Which would include the edges around the mounting surface and any other surfaces like that. I will try to look at the factory cover for draft. I've never really looked before but I bet those edges that I think are square to the mounting surface are probably slightly tapered.

3 hours ago, Patcon said:

I will try to look at the factory cover for draft. I've never really looked before but I bet those edges that I think are square to the mounting surface are probably slightly tapered.

The R180 alloy rear covers were manufactured using the pressure die casting process, so there will be some fundamental differences in comparison to any of the casting techniques being discussed here. 

11 minutes ago, HS30-H said:

The R180 alloy rear covers were manufactured using the pressure die casting process, so there will be some fundamental differences in comparison to any of the casting techniques being discussed here. 

Understood, I figured the design would still have relevance because of the need to get either out of a mold.

The $40 seems really low if they're building a hard mold.  Hard to believe.  I'd guess that they could 3D print the part and cast plaster around it.  Then they'd have to worry about draft.

It does seem an interesting place.

https://lancasteronline.com/opinion/editorials/atf-investigation-of-lancaster-county-amish-farmer-highlights-the-importance-of-gun-regulation-editorial/article_b519cf3e-8096-11ec-ae18-b7900627a47f.html

I don't fully understand the process but I'm sending the caster a 3D printed part for them to create the mold. Its tempting to visit the caster's forge but its a 5-hour drive.

I got hung-up on the computer file in your first post and completely misunderstood what you were doing.  Thought you were sending them the computer file only.  I see now.  

Can you post a picture of the part after you "print/manufacture (additively)" it?

There's powdered metal additive manufacturing now.  You end up with a real metal part, direct from a computer file.  Pretty amazing.

 

Looking forward forward to anything and everything you can pass on!!!

I just got the prototype printed. It took ~45 hours and 450 grams of PLA plastic. I test fitted the cover on my diff and there was a clearance issue that I'll need to address in the next iteration.

I'm sending it off today to the guy in PA with a forge for him to offer suggestions. That brings up the question, is an operator of a forge called a forger? 

5 minutes ago, Jeff Berk said:

I'm sending it off today to the guy in PA with a forge for him to offer suggestions. That brings up the question, is an operator of a forge called a forger? 

 

 

 

Yes, Lol

https://www.merriam-webster.com/dictionary/forger

Also, nice work.

Nice work. Looking quickly at the model, I've got a couple questions, etc.

First, the small pilot holes for the mustache bar bolts might be trouble. I think those may be be too small and too fragile of a sand tower and will just snap off when they pull the master out of the sand. I would just make that surface flush, maybe leave a small locating dimple or something, but I'm not sure you're going to have good success casting those pilot holes. And... You're already going to have to drill all the mounting holes around the perimeter, so it's already going to be in the mill. Why not just locate those holes when you do everything else? Why do you need a pilot?

Second, I can't tell from the master part if you've got draft on all the necessary surfaces. I'm assuming the foundry will look into that in detail.

Last, hard to tell just from pics, but it looks like you might have an interference between the oil hole (fill hole?) and the internal cast rib. Maybe the fill plug hole misses that internal rib, maybe not? Can't quite tell.

I whipped up a quick sketch to help explain what I was talking about above:

Also, I'm not too far away from Lancaster, PA. If you do go forward with this, I could possibly be used as boots on the ground locally if necessary.

CO,

Thanks for the review. I agree about the mustache mounting holes.  The fill hole is offset from the internal fin. The Inspect>Section Analysis feature in Fusion 360 was handy for positioning these features. Unfortunately, I didn't spot the Inspect>Draft Analysis option in Fusion until after I printed the part. I noted a few faces that looked troubling in the analysis in my letter that accompanied the part to the forger.  

There's a steep learning curve with Fusion especially if you are not a CAD person.

Unfortunately, it looks like you and the forge are about 6 1/2 hours away.

Jeff