What is the material that they make fin boxes and leash plugs out of? I need to make something similiar and I would like to know where to start. Can you pour the stuff into a mold? Where would I buy some?
try using chopped fibers and resin
Hi Dan,
Typically, it’s injection-molded thermosetting plastic in 'em. PVC, polyethylene, Lexan, what have ya. Lots of different types used in molding , as needed by the application, including nylons and similar. It’s supplied in pellets that get fed into the injection molding machine under pressure ( often an auger type screw feed) , such high pressure in fact that the stuff liquifies and flows into the mold.
While that’s a great way of making said parts, by the tens of thousands, it’s not practical for one-of-a-kind stuff. For starters, you need to machine a multi-piece mold or molds ( usually out of solid blocks of thick aluminum - the pressures in those things are damned high besides which the aluminum stays cooler and is easier to machine than steels), buy (or rent time on) the injection molding machine ( and they are pricy as well, make full-on shaping machines look like economy items ) , etc.
This also explains why nobody has made a whole lot of old-style WAVE-Set fins or some of those other extinct fin base fins. You’re looking at around $10-20,000 US up front to make the fairly simple mold and do a ‘small production run’ of a few thousand. While you could maybe get $50 each for the fins, nobody so far has wanted to come up with the money up front.
Now, that possibility having gone over the side, I’ve had some luck making stuff ( like WAVE-Set base reproduction fins) out of that plastic cutting board material - probably a polyethylene. It saws, files, wood-rasps and sands okay, though with power tools you want to use sharp blades and bits along with low speeds 'cos otherwise the stuff melts and re-freezes behind the tool, not unlike what styrene foam will do if you go at it too aggressively. You can get it quite thick, upwards of 1" ( 25mm ) , from restaurant supply houses and the like.
That help any?
doc…
Hey Dan,
I lost the link a while ago but there used to be a website that let you design a one off project with their software and they would manufacture it for you. it was really cool - EDesign or something like that - with various processes available for making what you want. I’ll look around for it.[url]
have you ever heard of a 3-d printer???
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What is the material that they make fin boxes and leash plugs out of? I need to make something similiar and I would like to know where to start. Can you pour the stuff into a mold? Where would I buy some?
Molded becomes cost effective in the 200-500 items per for things like finboxes. Doc is WAY off on his price estimates, you can do good molding in America for under $1000, and much cheaper than that in Asia.
Doc mentioned lots of plastics, mostly it is delrin, polycarbonate, nylon, or glass filled versions of the same (Red-X is however high density glass filled polyurethane).
PVC and polypro are cheap and soft, not worth your time unless you have a very low strength part.
for prototypes stick to the stiff but affordable machineable plastics like delrin, nylon, and polycarbonate. Its cool to do them in lexan, you can have a clear part then…don’t use glass filled, they are a pain to machine (but easy to use molded).
hth
Fins Unlimited, Future, O’fishl, Lokbox are injection molded Lexan I believe.
docs pretty much got it, i used to work in an injection molding plant…what your looking at is bassically a plastic (nylon)(polyester)(etc) mixed with glass…comes in pellets, melted under very high temps, and injected into a mold that is in a press that holds it under tens of thousands pounds of pressure …or else the process wont go right…
lets just say unless you have about 200,000.00 to get the process started its probally easier to pay the .97 for the leash plug…
this is not to say you cant make your own boxes and plugs but i dont think you’ll be doing it by injection molding…
There is also the MfgQuote service:
I have had good experience getting very small runs of machined metal parts made, surprisingly cheaply. As Doc notes, plastics are different, and injection molding has typically been limited to mass production quantities (although that may not be an intrinsic limitation - see next item) but it doesn’t cost anything to place an RFQ.
I cannot speak to the quality of information in the following book from personal experience. I can, however, tell you that the late Dave Gingery, and now his son Vince, have been successfully showing people how to duplicate sophisticated industrial processes in hobby or small commercial-scale operations for a variety of materials and methods for a very long time (the other Lindsay’s Technical Book listings may be worth a browse as well):
http://www.lindsaybks.com/…bk/inject/index.html
-Samiam
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I cannot speak to the quality of information in the following book from personal experience. I can, however, tell you that the late Dave Gingery, and now his son Vince, have been successfully showing people how to duplicate sophisticated industrial processes in hobby or small commercial-scale operations for a variety of materials and methods for a very long time (the other Lindsay’s Technical Book listings may be worth a browse as well):
http://www.lindsaybks.com/…bk/inject/index.html
-Samiam
Well I will be damned…That is NEAT!
And then there’s the rest of the stuff there, up to and including vaccum-forming plastic, making your own melting crucibles for casting metals, etc…
I have heard of the Gingery lathes and such, kinda figured ‘that’s nice, but I can find old South Bends for a couple hundred bucks’… but this opens up all kinds of possibilities.
Thanks, Sam…
doc…
Dan, are you planning to make a couple/few parts?
If so, then forget about all the injection molded gobbledygook. That tech is for making thousands of parts very fast and very cheaply.
