HEAVY Garage Door Eats Sheaves for Lunch

[Colossus]

Hi Folks,

I've visited GJ many times over the years and always learn something new. I just registered so that I could ask for advice about a very vexing problem.

My garage door is 8' x 16' and built like a tank; heavy wood reinforced with horizontal steel ribs. I have no idea what it weighs, maybe a thousand pounds? The balance springs (extension type) are as big around as my little finger. And yes, there are safety cables

The problem is with the sheaves (pulleys). They just don't hold up to the forces that the cables put on them. All I've ever found for sale are the crappy stamped steel sheaves riveted together around a crude shaft and loose ball bearings. Those may be fine for a 300 pound door, but they wear out after a handful of months of use. It's a fairly time consuming job to replace them and I'm getting sick of it.

I've thought of throwing in the towel and replacing the door with a modern, lighter affair, but this one is in perfect condition, and with new sheaves it runs smooth as silk. It's only when the bearings all fall out and the pulleys are metal on metal that the opener struggles and sometimes overloads.

Can anyone recommend a source for heavy duty sheaves? It's a standard door, with two stationary sheaves at the top of the door, and two attached to the end of the extension springs. I think they're all 4-inch.

Thanks in advance for any and all advice!

 

[IlliniJeeper]

Maybe talk to a marine supply company? I'd imagine sailboats use some seriously heavy duty tackle.

 

[JakeKohl]

Better give your wallet some stretching exercises and get it warmed up before going the sailing hardware route. It is still cheaper than a new door, though.

This page is for blocks intended to run cables...most have load ratings.
http://www.apsltd.com/c-534-specialty-and-wire-blocks.aspx

You can also shortcut the load calculation by measuring your cable size and designing around the maximum rated load for that size cable.

 

[IlliniJeeper]

Better give your wallet some stretching exercises and get it warmed up before going the sailing hardware route. It is still cheaper than a new door, though.

This page is for blocks intended to run cables...most have load ratings.
http://www.apsltd.com/c-534-specialty-and-wire-blocks.aspx

You can also shortcut the load calculation by measuring your cable size and designing around the maximum rated load for that size cable.

To be honest, that's cheaper than I expected them to be.

 

[kbs2244]

Or switch to tension springs.
Then you will not have only a straight up pull on the cables.
No pulleys.

 

[Kevin54]

I can imagine the cables are tearing the sheaves up that bad unless something isn't balanced correctly. If the door is balanced, the cable should just run around it without putting undo pressure on the pulley's.

If you raise your door, can you leave it sit in any position without it dropping? If not, then things need adjusted. I understand the door is heavy, but you aren't the only one with a heavy door in this world.

Possibly look into a torsion spring instead of tension springs. I don't like tension springs whether or not they have a cable through them. My ex FIL had one snap and took out a truss in the garage.

With an tension or extension spring, when the door is down, the spring is stretched. Over time that spring weakens. Also all the time it is down, it is pulling back on the sheave. With a torsion spring, you don't have bearings for the sheave to roll on. It is a solid drum fastened to the shaft that runs through the torsion springs. Nothing to wear out.

BTW....welcome to Garage Journal. Don't be a stranger just lurking in the bushes.

 

[Schtauffer]

Lose the extension springs and get a torsion spring setup.

 

[rlitman]

I can imagine the cables are tearing the sheaves up that bad unless something isn't balanced correctly. If the door is balanced, the cable should just run around it without putting undo pressure on the pulley's.

I wouldn't necessarily agree with that. Each pulley has to lift half the door.
BUT, the force on the pulley (which translates to compression on the bearings) is greater than that since the cable wraps around it. With the cable tension pulling down and back at 90 degrees apart, the vector forces add up to sqrt(2) * weight of door / 2 or
.707 * the weight of the door on each pulley (and not .5 as you might expect).

The hardware stores around here (Ace, Lowes, HD), have 3" and 4" stamped steel sheaves. The ball bearings in these come dry. You could try greasing them with a needle to see if you can improve their wear life, but I agree that you really want to start with a heavier sheave.

