Jim - a big part of why i got a mill was to do my won prototypes. Id have a lathe, but really have no space. I may put a small one underfoot regardless at some point. Yeah, for fun, but i also want to see if some of my ideas are commercially viable. I've also used the mill for random work related things even more than i expected - modifying hinges, cleaning up stock parts, making widgets out of metal instead of plastic that are superior. This particular tool i am designing is commercially unavailable, and i do think there is some market, though not huge. There are other ideas in the pipeline, so a full pricing of this tool is a learning experience i will apply to those other ideas to see if they are viable. None of them may be.
What could I do differently to make it better, faster, cheaper? And maybe most importantly use off-the shelf parts. Sometimes I get pretty creative.
Without a lathe, off the shelf round parts have been my design parameter from the start - and most of them i have made work. I already have redesigned several major parts to be eliminated or altered. Most significantly to utilize online laser cutting services at great costs savings. All the aluminum parts are designed to be made from common sized as much as possible. Stock fasteners, DRO, handles etc. This one screw is the outlier and really needs to be short, with a substantial thread, very little cap height and a specific shoulder size. The large thread size and stubbiness of it seem to make it an oddball. I also always like another set of brain cells on my ideas to see what they come up with for alternatives - since i know no one with the relevant experience collected here, this is one of my last stops before moving on. If i ask here i'm usually past half a dozen major revisions and countless tweaks. Or i am ignorant beyond knowing where to start.
CRES is an artifact of my aerospace career. It stands for Corrosion REsistant Steel. In more common terms, Stainless Steel. You did specify 303SS.
I expect satisfying any "production" quantity requirement will be a "special" custom part, and you will pay dearly for a small quantity (<10,000) or need to buy a barrel full to get the piece price down.
As I stated, "I have a suggestion for improving the prototype producibility". I doubt you will find any "stock sleeve that works".
For six pieces, I would rather shorten an off-the-shelf set screw, make a separate shoulder/head part, and bond them together than make as per your graphic.
A tool called a rotary broach would probably be used to create the 4 mm hex recess you specified. IMO, rotary broaches are not ubiquitous in the hobby community so that may limit the sources for your one-piece design.
All helfpful. Next time i'll know. Im aware of the scale cost per part issue. I was hoping 100 count batches would be enough to reduce per screw cost to the point of viability. As of yet i have no cost numbers so i don't actually know; getting the actual cost numbers is just as important as getting the part. If 10k units are required to make these screws cost effective trying to make and sell this tool doesn't work. This will be a $1-3000 tool i expect so four screws that are $10 each in a final product isn't a deal breatker for me. but $50 each probably is.
I saw a video of a rotary broach and it seemed a little like voodoo to me. Super cool. Never know who has one......
I do like your barrel sleeve/set screw idea. Seems i'm always after a custom or hard to find shoulder bolt and that idea opens up lots of options!
It was suggested on this forum (for a different set of parts i posted for suggestions on) that i post here to see if anyone wanted to bid. I still may post those parts once i finalize some tweaks. I really appreciate the knowledge shared here, so id be happy to have a HM member make me some parts and get paid. Thus far no one is interested in pricing these screws, so i doubt there willb be interest in more complex parts.
