Author Topic: Making the cylinder head, design, patterns and casting.  (Read 3206 times)

Offline A7er

  • Full Member
  • ****
  • Posts: 197
Re: Making the cylinder head, design, patterns and casting.
« Reply #30 on: October 07, 2022, 11:10:24 PM »
The room is at 18c, I know it should be higher, at least 20c I think. I printed one half of the head pattern this evening. Flat on the build plate, raise it 5mm and add supports. I also added a few drain holes because of it being flat. It took 1 hour 40 mins to print. After washing and curing I could see it was a far better print than the ones I did earlier. It sits almost flat on a surface and seems to have very little, if any, distortion.

I will photograph it tomorrow and post the pictures along with what else I have done.
Lee

Offline Brendon M

  • Full Member
  • ****
  • Posts: 183
  • Melbourne, Australia
Re: Making the cylinder head, design, patterns and casting.
« Reply #31 on: October 08, 2022, 12:10:53 PM »
This is fantastic work, I always wondered if 3D printers could be useful for making casting patterns!
(This signature intentionally left blank)

Offline A7er

  • Full Member
  • ****
  • Posts: 197
Re: Making the cylinder head, design, patterns and casting.
« Reply #32 on: October 08, 2022, 09:09:19 PM »
I make all my casting patterns with a 3D printer. Up until recently I only used an Ender3 and pla filament. I am now also using an Anycubic mono 4K and water washable resin. The resin prints have much better surface detail and finish, but the pla prints are stronger and are less prone to distortion. Some of my resin prints are even distorting many hours after I have removed them from the printer. I tried clamping one of the prints to a flat surface and left it in a sunny warm place to see if that would help flatten it. It did to a large extent, but I am still experimenting different ways to resin print a piece to minimise distortion.

The first thing I 3D printed was the pattern for my sand rammer. I use that every time I cast something. I cast this name plate for a local engineer. I printed it on the Ender3 in pla and the cast it in an alloy know as ZL12, 88% zinc to 12% aluminium. The ZL12 was better suited for this because John wanted to use the name plate I made as a pattern to cast some in brass. The first image is the 3D print, then the name plate as cast, then a close up. The lettering is several mm high and is extruded about 2mm. I forget the exact details. The name plate is about 75mm wide by 50-ish high.

Lee



Offline A7er

  • Full Member
  • ****
  • Posts: 197
Re: Making the cylinder head, design, patterns and casting.
« Reply #33 on: October 10, 2022, 06:13:07 PM »
Progress has been slow. I had a lot of trouble getting a decent resin print of the new head patterns. I made two separate prints in resin, and one in pla on the Ender3.
I have now bonded the pla print to a match plate and will try to cast it during the week.

This is the water core and its mould. Some thin metal wire has been used to strengthen a few places. I used fine sand and sodium silicate hardened with CO2.





The three head patterns. The middle one is the pla pattern. It looks wonky because I didn't fit the locating pins to hold the two halves together. The other two patterns are resin. The copper wire is there to try and correct some of the distortion that occurred some hours after printing. I left the prints in a sunny spot for a few hours and that helped a lot, so I think a hot air gun on low setting would work.



The only 3D print waiting is the inlet/exhaust tracts. I then have to figure out how I will position the sprue etc.

Lee

Offline bent

  • Full Member
  • ****
  • Posts: 718
  • Wet side of Washington State, USA
Re: Making the cylinder head, design, patterns and casting.
« Reply #34 on: October 10, 2022, 06:54:56 PM »
Those prints look pretty good!  Beats the heck out of my first attempt to cast something.  I tried to make a friend a cigar ashtray by pouring silicone into a mold printed on the 3d printer (fdm).  Coated the mold form with spray paint to smooth it up a bit...but it turned out the paint may have caused cure inhibition, and the part was still "wet" and gooey coming out of the mold.

Frantic googling for how to "fix" silicone cure inhibition (i.e. recover a failed mold) didn't help...but I did remember a recipe for silly putty, and figured I would try modifying that.  It seemed to work, mostly: I used a wash made of boric acid (ant killer) and water, which helps set the silicone resin to something closer to a putty.  Then packed the surface with a wet slurry of boric acid, and set it in the oven to bake at 350 F for an hour or so.   The part came out of the oven with the surface nicely cured and not even tacky, though a lot of the fine detail was lost...still works as an ashtray according to him.

