freeing up a pulley

[Rossynant]

+1

because WD40 is only White Spirit plus an SAE5 sewing machine oil and a perfume, It has very little in the way of penetrating properties.

I don't know what they put in in, but is something else than old kind used to be. No lubrication really.
Problem is it has something to dissolve corrosion, but also attack aluminum, if left longer. Don't ask how I found out...

 

[reeac]

I've had this problem a few times with deck organisers. My solution may sound brutal but it works: place the working end of a straight screwdriver against the edge of the sheave and tap with a hammer. Once you get any slight movement then you're nearly there as you can thread a rope through and "enlarge" that movement. Keep going, using a spray lubricant, until the sheave is completely free. Yes, you end up with a slight dent in the edge of the sheave, but that won't affect its working. If access permits then water pump pliars may also work.

 

[Daydream believer]

Lensman's idea will only work if the spindle can be trapped to stop it turning whilst rotating the pulley. Plus there is not enough room to actually get tension on the strap & rotate the tool
I would forget all the time consuming proposals & just drill the spindle out & chuck the pullies away. then get a new spindle & Nylon pullies.
You might even try drilling some large holes through the pulley at 90 degrees to the spindle. Eventually the spindle will collapse & the pulley may come out.
This way you save the risk of drilling out of line when drilling down the middle of the spindle

 

[rob2]

Assuming that the boom can be removed from the boat for a few days, it may make it easier to work on at home in the warm. In addition, you can stand it on end with the offending parts in a bucket of water - I'm assured that it's as good a solvent for rotting aluminium as any. I've tried all the methods suggested (non-destructive) on masthead sheaves and the most effective for me where many kettles of boiling water and persistent hammering, wrenching and swearing. I believe that the agitation removes the corrosion a bit at a time with the water flushing out the bits that have been loosened until its grip can be overcome by the physical assault. I may be wrong about the mechanism, but it helps to believe you're doing something useful!

Rob.

 

[charles_reed]

I ended up drilling out the boom end rivets, taking the whole thing home and soaking it in diesel. Being able to get it onto a bench makes all the difference.
I threw away the aluminium pulleys (they'd been for wire control lines) and replaced them with ABS pulleys.
From memory I heated the boom end with a paint-removal gun and then drove the axle out (do remove the retaining cover and screw).

PS that leaves the problem of re-rivetting the boom end, I used a long-handle rivet gun and aluminum rivets.
PSS I also got a replacement boom end - still have it 20 years later.
PPS I used ABS rather nylon ( swells when wet) or delrin (soft and shatters easily a low temperatures)

 

[vyv_cox]

Before trying drastic solutions make certain that you are actually dealing with aluminium on stainless steel. Your photo looks very like my Kemp boom, in which the sheaves have a 'bearing' of nylon between the two metals. The sheaves in my mast are exactly the same. Over time the nylon swells after prolonged contact with water and seizes tight on the spindles. The spindle can be pressed out without too much effort. I then reamed the nylon slightly, since when, many years ago, they rotate perfectly. Heating with a blowtorch, immersing the boom end in hot water, or in solvents, might increase the seizure.

 

[danielefua]

Before trying drastic solutions make certain that you are actually dealing with aluminium on stainless steel. Your photo looks very like my Kemp boom, in which the sheaves have a 'bearing' of nylon between the two metals. The sheaves in my mast are exactly the same. Over time the nylon swells after prolonged contact with water and seizes tight on the spindles. The spindle can be pressed out without too much effort. I then reamed the nylon slightly, since when, many years ago, they rotate perfectly. Heating with a blowtorch, immersing the boom end in hot water, or in solvents, might increase the seizure.

I fully endorse vyv_cox because I have had a very similar problem with the nylon spacers of my large genoa/spinnaker turning blocks. Only difference is that the spindle (12mm diameter) would not agree in being "pressed out without too much effort" and I tried almost all without success. I ended up using a thin saw blade to make more room on the sides of the sheaves: a temporary and very unprofessional job, I reckon, but it worked.

Daniel

 

[eidiohir]

Before trying drastic solutions make certain that you are actually dealing with aluminium on stainless steel. Your photo looks very like my Kemp boom, in which the sheaves have a 'bearing' of nylon between the two metals. The sheaves in my mast are exactly the same. Over time the nylon swells after prolonged contact with water and seizes tight on the spindles. The spindle can be pressed out without too much effort. I then reamed the nylon slightly, since when, many years ago, they rotate perfectly. Heating with a blowtorch, immersing the boom end in hot water, or in solvents, might increase the seizure.

That is a good question. My boom is by John masts It might be good to give them a call.
By the way I have drilled out the rivets and removed the boom end. It gives me much more room to work on it here at home in the shed (nice and warm).

 

[vyv_cox]

That is a good question. My boom is by John masts It might be good to give them a call.
By the way I have drilled out the rivets and removed the boom end. It gives me much more room to work on it here at home in the shed (nice and warm).

I did the same, many years ago. When I replaced it I installed Rivnuts instead of pop rivets. This has proved to be a most useful modification on several occasions since.