Attempt to cast a cylinder

Douglas Binder /

Based on my experiences with casting intakes, I am working towards casting a cylinder. Nothing on the market has the type of porting I want so I will try to make my own. Casting the intakes and a few other things showed me that there is a lot to understand with the process so I threw together a 3D drawing of something that vaguely represented what I might be going for and printed it with PLA. It was a 22 hour print.

IMG_20181102_184157169.jpg

I had been using a small electric kiln to melt the aluminum so I needed to make something bigger. 16 fire bricks and a cheap weed burner and I had a kiln.

IMG_20181104_142513690.jpg

I had purchased a stove from the local reuse center which I use to burn out the PLA from the investment plaster (one part sand to one part plaster of paris). I do the burn out in the garage - it stinks.

Re: Attempt to cast a cylinder

Douglas Binder /
IMG_20181104_172529235.jpg

The results. I think the temperature was too low, that the sprue was too short and not wide enough, and that I need to vent the ends of the fins. The mold was at 550F when I did the pour.

This is the reason I did this test - to learn how to do it right when I have the design worked out.

Re: Attempt to cast a cylinder

Josiah Radebaugh /

Ooh this'll be interesting.

Re: Attempt to cast a cylinder

Blaine- The artist formerly known as Plumber Crack "(OFMC)" /

Awesome stuff. Glad to see the burnout process seems to work well for PLA. Good luck.

Re: Attempt to cast a cylinder

that print is gorgeous! Keep at it I'm sure you'll get it. A bunch of euro guys are making cylinders in their back yard for scoots. I have read you need a longer sprue to help create more pressure to force the metal into the tiny crevices. I am looking into getting into this myself in the next year. How did you create that cylinder? It looks exactly like a puch fin pattern.

Re: Attempt to cast a cylinder

Douglas Binder /

Will, agreed about the sprue. Also, the fins cool the aluminum almost like that is what they we're designed to do.

Re: Attempt to cast a cylinder

Josiah Radebaugh /

Would a 3d printed jug work? For how long.....

Re: Attempt to cast a cylinder

Douglas Binder /

I going to say 3 seconds, give or take.

Re: Attempt to cast a cylinder

Overpriced Parts /

How were you planning to machine and plate it?

Re: Attempt to cast a cylinder

Brandon Weiss (Detective brandon to you) /

mount that original cast on a plaque and keep it on your shop!

Re: Attempt to cast a cylinder

Douglas Binder /

Ken, there's a machine shop where I work. They are open to me using it. I plan to use a steel insert. Plating is expensive.

Re: Attempt to cast a cylinder

Brandon Weiss (Detective brandon to you) /

> Douglas Binder Wrote:

> -------------------------------------------------------

> Ken, there's a machine shop where I work. They are open to me using it.

> I plan to use a steel insert. Plating is expensive.

I think you can use ductile iron pipe?

Re: Attempt to cast a cylinder

Douglas Binder /

I've been having a hard time finding ductile iron small enough for a 50cc liner. Smallest I found was 3".

Re: Attempt to cast a cylinder

yeah you gotta hog it out from solid round. guys on the small engine forum 'smokestak' use just regular cast iron pipe for cylinder liners all the time but those are low rpm low stress applications, that is more of a grey iron than the ductile you would probably want.

then again, take something like a india-made Hero 65cc kit... what are the chances their metallurgy is realy that good? ductile goes through a pretty crazy heat treating process i doubt anyone is replicating for cheapo moped cylinders, so who knows.

if you call up durabar in chicago and talk to their application engineering folks, they'll send you a short engineering sample, but yeah, you gotta hog it out from solid. Durabar is good stuff though, cuts way better than steel but it has similar properties for fatigue and ductility.

There is a good video on youtube of a factory making two stroke cylinders, showing the casting process... i think it might be the polini factory or something?

One thing they do, similar to the way they cast engine blocks, is they make the entire base gasket surface a giant riser, basically extrude the whole base gasket face 2" up to the bottom of the skirt, feed it from a sprue into the 'top' of the cylinder which is upside down, and then that whole base gasket surface keeps pressure on the mold. Dont be afraid of making a giant riser, the other nice thing about it is that it keeps the whole casting hot so it cools slower and you get less warpy stuff, and it gives you a lot more flexibility if you run short of material to avoid a short fill, plus with a lost wax dealio, it will burn out better.

cylinder fins are notoriously difficult to cast, most air cooled cylinders are done in permanent mold exterior with no bake or plaster cores, the permanent molds can be heated up real hot so they flow. you want to be about 400 degrees to keep from getting blisters and weird surface finish problems.

I'm super stoked on your progress, this is huge! I'm getting my printer tomorrow and cant wait to get going on catching up to you, haha! I've got a long way to go on the printing front.

Re: Attempt to cast a cylinder

Douglas Binder /

Graham, the reason I did the initial post was to share the process in case others want to experiment along the same lines. I want to clean up the 3D model then try again with a longer sprue, better venting of the fins, and get the aluminum hotter before I pour. I used the red filament because that was what I had but I have some natural on order which I feel burns off cleaner.

Re: Attempt to cast a cylinder

Douglas, looks great, yeah i'm just kinda monday morning quarterbacking ya here, i've spent a lot of time doing research but not actually tried pouring my own cylinder... the patternmaking and all that is what has held me back.