Check these out (first ones I found on google). It seems that cast iron sheaves are still made:

http://www.amazon.com/dp/B00BWUIWCK/?tag=atomicindus08-20
http://www.amazon.com/dp/B00BWUIN8I/?tag=atomicindus08-20
http://www.amazon.com/dp/B0052UCL78/?tag=atomicindus08-20
http://www.amazon.com/dp/B004Z86J3U/?tag=atomicindus08-20

Looking at the sheaves here:
http://garagedoorpartsmart.com/product-category/parts-accessories/garage-door-springs-accessories/

The stamped steel ones are listed as having a 200lb rating, while the cast iron ones are either 400lb or 1200lb rated. The better one has ball bearings pressed in. It looks that that's your best bet:
http://garagedoorpartsmart.com/shop...ies/garage-door-5-12-sheave-pulley-with-bolt/

 

[Dcampbell98xj]

If your extension spring are only the diameter of your finger they are the wrong springs. On a door that big and made of wood you would most likely need custom load springs. A local garage door company should be able to weigh the door and tell you what springs you will need. Also while you are talking to someone from the company ask them about heavy duty pulleys. If you cannot get ahold off custom load springs you could convert the door to torsion springs or double extension springs.

 

[914wilhelm]

McMaster Carr is your friend: http://www.mcmaster.com/#rope-pulleys/=ts5kt6

 

[Colossus]

Thanks, all, for the welcome, links, advice - and even a math lesson ;-)

It looks like I have some links to investigate. The Garage Door Parts Mart (say that 3x fast!) looks like it might do the trick for the stationary sheaves. And a sponsored link that came up on one of the Amazon pages was for winching ****** blocks. I never thought to look into that option but it might just do the trick (and at a fraction of the cost of the sailing rigging sheaves).

But I'll tell you, I've heard the horror stories of the damage that these extension springs can do when they fail, and I have every reason to believe that these springs are over forty years old. That's a great incentive to at least look into getting new ones, or better yet, changing over to the torsion setup. Anyone have a ballpark idea as to what I'd be looking at money-wise to switch?

Thanks again,
Ben

 

[LB-1911]

More reading for you.

Introduction to Garage Doors
http://ddmgaragedoors.com/index.php

Do-It-Yourself Garage Door Tutorials & How-To Instructions
http://ddmgaragedoors.com/diy-instructions/

 

[garboui]

I wouldn't necessarily agree with that. Each pulley has to lift half the door.
BUT, the force on the pulley (which translates to compression on the bearings) is greater than that since the cable wraps around it. With the cable tension pulling down and back at 90 degrees apart, the vector forces add up to sqrt(2) * weight of door / 2 or
.707 * the weight of the door on each pulley (and not .5 as you might expect).

The hardware stores around here (Ace, Lowes, HD), have 3" and 4" stamped steel sheaves. The ball bearings in these come dry. You could try greasing them with a needle to see if you can improve their wear life, but I agree that you really want to start with a heavier sheave.

Check these out (first ones I found on google). It seems that cast iron sheaves are still made:

http://www.amazon.com/dp/B00BWUIWCK/?tag=atomicindus08-20
http://www.amazon.com/dp/B00BWUIN8I/?tag=atomicindus08-20
http://www.amazon.com/dp/B0052UCL78/?tag=atomicindus08-20
http://www.amazon.com/dp/B004Z86J3U/?tag=atomicindus08-20

Looking at the sheaves here:
http://garagedoorpartsmart.com/product-category/parts-accessories/garage-door-springs-accessories/

The stamped steel ones are listed as having a 200lb rating, while the cast iron ones are either 400lb or 1200lb rated. The better one has ball bearings pressed in. It looks that that's your best bet:
http://garagedoorpartsmart.com/shop...ies/garage-door-5-12-sheave-pulley-with-bolt/

I was going to suggest just using some heavy/cast vbelt sheaves as theyre plentiful and cheap but those amazon parts look like a good way to go.

EDIt:also http://www.mcmaster.com/#rope-pulleys/=ts8q6q

 

[OccupantRJ]

Or switch to tension springs.
Then you will not have only a straight up pull on the cables.
No pulleys.

Aren't all springs tension springs?

