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  • #16
    So, after ramming up another mold with better gating, sprue and risers (I think anyway), I just finished pouring it, and the results were MUCH better. I think my sand is starting to be a limiting factor, so that will be remedied moving forward, but I feel like I'm making progress. I had some corner blowout on this one, but they are both on machined surfaces, so I wasn't too concerned. Still have porosity on the outer corners. Not sure if it's due to sand, or turbulence in the mold, and I need to rethink my gating situation. I don't degass my pours, but there are a lot of you tube casters that don't degas either yet don't have those problems, so I'm thinking that's not the cause. From my limited knowledge I think it's from having my sand too wet, but my sand it too poor it won't bind properly until it feels too wet.




    I'd be embarrassed to sell these as a finished product, but for what I need them for they will clean up just fine. I need 12 of them, so I hope to make some incremental improvements and try some new things over the course of the next 5 pours to see if I can better my results. I'm finding it really hard to split the mold after ramming the cope too, which is where I think I'm dropping the corners off. More draft perhaps on patterns moving forward wouldn't hurt either, as well as taking them to the paint and filler stage too, but my flask key design is pretty poor and tough to smoothly separate. I'm going to be making some new ones shortly, so will rethink that area for sure. I'm fighting problems from a few different issues it seems.

    I finished melting through my bucket of scrap and poured 2 more melts of ingots after that mold (and a butterfly for my daughter) before taking a break right now to make dinner. Not sure I'll get back out there tonight for a few more pours or not. Enough rambling Dan, more pictures...



    If I don't get back to it tonight, it's been a really fun weekend. I still need to better organize my casting stuff, so I can get to it, and get setup quicker, but will chip away at that the rest of the month. Work has died off for a bit thankfully, and it's not baseball or golf season yet, so I will have lots of free time to spend out in the shop.

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    • #17
      We're going to start calling you Mr. Pete.

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      • #18
        It looks to me like your appearance problem is due to your casting sand being too coarse. IIRC, straight HD play sand has a HUGE variation in grain size - try sifting the larger pebbles out. Your blowout is most likely due to your lack of clay. See if you can get some straight Bentonite clay for your mix. Degassing was introduced to try to minimize casting porosity, but ir actually does nothing. The porosity is due to the lack of laminar flow inside the casting due to poor design of the gating system, NOT from air inside the molten metal. Turbulent flow inside a mold will quickly render even the most basic casting garbage with all the air holes it introduces.

        You might want to try sectioning one of the components of your casting to check for air holes. It doesn't have to be the actual part, but can be the gates or the risers. If they are clean, your parts will most likely be too - if not, well that applies too.

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        • #19
          Originally posted by SLK001 View Post
          It looks to me like your appearance problem is due to your casting sand being too coarse. IIRC, straight HD play sand has a HUGE variation in grain size - try sifting the larger pebbles out. Your blowout is most likely due to your lack of clay. See if you can get some straight Bentonite clay for your mix. Degassing was introduced to try to minimize casting porosity, but ir actually does nothing. The porosity is due to the lack of laminar flow inside the casting due to poor design of the gating system, NOT from air inside the molten metal. Turbulent flow inside a mold will quickly render even the most basic casting garbage with all the air holes it introduces.

          You might want to try sectioning one of the components of your casting to check for air holes. It doesn't have to be the actual part, but can be the gates or the risers. If they are clean, your parts will most likely be too - if not, well that applies too.
          Thanks for the reply. I've been very suspicious of the "kitty litter" from the beginning. I will try and find some actual benntonite, but I'll put more effort into obtaining some actual casting sand. I've always found when trying to learn something new start with as little variables as possible, so you don't chase your tail running in circles changing stuff that isn't wrong.

          What you say about degassing is reinforced by all the "good" metal casters on you tube I've seen. Good casting and molding practices seem to take care of most of the problem. I'm sure there is a place for it in very controlled environments but the average home gamer like myself would see more benefits by just getting better at molding and pouring I think.

