Welding to a Coil Spring?

[VaughnT]

I've got a project in mind that will allow me to practice my welding again, and one of the key components is going to be a section of car coil spring.  Maybe a full coil, or a coil and a half, welded between two plates to give you a bit of wiggle between said plates.

 

This is a non-structural project and the worse that could happen is that I get embarrassed if someone sees it fall to pieces.  But, I'm wondering about the heat of the weld making the coil spring brittle.

 

With all the talk about heat-treating of knives and how the wrong temps can cause large grain and snapping blades, I can't help but wonder if the same thing would happen to a coil spring if you welded an inch-long bead to the end.  Would it be prone to snapping right behind the bead?

 

 

[jmccustomknives]

The proper way to do it is preheat the steel, weld with a special tool steel rod then post heat.  You might can cheat a little by welding with a 309 stainless after heating to about 450F and if you have a way to hold that heat let it cool very slow. 

The best way is to forge the weld, but in you situation it's not possible.

[John McPherson]

If it truly is non-structural, heat the end to red with a torch first. That will keep you from having a sharp heat affected zone at the weld. Works for bed rail as well.

[DSW]

Springs have a bad tendency to snap in the heat affected zone after welding. Heating a larger area will help to combat this, but on the other hand it also takes the temper out of the spring and can make it loose it's "spring". I've seen guys have mixed results trying to weld coil springs for things like DIY park rocking horses. The "fails" have run from the springs snapping and dumping the kid, to ones that just bent and didn't return. Some worked fine with no issues. I haven't really seen a great process that gave consistent results, probably because most times there wasn't enough consistency or tracking of the exact weld process to determine any useful data.

[VaughnT]

Removing the temper from the ends, spreading out the softening so there isn't a sharp delineation between the two zones, could be feasible if I use two coils.  That would still leave plenty of spring for the wiggle.

 

Might just be best to do it the hard way and weld some clamps to the plates, though.  Better safe than sorry.

[Jim Coke]

Greetings Vaughn,

 

Sounds like an interesting project....  You might consider welding a tube to the plates to slide the spring ends into..   Than a simple braze to pin it...  That's assuming it is for sure non structural.   A picture would help...

 

Forge on and make beautiful things..

Jim

[VaughnT]

Definitely non-structural, unless you count my fat butt sitting on it.  I'm making a shop stool and want a little bit of flex between the seat and the support so it doesn't stress the joint.  The seat is pressed sheet metal with some serious corrosion, so it could rip when you lean over to grab something.  It would take a few repetitions, but metal fatigue isn't something I really wanted to deal with.

 

So, I thought I'd weld some heavier sheet to the underside of the seat, then attach the spring to it.  The spring would be an intermediary between the actual seat and the main body.

 

Pictures just as soon as I figure out what I'm going to do.  Hope to get something roughed in today, but keep getting stuck on the spring part.

[ironwolfforgeca]

when I have to weld a broken trailer leaf spring together I use 110-18 pre heat weld area post heat NOT something I like to do ! but

sometimes no choice & have had good luck & there still out there working last time I looked  :) 

 

note a good welder always ck his work from years back to see how it doing, kinda like ck-ing on the kids lol

308 or 309 SS is also an Idea

[Rich Hale]

Clamp it in place.

[Chinobi]

I would be in favor of a 'mechanical' type joint for something like this, but that's probably because I can barely weld :)

 

that said, I have used a joint similar to what Jim describes with the tubing restraint for a project that needed to restrain springs without getting in the way of their operation but still provide resistance to buckling.  and I actually have a relevant picture this time! :) 

 

 

rereading your intent though I think you are using very short (vertically) pieces of spring, assuming you are using 'coil' as one complete circle of the spring.  you could weld a tube with one end closed onto your top and bottom plates horizontally and if you place them carefully you could force the spring ends into them and have the springs own force act to keep them in place.  that way you avoid any hot connections on the springs themselves and the whole thing can rotate without stress.

 

are you planning to put a hinge on the side opposite the springs? or just finding some way to place two springs on the backing plate to give it some flex?  you might be better off restraining the motion with a hinge of some sort IMO :ph34r:

[VaughnT]

Considering my welding skills, fancy welding is definitely out of the equation.  If it can't be done with 1/8" 7018, it can't be done in my "shop".  

 

I can probably fab a clip or two that can be welded to the seat and upright.  I'll dig through the scrap pile and see what I have handy!  Standby for a frankenstein stool!!

[Frosty]

Draw a tenon on each end or the section of coil you want to use. Bend them 90* so they're parallel to the center of the coil. Punch a hole in each plate being sure to cut a notch or drift it out of round. Insert tenons and pien flat. Make sure you file or otherwise clean up any burrs, you don't want non-stock holes in your butt.

 

Frosty The Lucky.

[Chinobi]

Frosty, how do you combat the loss of temper after having forged the ends and creating an HAZ?  might be kind of tricky to fix the HT on a spring with a seat and post attached :)

 

looking forward to the Frankenstool!

[Frosty]

It's car spring and probably less than a whole loop. Are you saying Vaughn is heavy enough to break a car spring?

 

Okay, so forge and bend the tenons. Heat treat, then use a torch and pein them into the seat.

 

Of course it'd be just too easy to make or buy a couple clamps, drill and screw the spring to the seat.

 

Frosty The Lucky.

[BIGGUNDOCTOR]

I would say 7018 with a post heating to cool it down slowly. Try it, if it doesn't work try something else.

[Charles R. Stevens]

I have torched off half a coil, and flattened the coil end for hotrods. Used to be standard practice to get a slightly stiffer spring and induce rake in a car. If you can flatten the first loop, a simple bare with two fullers groves will clamp across the spring gripping both sides of the coil. Frosty has a cool forged idea, but I like KISS.

[RGraff]

I'd fabricate a clamp. 

[MLMartin]

Clamp the spring in place. Falling off a broken stool with sharp broken points sticking up sounds less than fun.  I bet some U Bolts could be used to fasten a spring in place well. 

[Hillbillysmith]

If it's a non-structural application and you don't want to worry about it breaking, drill and bolt it. But if you truly are set in your ways of welding it, preheat to minimum of 350 degrees and weld with a nickel-based filler material such as E-309 (as jmccustomknives said). Any 300-series stainless will work but more costly than mild steel filler. With same preheat, use E-7018 rod and peen the weld to reduce cracking. Far as post weld heat treatment; I find that unless the tooling material is THIN or classified under the "Air-Cooled" type, just let it cool in the ambient atmosphere (roughly 70ish degrees).

 

-Hillbilly

[arftist]

Post heating helps prevent cracking simply by slowing the cooling rate. There is no good reason to skip the post-heating, when welding any high alloy or high carbon (even cast iron).