Anchor Roller Refurbishment?

[Nigel]

Originally posted in YBW...

My Anchor Roller needs refurbishment.




Is there any reason the rollers are normally in a solid lump? It occurred to me that I could just replace the middle of the roller, so two tapers on the sides, and a flatter section in the middle; it looks like UHMWPE may be the ideal material for the middle part. Something like the attached drawing.

For the axles I hope to bore and tap the existing rods and use countersunk A2 screws, countersinking the side plates will be a bit of a bugger though.

Has anyone else replaced their rollers? How did you do it?

Does anyone recognise the logo of the roller manufacturer? [Edit: Niro Petersen]

[Yngmar]

UHMWPE (the same stuff Dyneema/Spectra fibres are spun from, which share the same disadvantage) suffers from creep under static loads, which I believe makes it unsuitable for the anchor roller job, as there'll be a constant load in one point for a long time. Add tropical temperatures (if you're lucky - my sunny day of taking the cockpit table apart was just cut short by a rain shower) and the low melting point of 130°C and it may not last very long before losing its round shape and accepting that of the anchor shank instead.

POM (Acetal/Delrin) is probably better suited and also easier to machine.

The reason the roller is made of one part and not multiple is very likely the obvious one - it's simpler and easier to make and assemble one part than three. I see no problem with making it in three parts that are tensioned by the shaft end pushing them together, except perhaps accumulation of dirt/salt in the gap between them and subsequent wear.

I'd love to identify that NP-calipers logo as well. Seen it in plenty places on my boat.

[Nigel]

POM (Acetal/Delrin) is probably better suited and also easier to machine.

It seems even that choice is a minefield: Acetyl Or Delrin

[Yngmar]

POM (Acetal/Delrin) is probably better suited and also easier to machine.

It seems even that choice is a minefield: Acetyl Or Delrin

Very interesting! I like a supplier that cares enough to educate their customers. I didn't know they were subtly different. So by that, the POM-H (Delrin) type would be slightly better suited (higher rigidity, hardness and operating temperature) than POM-C and the centerline porosity won't matter because the center will be drilled out - that's where the axle goes.

[Salty]

For what it's worth, on my B36, the anchor roller is made from a single lump of black plastic material. It's a while since I last removed the roller, but I'm fairly sure it rotated around a centre full width bearing which consisted of a stainless tube with a long central bolt to form the axle going through both cheek plates and the tube.

[Nigel]

I'd love to identify that NP-calipers logo as well. Seen it in plenty places on my boat.

Thanks to "Tradewinds" on YBW it has been identified: Niro Petersen

... rotated around a centre full width bearing which consisted of a stainless tube with a long central bolt to form the axle going through both cheek plates and the tube.

From what I can see the main swivel is as you describe, but the three cross-members appear to be solid rod which has been pressed into a rivet head on each side. I'm a little nervous about drilling these out in case I can't refit them, I plan to use countersunk machine screws.

[Impavidus]

Nigel. Hi, I can turn these up for you? I don't have any Delrin or similar in stock but if you can get hold of some and give me a drawing? The fixed bars can be milled or drilled then tapped and threaded. They will then take a M6-M8 bolt in 316? Again I can do this in the workshop. Get to Portsmouth you can have a crack at making them yourself 

Best regards.

Ant.

[Nigel]

I've decided to upgrade the axles to 16mm to allow an M8 countersunk screw either end. It worries me slightly that this will require a much deeper countersink cut into the side plate. 

However, looking at it again, I'm wondering if I need to be concerned about making the screw heads flush at all! The main swivel is central between the axles, and roughly half way up the box fixed to the bow. Can the ends of the axles pass inside the box when swivelled either way?

[Edit] It seems they do pass inside the box, but a spacer would work.

[Impavidus]

Nigel. How much clearance is there now between the main body and the outside of inner side plates? If disassembled, the inner moving part and the rollers could be made slightly smaller to give more clearance. Then centred using two small bushes on the main pivot pin? This would enable you to use half nuts and skim a few mm off the bolt heads for the new rollers? All doable with off the shelf fixings?

best regards

Ant

[Nigel]

Not possible to use bolts, skimmed or not. The axles also have to seperate the side plates, so need a step before passing through.

[ANTREVELL]

If you can tell me how to upload a picture I will send a pic of the mod I did on my anchor roller allowing to tilt in the same way that Nigels does

Regards Tony  Pegatha

[MarkTheBike]

Tony, click the 'Additional Options' under your -Reply- text box. There's an option to browse for file(s) to upload...

[Neil]

My anchor roller is a similar design. The rollers themselves are not worn, but soon will be on one side as they are not turning. Very frustrating design as they cannot be easily taken off for servicing/ lubrication/ replacement as the above experience shows. Any tips for easing or lubricating in situ so that they roll freely?

[ANTREVELL]

I have attached my modification to the bow roller . I added the attachment to the existing bow fitting . It makes launching the anchor easy as it is effectively unbalanced so launches as soon as the chain is slackened and it  keeps the anchor away from the hull.
Regards Tony Pegatha

[Nigel]

Update on completed unit. I increased the axles to 16mm, narrowed the whole swivel unit by 4mm to allow for a small protrusion of the screw heads and made 2mm washers out of acetyl. The end tapers of the larger roller are made from the original roller, this meant I only needed to buy 70mm diameter Delrin. There is a 0.5mm step on each end to reduce friction.

[Impavidus]

Tidy 

[Aquila]

Great job!

[MarkTheBike]

Very neat... 

[Neil]

I'm suffering from anchor roller envy. Lovely solution.