You've already inspired me to order the printer, had a lot of stuff this summer pulling me in that direction since the Prusa MK3 machines came out, seeing your progress took me over the edge.

My problem is always modeling, spending 9 hours a day staring at a workstation, the last thing i do when i come home is fire up solidworks, haha.

Re: Attempt to cast a cylinder

Douglas Binder /

Graham, fortunately for me, I'm an electrical engineer so I rarely use Inventor at work. On the other hand, I bet you could model a cylinder far faster than I can.

Re: Attempt to cast a cylinder

Douglas Binder /
IMG_20181107_184235577.jpg

I got sidetracked making a Reed block for the crankcase.

Re: Attempt to cast a cylinder

Ohh this is intriguing!

Re: Attempt to cast a cylinder

I don't plan on casting anything but this is only thread I'm interested in right now.

Re: Attempt to cast a cylinder

Kevin Bishop /

I like the intake. Where did you get the file for printing it? I have access to a printer just never used it.

Re: Attempt to cast a cylinder

Douglas Binder /

Kevin, I drew it up in AutoDesk Inventor. If you look in the background, you can see an earlier print that I used to test the first part of the drawing. It doesn't match the crankcase very well (I'm self taught in Inventor) but the part will be attached to the crankcase with JBWeld so that will fill all the mismatches. Next I have to design the part that connects this to the throttle body.

Re: Attempt to cast a cylinder

Got the printer setup and ripping on Wednesday night, way easier than i expected. I have a backlog of years of parts i've drawn up hoping to someday 3d print them so i'm making some slight tweaks now that i understand the technology better and ripping them off.

Ran this over last night, I bought commercial investment plaster which also showed up wednesday, and i'm going to try to invest and burn this out this weekend. I broke my air compressor on Tuesday night so i gotta either fix that or find another way to melt aluminum, since my melting furnace runs on compressed air and waste motor oil.

polinivmintake.jpg

Got a cool lil' SHA air filter adapter dingus guy that i've wanted to make for YEARS printing at home right now.

Re: Attempt to cast a cylinder

oh hey on that reed valve adapter dingus, i have one of those drawn up too.

my plan was to just take the flat bottom intake and file it by hand, test fit, file, test, file, until i got a fairly good gap.

you could also melt wax along the bottom edge, heat up your case, and press it on there to get it 100% perfecto, then when you invest it, the seam will be dead on.

my plan was to cast the aluminum then use 'alumiweld' which is basically a brazing alloy for aluminum. If you 'tin' both the surfaces and get it to flow out on the aluminum, you can set them together and do a furnace braze. I did that to braze a block of aluminum onto a peugeot case to build up transfers and it worked perfecto. I didn't actually do a furnace braze, but i just very evenly heated the whole part with a torch until the alloy flowed. Its only a couple hundred degrees between the alloy melting and your whole case turning into a puddle so it would definitely be cool to do it in a furnace.

Re: Attempt to cast a cylinder

Douglas Binder /

Looking good Graham. Message me if I can be of help. I think I may do a series of photos when I cast the reed block to better document the process.

Re: Attempt to cast a cylinder

OH GOD YES

> Douglas Binder Wrote:

> -------------------------------------------------------

> I got sidetracked making a Reed block for the crankcase.

Re: Attempt to cast a cylinder

yeah absolutely, i like keeping the discussion on here to motivate/inspire/help anyone else that wants to get into this.

i'm going to draw up a sprue tube mold that i can use to cast sprues out of wax, i think i saw a chunk of 4" pvc sitting around in the barn somewhere so i'll use that as a flask and maybe stuff some short sections of PVC around the pattern so i don't have to burn like 5 lbs of my super expensive investment plaster.

i'm also going to make a better burn out oven using one of these:

EDIT: oops, ADD...

Halogen heating element

(edited)

Re: Attempt to cast a cylinder

Douglas Binder /

I just went to the reuse center and bought a used electric stove for $55. I set it to ~130F to dry the mold overnight (actually, in the cold weather, I use the kitchen stove to also help heat the house), then raise the temperature to 300F for a few hours (NOT in the house!), then to 550F for 6-8 hours for the burnout. I'm going to try taking it to 800F in the self clean mode to raise the mold temperature closer to the molten aluminum temperature to help prevent rapid cooling of the aluminum before it is done flowing in the mold. Don't forget to paint a thin layer of plaster onto your part to eliminate air bubbles. Also, I drew the sprues right onto the 3D cad.

Re: Attempt to cast a cylinder

supposedly going over 400F on the mold will cause the surface of the aluminum to oxidze and blister, i've never tried it. usually i pour them probably 200 ish or so?

I really don't think preheat is your problem, based on how that filled it looks like a gating/venting issue to me, just make sure you have large feed and riser volumes, for something like that i would say at least 1.5-2x the volume of your part in riser/sprue

oh here is that video from S3 cylinders, look at how their mold flows and how much riser they have on top, its bigger than the cylinder itself almost. Lots of good knowledge to be gleaned from watching this.

Re: Attempt to cast a cylinder

Douglas Binder /

Great video! Do you think riser volume is important or is it riser height? I may need a larger crucible.

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account