How do I go about finding a stronger spring?

In My Humble Opinion
1

If you need that backstory, what I have is a cardboard compactor (identical to this one). When the door is down, there are two heavy springs that are stretched. When you lift it, they retract. This keeps the door (semi) balanced. While it still takes a bit of paying attention to lower the door and even though it’s supposed to lift on it’s own on during the second half of the cycle, if it doesn’t it does take a small amount of effort to lift it )and with how heavy it is now, sometimes it falls as it’s on it’s way up).
However, a few months ago we did some repairs to it. We welded some new parts to it (see below) which added a few pounds it. Now it’s ‘feels’ much heavier. What I’d like to do is get some stronger springs. Just enough to add a few pounds of lift to it. It should be noted that weighing the door won’t help since since the springs are attached to some levers (which actually make them work harder, I think, never actually checked). Here’s the tricky part. I think they could be a bit wider, but they must be the same length or they won’t attach to the same anchor points.

There is a spring manufacturer very close to my store, however, when I called them, they told me that they don’t warehouse a vairety of springs. Everything they do is custom/one off, mainly designed for HUGE companies (caterpillar, airlines etc) and a single spring tends to run around $1500. OEM springs are like $10.

Also, before anyone says it, I did call the manufacturer (or at least the people who’s badge is on it, that we buy all our parts from) after rolling my eyes at the owner when he told me to do that since I knew the answer. Yes, they only sell the spring that belongs on the machine, not stronger springs on the off chance you happen to add a bunch of weight to it.

One of my other thoughts is to call my welder and have him add another anchor about an inch away from where the current one is (closest it could be) and see what that does. If it doesn’t work it doesn’t work and I’ve still got the original one.

This all dates back to this repair. By the way, if anyone has any experience with something like this, after we got it fixed, the door binds as it goes up and down. I’m guessing it’s now a bit too wide or narrow. Any thoughts? I’m thinking of putting some paraffin on the sides so (maybe) it glides a bit better. I’d prefer not to use aerosol lubricant (WD-40/Liquid Wrench/PB Blaster etc) since that’ll just make a mess, drip and probably get on everyone’s hands and clothes.

I’m trying to find a picture of how the springs are set up and not having any luck online. But if it helps, I have the manual at work with the exploded parts list PLUS I’ll be taking the door off to replace a broken spring in the next few days. As of right now, I’m just looking for some leads since I’m not even sure where to start.

ISTM, what I need, is for a ‘spring guy’ to come to my store and say 'yup, I got just what you need, I’ll send you a couple. I got a guy for everything…don’t have a spring guy yet. I did FB a friend that works in a machine shop, haven’t heard back from her yet. Just thought she might either be able to fabricate something or have a lead for me.

2

Are these coil springs? Tension or compression? How big are these springs and what is the range of motion?

There are devices to tighten tension springs and ‘boost’ compression springs. I have no idea if they would be practical to use in this case.

3

Sorry. I can take a picture of them in the morning if this thread gets legs. I think the technical term is an extension spring.

This is sorta what they look like. Off the top of my head, I’d guess they’re about 6 inches long, maybe .75" wide.
Strong enough that you (well, I cannot and I’d guess that most other people cannot) stretch them by hand, not even kinda, but you can’t bend them a bit.

The first times we replaced them we spent hours working with a break spring puller trying to get them hooked. We even considered cutting off part of the end loop to make it easier.

Turns out the trick is to remove the levers (that I mentioned earlier) from the door. Take the door off. Remove the lever (easy, now, with the door out of the way). Attach the spring to the body and lever (lever has to be removed to finagle everything together). Attach the lever to the body of the baler. Slide the door back on…then grab both levers and push them down and connect them to the door. Doesn’t take a lot of force, at all, but you still don’t want them slipping out of your hand and flying back up.

That’s all kinda moot, but I’ll try to get some pictures.

ETA No pictures of the baler mechanics, but I did find a picture on my phone of some spare springs.

