Reducing porosity in your castings

[@KravchenkoAudioPerth]

Thanks for taking the time to make this video. A lot of people who are disciples of the incorrect methods of pouring castings should be watching this! Mark

[@swdweeb]

Thanks Mark. You know it's funny a lot of them have but I've seen no change in the way they pour. Maybe it's just not that important to them. In their defense though I know that this methodology takes more work, more planning and often times more than one pour to get things figured out. Still I'm a firm believer in it.

[@Mistertbones]

Martin the Oldfoundryman is one of my favorite channels. I'm always amazed at how well his castings come out.

[@swdweeb]

Well when you’ve been doing it for 136 years like he has.... ;-D. His castings are amazing and he’s been a huge factor in my casting life

[@olfoundryman8418]

OMG do I really look that old?... Martin

[@markfryer9880]

@@olfoundryman8418 Ummm, do you really want us to answer that question Martin? Just kidding. Grin

[@olfoundryman8418]

Mark, What are you lot on about? I mean, I still have hair 😊… Martin

[@CraigLYoung]

Don't know if you proved anything but it was fun to watch.

[@JakeSpader]

This is really helpful and the way you explain it is awesome. Thank you!

[@swdweeb]

Glad it was helpful!

[@SkullyWoodMetal]

From watching your videos and Old Foundry guy I am well convinced that your method works best. VegOilGuy has started using pouring basins on his lost wax castings with huge success. I have not poured anything yet. (I am getting closer everyday) The first thing I did was make a tapered sprue on the lathe. It is to big of course but I can easily make a smaller one. Keep up the good work, I enjoy your videos. You and your friends have me convinced.

[@swdweeb]

If you want a model of the tapered sprue that I use or a measured drawing, you can download them here drive.google.com/open?id=1glhKh318yuyX8l67ejB-t14ExvUBL4eh

[@stormtaker63]

Great video, its the little things that you learn that makes your casting come out better and this is a science for sure!

[@swdweeb]

No doubt, one that I'm only scratching the surface on. But its a hoot learning ;-)

[@wmcgeary]

Thanks just getting into casting and sometimes the simple things like that are overlooked. Much enjoyed video thanks again keep them coming. 😊

[@swdweeb]

Thanks boss, I appreciate that. Glad you did as well.

[@PaulsGarage]

Awesome demonstration with the water glass, that turbulence is crazy

[@askquestionstrythings]

Add some gelatin to trap the gas and it's even more like casting

[@swdweeb]

I know, it's even more impressive when I've seen it with a runner/gate/part. The air gets sucked right into the part. You figuring out that petrobond no likey cold weather? ;-) I store all of mine in the house now. It's unusable to me otherwise.

[@BrianDaleNeeley]

I would have liked to see you pour water into a clear narrow funnel, but we can't have it all. This was quite an instructive video. But I think you may have gotten better results will the pour as you normally do it partly because that's the way you are most comfortable with. I'm not disputing your results. I am interested in seeing more experiments (if you choose to do them). I think you are getting really good results. But as I've never done any casting myself, I can't say much, as any critique would have to come from my own experience (which is zero), and what I've seen. As you point out, most people are pouring with big gates and runners, so that is what I've seen. I hope you continue to show us good techniques and methods (I can't see why you would change), and hopefully I'll actually have a good idea of what I should be doing if I can ever get a foundry built.

[@swdweeb]

@@BrianDaleNeeley Thanks Brian, I'd love to build a clear pouring system so that we can see the difference between the two methods but it's more than just the funnel, the basin and ridge are an integral part of the whole thing as well. How to make all of that in clear plastic has me a bit stumped.

[@BrianDaleNeeley]

@@swdweeb i suppose it could be cast in a clear resin? I would guess the entire mould cavity (sprue, runners, gates, vent, and a part) would have to be a part of the model, and possibly at near full size. That would not be cheap, but it would be interesting. And of course, making the print out of something that could be removed from the model could be a problem. Paraffin wax maybe? The whole thing would be quite a project, and I couldn't see doing something like that for a single video. Unless you could do each section separately, and put them together like Legos (they wouldn't need to actually snap together), the costs wouldn't justify the expense; and maybe not even then.

