Driver Casting Repro

[KarlKobel]

Rub the pattern with graphite.
That made a big difference even with 3D printed patterns.

Karl

[Harold_V]

yes this will be gray iron.

Have you considered ductile instead? Far more reliable.

H

Reliable? How does gray iron fail?

David

Gray iron is prone to cracking, very unlike ductile. It is also much lower in tensile strength, depending on the alloys in question. All properties being equal, ductile is stronger. That's due to the fact that the free carbon (graphite) in ductile being tiny spheres instead of flakes. The result of using ductile is that it can be readily welded, it has greater tensile strength and is ****ductile****, very unlike gray iron.

Interestingly, chemically they're almost identical. Gray iron is inoculated in order for ductile to be poured. The one caveat is that the sulfur content must be low, otherwise it interferes with the inoculation process. With modern melting techniques (induction melting instead of cupola melting), it shouldn't be much of an issue to the foundry.

Where ductile really shines is that flanges are not easily broken. Ductile wheels have the potential to withstand a lot more punishment in a derailment. All in all, a better choice. They machine almost identically, although ductile yields chips that tend to hold together, but are readily broken, while gray iron tends to yield crumbles. Both are "dusty" (therefore dirty) to machine.

H

[jlakes85]

Dave,

I watched your video on the driver pattern a few times before I started prepping everything..and then a few times more when I was mixing the stuff. Top notch as always.

-jlakes85

[Pipescs]

Are you using Kwick Kast parting wax?

[jlakes85]

Charlie,

I just had my first quart delivered today..no more screwing with furniture polish..I learned my lesson

[optigman]

Challenge 95 release from BJB Enterprises in Tustin, Ca works as it's supposed to in a Patternshop environment. Must dry completely before any plastic is poured against it. Lacquer sanding sealer is far better than paint as a sealer for the wood or plastic pattern. Proper draft and smoothness of pattern is critical.

[RONALD]

I did some drivers by a different method, I made three Match Plates.

I then used CO2 sand to make the mold, and being hardened it was easy to bring the molds to that iron foundry mentioned below:

http://www.chaski.org/homemachinist/vie ... 7&start=12

[jlakes85]

Hi All,

Here is the end result. Not too bad I don't think. I'm letting this park on the band saw table overnight to set. Thanks for all of the pointers and suggestions. Next up are the cylinders.

-jlakes85

[Trainman4602]

What is all the roughness from. It should be smooth as a babys butt

[Trainman4602]

This is picture of a mold for the 0-4-0 driver and also the match plate

[John Hasler]

This is interesting:

http://www.ijirse.com/wp-content/upload ... /1160B.pdf

They are 3D printing the moulds directly with sodium silicate/sand using a process similar to the laser sintering process but with a CO2 jet instead of a laser. No pattern at all.

[jlakes85]

Hi Dave,

The white stuff is plasticine that was used in a couple of questionable areas. I still have to remove that and give the pattern a once over before mounting