Mold construction question!!

[stoneyberk]

Hey guys...

I have a question regarding mold material to build a mold, I've been thinking about building a mold on my sheet metal type rear end.. I want to build one that i can pour aluminum into as an casting so to speak... I know a few of you guys have built your own molds to pour the quick change rear end and was wondering what you built them from... I don't want to cut any corners here either... I want to build a mold that's going to hold up for some time...

Any input is greatly appreciated!!

Stoney

[Mike Casey]

The QC molds are Investment Cast style. The molds can be made of high temp epoxy backed with a ridged material like poly or aluminum. Or you can make a aluminum mold. The most cost effective way though would be sand casting and you may be able to get away with it on that rear. Plus if you find a good foundry. They can do it without a tool. They can place your original in the sand and make a handfull that way if they are good. You will need to fill some of the holes and lips.

[stoneyberk]

Hmmm... I'm quite sure i follow you on the filling of some of the holes and lips... I would like to make it a two piece rear end.. The housing would have all the necessary brackets and mounting tabs... And the face plate would have the third member built into it... If i were to do this way then all i would need to do is build a lip on the inside of the housing to bolt the face plate to then...

Will i need to make a male & female mold mike? I know i sound a bit dumb here...lol.. I mean i would think i would need both... If not i would think the inside of the housing / third member would just fill up with aluminum.. Correct??

As for the investment style goes... Can you by chance post some links to where i can purchase the needed materials?

Thanks
Stoney

[Mike Casey]

I will take some pics of different style molds tonight so you can see.

[stoneyberk]

O.K. Mike that will help... I've done a little research on it on YouTube and ran across some interesting videos on it... It's quite a process i take it... I could always just machine them as well but that would be to time consuming for me...

http://www.youtube.com/watch?v=BX8w-GUPz1w
http://www.youtube.com/watch?v=NKXj5Ng3 ... re=related

Thanks again
Stoney

[c103110]

I'd make a steel jig and TIG weld the axle tubes and sheet metal housing out of 6000 series aluminum. It would be light and look fantastic polished or anodized. The center section could be machined from billet. Not sure why you want to cast it.

But if you still do...

If you want to do some short-run castings out of aluminum and don't want to go through the expense of hard tooling, you can make Stereolithography (SLA) patterns using a quick cast build style (photocured resin). You'll need a solid CAD model of the part. You can write out a .STL file from most CAD programs. The quick cast pattern is used in place of a wax pattern and is fired to create the investment cavity. I've made low-volume, prototype castings many times with this method. There are many SLA service providers around who can build patterns with the quick cast build style, and smaller casting houses can work with quick cast patterns.

Look up Stereolithography Providers - Quick Cast for info.

I can add some photos of a pattern and cast inconnel part.

[c103110]

Pictures of an investment cast, specialty wrench I made to solve a production problem we had. I received quotes of six months and 100K from the name-brand tooling manufacturers. When you only need a half-dozen parts, this method works pretty well.

I made a CAD model of the assembled parts and wrench in AUTOCAD; added a positive scale factor to the model of the wrench as cast INCONNEL shrinks when cooled; wrote out an .STL file; ported it over to the SLA machine; printed out a dozen quick cast patterns; brought them to the casting supplier; and in a week, I had my wrenches.

[stoneyberk]

Thanks!

I'll have to look into this... i run SolidWorks Premium from time to time..As for the rear end... There is no center section in my design... It's a sheet metal housing and the third member... Here are a few shots if it in case you haven't seen it....It's not finished in any of these shots but it kinda gives you an idea on what it looks like..

I would like to make castings of it because i may eventually sell them...I don't have alot of free time these days so machining them is pretty much out of the question... Weight is a huge factor here... As it is now my rear end weighs around 10 lbs... Although it is nearly done i do still need to finish up all the required welding... I'm thinking it will weigh around 12 lbs once done... I'm willing to bet a complete aluminum casting would weigh around 2 lbs top's...

[fuzzymuff]

Hi Stoney.
If you sent me the dimensions of the diff housing and brackets I could build you some housings in sheet steel.
The housing would be fully welded and all the brackets would be silver soldered on.They could be chromed or powder coated whatever you wanted...I also have a supply of gears that would fit.
All the brackets would be water jet cut .And I would install axle tubes with bearing housings and brake caliper brackets.

Let me know if you are interested.
Graham

[stoneyberk]

You evidently over looks the point here partner... I'm not looking for someone to weld these up for me... As i can/did do this myself... I'm looking into the making of a mold to pour them in cast... I have been doing alot of research on this and may very well produce these in cast form... The only reason i wouldn't sell them as it is built now is because it's a very complicated design to weld correctly..And to be quite honest to darn time consuming to weld.. If i do decide to produce these in cast form i may even offer them in various cast types...

Such as:::

Aluminum
Ductile iron
Gray iron
Red Brass
White Brass
Yellow Brass
Tin Bronze
Manganese Bronze
Aluminum Bronze
Nickle Silver

But don't quote me on this guys... I'm a lookin into it!!!

[c103110]

The scale shouldn't matter. If making a fabricated rear end by investment casting makes sense at quarter scale, why don't the full-scale manufacturers do it (Comp. Eng., etc...)? Because, welded sheet metal and tubes are the best option for this particular application.

I agree, the design of the quick-change rear ends lend itself to casting.

What's needed for this design of rear end housing is a jig, some 6000 series sheet and tubing, and a waterjet machine (or shear). A good TIG welder could turn out three or more rear end housings a day...

Casting a whole rear end may become a costly nightmare...

[c103110]

I plan on making a sheet metal rear end in aluminum sheet and tube for my Pro Stock car. The quick change is nice; however, I've never seen a quick change in a real NHRA Pro Stock car. TBC.

[Mike Casey]

QC rears dont belong in half the 1/4 scales they are in! Sprints and hotrods are cool with them. Anything other then those two need a regular rear.

[Mike Casey]

c103110, that is awesome about the one off stuff like that without the molds. Thanks for telling us about it. I asked my foundry about it and they said they can do those, but one part costs about $200!!! Still, wicked cool.

Here is a picture of the skellenger investment cast tooling. Its a bit complicated when you really look at it. Tons of work here.

[Mike Casey]

Now, here is a sand cast patern. This is the PBS rear. Very basic and sand casting is quite crude.