Offline A7er

  • Full Member
  • ****
  • Posts: 197
Re: Making the cylinder head, design, patterns and casting.
« Reply #35 on: October 10, 2022, 07:05:16 PM »
I got a bit lost there bent. Did you try making an ashtray from silicone rubber, or was the rubber used to make a mould for casting. I know there are silicones that can stand a high temp.

I watched a lot of vids about silicone by a company called "brick in the yard" also a youtuber called Robert Tolone. I did wonder about using a high temp silicone and a low temp metal, such as tin or pewter, to produce patterns for casting. I haven't tried yet, too much going on already!
Nice save.
Lee

Offline bent

  • Full Member
  • ****
  • Posts: 718
  • Wet side of Washington State, USA
Re: Making the cylinder head, design, patterns and casting.
« Reply #36 on: October 11, 2022, 06:21:50 PM »
Sorry A7er, it is a silicone ashtray (silicone in any version is reasonably good (at least compared to PLA!) at high temperatures, not that an ashtray sees that high of a heat).   The friend/work colleague is a cigar smoker and recently married, so I asked him what he wanted as a wedding present and that was his answer.  We tease him when he messes up at work by claiming his replacement (with a mangled version of his name) will do a better job, so of course the ashtray has the mangled version of his name embossed in it.

I had picked up a silicone kit some time ago, thinking of making some pewter molds...most anything I mold will be a one-off, so it seemed like it might work.  And yeah, I saw the Tolone video where he casts some ZA-12, and gets several pours from it.  I was thinking it might work for simple parts like your nameplate, again in onesy-twosy uses.  I will probably try that before moving on to real foundry work like you are doing, LOL.

Yeah, the "save" made the part usable, and the embossed name is still there if a bit blurry, so it got the requisite chuckle. 

Offline A7er

  • Full Member
  • ****
  • Posts: 197
Re: Making the cylinder head, design, patterns and casting.
« Reply #37 on: October 11, 2022, 11:58:04 PM »
Thanks bent. You've got to keep it simple when you explain things to me. Go slowly, and don't use big words.

I would like to explore the world of using silicone for casting. Like you I thought of using pewter. But there is nowhere here in Cornwall to buy it. I thought I would buy old items made of pewter at local junk markets. No luck there either. Now, Cornwall is big on tin. But digging it up and getting it in a fit state to use is a big job. Some on this and other forums have suggested that getting aluminium from a car wheel might not be a good idea. A wheel is die cast using a different type of aluminium, so I am given to understand. I am now wondering if I should visit a car breaker yard and look out for sand cast aluminium parts like a cylinder head or gearbox. Getting aluminium ingots is a bit difficult too, unless you want at least 1000kg. I did email a supplier of ingots and explained my position. He very kindly offered to sell me a dozen ingots if I picked them up as he couldn't justify posting them. It was in the middle of the pandemic and his factory was 350 miles away. I had to say thanks but no thanks.
I will just have to use the wheel.
Lee

Offline Jasonb

  • Full Member
  • *****
  • Posts: 8621
  • Surrey, UK
Re: Making the cylinder head, design, patterns and casting.
« Reply #38 on: October 12, 2022, 07:03:17 AM »
Someone like Tiranti's should be able to supply Pewter and other low melt alloys which will be cheaper than pewter

https://www.tiranti.co.uk/Products/white-metal--tin-alloys

Offline A7er

  • Full Member
  • ****
  • Posts: 197
Re: Making the cylinder head, design, patterns and casting.
« Reply #39 on: October 12, 2022, 03:22:35 PM »
Thank you Jasonb, I will check them out.

I have bonded the pla head pattern to a match plate and worked out where I think the sprue and feeder should go.



Hopefully any loose sand will end up in the bottom of the head where I have allowed 2mm extra metal to be machined off.