[@askquestionstrythings]

I would suggest that the big sprue and vent acted somewhat as improperly sized risers which is why there was less shrinkage in that block than in the B block with the proper tapered sprue. Doing a little quick estimation on the riser sizing using Chvorinov’s rule for those cubes... I estimate those are 5.1 cm cubes (2in) TTS = total solidification time [min] V = volume of the casting [cm^3] A = surface area of the casting [cm^2] n = an exponent usually taken to have a value = 2 Cm = the mold constant [min/cm^2] its value depends on the particular conditions of the casting operation, including mold material (e.g., specific heat, thermal conductivity), thermal properties of the cast metal (e.g., heat of fusion, specific heat, thermal conductivity), and pouring temperature relative to the melting point of the metal. TTS = Cm*(V/A)^n we design the riser to have a larger volume-to-area ratio than the casting First determine the V/A ratio for the cube (5.1^3)/(6*5.1^2) = 132.65/156.06 = 0.85 we'll select to solidification time of TTS = 1.6 min now solving for the estimated mold constant Cm we get 1.6/(0.85^2) = 2.215 [min/cm^2] using this estimated Cm value and a 25% longer riser solidification, we solve for the cylinder for the riser will have a diameter-to-height ratio = 1.0 V = (pi*D^2*h) /4 A = (pi*D*h) + (2*pi*D^2)/4 using a D/H ratio = 1.0, we get D = h V = (pi*D^3) /4 A = (pi*D^2) + (2*pi*D^2)/4 = 1.5*pi*D^2 V/A simplifies to D/6 Now solving Chvorinov’s rule for the risers we get TTS_riser = 1.25*TTS_casting -> 2 = 2.215(D/6)^2 we solve for D sqrt(2/2.215)*6 = D = 5.7 cm so a cyclinder with a diameter of 5.7cm and a hight of 5.7 cm you had a sprue and vent with about 1.9cm diameter and the hight of your cope plus the extenders (wild shot in the dark 15.24 cm~6in) V≈43.21cm^3 A≈96.64 cm^2 V/A = 0.447 (each) so with Two (sprue and vent) you get 0.89 you needed a riser with a V/A of 0.95 or 0.89/0.95 = 94% of the value needed, hence why the shrinkage was less for Cube A than for cube B

[@olfoundryman8418]

Ask, Improperly sized feeders (i.e. too small) inevitably suck from the casting, thus I would expect shrinkage in A to be worse than B were it not for the extra gas/air caught in A compensating. On the subject of providing adequate feeders I take a more rudimentary approach. All my feeder formers have a bottom that is reduced in diameter to about 2/3 that of bulk of the feeder, the reduction taking place over about one diameter. I look at the casting and choose a feeder with a connection (bottom) diameter of about the thinnest dimension of the area I am trying to feed. Feeder height is about twice its large diameter, total feeder weight -there maybe more than one - about 75% of casting weight more for thick work less for thin. I guess after all these years its an eyeball thing for me. I simply do not have time to go through all those calculations for each and every job. Although for the less experienced the calculations plus after casting observations can be used to tune the eyeball... Martin

[@askquestionstrythings]

@@olfoundryman8418 there is definitely value to those "rule of thumb" selections, I'm sure there is probably a table for selecting the right size feeder in some industry handbook somewhere too. I would normally agree that a small feeder which solidifies before the casting would normally suck metal from a casting, but my gut feeling on this is case is the solidification time for the sprue and vent would have been very close to the solidification time for the casting (I would need to run the numbers to be sure). I think this is a case where they solidified at close to the same time, and are not severely undersized. I do agree that the trapped gas in the casting will also puff up the casting making the solidification shrinkage less apparent.

[@askquestionstrythings]

Looks like I was way wrong on my assumption that the sprue and vent would solidify at close to the same time as the casting. Running the numbers they would likely solidify after 0.44 minutes, long before the casting solidifies.

[@olfoundryman8418]

@@askquestionstrythings, Not surprised, the casting is a cube, lots of volume little surface area close to the impossible to feed sphere. Just with the old eyeball I would judge the sprue and vent to have a way higher surface area to volume ratio. To successfully feed those cubes you would need a feeder that would look almost stupidly massive...Martin

[@markfryer9880]

All this formula is making my head spin. I think that I will use the Mark I eye ball method and a bit of the rule of my thumb.

