4x4 LFR for snatch recovery of vehicle - marine application of the LFR, no mention of anchors :)

[Neeves]

The problems I had with the sheaves such as shown above are:

• Too narrow, no flare. Not tolerant of lines crossing at an angle. LFRs do better.
• Wear on the edges. Plastic sheaves are notorious for wear on the edges if the line is off center. They quickly groove and then become prone to jamming.
• Sharp edges. If they were metal they would wear the rope. LFRs are smooth on the edge.

Not sayin' a commercial sheave could not work, but it was the LFR shape and material that I wanted. There are good tulip shaped winch feeder blocks, but they were all too tall for the space available. The above sheave is perfect for ropes running in exactly the plane of the block, but for example, genoa leads don't look like that. The LFR gave me a workable shape in a very low, compact package. For me, it was very easy and fun, but it was, perhaps, a little shop intensive. Special tools help.

quote

For me, it was very easy and fun, but it was, perhaps, a little shop intensive. Special tools help.

unquote

This IS, after all, PBO

Jonathan

 

[thinwater]

There are a few other interesting characteristics that I'm not sure what to make of.

• Unlike a plastic sheave with a plain drilled bear hole, the bearing surface is huge. In my case, over 1" compared to 3/8". Less wear. Higher load carrying capacity.
• By using a low friction ring (or other similar low-friction sheave on the outside) you get Teflon filled anodizing running on HDPE or similar. Very low friction and wear.

It's an interesting composite of wear surface and bearing materials and bearing size. The plastic core is NOT turning on the bolt. For example, if the "ring" was available in different shapes, it could make a superior genoa guide; they seem to either wear out (plastic) or bind (metal). I may have to play with my leads, but that would mean figuring out low friction anodizing.

 

[Neeves]

There are a few other interesting characteristics that I'm not sure what to make of.

• Unlike a plastic sheave with a plain drilled bear hole, the bearing surface is huge. In my case, over 1" compared to 3/8". Less wear. Higher load carrying capacity.
• By using a low friction ring (or other similar low-friction sheave on the outside) you get Teflon filled anodizing running on HDPE or similar. Very low friction and wear.

It's an interesting composite of wear surface and bearing materials and bearing size. The plastic core is NOT turning on the bolt. For example, if the "ring" was available in different shapes, it could make a superior genoa guide; they seem to either wear out (plastic) or bind (metal). I may have to play with my leads, but that would mean figuring out low friction anodizing.

If you turn the insert (the core), nylon - no sign yet of swelling - I think its, water absorption, is a phurphy for large pieces. accurately and make a tool to follow the compound shape of the LFR then the bearing surface is huge.

Anodising is not difficult, simply another PBO type process. Hard anodising, meaning you would need to re-anodising less frequently, is possible but I'm not sure how you know how hard your anodising is (is it much different to ordinary anodising where done at home)). Low friction anodising, adding Teflon - I have no idea if its possible for an amateur. My attempts at coloured anodising were poor - the colours very understated. Lots of you-tube vids on anodising

If you use the 4x4 monster sheaves they are hard anodised and cheap as chips. If you need smaller LFRs try Temu or Aliexpress, you can buy them cheaply and they come marked Ronstan, or other, as most LFRs are made in China.

You need to use the 7075 alloy, which is hard, and thus more difficult to machine (all LFRs are 7075) and being hard will be more difficult to polish - but not impossible (I used it on some of my snubber bridle plates). But again possible. I had some of my bridle plates made in China and bought my 'Ronstan' LFRs from the same factory (again cheap as chips)

The unknown is the teflon or hard coating - but .... is it needed ? if you have a good polish.


Personally I'd use 'factory' made LFRs and make up the plastic core. But if someone knows teflon filling is possible - I'd give it a try.

Jonathan

 

[noelex]

You need to use the 7075 alloy, which is hard, and thus more difficult to machine (all LFRs are 7075) and being hard will be more difficult to polish - but not impossible (I used it on some of my snubber bridle plates). But again possible.

Many companies that make marine low-friction rings do not specify the type of aluminium used, but those that do use 6061 aluminium. This makes sense; 6061 aluminium has far better corrosion protection than 7075 aluminium. Maybe someone makes marine low-friction rings from 7075, but I could not find anyone with a quick Google search.

Companies that indicate they use 6061 aluminium in their low-friction rings include: Harken, Wichard, Schaefer, Tylaska, Blue Shark, Blue Wave.

