1/12 Scale Cat D11 Bulldozer project

[RB211]

Here's the start of the official thread to the Cat D11 project. I decided to start off this project with the design and engineering of the drive sprocket and track chain. It appears in 1/12 scale, the drive sprocket scales perfectly to 1/2" pitch, which makes it compatible at least in spacing with a #40 roller chain. I personally am not going to use #40 roller chain because the real track links scale out perfectly to 1" pitch. So I am scratching my head, wondering why the tell the sprocket clearly scales to 1/2" pitch, but the track links are double that? Well, I had a EUREKA moment when I realized the real drive sprocket has an ODD number of teeth. Pure brilliance, if my line of thinking is correct, the tracks would have to go through two complete travel cycles for each tooth of the drive sprocket to complete 1 cycle. So it looks like the link chain skips a tooth which allows the 1" pitch to work on a .5" pitch sprocket.

[RB211]

#40 test fit into the canvas, courtesy of Gearotic Motion for generating the DXF. Skipping one link pin underscores why you never see these things with tight chain links. Needs some wiggle room.

[rebelrodder]

Subbed.

Interested to see where this goes!

[Hawkeye]

Would #2040 chain (#40 double pitch) work for you?

https://www.usarollerchain.com/C2040...ller-chain.htm

This 23 tooth sprocket is 3.70” pitch Dia.

https://www.usarollerchain.com/2040B23-Double-Pitch-Sprocket-p/2040b23-sprocket.htm

[RB211]

Would #2040 chain (#40 double pitch) work for you?

https://www.usarollerchain.com/C2040...ller-chain.htm

This 23 tooth sprocket is 3.70” pitch Dia.

https://www.usarollerchain.com/2040B...3-sprocket.htm

Possibly, I am making it compatible, at least in pitch and roller diameter so others may easily use #40 chain. I am designing my own links that resemble the real thing but greatly simplified.

[RB211]

The real track links look to be forgings, and unique left and right links. I had to take liberties, made my links universal, so they can be flipped around for left or right, and are 1.5" long, 5/8 deep, 3/8th wide. The pitch is 1" which skips a tooth on a #40 sprocket, but the roller diameters, or in this case, the link pins, are 5/16" which is the same as #40. Another difference however is that my links will be 3/8th apart, instead of 5/16.

[RB211]

Further refining of the links, I imagine I'll need to give a bit more clearance on the links for rotation. I have to start packing my bags and reposition for my next flight. When I get to a point of some maturity of the design, I'll upload the native Fusion360 files to Github so everyone will have free reign on redesigning any part they want.

[SVS]

Your EUREKA insight is correct. I’ve heard it called a “hunting tooth” and even and extended wear IS the purpose.

[Willy]

I salute you sir for even considering a project of such daunting proportions and complexity.
You've definitely got your work cut out for you, but then that's what a project like this for, testing your skills.
Like the old saying goes, if it was easy everybody would be doing it.

Just the research and information gathering for this project must be mind boggling. You're going to be on a first name basis with everybody at the local Caterpillar dealership before this is done. Speaking of which, I'd bet they too would be keenly interested in this project, perhaps to the point of wanting it on display at some point down the road once they see how it has turned out. You may even be able to do some bartering with them in exchange for info once they see how serious you are in doing this project justice.

Good luck with biting off a whole lot more than I could chew. I wish you well and will be following your progress, although I think we all know that this will take time, time that I know can be scarce when you've already got a full plate.

[Cuttings]

Wow, quite a challenge. I spent a lifetime working on the real thing up the D10 size. There was no D11 when I packed it in. This is definitely one thread I will be watching with great interest.

[Mcgyver]

Big project, take lots of pics.

When I see stuff like this completed, I always wonder how they came up with the drawings? You'd almost need access to a full size one to photograph and measure. That's what the better model engineering guys do. That wonder leads me to wonder how the plastic kit manufacturers do it, how they create what seems like very prototypical models. With military items there are various published almost GA drawings, but how do they create the other things; cars, trucks, equipment etc? Then I wonder if would a good quality plastic kit would suffice for the prototype, something to do take offs and create drawings from?

[RB211]

Big project, take lots of pics.

When I see stuff like this completed, I always wonder how they came up with the drawings? You'd almost need access to a full size one to photograph and measure. That's what the better model engineering guys do. That wonder leads me to wonder how the plastic kit manufacturers do it, how they create what seems like very prototypical models. With military items there are various published almost GA drawings, but how do they create the other things; cars, trucks, equipment etc? Then I wonder if would a good quality plastic kit would suffice for the prototype, something to do take offs and create drawings from?

Some artistic leeway is needed but scaling off CAT’s own 3views seems to work alright, 1/12 gives nice round numbers. Using the 3views as a canvas, scaled is pretty powerful. I’ve never touched a D11, let alone seen one in person. There is such a thing as too scaled, where small details get in the way of what makes logical sense. Not everything scales down. Now the GE44 ton locomotive in 1/8 that I’m also doing, but on the back burner, I actually went to a museum with a tape measure and paper and got all the measurements. I’d gladly do the same here if I could.

[Noitoen]

For the tracks you could try 3d printed stainless steel.

[Dan Dubeau]

This will be a fun one to follow along. Looking forward to seeing it come together.

One of the big project I want to accomplish in my life is a 1/2-1/3 scale model of a Honda rc166 gp bike. It's one of the driving factors behind me having a home shop, and all the tools and skills I've accumulated along the way that will be required to build it. One day......

For reference pics, I think I've got every pic and vid of the bike saved on my computer. I also bought the model kit, and periodically check the internet for this really detailed, but all Japanese model makers book on the bike. It shows so many detailed pics from all angles, and it's hard to come by. This will be a project for when the kids move out, and I've got a lot more free time on my hands. Well, I hope that's how the future works out lol. .

I think model makers need to take some liberties here and there based on practicality and functionality. Some details just aren't practical to replicate, and really don't matter all that much. But, I'm always awestruck at some of the really finely detail models in tiny scale that people produce. To be honest I don't really have a lot of interest in building model steam engines and other types, but I love watching the videos, and seeing the pictures. I can appreciate all the hard and intricate work involved in producing them.

It's different things and projects that drive us all, but there is a common tie that binds.

[RB211]

This will be a fun one to follow along. Looking forward to seeing it come together.

One of the big project I want to accomplish in my life is a 1/2-1/3 scale model of a Honda rc166 gp bike. It's one of the driving factors behind me having a home shop, and all the tools and skills I've accumulated along the way that will be required to build it. One day......

For reference pics, I think I've got every pic and vid of the bike saved on my computer. I also bought the model kit, and periodically check the internet for this really detailed, but all Japanese model makers book on the bike. It shows so many detailed pics from all angles, and it's hard to come by. This will be a project for when the kids move out, and I've got a lot more free time on my hands. Well, I hope that's how the future works out lol. .

I think model makers need to take some liberties here and there based on practicality and functionality. Some details just aren't practical to replicate, and really don't matter all that much. But, I'm always awestruck at some of the really finely detail models in tiny scale that people produce. To be honest I don't really have a lot of interest in building model steam engines and other types, but I love watching the videos, and seeing the pictures. I can appreciate all the hard and intricate work involved in producing them.

It's different things and projects that drive us all, but there is a common tie that binds.

Well, I’d say 10 times more people have shown interest in this bulldozer than the diesel locomotive. Everyone loves Earth moving equipment apparently, especially R/C.