4 ms·

Plenty of comments already cover a lot of this. I'll throw my two recommendations here as well: - OSHCut for sheet metal cutting and bending. - 3DHubs (very

by maicro 3y ago

Plenty of comments already cover a lot of this. I'll throw my two recommendations here as well: - OSHCut for sheet metal cutting and bending. - 3DHubs (very very recently became Protolabs Network) for aluminum machined parts. In general, the task you're now on could be considered "design for manufacture" - you have the basic concept, but now need to figure out how to go from general design to manufactured product. Design for manufacture includes keeping in mind the process/technology that will be used to produce the part: - you can do some amazing things with laser cut and bent metal, but you're limited to a single thickness per component; - lathes are extremely precise and great for making round/concentric items, but the part is limited to rotational symmetry (barring fancy machines and/or moving the part to a mill for further work); - mills are great for all sorts of things but really shine in "2.5d" work - where you have different profiles milled down to different depths, but from a single direction. Mills also can't handle overhangs (without a 5-axis, multiple setups or very special tooling) or features in different directions without multiple setups (which add time/complexity/cost/risk of misalignment of features). For one-off or small run products, you can get away with being very inefficient in the process - starting with a piece of stock and milling 90% of it away for instance. For the one part I saw you post a picture of, that could be done through either SLS or similar metal 3D printing (as someone else said), or one of the "official" ways to make a gear is to cut it with a custom single tooth cutter - where you run a special cutter along the length of the gear, rotate the gear one tooth, and repeat, cutting away the space between the teeth each time. Clickspring on Youtube has a bunch of videos covering the topic. I don't know who could do that as a service though. If you post more pictures / sketches of the project, people here might be able to give better guidance for specific parts and operations.

UncleEntity 3y ago
> ...or one of the "official" ways to make a gear is to cut it with a custom single tooth cutter ... I don't know who could do that as a service though. Any local machine shop? I remember watching a video a while ago where they were talking about how it's better/cheaper/easier to buy a part out of a catalog than custom machine whatever you are needing because chances are really, really high you don't actually need a custom part. IIRC they were talking about bearings but I'd imagine gears would be the same.
- maicro 3y ago
  Ah, caught one of my unspoken assumptions when talking about suppliers - I try to avoid operations that are very custom / very different from their normal operations. In this case, yes, any local machine shop could theoretically get or make the gear cutters, get a piece of the stock the correct diameter (/turn down from larger), mount it in a mill with the stock in a rotary fixture of some sort, then cut the teeth. Again, Clickspring has a bunch of videos on the process, including different ways to make the cutter. All that being said, you'd have to be on very good terms with your local machine shop folks, or be willing to pay for all of that new tooling and setup stuff, to get any random shop to make the part. Going with someone like SDPSI might be better for this specific part, as it's in the realm of what they do. Could also look at starting with "timing pulley stock" - it's basically the part that was shown elsewhere, but without the internal keyway cut. https://www.torontogear.com/bar-stock/ https://www.torontogear.com/bar-stock/ - starting with _that_ - yes, any local machine shop should be able to cut it to length, mount it in a mill and mill out the slot (with a small enough endmill). One more recommendation here, based on what Uncle said about buying stock - and this is a part of design for manufacture in general - is to design around standard parts. Look at SDPSI/Toronto Gear for common gear specs (IIRC "module" is the main property defining a gear and how they will mesh with other gears - so stick with one module size), pick one and change your design to use those off the shelf parts.
huhtenberg 3y ago
Thanks, this is very helpful. You are correct that I'm in the "design for manufacture" phase... and it's somewhat overwhelming. With regards to the specifics, here's one of the parts - https://i.imgur.com/1oqjQ7r.png https://i.imgur.com/1oqjQ7r.png - basically a flat (bottom) piece that can be laser-cut and a cylindrical clutch-like bit with a cutout for a "flat-leaf" bolt. The idea is to pass a rotating axis through the central hole and to affix the part to it to have it rotate with the axis. Needs to be all metal as it's a high-temp (BBQ) setup.
- maicro 3y ago
  Still not sure the general layout of this - is the end goal to have some form of rotisserie that has multiple rods, each of which rotates about their own axis in addition to the primary axis, so that the food is cooked more evenly? If so, be careful about your gear ratios - you don't want the rotations to match up every time, otherwise you won't actually gain anything from the secondary rotation axis (the same side of the food will be rotated down closest to the flame on every rotation). I'd have to do the math / play with it, but off the top of my head I'm thinking as long as the gears aren't the exact same number of teeth you'd had full secondary rotation after [larger number of teeth] rotations. That being said - to make that part, if concentricity isn't _critical_, you could easily split that into two sections. As you said, the bottom flat section would be laser cut (/water jet) out of sheet material; you could add some mounting holes around the central axis, then threaded holes in the rod mounting boss (or through holes for very long bolts and nuts, but that's better for prototyping with limited tapping/etc. capabilities).
  - huhtenberg 3y ago
    > Is the end goal to have some form of rotisserie that has multiple rods, each of which rotates about their own axis in addition to the primary axis, so that the food is cooked more evenly? That's exactly it. Well-deduced. Secondary rods are just skewers. > If so, be careful about your gear ratios. Yep, got that covered. The gear ratio is 16/11.
    - 3y ago

