Have you tried winding coil springs on your Sherline Lathe ?

[j ferguson]

Winding springs on a larger machine looks pretty obvious. I need some 6mm OD .020 +/- music wire coil torsion springs which are unavailable anywhere I've been able to find. The spec is loose, but not the diameter. My idea would be to use the handwheel included in the threading kit and do it by hand - thinking that the motor wouldn't generate enough torque at the slow speed I'd need to make 6 to 8 turns.

If you've done this with a Sherline, what did you do?

 

[Nubbles]

I haven't tried it myself, but... Were you planning on having the wire go through a toolpost on the cross slide or holding it manually? I think if you're using a toolpost the threading kit would be the right call, as you'd want the carriage to move as the spindle turns. With controlling the wire manually you may be able to do it either way--The motor can turn pretty slowly though you're right that you have to see if torque was a problem. Could always move the motor to the higher torque pulleys but if you're only making a few small springs might be more trouble than it's worth

 

[eotrfish]

I've made a lot of springs on my lathe but found that it's not really worth the effort.

Try these from AliExpress - you don't have a lot to lose.

 

[j ferguson]

Hi eotrfish.
unfortunately these must be torsion springs in a specific size and handle 180 degree deflections with both minimum and maximum torque limitations. The blessing if there is one is that they will be small so I should be able to wind them on the Sherline. I wish I could have changed the design to use what I could get from McMaster Carr. I bought all of their sizes which were close, but none of the samples did my job.

I should add that there is another part of the project which only required 90 degree deflection and they had a couple of springs which are working perfectly.

john

 

[eotrfish]

Hi John

Sorry - I missed the TORSION part of your requirement. Have you tried SDP-SI? They list some small torsion springs.

Brent

 

[RJSakowski]

Lee Springs is my last word for springs. They have literally tens of thousands of spring configurations. The only down side is you have to purchase a quantity to be economical. https://www.leespring.com/compression-springs

Another way that I liked to use their information was for designing my own springs. They provide sufficient engineering data that you can custom wind a spring to meet your particular needs.

I have made many torsion springs on my Atlas/Craftsman 6x18 lathe. I use the motor for winding but loosen the belt so that I can control the winding. I used to use a pair of Vise Grips to restrain the winding but have progressed to using a winding tool which provides more uniform coils with less spring back. The tool is simply a length of 1/2" rod drilled through with a reduced diameter nozzle on the end nearest the mandrel and the top half of the nozzle removed to allow placing close to the mandrel. There is a good discussion in this thread. https://www.hobby-machinist.com/threads/spring-winding-jig.104748/

 

[MikeInOr]

Could you share the project and maybe a picture or two? Some great ideas have come from this forum when we know the application.

I have tried winding springs on my Southbend 13" and have produced springs but they did not work for the project they were made for... restoring an old rifle.

 

[j ferguson]

Here it is, an attempt to reverse-engineer the Aerovironment Switchblade 300. Wingspan about 24 inches.
This version is the mule with which I plan to get sharp on controlling a tandem wing design. It will be built from combination of foamboard and 3D printed motor mount, leading and trailing edges, rudders, and elevons. The wings will not pivot on the mule but I have figured out how to do it in the final version whcih will be vacuum molded carbonfiber reinforced plastic - wings and fuselage. Foamboard now because I think I'm going to wreck a lot of them. I built a needle foamboard cutter adaptor for my 6040 Chinese CNC router which makes it possible to cut all the foamboard parts for one of these things in about 1 1/2 hours.

Elevons and Rudders are sprung, the Elevons so that they can be controlled by servo-powered vertical plunger actuators once they are deployed, and the Rudders which fold against the fuselage and then swing through 180 degrees where they are controlled via magnets by the push system shown in the detail. The geometry of the tail allows pushing one rudder out at a time with the other staying where it is. If you look at the geometry, you'll see that there will also be a pitch component combined with the rudder's effect on yaw. This will be an R/C plane but I doubt that it can be hand-flown without stabilization so it will have stabilization but will not be semi-autonomous -- yet.

The rendering and the drawing shows the springs I need. The one shown is for the rudders. A simpler version will be used at the wing-roots for the elevons. The shafts are 3MM carbon-fiber. As you can imagine, I couldn't buy anything exactly like this of course assuming that I would bend the dog-leg on one end myself. I was able to convert an expansion coil spring to work but it loads up by expanding radially rather than contracting the way the more usual torsion springs work.

Since all the springs will be the same diameter, wire size but possibly with different number of coils, it may make the most sense to make a dedicated spring winder for this project.

It doesn't look like the attached PDF cna be viewed but it can be downloaded.

I use OnShape for design and AutoCAD LT and SheetCAM to generate the G-Code for the foamboard parts. Anything requiring CNC on my Sherline 2000 is done with Creo (Pro Engineer) which unfortunately requires an expensive subscription, but I know it well from using it since 1988. So far, it appears that OnShape's CAM package is still on the horizon. OnShape is free if you don't mind having your files accessible to any other OnShape user. This project is for fun, so I don't care if anyone else gets into it.


John

 

[MikeInOr]

Very cool project! The Switchblade folds up because it is supposed to be tube launched? I will avoid the topic of onboard ordinance. The magnetically linked controls are very interesting. I never considered how folding wing surfaces would be controlled. Does the propeller hold for launching too? Does the motor rotate 90 degrees to achieve stowing the propeller?

It sounds like you are working from your own plans? The springs are for deploying the wings while being tube launched? The only knowledge I have of the switchblade is from a little blurb on the History channel. Is the landing gear you own addition to the design?

 

[j ferguson]

no ordinance. propeller will be folding, but not now. motor is hard-mounted. I didn't show the wing pivot springs - bigger and different arrangement and very slick, imho.