          I've already melted the gates and riser from these pours but will cut them open in the future. I did just come in from machining the castings, and aside from being a bit soft, they seemed fine internally past the initial pocked marked skin. Promising result. The cleaned up better than I thought they would

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          • #20
            After dinner It was coin flip time. Cast the rest of the pieces I need, or machine the 2 good casting I have. I skipped to the good part and fired up the mill.

            I should have planned this better and left a bit more holding stock for this op. Turned out ok, but I babied it. Used the spindle housing face (NOT bearing face) to align the lightly clamped part with a parallel, then snugged it down.

            I chewed the bulk of it down with a 10mm 3lf, then I licked it clean with a fly cutter (Don't have a face mill for the tormach yet. Maybe my next build????). I picked up the center with an edge finder, and drilled my clearance holes for a Private Messages woodscrew.




            Then I did a repeat of the first op on the angled face. A bit more to hold in this op.



            Next was laying out the x location of the 1/4"-20 hole. I snapped a quick pic from cad of the critical dimensions, and layed them out with a caliper and scriber. Then picked up that line with a single lip scriber. There are no really critical dimensions here, so no need to get fancier than this. I retained the y from the previous setup as I was holding the part the same way. Good quick and dirty time saver tip. Save the time and fuss for operations that matter, and you can really speed up your throughput.





            All done in the mill, I then tapped the holes with the cordless drill, and countersunk the holes in the drillpress. Clearance is clearance .


            Both parts milled it was time to clean up some flash with a flap wheel for the big stuff, and a few different flavours of files.


            Done, they looked ugly and rough in the beginning, but cleaned up pretty presentable after a bit of work . I'm kinda curious how they'd come out of the tumbler if they'll fit. I'll try the next set.
            y


            I brought my newly minted parts in the house to show the wife. She said "cool". Women are so hard to please. Don't you know how many thousands of dollars these brackets cost, woman?

            Back out to my shop It didn't take me long to get them put together and mounted on the wall. These should help clean up the mill control area. As you can see I've been temporarily using them for a bit already






            I still have 5 more sets to cast and machine (3 racks for each side of the monitor), but I'm pretty happy with the results of a weekends worth of work. I'll chip away at them through the week. A bit more effort and learning on the casting side of things, and I'm really looking forward to what is possible in my little shop now. I could have machined them all from barstock by now, or designed them different, but that wasn't the point of this exercise.

            Thanks for following along this for this rambling work in progress. Cheers.

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            • #21


              A week later, and I'm back at it. We're back to 4-10's at work, so I get Fridays off again for next little while. I'd say it's nice, but I'm really starting to get 2008 vibes from a lot of different cues.....I hope I'm wrong, but I'm starting to get a feeling.

              I have enough time to cast a set of brackets before I need to pick up the kids from school. Hope to get the rest of them cast/machined this weekend so I can get started on the 10 other casting projects I thought of this week lol.

              Also watched a bunch of casting videos this week on gating and molding in general, so I think I've got a bit better handle on things. We'll see though lol. I have a memory like an old steel safe, but I sometimes forget the combo.

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              • #22
                Done. Some wins, and some fails.

                First up, it's MUCH nicer casting from ingots, than scrap. From now on I think I will go this route always. no dross, and straight to the point. I sized my ingot mold so that I could fill a crucible from cold almost with just a top up required before pouring. I'm going to makes some mods though, that I "think" will be for the better, we'll see.


                Poured with no issues, but during shakeout it seems I had some mold collapse when I closed it the last time. A bit better surface finish in spots, and a bit worse in others. I think a big part of my problems, are due to poor pattern finish. I can't pull the pattern as clean as I'd like and it's loosening the edges. I tried to see how little pattern prep from printer to sand I could get away with on this project and I think I have my answer..... I'll cast the rest of these parts as is, but moving forward, do some proper prep and paint on things that matter. also a bit more draft wouldn't hurt. this one has 3*, and I could have got away with a lot more.