[@kcraig51]

Planning on doing my first pour this weekend. Good tip. Thanks!

[@swdweeb]

How exciting! Be safe and hope it goes well

[@tomharrell1954]

I cast bullets. Porosity is a real problem. You are correct any turbulence, splash ect in the mold should be avoided. It causes bubbles wrinkles, and lines and more

[@swdweeb]

I'll bet. Its a wonder more metal casters don't get that. 😀

[@BEMetalMelting]

I’ve been trying so hard to get less badness from my pours thank you! Haha

[@swdweeb]

How fun, my next video is going to reference those old videos and tie them to the video I released today.

[@RockingJOffroad]

Perry, cut then open with the band saw, use WD40 or kerosine as a lubricant when culling, also sand the cut sides and you should be able to see all but the tiniest pores.

[@swdweeb]

Unfortunately I don't have a bandsaw and would have to do this with a hacksaw. My use of a hacksaw is appropriately part of the name "hack" ;-) I still have the blocks as I would love to do exactly what you suggest. I just need to figure out how to get it done.

[@AJR2208]

Hi - Thanks for taking the time to demonstrate this. Maybe if you repeated this experiment but make the parts long, triangular prism shapes / wedges. Once cooled they can be hammered / broken in half and you could examine the triangular break for grain structure, edge cooling, shrinkage, color uniformity and porosity. You could also test surface profile finish if the part was vented or not.

[@swdweeb]

Thanks. I pretty much took this as far as i could stand. ;-) I did a series of videos on it to the point where I just wanted to move on. I felt I had proven what I needed to prove and learned a lot from it. The series if here, kzbin.info/aero/PLU1QP34Dv8Y6-qXska4MOagRMSVWan40k, if you're interested in taking a look. I might revisit the subject in the future. If I do I'll certainly keep your suggestions in mind. Thanks again.

[@unclebobsbees4899]

If you go to Martin's page, make sure you read the comments. There is as much information as in the videos!

[@swdweeb]

Yep, tons of great info there.

[@markfryer9880]

Very interesting video Perry.

[@swdweeb]

Thanks Mark

[@smallcnclathes]

Science with Uncle Perry, makes for a good video. I liked the gurgle sprue, must be why so many use it, the noise means it is working!

[@swdweeb]

It does have a soothing sound to it, it’s only redeeming quality ;-)

[@olfoundryman8418]

SW, I thought that highlighting the sound was a brilliant idea @@swdweeb- it sort of "said" it all for all the hear. Interesting too as it was a new noise to me having never used big high sprues I have never heard it... Martin

[@RealRuler2112]

Something interesting would be to machine both of those cubes to exactly the same size & weigh both... would tell you precisely how much air is in the more porous one.

[@swdweeb]

Yeah, that would be really cool. Unfortunately I don't have the capability to do that. I do know a guy with a mill... maybe it's time to reacquaint myself with him ;-)

[@pumpkinlemonjuice]

Kind of old now, but you could displace water with each cube to measure their volumes and find their respective densities that way.

[@nutsandbolts3729]

Ok, I’ve got a question. And I have no idea why this hasn’t come up yet. Other than ramming being kinda a pain, what about a tapered diagonal pouring? Would the offset of the angle help to 1 slow down the metal and 2 help with that right angle that causes all of the wild turbulence? No sharp corner to turn just a gentle 45* angle to slide right down the Shute and slip across the runner to the part cavity? And if yo were to do it in a way that it would swirl to fill and never hit head on to a wall. Kinda like the angle of the burner in your foundry pointed so that it swirls around the walls and up out the top. .? I’d like to see a video taking this in to consideration and testing it.

[@SkullyWoodMetal]

I am sure swdweeb will chime in, the first thing that came to mind for me was the flask size would have to increase. If there is a way I would like to see it as well.

[@swdweeb]

well, from what I've been told, angling the sprue doesn't slow the flow down as it is still falling the same distance. I asked that same question about pouring a tall sprue for a large bell and was told that it wouldn't help.

