Another Knucklehead, built via castings, as a Draw-Tech design, upscaled

[Scott_M]

That looks like nice unit! I am also a big fan of probes.
I am curious though, All of the different probing routines I have used for a bore do X twice.
The first one on X can be anywhere in the bore. Close to the center is good.
It then does Y
And then repeats the X probe routine to refine its position.
I have often seen it change X afterwards. Maybe only a few tenths, but it does "refine" it.

And like scottyp said " be careful in Z "
And the tool setter touch pad is also hard to live without after you use one.


Scott

 

[Foketry]

Lost PLA, Harley Davidson heads

I tried to make the heads with the lost PLA technique to avoid hours and hours of milling, some positioning on the milling machine. I thought it would be difficult to obtain cooling fins with a thickness of 1.3 mm but I wanted to try.
The technique for making molten aluminum penetrate very small thicknesses is to create a column of aluminum that generates pressure and keep the hot plaster mold at almost the same temperature as the molten aluminum.
Another solution is to use a vacuum pump that sucks the mold, but it is used for very small pieces such as gold rings .

the drawing

3D printed heads

the heads drowned in plaster

the finished heads (without machining)

milling of the combustion chamber and drilling

 

[The Ignoble Troll]

Those came out fantastic

 

[GreenTwin]

Beautiful casting work !
Most impressive.

.

 

[petertha]

@Foketry very nice work. Maybe I asked you this on another build, but what is your method for selecting / sourcing your casting aluminum? For example do you confine yourself to bars of a known, specific alloy for things like heads & cylinders where they have more complicated geometry like fins, or require lots of small tapped holes or hotter service temperature... And maybe bigger parts like crankcase ok to use recycled / scrap material? Or maybe you use the same source stock regardless because its not worth the headache of possible results variation?

After casting, do you do any form of heat treatment or artificial aging? When I look as some of your swarf it reminds me of some MIC-6 cast aluminum I have used for a different purpose. The swarf is more crumbly, not strings like typical bar stock alloys. Not that it is a bad thing. It machines beautifully & is very stable, but is definitely a bit weaker in certain respects compared to plain 6061-T6 when the material gets thin or say fine pitch threaded holes.

 

[Foketry]

@Foketry very nice work. Maybe I asked you this on another build, but what is your method for selecting / sourcing your casting aluminum? For example do you confine yourself to bars of a known, specific alloy for things like heads & cylinders where they have more complicated geometry like fins, or require lots of small tapped holes or hotter service temperature... And maybe bigger parts like crankcase ok to use recycled / scrap material? Or maybe you use the same source stock regardless because its not worth the headache of possible results variation?

After casting, do you do any form of heat treatment or artificial aging? When I look as some of your swarf it reminds me of some MIC-6 cast aluminum I have used for a different purpose. The swarf is more crumbly, not strings like typical bar stock alloys. Not that it is a bad thing. It machines beautifully & is very stable, but is definitely a bit weaker in certain respects compared to plain 6061-T6 when the material gets thin or say fine pitch threaded holes.

For my aluminum castings I use both ingots and scrap machined pieces to be melted again but all of the same type of aluminum (Al Si 9 Cu 3) (USA ASTM B179-82 333.1 - 332.0 )
This aluminum alloy can be hardened and aged artificially, but I have never tried, sooner or later I will.
Hardening is done in the oven at 520 degrees C for 6 hours and aging at 160 degrees C for 10 hours
I tried milling and drilling the waste pieces that I buy for casting, they are hardened, the workability is better, the chip is longer and it is easier to make small threads.
I would like to temper the pieces that I cast because in the small threaded holes for example M3 (3mm) if you screw and unscrew the screw many times, the thread in the aluminum gets damaged and therefore I have to use Hely Coils to repair or strengthen them.
6061 is undoubtedly the best aluminum in bar, but I enjoy making castings rather than scraping an engine crankcase from solid

 

[GreenTwin]

A356 aluminum alloy is used quite a bit for sand and die casting, and it has a high castability rating.

For comparision with Foketry's method, I have used the solution heat treatment process with 356 aluminum, same temperature as Foketry (520 C, 968 F), but for 8 hours, since a white paper I saw said the solution process does not begin until after 6 hours, followed by a cold water quench.

Then a precipitation hardening (artificial aging) at 204 C (400 F) for about 4 hours, no quenching.

This is one of the methods used for a T6 aluminum temper, which makes the aluminum quite a bit harder, cleaner to machine, and easier to drill and tap.

