Friday, July 17, 2020

Casting Process Successful!

I received a nice shipment from Curto containing 3 full sets of usable castings!  It is usually pretty cool when parts for a client's project come in but when the project is your own baby, the excitement is greatly magnified.  Imagine seeing a new dirt bike in front of a Christmas tree and you are in the right ballpark.

The combination of gating assistance from Curto and the 3D printed sand molds from Humtown resulted in parts with crisply defined features and just a bit of surface roughness, a traditional characteristic of the 3D sand printing process.  Though a bit rough, the finish was very consistent.  Think of it as a mini heatsink!

Both the pour and the post processing of the parts by Curto was excellent.  The T6 heat treat left no appreciable distortion at the gasket surface, and if I did not do the mold CAD myself, would not be able to tell where the feeders were attached.

 The high damping properties of magnesium and the internal and external ribs on the oil sump and left side cover (along with the hydrodynamic crank/counterbalance bearing system) will help keep transmission of internal mechanical engine sounds to a minimum and allow the intake howl and the exhaust growl to dominate the aural frequencies.
The clutch/generator cover's deep cylindrical shapes are themselves resistant to vibrational excitation, so less ribbing is needed here.  Internal features on the generator mount allow use of an unmodified Panigale stator with its wiring, crankcase seal, and waterproof connector.  It is a minor detail, but the stator is an electrical part subject to failure, so it is nice to be able to drop in an off-the-shelf replacement part.  The same goes for the voltage regulator, which is also an OEM part and easily accessible.

Having not worked directly with sand cast AZ-91-T6 Magnesium before,  I requested a piece of the runner/feeder system also be heat treated and sent along with the parts.  I will use this piece to do some machining speeds/feeds optimization, but more importantly to do some pull-out testing for the few M6 threaded inserts and for the oil drain plug in the oil sump and the M5 inserts for the clutch cover.  Magnesium is quite a soft material so I would rather not depend on threads created in it.  I will test both E-Z Loc and TimeSert inserts to see which works best.  TimeSerts are very low profile so maybe use them first and if there is a failure, there will still be room for an E-Z Loc.

Due to casting being a slightly unpredictable process, I was not sure if all the parts would be fully filled and usable but it turns out my fears were unfounded.  Curto's design assistance was top notch and with this completely successful pour, I now have 3 sets of castings.  They mesh up nicely with the 3 sets of billet blocks for crankcases, and enough 4340 VM steel for 3 sets of crank and counterbalance shafts.  A bit of ebay shopping later and it is possible to have 3 engines, and then a bit further, 3 bikes!

One last, unrelated item: last week I made a significant change to my original plan of using a hacked OEM Panigale ECU to do the engine and chassis management.  This did not go as planned and required some regrouping and rethinking, and in a week or so I will be able to go into some more detail on the new solution.

All right, time to stop typing and start doing!