ETA2, as for how much they stretch, I’m not sure, maybe to 1.5X-2X, maybe? I’ll see if I can get a picture of that as well.

4

There are kinds of springs at places like Amazon and eBay or you can do a Google search for springs and some suppliers will show up. The question is what search terms do you use to find the spring you need.

5

Just contact a spring manufacturer. Have a photo ready to email or text to them if they ask for it. For stuff like this, go right to the (a?) source whenever possible, IMO.

6

The problem with that, however, is that I have no ability to measure how much force this spring exerts (much less how much force it exerts when you first start extending it vs when it gets to it’s maximum extension) or how far it extends. Even if I could get a device to measure that, it would mean hooking one end up to something stationary and the other end to our forklift or a come-along and then, what, until it’s 'stretched out? breaks? I don’t know. I’ve got to do some googling tomorrow (but spring manufacturer might be the right string, along with Milwaukee), to get someone to come out and look at the application or that I can just bring the spring to their shop.
What’s tough is that I just need a few of them. It’s not like I can call them and say ‘so, I need like 1500 of these…’. They’re not exactly banging down my door to give me a quote.

I’m just hoping someone can say 'oh, that’s a 6942E, here, try a 7242E, should be perfect, it’s $10".

7

Is there space to add a spring in parallel? For the most part, the forces to extend or compress springs in parallel are simply added.

8

This is a simple approach. Any spring as long as the original or shorter can be used if there’s a place to hook it. Doesn’t even have to be perfectly parallel it could go off at an angle. If the spring is shorter take up the slack with wire of a Ubolt or something.

9

No, not without welding something on to hold it. Even then, I wouldn’t know what specific spring to add so that it A)adds some force to the door and B) doesn’t add too much force. The door is meant to balance (kinda). Not fall, not raise on it’s own.

I’m going to get some pictures when I get to work. I’ll post them here, plus I have a friend that works at a machine shop that seemed pretty confident she can help as well.

10

If there’s no where to hook it then you can’t do it. But small springs are cheap, you could try a few and find something that works. I understand this kind of thing is tricky. I doubt you’ll be able to calculate an exact spring size though, you probably need to get something shorter and adjust the tension.

11

A spring manufacturer won’t sell you just a couple.

Have you tried a hardware store? They generally have a basic assortment. Generally speaking for springs of the same diameter and length, the heavier the wire the stronger the spring. Other things do come into play. Sometimes it takes trial and error to find the right spring.

For a better selection, try Mcmaster-Carr. Extension springs continue to page 1269.

12

Certain hardware stores have maybe 50 different springs in stock. Other hardware stores have none or just a few. So check around. (Ask at each hardware store, sometimes these are kept in the back.)

13

As promised, here’s a few pictures:
This is a brand new, OEM spring.

This is the spring where it sits in the machine. As you can see, there’s really no space for a second spring. However, I think a slightly longer/shorter/wider spring might work, but I’d have to take a closer look. FTR, regarding there being two holes to attach the spring on the right side, as far as I can tell there’s no noticeable difference. However, I’ve considered having another anchor welded on above and behind the left hole (behind the frame) so the spring has to stretch an extra inch or so.

This is the machine with both the springs reattched. If you look at this picture (not mine), you’ll see a small ‘dot’ just below the “Little Giant Corp” badge in the center of the door. That’s the pin where the two bars angle down* and meet in the middle. When someone brings the door down, the springs stretch so most of the weight in on the springs instead of the 50 pound (I weighed it today) door slamming down…and it does fall hard.

Here’s two more random pictures. One from above with the door down before I took it off, you can see it stretched out and one with the door removed and me pulling the arm down so you can see sort of see what happens to (half of) the mechanism as someone brings the door down.