[@random-kc8gx]

Turbulence is a real issue, use wells or bottom up filling if possible. Shrinkage and swelling can occur if gating is poor and also pouring speed is too high or too slow. We do this everyday, in green sand and sugar cane mollases sand, old technique but works. Green sand will give you much better dimensional accuracy with rough texture. Mollases gives you a very smooth surface but molds can deform if not handled with care. once hard it's much harder than green sand.

[@swdweeb]

I’m curious, do you use anything like clay in your molasses sand or is it just those two ingredients?

[@random-kc8gx]

@@swdweeb it's just sand and mollases with a good atleast 80+ brix rating. One side effect is compared to greensand this mollases mix produces a better surface finish and surface hardness probably because of more carbon is available ... Not sure just an idea.

[@random-kc8gx]

Forgot to add, it produces a really bad smoke! Everything will stink like burnt mollases!

[@ehuiyaqui6879]

Thank you so much swdeweeb I have learned a ton on porosity. a big cheers from the southland of sombreros. Hasta la vista amigo.

[@swdweeb]

No problema cabarello es un placer ;- ) I grew up in Southern California and worked in Madrid.

[@Fairlanecustom300]

Tried this with a small casting today, seems to improve surface finish compared to the usual method as you showed. I have to make some tapered sprue patterns and will see how I go in future. Previous castings had porosity on the surface as you showed, which I didn't mind unless the part had to be polished. Then it was a lot of work trying to get all the pits out.

[@swdweeb]

If you want a model of the tapered sprue that I use or a measured drawing, you can download them here drive.google.com/open?id=1glhKh318yuyX8l67ejB-t14ExvUBL4eh

[@Fairlanecustom300]

Thank you @@swdweeb

[@raydirkin9107]

The proof is in the pudding 😂 the thicker the casting the porosity chances increase. Cut that open I bet it's full of porosity, Martin knows what he's doing it's not just a hobby for him. I'll be doing some test myself that's the best way to learn, even though it may be only a hobby I'd like to learn how to do the best way possible. Thanks for sharing with us Perry.

[@swdweeb]

When I get home from work today I plan on trying a volume versus weight measurement to see if I can see anything. Martin suggested that the more pronounced shrinkage was due to a less porous pour as well. Given the relatively small size of these castings I don’t know if I’ll see much in terms of weight evidence. It’s also been mentioned that, as you say, I should cut it in half and look. That might be in the future as well

[@askquestionstrythings]

@@swdweeb yes, machine some of those surfaces and cut the cubes apart. The unmachined casting surface only tells a small part of the story. There is also a dye test for penetration you could consider. Dye Penetrant Testing, aka liquid penetrate inspection, tells a story beyond what you can see with your eyes. (it's also used in inspecting some welds for porosity)

[@swdweeb]

Sure, just machine the surfaces ;-) Let me run out and get a mill first

[@askquestionstrythings]

@@swdweeb lol, you'll need to run out and get a larger garage too. ;-) then you can plan on getting a lathe, a shaper, a surface grinder, a laser sintering metal 3d printer, a laser cutter, a waterjet, ultrasonic inspection equipment, handheld XRS spectroscopy, and a 5-axis CNC. Got to plan for all the toys in the shop. =D but for what your doing here you should be able to see the general defects by grinding or belt sanding the surfaces and consider that as your "machined" surface.

[@olfoundryman8418]

Ask, Yep, you have to collect all the toys - its the natural order of things. But first you need a big shed to fit them into and in your climate a heated shed at that. But for now a bandsaw and a disc sander plus a bucket of caustic soda solution will suffice to show porosity... Martin

[@charliechancontraptions5951]

Makes perfect sense to me...well done.

[@swdweeb]

Thanks. You'd be surprised how many people think it it doesn't matter

[@charliechancontraptions5951]

@@swdweeb By doesn't matter, do you mean having inclusions? I cast small bronze billets for bushing manufacture (DIY) and any inclusion is a menace. I produce alloys that aren't in any table known to mankind ;-). I have a great deal of admiration for myfordboy (not just because he's also British) but fail to see how making bubbles in a melt removes bubbles. If it was for de-oxidation..maybe. I use Borax as flux and the occasional spider's kneecap if I can't get a delivery from Hogwarts of Shazam dust. One thing I found out relatively recently

[@swdweeb]