In contrast the large 4X4 low-friction rings mostly specify 7075 aluminium; obviously, corrosion is less of an issue for their designed application, but there are a few made from 6061 if you look around. On the other hand, the 4x4 low-friction rings are cheap enough that corrosion is less of an issue.

 

[Neeves]

I note that Ronstan and Allen Brothers don't specify their aluminium alloy used. For confusion Allen Brothers call their LFRs 'thimbles' and their 90mm version costs over Stg50 (ouch!). Allen make (what we call LFRs) stainless thimbles. Both aluminium and stainless thimbles can be sourced as a 2 part threaded component.

Provided the anodised coating is adequate corrosion should not be an issue, at all. Given the price structure I'd source via Temu or Aliexprerss and actually not worry about the base alloy.

I note that you are using the big LFRs made for RV 4x4 application - for your runner blocks. The normally accessible versions are made from the 7075 alloy - have you noticed any corrosion issues? or did you specifically opt for 6061 versions (and if the latter - what was your source?)

As far as I know the 7075 is the strongest aluminium alloy so it is a compromise, strength or corrosion resistance - and my experience with the 7075 alloy is that anodised - strength wins out.

7075 Aluminium vs 6061 Aluminium

Ringe mit geringer Reibung R5X4 R7X5 R10X7 R14X10 LFR Mohamed Qualität Segelboot Aluminium 6061, hart eloxiert mit PTFE-Beschichtung. Für Yachtsegel - AliExpress 15

These are the 6061 alloy and described as the same quality as Antal. Note the prices are in A$

Jonathan

 

[noelex]

I note that you are using the big LFRs made for RV 4x4 application - for your runner blocks. The normally accessible versions are made from the 7075 alloy - have you noticed any corrosion issues? or did you specifically opt for 6061 versions (and if the latter - what was your source?)

They were advertised as 6061, but I have subsequently also seen what looks like exactly the same model listed as 7075 .

I think it is a little like the inexpensive "no name" MPPT solar controllers that turn out to be cheaper PWM models in reality. We need to remember that these 4x4 LFR are incredibly good value so they should not be expected to conform to the same standard as the marine versions. All our smaller marine name brand (most are Wichard) LFR are 6061 and these are holding up well, but we have only used the large 4X4 models for a short time.

You have to search a bit to find the 4x4 LFR in 6061 (rather than 7075), but they are available, just from Amazon etc (if their claims are accurate).

If you do end up buying a 4x4 7075 LFR the anodising helps significantly in reducing the potential for corrosion. They are also likely to be much stronger than is needed for most of the applications we will use them for (so they will likely still be strong enough even with some corrosion). This combined with low cost (so periodic replacement, if needed, is feasible) means that inexpensive 7075 LFR are still worth considering, but 6061(or one of the other six series aluminium's) is better for marine use.

 

[thinwater]

I don't know. I do know that climbing carabiners (7075) do great on the boat until the anodizing fails, then they corrode like mad.

I think I'm going to try turning a new genoa lead block from some 6061 I had, anodizing, and then impregnating with Teflon. We'll see how it goes. The core will be as large as practical, and probably Teflon; if the coating doesn't work it will wear in. Something to do. I'll leave the other side alone and compare performance.

 

[Neeves]

They were advertised as 6061, but I have subsequently also seen what looks like exactly the same model listed as 7075 .

I'm not sure what you mean by 'exactly the same model' but the RV 4x4 models I see all look as if they are all made by the same company (possible but unlikely) or all good copies of each other. I do note they all claim exactly the same UTS. Strangely they all came to the market at roughly the same time. I do know there were variants - but they seem to have disappeared.

I don't know. I do know that climbing carabiners (7075) do great on the boat until the anodizing fails, then they corrode like mad.

I think I'm going to try turning a new genoa lead block from some 6061 I had, anodizing, and then impregnating with Teflon. We'll see how it goes. The core will be as large as practical, and probably Teflon; if the coating doesn't work it will wear in. Something to do. I'll leave the other side alone and compare performance.

How are you going to 'impregnate' with Teflon? Impregnation implies porosity and I would have thought anodising is pore free.

A reason I would source my LFRs from Alibaba, Temu or Aliexpress - my lathe and tools are for wood rather than metals and the Chinese LFRs are so cheap.


Jonathan

 

[Chiara’s slave]

I’ve got a use for one, I’ll put one, semi permanently, on my port ama tip (there’s a U bolt there) to thread a mooring line for springing off our mooring. It will aid recovering the line when we are done.

