Anyone able to advise on patternmaking for alloy castings

[CJH]

This is the sort of job 3d modeling is good at, how on earth people used to do this stuff before 3d CAD I don't know, I suspect alot of trial and error and foam/clay models was involved. I gave up full time drafting before 3d was established but I'm supposed to be getting a solid works seat at work and so I'm going to have to learn, my drafting currently is limited to 2d Autocad but I have 3 draftees in the office to learn from.

To do it properly you would of course need to model the engine, gearbox, starter....

The dfaftees at work draw the part then discuss with the foundry about how it will be cast, wall thickness, rads, flow etc then incorporate these details.

Yes, the more I use Autocad the more impressed I am with what it can do. I found it incredibly frustrating to learn, but making the most of its power depends on a learning a few key things about the way it works, which aren't always intuitive or common to the way things tend to work in other programs. I think that's something of a feature of the most powerful programs.

So where you work you can go straight from a CAD model to a foundry casting? Do you know how they do that? Is it a 3D printed sand mould, or do they 3D print a prototype casting and then make a mould from that?

[CJH]

Chris the basic form looks about right to me.
Yes there are a few bolt access/assembly matters to resolve but I seem to have identified all of them and have solutions to hand. At least all the UN1 bolts comfortably miss the VW four (on a polar/angular pitching btw) with no risk of overlaps or breakouts.

I'll wait for your directions in that case. When I took the rough measurements from the bellhousing I have here I ran up against a fairly basic problem - I don't have big enough calipers to make proper measurements of the outer radii at the key points, so my approximate measurements were simply made with a tape measure across the top of the casting. So if you can make better measurements and provide the key dimensions I'll be more confident about the drawing.

[itchyfeet]

where you work you can go straight from a CAD model to a foundry casting? Do you know how they do that? Is it a 3D printed sand mould, or do they 3D print a prototype casting and then make a mould from that?

No we supply a cad model of the part with the agreed features the foundry need, they make a pattern and cast the part. If you supply your own pattern then there are all sorts of arguments when the finished part isn't to spec, if they supply the pattern they are responsible.

This might not be much help to SB but the point is you really need to be in discussion with the foundry you are going to use.

[silverbullet]

Ok Chris I will get some more numbers for you. FWIW my foundry of choice is Harling Foundries, near Hastings. Used them many times over the years.
The work is second to none, considered good enough to be selected by Audi when they wanted new engine castings for the Auto Union V16.
They tend to work with traditional patternmakers afaik.

[silverbullet]

I am adding this snippet of info to keep it out there on the interweb! I had to dig around for ages to find this last time, can't find it now but thankfully it's still on my clunky old Latitude 166 that I use for machine program transfer and basic quick geometry calcs.

So, keepin it old skool:

VW Type 1, Type 2, Type 4, flat four and early Porsche 911 4-bolt pattern is...

PCD 296mm (R148mm), top pair plus/minus 42 degrees from 12 o'clock, bottom pair plus/minus 45 degrees from 6 o'clock. All 10mm clearance diameter of course.

The spigot diameter is 282mm diameter.

[tobydog]

I would go down that route if I had the 3d software & modelling skills.
Not sute if a polystyrene maquette pattern would be dimensionally stable on a job like this? I have been told that from such a virtual model an STL(?) data file could then be used to make the vasting patterns directly.
I suppose that a master could also be scanned and turned into a vector data file.
I could in theory make one from a solid blank, but carving one down from a 300 x 400 x 150 alloy slab would take a bit of time and no small amount of machine programming and manual work too.
If I had confidence that I could sell a few wbx/type 1-to-UN1 bellhousings to bug or rail racers then I would wade in and get it patterned. I suspect that its just too much of a niche product.

How do you do your programming? For that sort of size (I guess low quantities) 3D cad / cam might make sense.

First of all, you need to produce an accurate 3D model of your part. 3D cad is incredibly powerful, you need to be using it routinely to enjoy the benefits. If you can work in 2D cad competently then you'r 80% of the way to working in 3D (don't tell anyone how easy it is, you'll loose respect). For a part like this with all the dimensions and geometry available, a mornings cad time would suffice, a day at most to create a 3D model. The measuring and co-ordinating the data would take much the same time.

Next is the producing the 3D cutter paths. Going back at least 20 years, 3D (high speed) machining from 3D models is the way. That's another set of software to master.

It appears very simple but there's a lot more too it....

PS
Started designing injection moulds in 1979, went from manual drafting to autocad in 1986 (version 2.5?)
Now use Inventor for product design - everything in 3D parametrically.

PPS
Mate has a set of boards/motors etc. from an Agie wirer going for free, highly unlikely to be of any use for your sparker though. Your welcome to take them away, he said.