@@charliechancontraptions5951 Most people that cast on KZbin refuse to adopt any of the techniques espoused by Professor Campbell (another Brit). I routinely see people pouring down large open sprues into a air mixing bowl at the bottom of the sprue and then running directly into the part at full velocity. All of these things are "designed" to create porosity. They can't help not to. Then they pull castings out of the sand that look like sponges. A lot of them watch my channel but to them none of this matters. They will continue to pour the way they do. Regarding degasing with bubbles, I assume you mean bubbling inert gas through the metal, the proper way to try and float oxides and you're not referring to people running to their kitchen cupboards and finding somethin to dump into the metal. A lot of people have bought into the idea that you can dump crap into your metal and it will somehow magically clean the metal up. I talk about steel crucibles in a video I recently did about casting ingots. (I know I know, some times you have to pander to the masses) Aluminum will eat your steel crucible as well. kzbin.info/www/bejne/nHekda2rlqinh9U I always melt the lower temp metal first and let the copper melt into it. One time I melted copper and then added aluminium to it to make bronze. Big mistake. Even after preheating the aluminium it still created a big white cloud when I added it to the super hot copper. Never again.

[@charliechancontraptions5951]

@@swdweeb No the gas bubbles are being created by the degassing sachet which is plunge into the melt. Yes I'm sure you do alloy brass correctly. I just couldn't understand how it could be created with the melting and boiling point of zinc being so close together and much lower than the copper. Until I saw a video.

[@unclebobsbees4899]

Hate mail to Martin? No frickin' way. One does not send bad thoughts to the Jedi Master of casting..LOL. If my castings come out 1/2 as nice as his I've learned something.

[@swdweeb]

That does seem like rather risky business doesn’t it ;-D

[@hippie-io7225]

Cut through the middle of each casting and show us in your next video :) And FireMakeMe KING, you're right, I would certainly want Martin in my neighborhood!!

[@olfoundryman8418]

Fire, Hate mail - let them bring it on, I like a good challenge 😊… Martin

[@unclebobsbees4899]

@@olfoundryman8418 please provide email address. You will receive winners like this "Please help rescue our astronaut who has been stranded on our space station for a year" Nigerian Space Program.

[@olfoundryman8418]

@@unclebobsbees4899, Drool, dribble, how much do I win? .. Martin

[@stickyfox]

re table salt; I've read that NaCl or KCl will just lie there unless it actually melts and becomes free ions; but both have a melting point above that of aluminum. If you mix and pre-melt the two chemicals prior to casting at a 1:1 molar ratio, you get a flux that melts before the aluminum; that's the key. So table salt alone probably does nothing unless your melt is way too hot. Most hydrocarbon compounds make a poor flux by themselves, and soap probably decomposes in heat to become a tarry mass of sodium-bearing goo that has *some* noticeable effect on the pour but who knows, even sawdust works for some metals.

[@swdweeb]

Never heard of mixing them. I'll have to ask my profession foundry dude about it.

[@stickyfox]

@@swdweeb me neither! I just ordered some KCl tho, and if it's a lie I promise I'll come back and share my findings. Everyone says mix the two salts and make ingots, and throw those into your melt.

[@ivansamaniego8243]

Very enlightening talk... beatiful class

[@swdweeb]

thank you

[@danharold3087]

Great video and lots of good comments. Any ideas on how to make the connection between the tapered spru and the runner a curve like you had in the drawing ?

[@swdweeb]

Thanks Dan. A couple of ways. You can do it like I did with the runner pattern. The curve is on the pattern. The curve on the top of the runner can be cut with a brush. Cutting it by hand will be a bit trickier but I suppose it can be done with practice.

[@raydirkin9107]

Been studying on how one could get that curve instead of a sharp 90 if I come up with something worth mentioning I'll let you know.

[@danharold3087]

@@swdweeb Not at all sure we are on the same page. The drawing you made has a spru that curves to meet the runner. Obviously this would be impossible to withdraw from the sand. Maybe a core could be used to do a gentle, smooth, vertical to horizontal transition with uniform cross section. Not criticizing at all here, my plumbing looks like what you are showing at 12:45, more or less a right angle. I am wondering if we can do better with that nice curved transition

[@swdweeb]

Dan, email me at [e-mail]. I'll show you a picture of what I mean

[@rockelec]

Good demonstration. Going to try the smaller tapered sprue.

