Custom Single Cylinder Heads’?

A call to this chap should help ....

Carl Harrison Motorcycles - Servicing

 

Do you mean just machine or cast and machine from CAD - or do you mean design and manufacture?

 

I just joined the forum and saw this post. Did you get sorted?? I am a Mechanical Engineer with 3D CAD and CNC. I make patterns for casting or can possibly 3D machine a head from an aluminium billet, depending on the design detail. I also can laser scan existing castings should you, want to lift porting details etc from an existing casting into the CAD data.
Before everyone gets excited, this type of work is very time consuming so isn't cheap. I have started work on "reverse engineering" a Pantah rear head (rear facing . original type)

 

That's interesting. So may I ask in what way this expensive reverse-engineered Pantah rear head will be an improvement on the standard Pantah rear head? Presumably it must be a lot better in some way, or it would not be worthwhile doing it.

 

I am not claiming to be producing a "better" head for the Pantah, I just see the original rear heads getting more and more difficult to find and prices rising to the point that it is probably just about worth remaking them. I also see the Pantah racing more and people building TT2s so maybe it has some legs as a project....
One benefit of having bare castings to hand is that I can possibly move the valves apart to allow larger valves within the 750 motor, I have a stroked / bored (64mm x 90mm) 815cc pantah so I could better make use of the larger bore. One problem with fitting larger valves in the Pantah head is that the "bridge" in between the valves gets hot and the heads can crack.
There is also an opportunity to use more modern porting without needing to weld. I can CNC port the castings.
In summary, I am just looking to provide parts that are now hard to find and expensive. Using a more modern "reverse head" wont be allowed in classic racing.

 

Off the to0 of your head wot would the aprox cost be?

 

Ironic, isn't it. A reversed head from a 1986 Paso would not be allowed on a 1986 F1, whereas a totally new 2015 head would be OK.

It would be quite a complicated job to start with a reversed head, weld it up and re-machine it so it ends up looking and functioning like a Pantah head - but surely not as complicated as starting with a brand new casting and having to machine everything from scratch.

 

Pete. you are probably right! I am always a bit nervous about all that welding on a casting due to the reduced fatigue life and the potential distortion that can occur.
I agree that the classic rules seem crazy at this level and even more so when you see brand new Manx Norton engines racing because the originals are all either work out or too valuable to risk.
I am doing this kind of reverse engineering, pattern making, CNC work etc for a living so its no different for me to other guys on the forum who are good fabricators bringing their "day job" home! I have a rotating axis on my mill so there isn't too much machining to do on the castings although what there is has to be accurate. The biggest commitment is in machining the patterns for the foundry and this is performed on soft material so is much easier / faster.

 

I also quite fancy cutting my teeth on the 750 motor heads and then looking at the 900 / 1000 or even a 3 valve head for the air cooled motor using ST3 internals????

 

There is a company making the rear heads,i think they are a bit pricey compered to welding and new seats.

 

Do you mean the company in Holland? They are CNC machined from solid and I had thought about that.... Casting is really only worth it if there is enough interest to justify a higher initial investment but then lower cost per part ....

 

Yes i think so,the main cost in castings is getting the wood patterns made first.

 

Agreed, but that's where I have an advantage as I do that stuff for a living and have my own 3D CAD, CNC mill etc,
Just a case of my time and whether the whole thing makes some kind of financial sense... Just looking to cover the costs really.

 

Can you make multi piece casting moulds? For future refrance.

 

Multi piece casting moulds are possible and quite common. The Pantah heads would have to be multi piece to allow them to be removed from the casting.

 

I was talking to some people the other day that can 3D print in a carbon rich kind of plastic. By that i mean not weave like we are used to.
The object is then used as a pattern for casting. It might be easier than machining a casting pattern. Of course you have to be able to point map your object first.

 

Yes, I have used SLS type patterns before and they can work well. 3D printing is moving along with better resolution so is giving better resolution in castings than it did, a few years ago 3D printed parts had distinctive layers that could be seen on anything that was made from them as a pattern.
Another route for prototype is to print wax that is then used in the lost wax process. Unfortunately, the wax is melted out during casting so a new 3D part is needed for every casting so it isn't economic in volume.
You have also hit the nail on the head as most of the work is actually in producing the CAD model from the scanned point data. Also see the attached simple scan of a 2 stroke Bultaco head and you can see that the scan includes all the lumps, bumps and defects that need to be cleaned up. Machined faces then have machining allowance put back on and the model is scaled to allow for the casting shrinkage, the model is then ready for CNC or 3D printing.

 

Scanned head screen captures from CAD