My friend that works in the machine shop sent me a link to a spring place that she works with. Problem is, A)they don’t seem to have springs this big (but I’m going to call them) and B) I have no idea how much force the spring exerts, which is one of the bigger stumbling blocks. She did also mention, like a few other people, to just go to Ace Hardware and see what they have, though I have my doubts they’ll have springs that are 8x1.5 inches (or bigger). But maybe.
As I said earlier, what I really need is someone from a local spring company to just come see what I’m dealing with. I break enough of them that it’s not just going to be one and done, it’ll be a few a year. But at least this time I saved the broken one so if a out of state spring company seems promising, I can send this one to them to take a look at.
*For full disclosure, when I mentioned that part about those arms being ‘angled down’ to meet at that pin, they should have been angled up. I fixed it before I finished the job.

14

You may also want to try at a farm machinery/implement supply parts department. Like John Deere. Those and their attachments (implements) have all sorts of large springs like that.

Another option would be to have a welder weld on extensions where each spring is, then simply add a second spring. You would then have two springs on each side instead of one.

15

I buy springs on line all the time. You can speck out exactly what you are looking for in most cases.

16

Since you have a second hole in the bracket you just need to weld on a little piece or drill a hole in the back plate to hold a second spring. Probably better off that way, finding a second spring that will get it right is going to be easier than finding a replacement for the original.

17

^ What I was going to say.

Also, it’s very similar to a plow truck spring. They keep the plow vertical until you hit an obstruction and the spring allows the plow to ‘fold over’ and get over the obstruction. Your spring is smaller though. Something that you might see on a plow attachment for an ATV.

Your pictures show levers to raise the door that became heavier. It’s because the door weighs more now (per your OP). Could you place counter weight on the lever to keep the door open? I would try that first, if possible.

18

Yep - That’s what I’d try. Your spring-lever combination has a tremendous mechanical advantage in certain positions; it may go through an over-center condition. You’re not going find your perfect spring in some online guide or catalog. I would look for something long and skinny like a large screen door spring in the 2nd hole that would add a more/less constant force throughout the range of motion.

19

I’m familiar with (snow) plow springs (been plowing snow since I learned to drive), something like that might work, it’s about the right size. My machinist friend gave me a link to McMaster-Carr, but also mentioned that I might be best off just hitting up some hardware stores (specifically Ace/True Value). I’d be surprised if they had anything that big, but Farm And Fleet might (I see they’re regional, but they have good selection of farm repair parts).

I ended up calling McMaster-Carr. They pointed me to a spring that’s a hair bigger than what I have, based on measuring it with a tape measure, as opposed to a caliper. Fortunately, a hair bigger is what I need, however, I don’t know exactly what metal mine is made of (looks like steel, it is magnetic).

As for some of the other suggestions, I don’t think two springs will work. There’s not a spot to add a second spring (on the body side), that would involve welding on another anchor. If I’m going to do that, I think I’d be better off just adding a second anchor an inch or so away and using that one. Besides, the hole in that picture is almost worn through, so I’ll need to get it repaired soon anyways*. Also, maintaining 4 springs instead of two is just going to be twice as much work, moreso if they end up rubbing.

Counterweights, that just seems like something that’s going to break on an regular basis. Something that needs to be accepted in life is that employees abuse things. Setting up a system of pulleys and counterweights would mean pulleys that have to be greased and counter weights that have to be dealt with when they toss a box past one of them and it hits something. It also means bringing in a welder.
*Bossman said ‘uh, just drill a new hole’. Yeah, I don’t think I can drill a hole through 3/8" thick hardened steel (vertically too). His reply was ‘well, it was done the first time’. Yeah, with a drill press and clamped to a table, possibly even with a CNC machine. Let’s just wait until we can get the welder here and he can deal with it.

On a side note, again, I really want/need to learn how to weld someday.
On a side note 2: I still can’t believe I don’t have a ‘spring guy’.

20

Not seeing how the handle of the unit operates, I was thinking about adding weight to the handle that operates it. I’m guessing that you push down on a lever and it opens the door? I thought that you could just add weight to the handle. Just spitballin here.

Also, if you are familiar with plows, the springs have a tensioner bolt. Yeh, it would take some foolin with. New holes and perhaps some welding, but would make the spring adjustable.