[@swdweeb]

What??? You mean you aren't already?? ;-)

[@olfoundryman8418]

rock, You will not be disappointed except in that you may be disappointed that you did not try it sooner😊 ... Martin

[@rockelec]

Absolute newby learning on the fly. Pick up tidbits of information and experience from you guys. Each one brings a better casting. I had been just casting ingots of AL, CU, ZN and Brass as scrap management. Decided to try other things recently so yep my first castings were rather dismal! 😁 lol

[@swdweeb]

Everybody's are ;-) Keep at it

[@highplainshomestead4007]

I am wondering if you recondition your green sand and how? I'm kinda new at this and would love any input you can offer.

[@swdweeb]

I actually use oil-based. I say that because it started off as petrobond but has been reconditioned so many times that calling it petrobond may be a bit of a misnomer. I have a video on how I repurpose it. kzbin.info/www/bejne/hpW6lqeVhqiMp5Y Basically I stir it using a "paddle" I made and my drill press. If I feel like it's getting too dry due to the number of times it's been burned I add a little non-detergent motor oil to it. If you're using green sand, you might search through olfoundryman's channel. He did a video on how he does it over a year ago. Guys like Tobho Mott have built mullers to recondition their green sand as well. He's got a series of videos on how he built it and watching it run. Don't hesitate to ask if you've got other questions. I may not know the answer, but I likely know someone that does.

[@Eisenmann86]

thank you good advice

[@swdweeb]

Thank you

[@jackmclane1826]

If you are serious about casting, degassing is absolutely necessary. OF COURSE it's not the only tool in the box, but it targets a different kind of porosity. You have to separate entrained air bubbles and hydrogen porosity as different fundamentals.

[@swdweeb]

I don't disagree with you, but I am curious how you would degas aluminum

[@jackmclane1826]

@@swdweeb Stirring inert gas bubbles through it is pretty effective and an easy rig. But needs some knowledge and guesswork when it's done. Of course it's pretty useless if you screw up the actual casting process as you showed in this video. In a professional setup it's done increasingly by a vacuum treatment of the melt. It's a bit more complicated setup, but can eliminate all guesswork and all room for user error. Pump it down and hold pressure x for y seconds, done. This is also what I'm using for my hobby stuff. Sounds more complex than it is. An old large stainless steel cooking pot with some glass wool on the inside for insulation, a lid with a high temperature silicone seal and a vacuum pump. Works a charm. But the primary reason for me doing this is because I already had that vacuum setup. ;) Be careful with plexiglass lids... they melt in seconds under the heat radiation of a crucible full of liquid aluminium! ^^ For large scale mass production both are combined for speed and quality control. Put a hydrogen sensor in the gas stream and actually measure the hydrogen content of the melt. Automotive OEMs love it as it gives them more frickin dataaaaa! ;) It's pretty awesome for part tracking though. You can find the hydrogen content of the melt of any random part that was produced years ago, in case of a strange defect cluster occurs. If your whole production process is tracked like this you can pinpoint the cause of the defects and find every car the possibly defective parts were used in.

[@swdweeb]

@@jackmclane1826 That's what I wanted to hear. Had you said something like "dump table salt into your melt" I would have removed your comment 😄 Thanks for taking the time to point this out. Always good to have "instructive" comments out there.

[@JulianMakes]

Nice, love a bit of science!

[@swdweeb]

Thanks mate, sorry for the late reply been a little busy.

[@JulianMakes]

busy is good mate :) I hope you've been bust making new videos?

[@swdweeb]

@@JulianMakes I shot two last weekend when I shot this one so I should have another come out in a couple of days.

[@JulianMakes]

@@swdweeb horray!

[@wolfgangkramer7228]

Einfach nur super 😎 👍🏼 💪

[@swdweeb]

Danke dir!

[@alejandrobogado3154]

Dear Sir, Im trying to cast billets for extrusion 4" x 400 mm and 5 " x 450 mm. U have some tips or advice to have success with this task?