 

[Neeves]

I’ve got a use for one, I’ll put one, semi permanently, on my port ama tip (there’s a U bolt there) to thread a mooring line for springing off our mooring. It will aid recovering the line when we are done.

I don't understand - a photo (better a video ) might make it obvious to my aged grey matter - but I think you are over engineering - but maybe that is the intent. You can source cheap carabiner rings or just an alloy carabiner, see Thinwater's post 27.

These 4x4 rings are quite chunky - not something a sporting tri would carry, semi-permanently.



Jonathan

 

[Chiara’s slave]

Mine are about 40mm. I’d have to draw it, the idea is to move the attachment point of the spring outboard for maximum effect, and still be able to pull it back on board afterwards. Friction is a big deal when there’s 15m of rope and your crew has artificial wrists

 

[thinwater]

I'm not sure what you mean by 'exactly the same model' but the RV 4x4 models I see all look as if they are all made by the same company (possible but unlikely) or all good copies of each other. I do note they all claim exactly the same UTS. Strangely they all came to the market at roughly the same time. I do know there were variants - but they seem to have disappeared.





How are you going to 'impregnate' with Teflon? Impregnation implies porosity and I would have thought anodising is pore free.

A reason I would source my LFRs from Alibaba, Temu or Aliexpress - my lathe and tools are for wood rather than metals and the Chinese LFRs are so cheap.


Jonathan

No, from what I understand it is semi-pourus until sealed. That is how it can be died. But we'll see. I'm no expert.

I'm thinking that if it is running on a Teflon core it probably won't matter.

I agree, I would not make LFRs. Too easy to buy. This is for something special where I need a different shape.

 

[noelex]

One noticeable difference between the 4x4 LFR (at least on the two I have purchased) and the marine LFR is the appearance and slipperiness of the anodising.

The marine LFR has a significantly more slippery (to the finger) coating.

I am no expert, but I understand there are several types and different methods to anodise aluminium, from the simplest type I to the more complex type III.

The advantage of type III is that it is a much thicker, tougher process, but has greater "ability to retain lubricants and PTFE coatings”. Google also reports "Type III's inherently thick, dense, and dark base often produces deeper, more muted colors compared to Type II anodising…. 6000 series aluminiums turn almost black"

I wonder if the marine LFR has the type III anodising and the 4x4 LFR has a lower quality coating. Not a deal breaker, but a surface with lower friction is obviously a help. It does also help justify the higher cost of the marine rings, especially as they are still very inexpensive in marine terms given what they can do.

 

[thinwater]

One noticeable difference between the 4x4 LFR (at least on the two I have purchased) and the marine LFR is the appearance and slipperiness of the anodising.

The marine LFR has a significantly more slippery (to the finger) coating.

I am no expert, but I understand there are several types and different methods to anodise aluminium, from the simplest type I to the more complex type III.

The advantage of type III is that it is a much thicker, tougher process, but has greater "ability to retain lubricants and PTFE coatings”. Google also reports "Type III's inherently thick, dense, and dark base often produces deeper, more muted colors compared to Type II anodising…. 6000 series aluminiums turn almost black"

I wonder if the marine LFR has the type III anodising and the 4x4 LFR has a lower quality coating. Not a deal breaker, but a surface with lower friction is obviously a help. It does also help justify the higher cost of the marine rings, especially as they are still very inexpensive in marine terms given what they can do.

Some times it seems everything marine is marked up. Some times you pay your money, you make your choice, and get what you paid for.

I prefer wire gate (not locking) climbing carabiners for many utility uses. Holding trolling lines. Securing bit of rigging in standby (not working) positions. Climbing, of course. Jury rigs. They just work better; climbers will not put up with snaggy gates when standing on a dime-edge. They are light weight and very strong. 6 sigma testing is required under the standard. On the other hand, the anodizing is not as durable, but for the use it is good enough. When it fails and they corrode I pitch them and feel OK about it. They were half the price and twice as functional while they lasted.

Not sure where 4x4 LFRs figure in this sort of math. If for occasional use, almost certainly just fine. If I decide to make new lead blocks, I will be research the heck out of the anodizing process. I will like treat a few blank parts first and leave them in seawater for a while.

 

[Neeves]

One noticeable difference between the 4x4 LFR (at least on the two I have purchased) and the marine LFR is the appearance and slipperiness of the anodising.