I also have all the cores made. I have made two water cores, one in sand + sodium silicate, the other with sand + epoxy resin. The inlet and exhaust tracts, right of picture, are mainly sand + sodium silicate, plus I have made one with a stronger mixture of ss+sand, 15% ss instead of 5%. I also left it "cooking" in the plastic box filled with CO2 gas for 30 mins. I made an extra combustion chamber mould the same way. It's the one in front with 15 written on it. I want to see if it works better than the weaker mixture, it certainly feels better and has a good texture. The two parts still in their moulds are the water core at the back and an inlet/exhaust tract at the front, both made with sand/epoxy. So a few spares in case I break anything. I feel a pour coming on!



I also have the other two head patterns ready to fit to match plates if the pla pattern doesn't give an acceptable finish. Mind you, the head will be painted, so perhaps I am expecting too much from my setup?

If this casting comes out OK I will start working on the block. It not only has a water core but lettering down each side. The name of my fictitious engine company, A.J.L.S.

Lee

Offline AlexS

  • Full Member
  • ****
  • Posts: 224
Re: Making the cylinder head, design, patterns and casting.
« Reply #40 on: October 12, 2022, 04:09:13 PM »
Looking great! Nice usage of a 3D printer, is it not possible to heat up the area of the printer so the temperature of the printed part can so be more be controlled?

Should aluminium casted EN AC 5083 plates work?

Offline A7er

  • Full Member
  • ****
  • Posts: 197
Re: Making the cylinder head, design, patterns and casting.
« Reply #41 on: October 12, 2022, 04:21:42 PM »
AlexS.
My Ender3 printer that produced the pla patterns has a heated bed. There has always been a small amount of distortion with the printer, I don't know if that's normal. My other printer is a resin printer, so I am still learning how to use it. The printer doesn't have a heater of any sort, but it likes temperatures just over 20c to work properly.
I have to admit I don't know what EN 5083 is. If it's some sort of pattern plate I am just using 9mm play and sometimes 15mm melamine faced chipboard. Because my plates don't need to be bigger than 200mm X 200mm These boards are strong enough.
Lee

Offline ddmckee54

  • Full Member
  • ****
  • Posts: 506
  • We're having fun now --- or so I've been told.
Re: Making the cylinder head, design, patterns and casting.
« Reply #42 on: October 12, 2022, 04:31:56 PM »
Lee:

When you say there's always been a small amount of distortion with the printer, what are you talking about?  The part lifting from the print bed, round holes printing oval, the part not being the correct size, or some thing else?

Don

Offline A7er

  • Full Member
  • ****
  • Posts: 197
Re: Making the cylinder head, design, patterns and casting.
« Reply #43 on: October 12, 2022, 05:30:17 PM »
Don.
When I printed out both halves of the head pattern on the Ender3 in pla and then put them back together with dowels, the two halves generally line up, but not the four "arms" that form the location of the water core and inlet/exhaust cores. They were slightly out of line with each other. The two halves of the pattern were formed by the splitting of the 3D drawing, so they should have lined up. Apart from that some of the flat surfaces on my prints have been a bit concave or convex. They have needed sanding or filling. The print has often lifted from the bed, I have the bed temp at 60c, anything lower and the print won't stick. Sometimes a corner of a print will lift. Holes never print at the right size, I even printed out a hole gauge with a series of holes in it from 5.9mm to 6.5mm in .1mm increments so I could determine which size I should use in my designs. Even now if I want a hole at 6mm dia I have to draw the hole at 6.3mm dia. But I expect something like that with a printer that is squirting out liquid plastic layer by layer. I have seen others get better prints from different manufacturers. It's only the price of a Prusa that stops me buying one.
Lee

Offline bent

  • Full Member
  • ****
  • Posts: 718
  • Wet side of Washington State, USA
Re: Making the cylinder head, design, patterns and casting.
« Reply #44 on: October 12, 2022, 05:40:14 PM »
Yup, even on nicer printers, shrinkage and warping occur when the PLA cools down.  I made my PLA-printed mold twice, because I tried to bake the paint finish on it at 150-200 F...and that made the thing warp and twist like crazy.  There is a lot of built-in shrinkage stress in 3d printed parts.