[@swdweeb]

I love it when you mix measurement systems 😂 (inches and mm) I assume that 100mm x 400mm and 125mm x 450mm is what you're trying to pour. You're correct in being concerned with shrinkage. Something that big will want to shrink, a lot. If it were me, I'd try to do a bottom-fed, vertical pour with plenty of extra height to allow for the shrinkage. Feeding from the bottom will reduce porosity (assuming you keep your sprue full). I'd also leave the top of the mold open so you can see the metal in the mold as it rises and cools. When you're done, you can cut the billet to length removing the section with the big shrinkage hole in it. Good luck

[@alejandrobogado3154]

@@swdweeb Thank you Sir. I usually use measurements in inches for diameters and millimeters for lengths.😅

[@ArtByAdrock]

Great demonstration Perry! Do you think it would have made a difference if you poured the metal faster in “A” like what Bob was saying in a previous video? 🤷🏻‍♂️ but great job though 👍🏻

[@olfoundryman8418]

Art, Unfortunately what Bob said is a bit open to misinterpretation, to me he said pour fast enough to avoid miss fills but keep the velocity low. I do not think Bob was suggesting that we should just dump the metal into the mould in an instant. AS John Campbell points out it is surprising how slow you an p[our a mould and get a well filled casting. I have seen 10 Kg castings filled in 5 seconds that showed evidence of miss run because of the chaotic fractured metal front. The system was redesigned to fill in 20 seconds and no sign of miss fill because now the metal front was a steadily advancing wall that tended to keep it self hot. In essence what I took from Bob's statements was keep the Lbs per second high enough to avoid miss fill but keep the feet per second low enough to avoid undue turbulence - correct gating design can achieve this.... Martin

[@ArtByAdrock]

Olfoundryman thanks martin 👍🏻 so would you say a tapered sprue is necessary or it’s more important for proper gating? Also the basin in the cope to let the metal flow over and in?

[@swdweeb]

@@ArtByAdrock hey bud, sorry I missed your original question. Let me jump in here to try and answer... Martin correct me later, he's never been shy about that. ;-) The basin/ridge is there, to minimize the turbulence and "sucking of air that happens when you pour directly down the sprue. If you notice (i'll do anything to drive more views) when I poured into the basin there was a solid, short stream of metal between the crucible and the basin as the basin fills in a fairly calm manner it runs over the ridge. The goal is to maintain a flow rate that keeps the metal over the ridge AND the sprue full. That will virtually eliminate air coming down the sprue and into the part. The taper is there to prevent the metal from having space between the wall of the metal (think of the metal flowing inside a pipe it has made) and th sides of the sprue. The taper reflects the fact that as the metal falls it gains speed. As it gains speed it the pipe gets smaller and smaller (diameter) . Just like the water coming out of your faucet does if you turn it on a low enough rate to get solid flow but not drops of water. The runner is pretty much extensions of the sprue. If they're too big, metal has room to slosh around. If they're too small, you restrict the flow. Gates, as Bob said can be larger to slow the flow of the metal but I think they should be the same area, in cross-section as the runner. If you have two gates, they should each be half the size of the runner.

[@olfoundryman8418]

@@ArtByAdrock, I think of it like an F1 racing car - all the bits (including the driver) have to be well deigned and working in harmony to win the race. That said if cornered on the subject I would say that the small tapered sprue is the most important, a close second is the ridged pouring basin design and these are very easy for anyone to do - there is not really any excuse for not using these. The runner and gates are a more difficult thing to get right and their correct design can vary a lot from casting to casting making it more difficult for us hobbyists. But if we at least keep the runners etc on the thin side (less than 12mm) so the metal in them can not fall over itself and thus trap oxide and also tends to stay in a solid front that fills the runner completely we won't be too badly off. There are other refinements that we can try and I think SW has an upcoming video that might show some of these.... Martin

[@ArtByAdrock]

Olfoundryman ok thanks 👍🏻 if you watch this thursdays video I put out when I do the sand casting I would love to hear your input and any advice. I’m sure other followers would as well

[@ruperthartop7202]

Great video cheers

[@swdweeb]

Thanks, I appreciate that.