The marine LFR has a significantly more slippery (to the finger) coating.

I am no expert, but I understand there are several types and different methods to anodise aluminium, from the simplest type I to the more complex type III.

The advantage of type III is that it is a much thicker, tougher process, but has greater "ability to retain lubricants and PTFE coatings”. Google also reports "Type III's inherently thick, dense, and dark base often produces deeper, more muted colors compared to Type II anodising…. 6000 series aluminiums turn almost black"

I wonder if the marine LFR has the type III anodising and the 4x4 LFR has a lower quality coating. Not a deal breaker, but a surface with lower friction is obviously a help. It does also help justify the higher cost of the marine rings, especially as they are still very inexpensive in marine terms given what they can do.

Marine LFRs commonly have teflon, somewhere, somehow, in the coating. As soon as aluminium is exposed to air it 'self' anodises - but the coating is thin. Anodising is sometimes described as hard. There is a subtle difference between normal and hard anodising (at the deeper recesses of my mind - hard anodising is completed cold), During 'home' anodising the acid bath warms up - cooling it is an extra complication (that I ignored). Colour is incorporated in the anodising process, its completed at the same time. Effectively as the anodised layer is developed and is encouraged to be thicker the dye is incorporated in the coating. The coloured layer is irrelevant to performance - it just makes the item stand out or not, it has no technical advantage. However as anodised components wear the coating will be lost and eventually the imposed layer will be removed - if the imposed layer is coloured the new layer will have no colour. Dylon is the common dye used for home anodising - I did not get it to work - my dyed, anodised 7075 was wishy washy. However it definitely had an anodised coating it was 'different' to the natural layer - it felt denser and looked 'coated'. It looked as if it had a thin varnish layer.

The anodised layer is aluminium oxide, which is slightly softer than diamond. It might be hard but it will still wear - but should, in theory constantly replace itself as raw aluminium is exposed. I assume a product that is hard anodised has a more dense anodised layer.

7075 when anodised does not corrode but raw 7075 does corrode, in the marine environment. But as all items are anodised, those pretty colours - 7075 does not corrode until the coating is lost.

Home anodising is quite simple, basically a source of 12v (battery or battery charger), sulphuric acid, a highly polished and scrupulously clean item and a bath and patience. AFAIK - hard anodising would need a chilled bath, replaceable ice, within which you would hold the process (in an inner bath).

Jonathan

 

[noelex]

7075 when anodised does not corrode but raw 7075 does corrode, in the marine environment. But as all items are anodised, those pretty colours - 7075 does not corrode until the coating is lost.

I agree with your and Thinwater’s comments (post #27) that raw 7075 corrodes in the marine environment (like mad ! ). I was always surprised by your use and endorsement of the aluminium Anchor Right Excel anchor which has a raw uncoated and non anodised 7075 shank. This is not an anchor thread, nevertheless it shows manufacturers don't always choose ideal materials.

As an owner of an aluminium yacht, it is frustrating to hear of instances where non-marine grade aluminium is used, especially in products designed to be immersed in seawater. This gives aluminium an undeserved poor reputation for corrosion resistance.

Home anodising is quite simple, basically a source of 12v (battery or battery charger), sulphuric acid, a highly polished and scrupulously clean item and a bath and patience. AFAIK - hard anodising would need a chilled bath, replaceable ice, within which you would hold the process (in an inner bath).

Anodising is a simple and useful process, but the higher grades of anodising (type III) involve complex industrial processes with high voltages that I understand are beyond the capabilities of the DIY owner. I am also not sure if the additional slippery coatings that have been applied to marine LFR are viable as a DIY process. They don’t seem to be incorporated into the 4x4 LFR, and the internet suggests that these low friction coatings are only durable if type III anodising is also used, but I am not an expert.

 

[Neeves]

I agree with your and Thinwater’s comments (post #27) that raw 7075 corrodes in the marine environment (like mad ! ). I was always surprised by your use and endorsement of the aluminium Anchor Right Excel anchor which has a raw uncoated and non anodised 7075 shank. This is not an anchor thread, nevertheless it shows manufacturers don't always choose ideal materials.

As an owner of an aluminium yacht, it is frustrating to hear of instances where non-marine grade aluminium is used, especially in products designed to be immersed in seawater. This gives aluminium an undeserved poor reputation for corrosion resistance.