The solution heat treatment temperature needs to be carefully controlled since it is pretty close to the melting point of aluminum.

A356 is readily available in the States.

.

 

[ddmckee54]

Foketry:

Those are some beautiful castings. What did you use for your investment plaster? Just out of idle curiosity, how large were the flasks, and how did you orient the heads in the flasks?

Don

 

[GreenTwin]

Not to speak for Foketry, but I think a good guess is that you are not going to gate through a fin that thin without it freezing in mid pour, so that means fins down, gate and riser into the bottom of the head; with the bottom of the head facing upwards in the flask ?

It is also good practice to gate into a surface that has to be machined when possible, so that you can easily erase the gate during the machining process, and thus save grinding the gate off.

Since the fins seem to have completely filled, then perhaps the heads were poured on the hot side; ie: over 1,350 F ?

.

 

[Foketry]

Not to speak for Foketry, but I think a good guess is that you are not going to gate through a fin that thin without it freezing in mid pour, so that means fins down, gate and riser into the bottom of the head; with the bottom of the head facing upwards in the flask ?

It is also good practice to gate into a surface that has to be machined when possible, so that you can easily erase the gate during the machining process, and thus save grinding the gate off.

Since the fins seem to have completely filled, then perhaps the heads were poured on the hot side; ie: over 1,350 F ?

.

I generally pour the molten aluminum into the plaster model right after I remove it from the oven , 550 C or 1020 F, the aluminum remains liquid for at least 10-15 minutes and more penetrates into the small cavities.
I also hit small bumps on the plaster creating vibrations that facilitate penetration

 

[Foketry]

Foketry:

Those are some beautiful castings. What did you use for your investment plaster? Just out of idle curiosity, how large were the flasks, and how did you orient the heads in the flasks?

Don

Sorry for my late reply, in reality I don't use plaster but ceramic powder, it resists high temperatures better and has greater mechanical resistance.
However, it is more difficult to remove from the aluminum casting
This is the product I use
https://amzn.eu/d/5wG8X4S

this is also suitable
https://amzn.eu/d/429F06u

in this case the head fins are downwards so that the weight of the molten aluminum is on top and creates pressure

 

[ddmckee54]

Foketry:

Both of those appear to be casting plasters which would explain the difficulty in cleaning it off the casting. Have you ever tried something like Ransom & Randolph's jewelry investment powder, Ransom & Randolph, or it's Italian equivalent? (Search for investment plaster or jewelry investment.)

Investment plaster is designed to be able to capture fine details, resist the high temperature of the burn-out cycle without cracking, and still be relatively easy to remove from the casting. It might be a little more expensive than casting plaster though.

Don

 

[Foketry]

Foketry:

Both of those appear to be casting plasters which would explain the difficulty in cleaning it off the casting. Have you ever tried something like Ransom & Randolph's jewelry investment powder, Ransom & Randolph, or it's Italian equivalent? (Search for investment plaster or jewelry investment.)

Investment plaster is designed to be able to capture fine details, resist the high temperature of the burn-out cycle without cracking, and still be relatively easy to remove from the casting. It might be a little more expensive than casting plaster though.

Don

I tried 2 types of casting plaster but I had fractures and small cracks, perhaps because I didn't respect the burnout cycles perfectly , then I tried ceramic and I have no problems. I continue with ceramic , I can easily find it on Amazon and burnout is easier and faster
Iules

 

[Foketry]

Another milling step on the heads, valve cages seats

The project only includes the valve seat rings, but I prefer the complete cages where the valve stem slides on the bronze

 

[Foketry]

Bronze valve cages

 

[Foketry]

After the construction of the valve cages I milled, drilled and turned the other components for the valve system : roker arms , roker housing,roker housing cover , valvebox ,valve box cover , etc.

Some of these parts are made of brass, others are made of aluminium, I decided to build everything in brass for an aesthetic reason, even if it does not respect the real engine. Some of these parts will be polished to a mirror finish, but I still have to decide, I will only see it once the engine is finished

these are the parts that will probably make them shiny

I also have to thank Mayhugh (Terry) who provided me with some of these drawings, saving me hours of design

 

[ddmckee54]

That's a nice portrait of the Rocker family. Were all those parts carved out of bar stock, or were some of them castings you made?

 

[Foketry]

That's a nice portrait of the Rocker family. Were all those parts carved out of bar stock, or were some of them castings you made?

In these photos you can see how they were made

 

[Foketry]