 

[Schtauffer]

Anyone have a ballpark idea as to what I'd be looking at money-wise to switch?

Thanks again,
Ben

$400 should cover it. Where are you from, roughly?

 

[Colossus]

I'm in Southeastern Massachusetts.

 

[JakeKohl]

To be honest, that's cheaper than I expected them to be.

Yeah, I guess...I suppose it's when I re-rig a boat that I by 20-30 of them and all the supporting hardware that the cost starts to get to me.

 

[JakeKohl]

I'd imagine sailboats use some seriously heavy duty tackle.

It depends on the boat and the application...but they do have to stand up to a pretty nasty environment with salt water and sand.

 

[rlitman]

Aren't all springs tension springs?

Unless they're compression springs (not something you'd see in a garage door application though) or torsion springs, which is what I think he meant.

I'd imagine sailboats use some seriously heavy duty tackle.

They can. Some of the expense in sail racing gear is in weight savings, some in corrosion resistance, some in ease of use (like one side opening). Some is just because you put the word "marine" in the name.

I've also never dealt with any running rigging in a sailboat (parts that might run through a sheave or over a winch) that used wire rope. Stainless cable is often used in standing rigging, but that is pinned, or is tightened with a turnbuckle or something like that, but generally does not go through sheaves. Rope is used for that.

I was going to suggest just using some heavy/cast vbelt sheaves as theyre plentiful and cheap but those amazon parts look like a good way to go.

EDIt:also http://www.mcmaster.com/#rope-pulleys/=ts8q6q

I would think that vbelt sheaves can damage wire rope. Rope pulleys should be profiled to match the cable in use.

 

[jstroede]

Well I will say that I SERIOUSLY doubt that your door weighs anywhere near 1000 lbs. At 16x8, I would guess 400-450 unless you are talking about a $10000 custom 3.5" thick door.

http://ddmgaragedoors.com/parts/part/EXT-CNV8-400.html

That or something similar is what I would recommend.

John

 

[Dcampbell98xj]

If the door is over 40 years old and a 16x8 my guess is that it's made out of 2x4s and possibly some sort of tongue and groove cedar or pine commonly called a batton style door. Which with moisture being sucked into the wood for that many years. I'd say 1000 lbs is possible.

 

[rlitman]

If the door is over 40 years old and a 16x8 my guess is that it's made out of 2x4s and possibly some sort of tongue and groove cedar or pine commonly called a batton style door. Which with moisture being sucked into the wood for that many years. I'd say 1000 lbs is possible.

That's still a stretch.
A 2x4 on average weighs 1.28lbs per foot (it varies with the moisture content, and the type of wood).

Based on this, if I made a 16x8 door out of nothing but 2x4s stacked the tall way, it would weigh 562 lbs. If I stacked them the wide way, it would weigh 1310 lbs, but a 3.5" thick door with no panels. Really?

My current 8x7 wood garage doors weigh 130 lbs. Scaled up to 16x8, the same construction would weigh a hair under 300 lbs. That is SERIOUSLY heavy for a garage door.

 

[kbs2244]

Even a well painted wood door soaks up a LOT of water when exposed to a driving rain.
I have seen an over a 100 percent increase in door weight on a 16x 7 residential door after an over night thunderstorm.

I was replacing the opener gears, but I suggested a better paint on the door.

 

[Dcampbell98xj]

The type of door I was referring to is not a typical wood door that is used now a day. And those inserts are typically press board and when waterlogged will bow outwards and rot away if not properly primed and painted. A door that ways 130 lbs as an 8x7 is not going to way exactly double that based on the size. A 16foot wide door needs added support which in itself will add around 50 to 60 lbs to the door for it to be correct and not have worn parts every 3 months. So a 16x 7 door that your describing is going to be closer to 400lbs with added hardware. A door that has seen the elements for 40 plus years is going to weigh even more and any hardware or supports are going to weigh more because over time parts become cheaper made and lighter and they also don't usually last. As a garage door installer and builder who made custom garage doors I know how heavy they can get even when not water logged.

 

[Ironcrow]

Here's where I got some sheaves for a project at work:
http://esheaves.com/products/small-cable-sheaves.html