Delrin Sheaves

[Joe Blizzard]

One of my little projects for the winter was to make new sheaves for my masthead which I hope will be a little friendlier to my dyneema halyard than the original aluminum sheaves. I cut blanks out of a sheet of delrin with a hole saw, then shaped them in my drill press with a round file.

 

[Kings Gambit]

I believe Delrin will deteriorate with UV exposure.

 

[PaulK]

May be OK inside the masthead casting though, no? If not, he can reshape the aluminum sheaves to make the channel for the line more rounded and flat-bottomed, instead of v-shaped.

 

[dlochner]

I believe Delrin will deteriorate with UV exposure.

Depends on the Delrin some is UV stable.

Delrin® 527 UV Stable Acetal | Boedeker

 

[sailme88]

Necessity IS the mother of invention... Despite any negativism on life span, YOU did this ! Well done. And if you only get 8 years or so out of it, you've got the skill to make more.. Again, KUDOS !

 

[Kings Gambit]

Depends on the Delrin some is UV stable.

Delrin® 527 UV Stable Acetal | Boedeker

OK. It looks like he’s used the UV stable type, which is black. My (limited) use of Delrin has been with the original (white 550) type, which does slowly deteriorate, and crack. I see it has been discontinued & replaced with 511P. Good to know about the stabilized version. Always learning new things here. Keeps me logging on!
KG

 

[jon hansen]

YES! well done sir

thanks for sharing

 

[dLj]

One of my little projects for the winter was to make new sheaves for my masthead which I hope will be a little friendlier to my dyneema halyard than the original aluminum sheaves. I cut blanks out of a sheet of delrin with a hole saw, then shaped them in my drill press with a round file.

View attachment 189458 View attachment 189459

Just out of curiosity, what was happening with the original aluminum sheaves that you felt the need to switch them to the acetal copolymer sleeves?

dj

 

[Terry Cox]

Very nice inventive solution. Although the aluminum sheaves appear to have rounded bottoms, perhaps the Delrin will work better. Our originals are white synthetic material of some type. Likely need to replace at some point due to the wear over the years. Good idea of yours. I've got the tools to make my own as you did.

 

[Joe Blizzard]

Just out of curiosity, what was happening with the original aluminum sheaves that you felt the need to switch them to the acetal copolymer sleeves?

They were working fine. The halyard rides a little high in them, but it never caused any real problems. I just can't leave well enough alone.
The material I used is Delrin 150E, which is not one of the grades marketed as UV stabilized, but I'm not too worried about it. Maybe I'll lube them with SPF50 or something.
Speaking of plastics, I'm using a lifting handle for my little Evinrude outboard which I 3D printed in PLA. (PLA is a terrible choice for wet or outdoor environments.) I wanted to use ABS or ASA, but I couldn't get those to print properly on my Ender 3, so I ended up using one of my PLA prototypes and spraying it with a rattle can of farm implement paint from Tractor Supply to give it some protection. It made it through its first season without any noticeable degradation.

 

[dLj]

They were working fine. The halyard rides a little high in them, but it never caused any real problems. I just can't leave well enough alone.

Good to know.

You may wish to keep them, perhaps making the groove a deeper so the halyard does not ride high and if, hopefully not needed, the delrin does degrade, you can simply put those back in.

One thing I did notice was the outer surface of original sheaves showed wear patterns on the outer surfaces that indicated to me that you could improve those by adding in a thin polymer washer to improve the way they work in that mast head. It they were mine, I'd put them in a lathe, turn down a recessed surface to insert a washer that would stick out only a few thou, keeping the sheave from rubbing against the mast head. Just a thought.

dj

 

[SailingLoto]

i just ordered round stock delrin to turn sheaves out on my buddy's lathe. I never thought about cutting discs with a hole saw. genius idea man!

 

[jssailem]

i just ordered round stock delrin to turn sheaves out on my buddy's lathe. I never thought about cutting discs with a hole saw. genius idea man!

Reading the detail on the Delrin website, notable is the nature in how the product is made. It could be a factor for the raw product you buy and then fashion into your end product.

• Larger Cross Sections are prone to Centerline Porosity

I wonder if the flat piece and hole saw method is better than the round stock and a band saw cut piece in terms of the end product - sheave.

 

[SailingLoto]

Reading the detail on the Delrin website, notable is the nature in how the product is made. It could be a factor for the raw product you buy and then fashion into your end product.

that is a goos point. I will read up on that! Thank you for bringing it to my attention.