spring winding

[subsearobot]

Hi All,
I'm looking into the practicality of adding capability to create custom springs to our R&D department.
The lead time, and cost to iterate is very high using vendors. I am wondering about both the complexity of operating a machine, and the cost of getting one.

We do not need new springs often, but when we do, they always require more iterations than desired, which gives us a longer than desired development time.

2nd question: is there a cheaper method to make springs to high tolerances (but in low numbers). I saw (google, so I can't tell accuracy) a claim that with minimal tooling, a lathe could be used to wind compression springs. How accurately? We have a machine shop, so if true, this woudl be great.

If a spring takes an hour to make, that's fine. right now, we are ordering 1000 to test 1 spring, which then needs a design change...so we re-order, and wait 6-8 weeks for the next one. I'm dying over here.

thanks!!

 

[dgallup]

Why are you having to make so many prototypes? Springs can be very accurately designed, specified and produced. They have to be one of the most thoroughly documented mechanical components since the bolt. I frequently need a new spring but I almost never need to iterate the design.

https://i.imgur.com/A1c5H13.mp4

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[subsearobot]

good for you, DG. you must be very proud. I didn't realize I needed to justify my engineering in order to get a useful reply.

We have some tricky acceptance criteria that I can not get into, but here some constraints are: I need to rely on non-standard forms. Couple that with un-predicted fatigue issues, and unspecified audio requirements, and we now need to test some iterations. This is a handheld application, so, ultimately it is not the machine test, but a human application specialist that decides if it is good enough. I prefer to have options before choosing design paths.

That said, springs are 1% of our design, and experts we are not.

So, back to the questions:
-How difficult is it to operate a spring machine (I realize this is a general question. can I compare it to a hobby-level 3d printer, or should I expect it to be like operating a cnc mill- would we need expertise that I don't have time to develop). Can I expect to purchase a winder on ebay for a reasonable price, or, again, are we looking at cnc mill level complexity?

-Are there alternative fabrication methods that could adapt standard machine tooling to wind precision compression springs?

thanks for your constructive assistance!

 

[3DDave]

No need to justify anything. The less detail the better. But it doesn't seem like you have a spring fabrication problem, but a lack of ability to determine what that spring should actually do.

I would go all in. There are some very fine CNC spring/wire formers available in the $250K and up range, not including creating the tooling that is required to form each variation. I do enjoy the videos. Very relaxing.

 

[subsearobot]

Thanks guys.
Yes, I admit to ignorance. That's why I am here asking questions. Is there anyone out there with useful input?

There is a new engineering philosophy stemming from the rise rapid prototyping. It took me a while to embrace it but it is has a much faster learning curve. It's faster and allows a more complex design options than the older methods where prototypes were expensive (either in machinist time or cash outlay). It's called iterational design, and it excels especially where 3d printing can serve up functional prototypes. I'm looking for a similar cheap, easy way to prototype unconventional spring concepts for incalculable metrics like sound minimization.

My hope here is that there is a winding solution that can accommodate 5-10 iterations on 3 or four unconventional concepts inside a week or two. The problem is that we don't prototype enough springs to justify much more than the cost of a cheap new car. Iterations need to be cheap, and we only have a few hundred a year.

For example, can I 3d print a mandrel, accounting for spring-back, and turn a spring over it on the lathe? what do you think I can achieve +/- .010" on a 3/8 diam winding with .020 wire?

 

[3DDave]

That's the beauty of rapid prototyping. You can create a mandrel, try it, and if it doesn't work, then create a new one right away until you get within the size variation that's acceptable. Or start with an aluminum mandrel that's certain to be too large and shave it down on the lathe a bit at a time.

The problem I have in understanding the request is that there are hundreds of tutorials in how to wind both compression and extension springs using simple tools, but I have no understanding what you think is "unconventional" and that represents an infinite gulf.

 

[MikeHalloran]

Just having a spring winder tool is not really enough to satisfy arbirary requirements; you also need to stock appropriate wire in pretty much every size you can imagine, and you need an operator who really knows his or her stuff, and knows what to change, and how much, in order to tweak the results you get toward the results you want.

My iterational requirements have in the past been addressed by having half a dozen 'stock spring' assortments from a couple of different manufacturers, e.g Lee spring or Associated Spring.

I have managed to lose the BASIC program that I wrote for iteratively designing springs, but in decades of using it, I found that the typical stock springs were ideally designed for most applications, and using proportions much different from the stock springs gave results that were disappointing in performance and/or impossible to re/produce.



Mike Halloran
Corinth, NY, USA