                As you can see here, I had a mold collapse on closing. I even did a trial close first and nothing shook loose. Oh well, might be salvageable, but I have another pour from this week, where one side was good, and the other looked like this one, so it'll probably be back in the crucible for this guy. I'm will to accept lesser quality for shop made tooling, but this one is pushing it....


                Now, the elephant in the room. My homemade green sand sucks. As seen above, It's just too hard to get clean edges, and the bonding is pretty terrible. As you can see from cutting the gates and runner it's pretty rough sand. I am working on getting some actual foundry sand. Probably within the next week or so, and I should hope my results will improve a lot. If not I will ask George for a for sale ad exemption, and somebody will get a good deal on casting equipment . Took some lessons from this pour anyway, and got one useable part. Will cast some more tonight after dinner.



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                • #23
                  Maybe try oil bonding?

                  Pattern draft is your friend. Any castings we had done always needed about one degree, and they really preferred more for sand. You can get away with zero on one surface, if the opposite surface has more. They didn't like that very much either, but they'd do it.
                  CNC machines only go through the motions

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                  • #24
                    Not sure I want to go with petro bond. A muller is in my future though, whatever sand direction I go to. I've only got enough sand for one flask and a bit more (good thing too, because I've only got one flask ). And the effort to rejuvinate it by hand in between pours....I want a few hundred pounds of green sand, more flasks, and a muller so I can do it in bigger batches. Maybe a fluffer too like olfoundryman made. I'd love to be able to ram up 5-6 flasks and do back to back pours, and as I expand and eventually build a propane fired foundry have the gear in place to be able to do bigger pours. Working up to it. I have a very good idea (I think anyway) to produce good and cheap flasks, that I will be working on for next project.

                    The draft on the pattern is 3* all around except the backface. When I designed these parts I envisioned just hitting the backside on the belt sander, and drilling the mounting holes from the front. I didn't put draft on that side to leave me less cleanup, but that side is always full of blowouts , so it left me with a milling op anyway. 3* would have worked fine if these patterns were properly sanded smooth and painted etc, and I had good molding sand. 3* is what I always used when I modeled and cut patterns at work back when I used get projects like that. Moving forward if I do anymore quick and dirty straight from the printer projects like this I will be very generous with the draft. It would help a great deal being able to pull the pattern clean. There have been lessons learned from this to apply to future projects. I'm just not going to spend the time to remedy them on this one. Pick and choose your battles.

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                    • #25
                      Poured another one after dinner. Almost identical results as the first from earlier, but a quite a bit better in places (no pics). They will certainly clean up just fine. On a roll I decided to charge up the crucible for another pour, but despite my best efforts for the quick turn around, I was unable to successfully ram up another mold without the drag falling out, and my sand was just too crumbly. I thought I had it on the last one, but the bottom dropped out literally as I moved the mold over to the floor . I poured that crucible off as ingots and will give the sand some time to cool down overnight, and will give it a good working over tomorrow with more binder when I try it again. I only "need" 3 more successful pours from this pattern/sand, then I will move on to the next project. I will machine the 4 parts poured today after the kids go to bed tonight but right now I'm going to beat them at a board game. Probably Splendor, maybe Catan because the wife's not home and she hates that game (she always loses).

                      Oh, for anybody out there with the same little foundry. DO NOT touch the little plastic handle on the lid with hot crucible tongs. I don't know what kind of plastic that is made from, but that is a smell you don't want to smell, I can guarantee you that. I will replace that shortly with an aluminum one.

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                      • #26
                        Ok, we can stick a fork in this project. Well the casting part anyway.

                        I made 3 pours today, and had a bit of an "ah ha" moment while conditioning the sand for the 2nd pour. I honestly don't know what I did different than all the other ones, but the sand felt absolutley perfect, and I got the best ones yet. Rammed up great, patterns pulled pretty good with minimal edges falling off. I have just enough homemade green sand for 1.5 of my current box size, so I resevered the leftovers for the thinner drag for the last pour, just incase I couldn't find that lovin feeling again with it. Worked a charm, but while flipping over the cope I had a chunk fall out on the last pour. Still poured great, and now I've got some machining to do tonight to put this project to bed. Enough rambling, pictures....



