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Thread: Gearing up for sand casting

  1. #221
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    Nice finish Jeff. Love that sander, wish I had room for one but the shop is full.
    If you are going to do more of those plaques, look for a cheap corner sander. Makes quick work of sanding the numbers and edges. I have a Harbor Freight special and it's real light weight. I cut little wedges of sandpaper for use on it.

    I saw a Wen on Ebay Canada for 26C, free shipping.
    How do you like the pouring basin on the sprue? I tried that once and found it cumbersome to use, couldn't keep the sprue full.
    Bones

  2. #222
    Senior Member Tobho Mott's Avatar
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    Thanks Bonz, I like the edge/spindle sander too, but it really does take up a lot of space for how often I use it (not very). To be honest I don't really have room for it either! I probably would have grabbed my belt/disc sander instead if the belt wasn't still ripped from when I snagged it back in October working on a casting... It certainly would have been better than hand sanding for quickly smoothing out the borders and numbers... Got the spindle machine used for really cheap off kijiji (Canadian Craig's List) from this poor sad guy whose wife used it for some kind of arts & crafts stuff before she passed away. She could not have been very old (based on his age anyhow).

    Anyhow, the different spindle attachments had never even been used when I got it. Normally it sits up high on a tall shelf staring down at me and making me wonder if it was a smart idea to buy it. The long side of the plaque is actually a little too long to really get the best use from that machine - it overlaps the ends of the flat part of the edge sander belt to where the spinny bits are, which stick out a little. So I had to be careful to keep the plaque moving or it'd have sanded dents into the edge. The disc sander doesn't have that problem. But it doesn't have as nice and big of a table either... If I could only keep one, I do not believe it would be this one. Even though I can't do spindle sanding on my belt/disc machine...

    I think I have an old battery powered handheld sander like the one in your pic... somewhere buried in all of my junk. I really need to tidy up the shop so I can find it (and get the sander back up onto its perch instead of leaving it on the stairs where I have to climb over it)!

    I had trouble keeping the sprue choked full on this pour as well, but I am blaming it on the sprue pattern not having enough taper to it - the turkey baster tube I used sits too low in the hole I drilled for it in the gating, so the part where it starts to taper a little bit more was in the hole below the part that got molded, if that makes any sense. And this also made the base of the sprue a little wider than I'm thinking it needed to be. I did not have this problem when I cast the blank plaque pattern using a wooden pattern with a smaller hole for the sprue drilled in the well at the base. I have a couple solutions for this in mind as mentioned in the video, which I will try out next time I cast a plaque from this pattern. I have wooden sprue pattern I made a while back which I like a lot better than the turkey baster tube as well.

    Do you use a tapered skinny sprue? I find that is key to keeping the sprue choked throughout the pour. I always cut an oval-shaped pouring basin at the top of the sprue, with the sprue at the deep end of the oval. Got that from Olfoundryman on youtube, although he does them a little differently now I think, likely based on something from one of John Campbell's books, which he occasionally mentions in replies to his commenters. I even spent some of my birthday money on "The 10 Rules of Castings" which I have so far only barely cracked open. I find the Olfoundryman-style sprues work well - when the base of the sprue is small enough and there is enough taper - the sprue being at one end of the basin instead of in the middle theoretically prevents any whirlpool action (therefore any air getting sucked into the mold) as the sprue drains. I try to shape the bottom of the oval so it slopes smoothly down into the sprue. Most of the time my castings tend to end up a little smoother than this one did, and I think the sprue and pouring basin setup is part of the reason why.

    Jeff
    Tobho had learned to work Valyrian steel at the forges of Qohor as a boy. Only a man who knew the spells could take old weapons and forge them anew.

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  3. #223
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    I have a large and small tapered sprue. The large is for the grave markers because of it's size, I really pour fast with it. The small is used on most of the rest.
    I've been following Martin too and have adopted the no sprue well process. I make a straight bottom runner and put a choke like yours to form a well of sorts. I haven't been brave enough to get down to his size sprue because I try to pour as cold as I can and he does the temp probe thing.
    Bones

  4. #224
    Senior Member Tobho Mott's Avatar
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    Oh I see, sorry, thought you were referring to the top of the sprue.

    I usually do use a splash well/basin/whatever at the bottom of the sprue, and do not normally add that choke, which is next to the splash well on this pattern only because I was trying to to work around having made the runner deeper than I had thought I was making it. I'm still not sure whether it helped or is just in the way. I never tried not using a splash well, but im sure I've probably made them too deep and too shallow and too wide and too skinny on various occasions.

