advice? Springs necessary to prevent broken punching bag chains?

[Fungus]

For those of you that have experience with killing the punching bags? Do you think a damping steel spring is necessary?

I managed to break the chain links (twice) on the big punching bags in the dojo, the metal is likely subject to low cycle fatigue, or possibly been exposed to excessive peak forces that either are due to heavy sack swinging or on the kicking impact.

I noticed there is no spring damping, the sack was hanging off a huge beam, with the chains directly hanging in the bag. Any peak forces are directly absorbed by the chain links. I have a feeling there are different opinions on wether the springs are needed.

What do you guys see in your dojos? spring damping or not? How often do you replace the chains on the most heavy (full height) bags hanging?

 

[HighKick]

For those of you that have experience with killing the punching bags? Do you think a damping steel spring is necessary?

I managed to break the chain links (twice) on the big punching bags in the dojo, the metal is likely subject to low cycle fatigue, or possibly been exposed to excessive peak forces that either are due to heavy sack swinging or on the kicking impact.

I noticed there is no spring damping, the sack was hanging off a huge beam, with the chains directly hanging in the bag. Any peak forces are directly absorbed by the chain links. I have a feeling there are different opinions on wether the springs are needed.

What do you guys see in your dojos? spring damping or not? How often do you replace the chains on the most heavy (full height) bags hanging?

Use larger or higher tensile strength chains. A spring will reduce fatigue, but does change the dynamics of the bag.

 

[Fungus]

I guess that is a solution, however the existing chains doesn't exactly look unsuitable/small/weak. So you are telling me that its uncommon to use springs? I really have not clue, I'm curious whats the recommended way. I see that springs are sold for the purpose and they are presumable reducing peak forces in chains, and in the roof, and mayve in the bag attachmenets as well?

The bag is heavy doesn't swing like a smaller boxing ball, but it swings at worst I'd say 25 degrees on som thrusting kicks, so not alot, but normall it don't swing alot at all. but ther are up or down components as you work on it, not sure which is the major impacts.

 

[Buka]

If the bags are used for power kicking as well as punching, I’ve never found a way to make them stay up very long without good, strong springs.

We had a lot of guys in the trades training. They’d bring in thick springs, usually from trucks. There were I-beams going across our ceiling, supporting the floor above.

They’d drill a hole in the I-beam, put in an eye hook as thick as your thumb, hang the springs on that, then the chains of the bag on the spring. We didn’t use the chains that came with the bags. The trade guys would bring in much thicker chains. We had about eight bags up.

The guys also brought in elevator cable and ran it through two I-beams, hooked the bag up with a pulley thing. That way you could hit it and drive it back. No springs on that one, it made too much noise as it was.

In the boxing gyms we trained at, there weren’t any springs needed, they stayed up pretty well.

 

[HighKick]

I guess that is a solution, however the existing chains doesn't exactly look unsuitable/small/weak. So you are telling me that its uncommon to use springs? I really have not clue, I'm curious whats the recommended way. I see that springs are sold for the purpose and they are presumable reducing peak forces in chains, and in the roof, and mayve in the bag attachmenets as well?

The bag is heavy doesn't swing like a smaller boxing ball, but it swings at worst I'd say 25 degrees on som thrusting kicks, so not alot, but normall it don't swing alot at all. but ther are up or down components as you work on it, not sure which is the major impacts.

I would not call them uncommon. It just takes a little more work in the mounting of the bag and will actually put more energy in the bag post strike, so the bag may bounce around more.

Question: is it an actual chain link or the clevis used to attach the chain to it's mounting member? Maybe the clevis used is too small?

 

[Fungus]

I would not call them uncommon. It just takes a little more work in the mounting of the bag and will actually put more energy in the bag post strike, so the bag may bounce around more.

Question: is it an actual chain link or the clevis used to attach the chain to it's mounting member? Maybe the clevis used is too small?

In the top there is some clevis, but this is not what broke, what broke was the actual chain link that was deformed and pulled open. So clearly either the chain was too weak - or you need some damping as buka suggested, we do use it for power kicking, some even downward roundhouse so you will get a high impact not just from swinging but from the kick itself, that is pulling the chain, probably quite a bit.

 

[HighKick]

In the top there is some clevis, but this is not what broke, what broke was the actual chain link that was deformed and pulled open. So clearly either the chain was too weak - or you need some damping as buka suggested, we do use it for power kicking, some even downward roundhouse so you will get a high impact not just from swinging but from the kick itself, that is pulling the chain, probably quite a bit.

Ah, it sounds the bag currently has Unwelded chain. I am quite surprised this was provided with a heavy bag. It is for lighter-weight, static loads.
I do not know where you are located, but we have hardware stores like Home Depot and Lowes that sell several sizes of chain and clevis's. You should be able to find approximately the same size chain in the welded variety. I recommend going at least one size up.
Replace your chain and you will be good to go.

 

[JowGaWolf]

For those of you that have experience with killing the punching bags? Do you think a damping steel spring is necessary?

I managed to break the chain links (twice) on the big punching bags in the dojo, the metal is likely subject to low cycle fatigue, or possibly been exposed to excessive peak forces that either are due to heavy sack swinging or on the kicking impact.

I noticed there is no spring damping, the sack was hanging off a huge beam, with the chains directly hanging in the bag. Any peak forces are directly absorbed by the chain links. I have a feeling there are different opinions on wether the springs are needed.

What do you guys see in your dojos? spring damping or not? How often do you replace the chains on the most heavy (full height) bags hanging?

You may need a heavier bag and the bag may need to touch the floor so that the chains are not supporting all the weight. You may also want to switch the type of chain you are using to hang the bag. Purchase one that can take the punishment.

I don't think I've ever hit a heavy bag with springs before. Even at the gym I train doesn't use springs.