                        I tried a couple with the runner in the drag, and the gates in the cope, and I didn't notice a difference in either one, I thought it might slow down the metal filling the cavity, and create a bit less turbulece and create better surface finish. It's good to play around and learn stuff. The best surface ones were the 2nd pour today where the sand was perfect and they had both the gates/runner in the drag. There is a noticeable difference in those 2, which kinda backs up my suspicions that it's primarilly my sand that sucks . But it's good to know I CAN make it better. What I did, I have no idea, but it was encouraging. I'll take some better pics of those when I machine them later tonight (maybe). They are on the lower left in the above pic.


                        This was the last pour, pretty much same as the rest quality wise, so I doubt the change in gating really did much, but I'm sure it matter on some parts.


                        Here's two shots showing the castings, and the same spot on the patterns. As you can see, the patterns are pretty rough, and can still produce useable castings. For those in a hurry for quick and dirty projects (which is what this kinda was about), this is promising.

                        This is pretty much as print. A light trimming of the elephants foot, and some light sanding all around. No paint, no filler. just PLA printed at 20% infill, and took about 1.5hrs.


                        I printed another pattern for the next project while I was out pouring today. That was about 4 hours, and I will fill prep and paint that one properly, as now I want to test out the other end of the spectrum. You'll have to wait for that one though, it's not a high priority. Hopefully it'll be months, not years lol.

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                        • #27
                          Are you tearing out sand when you pull your patterns? It seems like all the seams are leaking.

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                          • #28
                            Originally posted by SLK001 View Post
                            Are you tearing out sand when you pull your patterns? It seems like all the seams are leaking.
                            Yes, there is almost always some breakaway at the edges. Partially my fault at pulling them poorly, I did try and work on getting better at that as I went. And partially from the patterns being too rough for a clean pull. I think more draft on "as printed" patterns like this will help a great deal in the future. I wonder if I could get a cleaner casting if I molded this as an odd side, instead of a split pattern. I haven't done that yet, and i'd like to try it. Changing the design slightly to cast these as a flat back would have helped too. All lessons learned moving forward.

                            I think it has to do with the layer lines as well. The way it's oriented, the layer lines are like a file when being pulled. Not sure I could have printed these patterns standing up, but I'll keep that in mind on the next one. I "did" sand these quite a bit after the first pour, but didn't fill them. There are a couple low spots where the print got a bit stringy.

                            Next "quick and dirty" casting experiment will be lost foam. Having watched Kelly Coffield's videos It's a process I really want to try. The results he gets are amazing, although he does put a lot more effort into the process than the typical lost foam youtubers. His whole setup, and process is really professional, and impressive for a guy in his garage.

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                            • #29
                              Originally posted by Dan Dubeau View Post
                              Having watched Kelly Coffield's videos It's a process I really want to try. The results he gets are amazing, a
                              Wow, that guy has a serious set up and is doing some large complicated stuff. building that complex foam intake manifold only to have a small flaw in the casting would be heartbreaking.
                              in Toronto Ontario - where are you?

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                              • #30
                                Originally posted by Mcgyver View Post

                                Wow, that guy has a serious set up and is doing some large complicated stuff. building that complex foam intake manifold only to have a small flaw in the casting would be heartbreaking.
                                Ya, it's pretty impressive. I've been to a customers, year ago where they did lost foam on a production basis, so I knew the process was very valid and capable, but most home shop lost foam is really rough with a rasp and hotwire. No offense intended to anybody that does lost foam with just a rasp and hot wire. When I watched Kelly's videos it was next level, and the results he gets really show the possibilities. Yes, he does have some time invested in those patterns, and a mistake would be a gut punch for sure. He seems to be able to make them pretty efficiently though.

                                His electric foundry is a thing of beauty. 😍

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