[@GaryForgingOn]

Good experiment . Science wins. :)

[@swdweeb]

What??? Clearly you haven't watched the news lately :-D

[@GaryForgingOn]

@@swdweeb Or my science degree is not in the right sciences. ;)

[@MrZhefish]

on this topic i can suggest a good book from c.w. Ammen, "The complete handbook of sand casting" on page 186 - 189 you can read up on techniques on bronze and brass casting which is quite intressting, coke and skimmer gate, to increase the flowrate by choking the gating. put the casting out of level, forcing the metal upwards while pouring and using tapered feeder. to aluminium i would say you can use it too, as it's also very easy flowing and faces similar issues during casting its realy an art to get it right and very intressting... anyway, i've allready made myself some tapered tooling for the future and will include your findings and those of the book into the future, as i need the castings to be spot on and with tight tolerances for models i plan to make. thanks mate

[@swdweeb]

I've seen guys tipping their flask to do that as well. I have a long piece I'm going to cast tomorrow I might just give it a try to see what happens.

[@MrZhefish]

@@swdweeb good luck :)

[@robinson-foundry]

Thanks for this. I will use this technique when necessary. I wonder if utilizing this mold design as well as degassing would work even better. What was the hate mail address again?? Lol

[@swdweeb]

[e-mail]. ;-)

[@constantinf.5764]

can you cut those cubes in half to see the bubbles inside? That would be more revealing than surface finish.

[@swdweeb]

You might want to check out the second video in the playlist kzbin.info/aero/PLU1QP34Dv8Y6-qXska4MOagRMSVWan40k Those videos were from two years ago the blocks are long gone now

[@ronyerke9250]

Do you cut the blocks apart in the next video?

[@swdweeb]

Quite possibly, if I can get them cut in half, I will ;-)

[@smallcnclathes]

I think you wimped out on the vertical extensions, not nearly high enough! Did you only have one can and cut it in half?

[@swdweeb]

That is a distinct possibility :-D

[@smallcnclathes]

Tut, tut, you can't go making scientific videos if you do not have all the apparatus you required. If only I had known I would have sent you an empty can.

[@olfoundryman8418]

@@smallcnclathes, I think that SW could not bring himself to use the full travesty of a full height bean can - it just goes so much against the grain of serious foundry work. I think he had to take something to settle his stomach after using just those 1/2 height extensions.... Martin

[@Gippetos]

@@olfoundryman8418 Attacks of conscience are an indicator that ones teachers have properly chastised such behavior. ;)

[@ronnybe7994]

If you cut those open and tried to break them...

[@swdweeb]

Yeah, cut them open is a recurring theme ;-) I'll see what I can do.

[@diydarkmatter]

heck im not mad i just like to watch brother lol . so let make something or kill some ants or something lol . fun fun fun .

[@swdweeb]

Man I'm all about ridding my portion of the planet of ants ;-) We didn't have any hills last summer, not a single one. Maybe this year I can pour metal down a hole in the ground again ;-)

[@glen1arthur]

I was think maybe checking the mass of each but you’ll need to use the same size block no a or b marking. Maybe you could send you blocks to one of those guy with a Water Saw. Ken sent me your way Well take care~eh

[@swdweeb]

Your wish is my command. Ken has been my most prolific viewer and commenter lately 😄 kzbin.info/www/bejne/jJS0YZt-bqlsarc

[@RockingJOffroad]

Perry,package them up and send them to me, I can cut them and machine to see and I will send them back to you!

[@swdweeb]

Hey John email me [e-mail]

[@RockingJOffroad]

Email sent!

[@swdweeb]

@@RockingJOffroad Hmmm never got it.

[@RockingJOffroad]

Maybe because I found it in my drafts.. could it be because I had back surgery this morning?

[@scottpittsinger1654]

aluminum the problem

[@swdweeb]

Those blocks are long gone having been poured over two years ago. My point is that porosity in our pours is very much related to way we pour. If you mix air into the aluminum through a turbulent pour you're going to have a lot of porosity. Granted there is hydrogen gas in the melted metal, unless you degas, but the stuff I see in most castings is because of the way its poured, not absorption of hydrogen during the melt

[@tonycstech]

Now cut them in half, machine to finish and see poracity or lack of it. Pointless video.

[@swdweeb]

I don't know why I'm bothering to send this to you as I'm sure it will only solicit another pointless comment. kzbin.info/www/bejne/jJS0YZt-bqlsarc

[@tonycstech]

@@swdweeb Thanks i watched that. There are LOTS of pores. Unacceptable results.