Any liquid resin that pours and hardens can be used to make low volume parts…polyesters, vinylesters, epoxies, urethanes, etc etc. But as mentioned, adding chopped glass fibers (or glass fabric) will improve the physicals…
concrete has great compression properties but poor tensile…so the aggregates and steel rebar is the “glass fibers” if you will.
I believe fiberglasssupply.com has different types of resins available, including a tooling resin…dont know any specifics.
Btw, Stereolithography has been around for well over a decade…forget about that too unless you like to throw away your money.
Hmm…where’s Tom these days…talk about MIA!
Earth to TOM!!!
check out last years little molding project…just mix and pour
Thanks everybody for all the advice! That book looks very intersting. I’m thinking that it might be best to try and fit some existing product to my needs.
I’m around. I’ve just been busy trying to keep up with projects. And, sailing on big fast boats. A couple weeks ago I raced Rag Time half way to Puerto Vallarta before we ran out of wind and time and turned back. A week ago I made the front page of the Daily Pilot trimming a jib on Pyewacket Roy Disney’s Max Z86 canting keel sled.
Dan our company is a small custom injection molding company. We make molds and have 8 molding machines to run the molds in. Our company started O’Fish’l and BZ prior to my involvment. We also made the custom parts for SurfMore and Bully’s. Since I’ve been here we’ve made Red X Fin system, the molded fins for LokBox and 4-Way fin system. We also make all the custom parts for DaKine, Block, Stay Covered leashes. Wax Research, Famous and Surf Ride Wax Combs and Rainbow Sandals display hangers. We also do medical and other consumer related parts.
Doc is right. If you want to do proto-types with physical properties that approach injection molded, start with blocks of the material you intend to use in production and have someone mill the detail into them. If you just want something that is a 3-D representation of the final part, stereo lithography is an option. But, it won’t have the physicals. You should also consider the chemical resistance of the material. Some materials like nylon will not bond well to polyester resin. So, be careful how you choose your material. And, always enter into a Confidentiality Agreement with whoever you choose to work with on your new idea.
Glad to be of help. Yeah, as we lose what remains of our industrial base, machinery like lathes and mills will likely only get cheaper. On the gripping hand, I think that somebody should hang on to at least the instructions for building this stuff from scratch. What happens if-when the last South Bend fails, and everybody is left staring at each other and scratching their asses? I sure as Hades don’t have time to master and practice all of those skills, but damned if I don’t intend to hoard away some of the knowledge, while it’s still available. As the margins get squeezed out of book selling, texts outside of the mainstream are becoming harder and harder to find. If-when Lindsay Books goes the way of Mike Hoy and Loompanics, it could be too late…
-Samiam
I do basic prototype work as part of my day job, and know LOTS of machinists who still have the skills. There are relatively few well-trained prototyping machinists under 50 years old, though, today in trade school they learn tool and die or CNC.
Its all good, though, the prototyping mills and lathes (non-CNC equipped) are getting dern cheap, and I can get my finbox work done on them if necessary.
danb, if you are in need of a professional prototyping machinist, I can hook you up with one or two or three…
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On the gripping hand…
Oh dear, another Niven-Pournelle fan… we’re in trouble now. Bad enough I’m here…
I agree - having some old Machinist’s Handbooks squirreled away that date from the 20s or 30s myself. Along with books on stuff like making your own paint, etc.
What if you can’t get a part for a gizmo 'cos it’s been out of production and when the company went under the spare parts in the back room were melted down.
Or, like me, you’re doing things ( commercial shellfish growing, not terribly unlike the surfboard biz in this ) that ain’t high tech but at the same time needs gizmos. And the industry is neither big enough nor mainstream enough that there is stuff made for it or other stuff that can be adapted economically… well, ya gotta make 'em. Invent from scratch, make the first one and modify it when the first Bright Idea isn’t quite the best idea.
And it’s not worth doing if you have to pay somebody else to do it… not at machine shop rates these days, with delays and having to be done on their schedule, not mine.
Or if the available product ( like latex paint) isn’t nearly as good as a no-longer-produced similar item ( like linseed oil paint ) but it’s made for lowest common denominator users.
If you’re making one-of-a-kind stuff, you can whittle it out of something with a file or rasp or Dremel tool, given time and a lot of patience and a certain amount of skill. Making a second one by hand that’s just like the first one, well, yeah, that takes the time and patience and a lot more skill. The third one comes along and the charm of hand-made goes away fast. Small production runs are something ya gotta be ready for. Consider ( in the Sways context) how to make a dozen identical fins…
Anyways… yep, I do believe I may go a little nuts with the Lindsay Books catalog when it comes. I can think of more than a few things I have that are waiting for a few replacement parts.
Thanks again
doc…
I’m glad you know such practitioners, but from my perch it’s pretty clear that their numbers grow smaller over time. Wood and metal shop were once among the most popular high school classes. By the time I got to HS (1963) wasting time on such things was generally frowned upon for “college prep” students. In many high schools of today, those classes don’t even exist.
-Samiam
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Quote:On the gripping hand…
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doc…
I decided not to take this any further from surfboard design. You have PM…
-Samiam