Boom sheave replacement

[mrangry]

I have a z-spars boom and have ordered replacement inboard and outboard sheaves to replace the original ones as most of them have split. The sheaves are held in place by a stainless steel pin which if I understand correctly is a friction fit. I have tried drifting the pin out with a hammer and punch but it wont budge. Has anyone done this before and offer any words of wisdom before I move onto the sledge hammer?

 

[Boathook]

I have sometimes found that the pins have the ends 'hammered' over to stop them sliding out. This is on fittings other than z-spars though.

 

[ianat182]

Might they be sprung taper pins that are removed only from one side , i.e. punch out from smallest dia end.?

ianat182

 

[mrangry]

Might they be sprung taper pins that are removed only from one side , i.e. punch out from smallest dia end.?

ianat182

Yes I think they are supposed to come out one side, but looking externally at the pins, each side looks the same

 

[LadyInBed]

I would suspect dissimilar metal reaction has welded them in.

 

[ianat182]

A drop of diesel or wd40 or other releasing fluid might help, leave over night with wrapping; perhaps even heat gun on the boom might expand slightly enough to release.

ianat182

 

[neil_s]

Gentle heating often works - boiling water might just do the trick

 

[RJJ]

I have similar on sparcraft.

I failed to do mine and passed on to the pros, who liberated it with heat, any form of penetrant, and a generous application of force with a lump hammer. When I asked how much force they said "you'd have cried if you watched it". Which left me feeling that I could have done it myself but was too much of a wuss (countered by the possibility that if they broke it they might help with the repair)

 

[Tintin]

Bigger hammer worked for me

 

[Bodach na mara]

Tip. Get something like a cable tie round the sheave before you remove the pin. If you don't, the sheave will drop into the boom and roll out of sight. This I know.

 

[Daydream believer]

If trying to drive the pins out I would suggest heat applied evenly to the whole of the aluminium part. Then when applying force one should make sure one supports the webs as it would be easy to start moving the pin through one web but not the far one & shear it off.

 

[mrangry]

Here is the offending pin on the inboard end of the boom

 

[mrangry]

The other side

 

[Stemar]

+1 for boiling water and a bigger hammer, but support the bottom of the casting with a lump of wood. I wouldn't want to try too hard with the boom in place!

Alternatively, take it to your friendly local engineering shop and get them to press it out.