallon buckets of green sand, so I'll give that a try when time comes.
  20. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    That's the spirit Jeff! Good Apocalypse Now reference too.....Duval, Brando, Hopper, Sheen and more great actors....that was a good one.

    Tobho Mott likes this.

Share This Page