[How do I?] Ordering a spring?

Cadillac STS

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I have an old Wellsaw 46 and the down feed spring is getting tired.

I contacted Wellsaw and they responded right away saying they don’t have that part anymore but sent me the specs on the spring.

Where would I order this spring?

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Lee Spring is the most comprehensive supplier of springs that I know and they don't have one that would meet your requirements. From the print, the spring rate is 5.14 lbs/in.

Winding a spring with .062" wire to that diameter would require a lot of force to form the wire. There will be considerable springback so you would require a mandrel considerably smaller than .385" in diameter in order to hit the i.d. requirement of .385 - .425". Winding on a mandrel tha will provide that length of spring will be best done using some sort of follower to support the mandrel. The forces are reversed compared to turning so the typical follower wont work unless you wind from the back side of the lathe. A custom follower could be made though.

Hitting the .238" pitch on the coils will also be difficult with wire that size. I usually wind my extension springs as close pitch and stretch the finished spring to achieve my desired pitch You could wind the spring by setting up the feed for 4 tpi which will get you close to the desired pitch.

You state that your spring is getting tired? By what measure do you come to that conclusion? Have you measured the free length of the spring or the spring constant? In my experience, springs usually fail by breaking. It is possible that you could revitalize the spring by stretching it. Your goal is to have a force of 18 lbs. on the spring when compressed to 6.5 inches. It would be fairly simple to make a jig to do this measurement. A disk with a slip fit hole for a guide rod to prevent the spring from going sideways when the spring is compressed and a bathroom scale. Mark the back end of the rod for the 6.5" length.
 
McMaster Carr has a large selection of springs, try perusing through there to find one that is similar. Lots of other spring manufacturers.

Springs are very much not standardized and finding exact replacements is frustrating. Ordering a single replacement spring to be made can be costly due to setup charges, while large quantities of springs are very cheap.

I'd recommend looking for something that is similar in size, then trying to find one with a relatively close spring rate. Anything close should be fine for your application.
 
Lee Spring is the most comprehensive supplier of springs that I know and they don't have one that would meet your requirements. From the print, the spring rate is 5.14 lbs/in.


You state that your spring is getting tired? By what measure do you come to that conclusion? Have you measured the free length of the spring or the spring constant? In my experience, springs usually fail by breaking. It is possible that you could revitalize the spring by stretching it. Your goal is to have a force of 18 lbs. on the spring when compressed to 6.5 inches. It would be fairly simple to make a jig to do this measurement. A disk with a slip fit hole for a guide rod to prevent the spring from going sideways when the spring is compressed and a bathroom scale. Mark the back end of the rod for the 6.5" length.

I should have thought of this first. I’ll check the spring strength before anything else.
 
Well the spring tests good. Over 20 lbs when compressed.

Lesson learned. Test the presumed bad part first. Duh..

I just thought it was weak and it does stay compressed over 99 percent of its life over 40 years.
 
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