Anodising is a simple and useful process, but the higher grades of anodising (type III) involve complex industrial processes with high voltages that I understand are beyond the capabilities of the DIY owner. I am also not sure if the additional slippery coatings that have been applied to marine LFR are viable as a DIY process. They don’t seem to be incorporated into the 4x4 LFR, and the internet suggests that these low friction coatings are only durable if type III anodising is also used, but I am not an expert.

Our aluminium Excel anchor from Anchor Right showed no sign of corrosion after about 10 years sitting on our bow roller or being used, as an anchor. I confess I was cautious and monitored the anchor - by looking. But over time and with an absence of corrosion I stopped worrying.

I have never heard anyone complaining about corrosion of the anchor, the ballast, I understand is lead, is welded into a sealed compartment. If there were regular complaints they would be known, bad news travels fast and it cannot be suppressed.

Whilst it is a bit of a mystery why there is no corrosion - the absence of corrosion (and news of same) allows the anchor to be still available. You have a personal interest - if there were problems or instant es of corrosion I am sure you would be the first to document same.

One answer may be - they don't actually use 7075, which was stamped into our shank.

Jonathan

 

[ash2020]

This thread has got me interested. I've just bought a length of 4mm Dyneema and a 30mm LFR. It could be a much cheaper alternative to swivel blocks. Question is, what makes an LFR work? is it the shape or the material? It looks like anodised aluminium. but doesn't the anodising wear fairly quickly? As the ring is the expensive bit of the combo, I am going to try printing a nylon one and doing a side by side test. It could be a Dyneema soft shackle and a 3D printed nylon ring might just do the job. Thanks for the inspiration.

 

[noelex]

Question is, what makes an LFR work? is it the shape or the material?

It is a combination of the shape and smooth surface, although keep in mind the name is a little misleading. They still have considerably more friction than the best low friction blocks.

It looks like anodised aluminium. but doesn't the anodising wear fairly quickly?

Yes, it is anodised aluminium. On the marine blocks, the anodising is quite durable. (Our 4X4 LFRs are too new to tell.) A couple of the LFRs have chips on the outside where they have hit the bulwark etc, but I have not noticed any wear on the inside from rope, and we have been using them for a long time.

I am going to try printing a nylon one and doing a side by side test. It could be a Dyneema soft shackle and a 3D printed nylon ring might just do the job. Thanks for the inspiration.

Let the forum know how well the nylon LFR works. This is PBO after all . You haven’t mentioned the application, but unfortunately, the lower strength and higher friction of nylon are likely to limit its usefulness, but I could be wrong, and it should be cheap and easy to try.

There are some cheap sources of "no name" aluminium LFR particularly direct from China, Others may be able to recommend a reliable source.

 

[thinwater]

... Let the forum know how well the nylon LFR works. This is PBO after all . You haven’t mentioned the application, but unfortunately, the lower strength and higher friction of nylon are likely to limit its usefulness, but I could be wrong, and it should be cheap and easy to try.

In fact, I use LFRs for genoa 3D lead guides with polyester sheets. I think many people do. The polyester is better in the hands and winches. I also use LFRs with Dyneema lines to pull the 3D leads outwards. In both case the deflection angle ranges from nil to 90-120 degrees. I also tested them for Screecher turning blocks (120 degrees) but went back to snactch blocks for other reasons--they worked fine.

I also use rappel rings (solid rings made from anodized aluminum that climbers used--there are similar marine versions, but no the sizes I wanted). They are less efficient than LFRs because of the smaller radius, but the trends are the same and they have some rigging advantages for certain low deflection applications.

I also did a bunch of tests for Practical Sailor, comparing block efficiency through 180 degree bend, with a variety of brands, sizes, and line materials.

The short version is that 180 degree turn efficiency was about 80% for Dyneema, 73% for nylon, 70% for polyester, and 96% for ball bearing blocks. Because efficiency is multiplicative, multi part LFR tackles are not good for anything that is adjusted frequently or under load; I used LFRs for two cascades, but they are not adjusted under full load bobstay on folding sprit).

LFRs are not for everything because of friction. But they are ...

• As durable as ball bearings IME.
• Immensely strong and reliable. This makes them good for standing rigging or a bobstay that bashed through waves.
• Dirt can't jam the bearings. The can't seize up.
• Light. Less banging on deck can make rings good for deflectors.

I have about 14 LFRs/solid rings, and about 30 ball bearing blocks. I think I have the right blocks in the right places, for me. Many applications can go either way.