    But like I said, I've only barely even cracked that 10 Rules of Castings book open so far, so I really have no idea what's even in it, only that supposedly it'll turn everything I ever thought I knew on its head. So who knows what crazy thing I may try down the road, once I've had time to read it and contemplate the shocking heresies within!

    Jeff
    Tobho had learned to work Valyrian steel at the forges of Qohor as a boy. Only a man who knew the spells could take old weapons and forge them anew.

    How I built my oil furnace | My Photo Album | My Videos | TheHomeFoundry Forums

  5. #225
    Senior Member Tobho Mott's Avatar
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    Quick pic of the finished casting with silver paint touch-ups on the little dings and a coat of gloss sealer:

    20180210_080857-800x600.jpg

    Edit - And a close-up of the small silver paint touch ups I did to cover the black paint that was messing up the illusion of smooth edges. Would you guys have done this, or tried harder to get the black paint out of there, or what? I was kind of winging it when I did that.

    20180210_101138-800x600.jpg

    Jeff
    Last edited by Tobho Mott; 02-10-2018 at 03:39 PM.
    Tobho had learned to work Valyrian steel at the forges of Qohor as a boy. Only a man who knew the spells could take old weapons and forge them anew.

    How I built my oil furnace | My Photo Album | My Videos | TheHomeFoundry Forums

  6. #226
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    That looks perfectly fine.
    What I've found is people just see the big picture. Small imperfections that we see because we're up close and personal with it, they don't see them unless you point them out. Twenty/twenty paint job syndrome.
    Bones

  7. #227
    Senior Member evlwht-guy's Avatar
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    Quote Originally Posted by FishbonzWVa View Post
    That looks perfectly fine.
    What I've found is people just see the big picture. Small imperfections that we see because we're up close and personal with it, they don't see them unless you point them out. Twenty/twenty paint job syndrome.
    Ditto....!!! others don't see any of that stuff they don't see sand inclusions, porosity or any of that stuff they're just looking at the whole thing.

    That being said Bondo and paint will cover a multitude of errors. Although it's hard on a filed clean peace like the actual numbers themselves.

  8. #228
    Senior Member Tobho Mott's Avatar
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    Thanks guys. I hear what you are saying, but even if only I could see it (which I'm not convinced of), I could not live with the left edge of the 6 looking like this:

    ugly6.jpg

    Cheating or not, to me it looks a lot better since I covered up the black paint stuck in those little pits with some tiny drops of silver paint. Of course I'd be even happier if the casting had come out perfect, but you can't win them all...
    ..........

    More recently I made some new ingot tongs. Needed to get out in my shed and make something useful, to keep myself busy now that I've decided my furnace is truly snowed in.

    Pliertongs3.jpg

    Although now we're in the middle of another unusual winter heat wave here (above freezing in mid February?!), so I actually probably could make another winter casting session happen... if I had something to cast. Maybe over the weekend, if I can think of something. Keeping busy with projects like the ingot tongs and the house numbers seems to help pass the time over the winter months here, when it basically sucks to be outside and cabin fever starts to set in...

    https://youtu.be/EwmNFKKvCeQ


    Mmmm, can't you just taste that 80A Power Fist fluxcore goodness?

    Creeping, cooped-up madness aside, does anyone recognize the design of these tongs made of pliers and rebar and what appears to be metallic bat guano?

    Pliertongs.jpg

    I swear I got the idea from some tongs a lot like this that I believe I saw here, and quite recently. Or maybe it was over on the THF forum... Anyhow, I've spent an hour or more hunting for the post in question everywhere I can think of and no luck. I'd like to give credit to the guy I stole the idea from if possible...

    Jeff
    Tobho had learned to work Valyrian steel at the forges of Qohor as a boy. Only a man who knew the spells could take old weapons and forge them anew.

    How I built my oil furnace | My Photo Album | My Videos | TheHomeFoundry Forums

  9. #229
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    nothing is stolen here, thats why the forums exist. Glad you like the idea and even gladderer that you have shared it in a post.
    J

  10. #230
    Senior Member Tobho Mott's Avatar
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    Yup, Artopsy's tongs were the inspiration I had no luck finding again. Thanks for the idea!

    Jeff
    Tobho had learned to work Valyrian steel at the forges of Qohor as a boy. Only a man who knew the spells could take old weapons and forge them anew.

    How I built my oil furnace | My Photo Album | My Videos | TheHomeFoundry Forums

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