by maicro 3y ago

UncleEntity 3y ago

> ...or one of the "official" ways to make a gear is to cut it with a custom single tooth cutter ... I don't know who could do that as a service though. Any local machine shop? I remember watching a video a while ago where they were talking about how it's better/cheaper/easier to buy a part out of a catalog than custom machine whatever you are needing because chances are really, really high you don't actually need a custom part. IIRC they were talking about bearings but I'd imagine gears would be the same.

maicro 3y ago
Ah, caught one of my unspoken assumptions when talking about suppliers - I try to avoid operations that are very custom / very different from their normal operations. In this case, yes, any local machine shop could theoretically get or make the gear cutters, get a piece of the stock the correct diameter (/turn down from larger), mount it in a mill with the stock in a rotary fixture of some sort, then cut the teeth. Again, Clickspring has a bunch of videos on the process, including different ways to make the cutter. All that being said, you'd have to be on very good terms with your local machine shop folks, or be willing to pay for all of that new tooling and setup stuff, to get any random shop to make the part. Going with someone like SDPSI might be better for this specific part, as it's in the realm of what they do. Could also look at starting with "timing pulley stock" - it's basically the part that was shown elsewhere, but without the internal keyway cut. https://www.torontogear.com/bar-stock/ https://www.torontogear.com/bar-stock/ - starting with _that_ - yes, any local machine shop should be able to cut it to length, mount it in a mill and mill out the slot (with a small enough endmill). One more recommendation here, based on what Uncle said about buying stock - and this is a part of design for manufacture in general - is to design around standard parts. Look at SDPSI/Toronto Gear for common gear specs (IIRC "module" is the main property defining a gear and how they will mesh with other gears - so stick with one module size), pick one and change your design to use those off the shelf parts.

huhtenberg 3y ago

Thanks, this is very helpful. You are correct that I'm in the "design for manufacture" phase... and it's somewhat overwhelming. With regards to the specifics, here's one of the parts - https://i.imgur.com/1oqjQ7r.png https://i.imgur.com/1oqjQ7r.png - basically a flat (bottom) piece that can be laser-cut and a cylindrical clutch-like bit with a cutout for a "flat-leaf" bolt. The idea is to pass a rotating axis through the central hole and to affix the part to it to have it rotate with the axis. Needs to be all metal as it's a high-temp (BBQ) setup.

maicro 3y ago
Still not sure the general layout of this - is the end goal to have some form of rotisserie that has multiple rods, each of which rotates about their own axis in addition to the primary axis, so that the food is cooked more evenly? If so, be careful about your gear ratios - you don't want the rotations to match up every time, otherwise you won't actually gain anything from the secondary rotation axis (the same side of the food will be rotated down closest to the flame on every rotation). I'd have to do the math / play with it, but off the top of my head I'm thinking as long as the gears aren't the exact same number of teeth you'd had full secondary rotation after [larger number of teeth] rotations. That being said - to make that part, if concentricity isn't _critical_, you could easily split that into two sections. As you said, the bottom flat section would be laser cut (/water jet) out of sheet material; you could add some mounting holes around the central axis, then threaded holes in the rod mounting boss (or through holes for very long bolts and nuts, but that's better for prototyping with limited tapping/etc. capabilities).
- huhtenberg 3y ago
  > Is the end goal to have some form of rotisserie that has multiple rods, each of which rotates about their own axis in addition to the primary axis, so that the food is cooked more evenly? That's exactly it. Well-deduced. Secondary rods are just skewers. > If so, be careful about your gear ratios. Yep, got that covered. The gear ratio is 16/11.
  - 3y ago