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I've done a bunch of builds like that before. Typically, machine shops specialize in some form of manufacturing type (milling / lathing metal, for example) or
by Scene_Cast2 3y ago
I've done a bunch of builds like that before.
Typically, machine shops specialize in some form of manufacturing type (milling / lathing metal, for example) or specific niche (metal stamping). If your parts require different manufacturing processes, you may potentially need multiple shops to get that done.
I found that Chinese machine shops are going to be both cheaper (about 8x in my experience) and faster lead time than North American shops. The exception will be that if you need something highly specialized (e.g. super tight tolerances), you may find it easier to get it done locally. I'll assume you'll be going with a Chinese place below. For finding Chinese places, I use Alibaba with MOQ set to 1.
Machine shops are always trying to expand and get bigger contracts with bigger customers. They dislike low order quantities and low volumes, and I found that I need to continuously cycle machine shops every couple of years as they move to larger customers. The other thing is that with manufacturing, there's a setup cost (flat cost per batch) plus a per-part cost. At single and low double-digit volumes, setup cost is going to be a lot. Make your part easy to manufacture - easy to clamp, made from readily available stock, use more readily available machining (e.g. 3 axis and not 5 axis, straight lines doable with a manual mill vs CNC), reduce manufacturing steps.
I found that cheaper machine shops (say, 2x cheaper than others) will tend to have a lower ability to understand what I'm trying to get done (will take a lot more & simpler communication) as well as a higher probability of the part being out of spec.
The more proficient you are at knowing what you want (obsessively defined specs and tolerances on everything you can think of) will get you much cheaper results. The less you spec out, the more they need to think about your design and your needs, and that's quite expensive from their side. My process is to have a drawing PDF that I send to 10 manufacturers for quotes, get 5 quotes back and select from those.
- huhtenberg 3y agoThanks, this is helpful. Say, if I have a part like [1], what's the best way to get it done? I'm now leaning towards laser cutting the flat bottom (the geometry allows for that) and then welding the top "clutch" after getting it lathed. Is there a better/cleaner/cheaper way to do it? The part should be metal. [1] https://i.imgur.com/1oqjQ7r.png https://i.imgur.com/1oqjQ7r.png
- Scene_Cast2 3y agoLaser / water / plasma / EDM cutting the bottom sounds quite reasonable. I'm trying to figure out what the application is here. It looks like you want to attach something to a shaft, and trying to use a collet with a set screw. Why not put the set screw in your bottom part? Or perhaps use a shaft key? What kind of forces and what kind of load is this thing taking? But if I had to answer your direct question: spec some screw holes, welding has downsides for what I think the application is (cost, axis alignment).
- huhtenberg 3y agoThe shaft is a part of the existing rotisserie device. The shaft has a square cross-section and it can accept various mountable attachments, e.g. [1] and [2]. They all use collets, so I'm just following their design here. Force-wise - about a pound of load per "arm", give or take, not much really. Re: screw holes - noted, thanks. [1] https://www.amazon.com/GRILLJOB-Stainless-Rotisserie-1-Pair-Hexagon/dp/B08TTKP5V2 https://www.amazon.com/GRILLJOB-Stainless-Rotisserie-1-Pair-... [2] https://www.amazon.com/-/en/25437-R%C3%B6sle-High-Quality-Barbecue-Skewer/dp/B08QJKZWB4 https://www.amazon.com/-/en/25437-R%C3%B6sle-High-Quality-Ba...
- Scene_Cast2 3y agoIn that case, if you make your mounting part a square or rectangular block instead of a cylinder, this way you can avoid the use of a lathe. Or if you spec the outside diameter of your cylinder to be some common size (+/- some loose tolerance), then that would avoid machining the outside (as there's cylindrical metal slock). I also realized that my original suggestion of "set screw on the bottom part" is also probably hard to manufacture.
- huhtenberg 3y agoNoted. Thanks again.