pic: Introducing BarBox: My First Attempt at Gearbox Design

[bardd]

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[jman4747]

I like it so far especially for a first gearbox I just wanted to add that you could aquire CAD files for vertualy any standard gear at rushgears.com and a good practice also is to go to some place like mc master carr's web site, VEX pro, or granger find stock gears to base your designs off of. Also I had a question about what your reduction was and how heavy this box is?

[bardd]

Originally Posted by jman4747

I like it so far especially for a first gearbox I just wanted to add that you could aquire CAD files for vertualy any standard gear at rushgears.com and a good practice also is to go to some place like mc master carr's web site, VEX pro, or granger find stock gears to base your designs off of. Also I had a question about what your reduction was and how heavy this box is?

Thanks for the tip, I'll look into it when I get the time for alterations. The gearbox is 2.7lbs, I'll try and make it lighter.

[cbale2000]

Originally Posted by bardd

The gearbox is 2.7lbs, I'll try and make it lighter.

Trading out the middle portion of the gearbox frame for a polycarbonate version might save a bit of weight.

Honestly I never understood why so many gearboxes (like the toughbox) use metal enclosures between the plates considering its probably the most structurally insignificant part of the whole thing.

[HammadB]

While I don't know which gears you're using specifically and thus their bore sizes, maybe try a smaller gear size on the second stage. You could obtain the same reduction using AM 14 and 28 tooths etc and make the box more compact and a tad lighter.

Additionally replacing the enclosure with some standoffs would retain structure but save considerable weight.

[magnets]

I'd recommend replacing the metal enclosure with some standoffs, then if you need to, put thin lexan shields around it. Also, the CIM motor shaft isn't supported on both ends, so you don't really need the outer plate to be that big, and you could make it about half size. Also, you could probably get away with making some holes in both plates, depending on their thickness.

I can't tell from the image, but it looks like the CIM is held on by two screws. It's a better idea to make the top of the CIM flush with the plate, and cut a 0.75" hole in the plate for the top of the CIM to sit in.

[KrazyCarl92]

From an interchangeable part standpoint, why not have the hole for the CIM shaft/boss in the side plate be on both side plates? This way, you can make 2 of the same part per gearbox and have more flexibility if you need to replace anything.

[Chris is me]

How are you making the metal piece in between the plates? Machining all of that from solid seems like way overkill for what a couple of standoffs could do.

If you want an enclosed design easily, you could take a page from the Toughbox Nano and build this gearbox out of tube stock.

[bardd]

Originally Posted by HammadB

While I don't know which gears you're using specifically and thus their bore sizes, maybe try a smaller gear size on the second stage. You could obtain the same reduction using AM 14 and 28 tooths etc and make the box more compact and a tad lighter.

I couldn't find a gear combination that can use smaller gears without altering the ratio too much. Unfortunately 14 to 28 can't work, both because in that case the output shaft will intersect the 50T gear on the first stage, and because there's no 28T with 0.5" hex bore. There is a 29T one, but still too small.

Originally Posted by magnets

I can't tell from the image, but it looks like the CIM is held on by two screws. It's a better idea to make the top of the CIM flush with the plate, and cut a 0.75" hole in the plate for the top of the CIM to sit in.

The hole exists. You can't see it in the picture though.

Originally Posted by KrazyCarl92

From an interchangeable part standpoint, why not have the hole for the CIM shaft/boss in the side plate be on both side plates? This way, you can make 2 of the same part per gearbox and have more flexibility if you need to replace anything.

The output shaft sits on two different bearing sizes (0.875" in the back and 1.125" in the front), so the front and back plates have different holes for the bearings too.



Most of you recommended standoffs, I'm going to try that. I'll try and make holes in the plates too. Christ- ehh... Open profile version will be coming early.

[bardd]

Made some changes, introducing BarBox 2.0:

New weight: 1.75lbs



Thanks for the tips everyone!

[Redo91]

One other thing to think about when designing your gearbox is how you would mount it.

[bardd]

Originally Posted by Redo91

One other thing to think about when designing your gearbox is how you would mount it.

It's a bit similar to how you'll mount a toughbox. You attach the bottom four screws to a channel with fitting holes, and have the shaft go through another hole in the channel. There are other ways to do it but that's the way I wanted to mount the gearbox so that's what I designed for.

[Redo91]

What machining capabilities do you have available to make your parts?

[bardd]

Originally Posted by Redo91

What machining capabilities do you have available to make your parts?

I don't, but this is not supposed to be manufactured, it's just for practice and fun.

[cadandcookies]

I'm liking your progress so far! It reminds me a lot of one of West Coast Products' gearboxes.

Small nitpicky thing on your latest version-- the edges are looking rather sharp. Whether you're planning on manufacturing it or not, it's best practice to design for manufacture, and nearly any manufacturing method that you would use in competitive robotics is going to need to have some sort of radius where you're cutting. I personally design most of my practice stuff to be manufactured with a 1/2" endmill because our primary machining sponsor uses CNC mills. Also for sharing screenshots, you might want to use shading with edges (most CAD programs have different rendering modes-- wireframe, shading, shading with edges, etc), which would make it a bit easier to pick out the finer points of your design.

Just something to consider for your designs.
(Also, I love the color scheme-- red and black looks very snappy!)