Does an LSD need better cooling?

[Captain Obvious]

Gordonville, PA.  In the triangle between Intercourse, Paradise, and Bird-in-Hand.

I'm a little over an hour away. 

And while I've never designed a casting myself, I've sat with the mechanical designers who did. And I've been in the review seat enough times to make myself dangerous. Like usual.    Several products I've been involved with had castings, but never sand. I've been involved with hard tooling die castings and investment (lost wax) a number of times.

You really want to pucker... Tell the bean counters that you're ready to cut the check to carve a six figure hard tooling mold. That'll make you review stuff beforehand!

[Zed Head]

Did you reproduce the original cover dimensions and just add fins to it?  I've not really examined a diff cover, let alone an R180's.

The one you show looks a lot different than your modified version in post #16.  What happened?

The factory covers have quite a bit of internal bracing.  Here's a Subaru's.

[HS30-H]

On 2/25/2024 at 9:46 PM, HS30-H said:

Rear covers with extra oil capacity and cooling fins are all well and good, but positive circulation, cooling and the directed spray of cooled oil are going to be more effective.

:polite cough:

[Patcon]

4 hours ago, Captain Obvious said:

Gordonville, PA.  In the triangle between Intercourse, Paradise, and Bird-in-Hand.

Thats an interesting collection of names you've got there! 😉

[Jeff Berk]

3 hours ago, Zed Head said:

Did you reproduce the original cover dimensions and just add fins to it?  I've not really examined a diff cover, let alone an R180's.

The one you show looks a lot different than your modified version in post #16.  What happened?

I originally tried to use a 3D scan but that got to difficult using the available software so I started from scratch.

This is likely my 3rd iteration of the part. The problem with the version in Post #16 was the expanded reservoir did not have enough draft and the only way to add it was to redo much of the reservoir. 

The internal bracing was mostly eliminated because I felt the one I was modeling seemed to be thick enough. The internal fins were intended to provide better heat transfer and also some internal support.

I was considering adding some internal channeling in the next iteration along with suggestions offered by the forger.

Edited March 6 by Jeff Berk

[Jeff Berk]

I just got a call from Emmanuel at Cattail Forge and his only suggestions based on the 3D print I sent him were to add draft to the cooling fins along the bottom and to create the holes for the mounting studs using a template post casting. He also said that I should assume 1.3% shrinkage (there's that image again). I confirmed with him that labor would be about $35 and the aluminum was $3 per pound. His next aluminum forging will be in about 4 weeks.

[Captain Obvious]

20 hours ago, Jeff Berk said:

his only suggestions based on the 3D print I sent him were to add draft to the cooling fins along the bottom and to create the holes for the mounting studs using a template post casting.

Yeah, that draft on the fins is what I was talking about when I said I couldn't tell if there was draft in all the necessary locations. I whipped another quick pic to show ehat I meant. Here's what I was talking about:

 

And I'm still astounded about the cost. That's fantastic for a one-off. Makes me think there are things I could have cast! Haha!

[grannyknot]

On 3/13/2024 at 1:31 PM, Jeff Berk said:

I just got a call from Emmanuel at Cattail Forge and his only suggestions based on the 3D print I sent him were to add draft to the cooling fins along the bottom and to create the holes for the mounting studs using a template post casting. He also said that I should assume 1.3% shrinkage (there's that image again). I confirmed with him that labor would be about $35 and the aluminum was $3 per pound. His next aluminum forging will be in about 4 weeks.

What?  That's like free. Maybe you should start a group buy.

[Jeff Berk]

CO,

Thanks for showing that. I think I have it fixed now. I used the drift feature in 360 Fusion to  the angles until they changed from red. I'm considering adding a channel to aid in the flow of fluid that's splashed up by the ring gear. 

Grannyknot,

You mean a group buy so we can get this part even cheaper? Lets wait until at least we see if this part works. Also, keep in mind that (1) a lot of post-cast work is necessary, and (2) I don't know what I'm doing. 

Jeff

[Captain Obvious]

Glad to help. Draft on the fins looks good. Remember... Anything perpendicular to the mold split line should have some draft.

Hard to tell from just a pic, but are these other surfaces OK?

And they may be shallow enough to not be a problem, but what about the inside edges of your counterbore for your mounting holes around the perimeter? Is there draft on those?

Edited March 15 by Captain Obvious

[Jeff Berk]

CO,

Emmanuel didn't seem too concerned about the areas you marked so I'm assuming draft is not too important if the depth of that portion of the mold is not too great. I'm also not too competent in using Fusion 360 so adding draft in some areas could take me hours, if not days to figure out. In some cases, I've had to scrap the model and start from scratch.

I'm currently struggling with modeling a channel to promote fluid circulation from the spinning ring gear. What is shown in this version is actually a model of the cavity. The solid portion of the channel will be covering it and then I'll change the channel part to a "cut". I'm sure the shell command would work better but I'm not too proficient in its application. 

Time is running out because Emmanuel only does aluminum castings every 3 to 4 months. If anyone has a suggestion, please speak up. 

Jeff

[Captain Obvious]

Yeah, I was thinking that for shorter and more stable (wider) surfaces, the draft shouldn't be as important. Think about it this way... As the master sample is being pulled out of the sand, those surfaces will slide (scrape) against the sand. But if they are short, and if there isn't a thin delicate section that needs to be preserved, it's not as important. That's why the cooling fins needed draft, but those other shorter stout walls might not.

About your channel, you could just add the extra metal on the outside now and take care of the internal features on the mill. In other words, lay down enough metal now in certain areas that will allow you to remove it mechanically later. If you're in a time crunch, that could be a way out.

I've not messed with Fusion, but I've spend some time in a couple other CAD packages. and I understand the unfortunate need to completely scrap what you're working on and starting over because the tool can't do what you really want it to.

Hope you get what you need. This is really a neat project!