The Gooseneck Diary

[Pete1177]

I think the next 'big' issue to resolve with the Supernova is the gooseneck. In the tradition of keeping a blog of progress I've decided to create a diary, similar to what I did with the tapered battens (see 'The Batten Diary'). I'd like to see this issue resolved, but it will be a long process of design, testing, redesign, more testing, more design ... you get the picture.

So what's wrong with the existing gooseneck, you may ask. If you sail a Supernova you will know. If you don't, you won't ... so here goes ...

The problems with the existing pin are several:

1. The wear surfaces of the pin, toggle and mast bracket oxidise easily and those pesky oxide deposits land on the boat deck surfaces especially around the mast step and control lines. As the gooseneck wears, more fresh metal is exposed to oxidation which results in more pesky deposits. This makes the boat look dirty and stained.

2. Although the aluminium alloy has high tensile strength, it is susceptible to permanent deformation under extreme stress conditions, such as a broach capsize downwind to leeward when the rig hits the water and the momentum of the boat causes high forces. This has resulted in the mast bending, the gooseneck shearing or breaking away at the mast rivets. In normal use, over time, the pin flanges can permanently deform and the toggle-pin rivet can start to pull away.

3. Depending on sailing conditions, the assembly can exhibit a high degree of wear, especially on the pin and mating surfaces. The wear on the mating surface of the lower bearing flange on the mast bracket is accelerated if a stainless washer is not used as a shim. Consequently, the gooseneck assembly can have a relatively short life, maybe 2 years or less. Although it is not an expensive part to replace, the mast bracket is difficult to replace on a DIY basis. The cost of a replacement assembly is £30.

4. An ‘extended’ ruggedized gooseneck is available for £55, although this still uses the same rubbish pin and toggle part. It does not eliminate the issues above except providing a more substantial mast bracket affixed to the mast by 6 rivets instead of 4. A ‘marketing’ claim is that the extra ‘extension’ of the bracket improves downwind sailing by taking the boom further out - a bit cheeky I think. You can get a stainless Allen pin from the swindleries for about £20 but this pushes the price beyond £80 (with P&P) and you still have to do some DIY machining on the mast bracket (that you paid £55 for) to make it fit.

I have tried for the last 9 months to get a 3D design house to design a new assembly with 3D printing technology. I met these guys at the NEC Classic Car show and gave them an idea of what I was looking for. I didn't pay any money out except for a new gooseneck assembly to give them and an Allen stainless pin. So you can say my investment so far has been sub £100 and a bit of my time (sourcing a scrap mast section etc etc). The general understanding is that 3D printing can do anything, with a home 3D printer - simply not true. Anyway, not to digress and to cut a long story short, the design house approach didn't go too well. To be fair on the guys they were a start up running out of a living room, then moved into some offices, and now about to move into new offices. A lot of business stuff got in the way and I think to design a new mast bracket with UJ (universal joint) is quite a tall order, when you think about it.

A couple of weeks ago I got a first prototype from them in engineered nylon (polyamide). I wasn't too impressed by what I got (both design and build quality). Having a rare spare couple of hours, and triggered by a thought from Gavin (Young) - our new Technical Manager that we could just do the pin and toggle, I decided to design the thing myself. Brilliant idea! Remove the difficult bit (the mast bracket) and have total control of the design. We would get a new gooseneck pin and toggle that fits to the existing mast bracket. Easy retrofit and potentially low cost too.

With a free CAD program I designed the pin and toggle in a couple of hours, created nicely radiused corners, designed the holes in the toggle for the 3/16"and 1/4" clevis pins we use, and reckoned I had a prototype design. Pretty well a copy of the existing part. I didn't think there was anything wrong with the design per se - just the way it's made.

CAD Drawing

IMG_1290_Low Res0003.JPG (15.38 KiB) Viewed 29097 times

A quick export to the right format and upload for a technical assessment - no problems - the part could be printed successfully. Right then, what about the material?

After a long evening researching materials I went for Kevlar-layered Markforged Onyx (the fibre not the mineral) in black because Kevlar has excellent durability, making it best for parts that experience repeated and sudden loading. It's as stiff as fibreglass and much more ductile, so it will accommodate some lateral stress. Kevlar reinforcement is extremely flexible and retains much of its tensile strength even while bent at sharp angles. I'm hoping this will preserve the part when subjected to excessive (say destructive) loading. Carbon fibre (which was also considered) and fibreglass are much stiffer and will fracture at bend radii that Kevlar can handle without issue. The Onyx is a fusion of high grade engineering polyamide (nylon) and Kevlar fibre and it has a nice surface finish. The Onyx/Kevlar mix is suited for end of robotic arm tooling which is subjected to regular and sustained stress, but it's more ductile than carbon fibre (so it's not brittle).

The Onyx needs a specialist printer (cost in excess of £50,000) so not something that can be done at home.

I ordered it in black to mitigate some of the vulnerability to UV exposure (this is a problem with all Nylons - they go yellow and brittle with age).

In case you are interested here's the link to the material: https://markforged.com/blog/introducing-our-new-markforged-material-onyx/

The manufactured prototype (which I've called SG1 for 'Supernova Gooseneck 1') arrived today by FedEx and I'm impressed. Nicely tooled, everything fits. Slightly bendy so should better survive those bad capsizes. SG1 is going to get some action this weekend.

SG1 Completed Assembly

IMG_1290_Low Res0004.JPG (38.66 KiB) Viewed 29097 times

I might do SG2 which will have beefed up sidecheeks (flanges) but this will need a longer dowel (25mm). SG1 uses a 20mm dowel with 4mm flanges.

In case you are wondering (and I am sure you are), the cost of SG1 is £30. At this price I think it's a renewable (i.e. service) part. I could do a full stainless part (or even titanium) but the cost would be around £150. Let's see how we get on with the Onyx. Time will tell.

I'll keep you all posted by way of this diary.

Pete
Class Secretary
SN1177

[JW]

Good work a Pete, as always. Will follow this with interest. I ordered the upgraded gooseneck on my new boat and was disappointed to see the same poor quality pin and toggle so will definitely consider changing to one of your prototypes to add to the trial.

[Pete1177]

Early stages yet John as I need to do some serious alpha training on the SG1 myself. Once I get through some hours on the water then I'll move to offering beta parts where more people could fit them for a real test - maybe looking for half a dozen beta testers. I'd be slightly worried if you are sea sailing unless you have good rescue cover (in case it fails).

Pete
SN1177

[Tony1246]

Great work Pete. I think you are going in the right direction. I have had 3 gooseneck breakages over the years and it's always been the pin that has failed.
I was going to order a stainless pin and copy the mod that my brother has done but I may wait a while and keep an eye on the reports of your trial.

[CliffMilliner]

Interesting stuff, I hate the existing pin with a passion!

I've done the Stainless Steel pin mod and think it works great. Only a simple 10 min job (assuming you know how to remove the pin on the new style gooseneck).

I think Gav is going to do a blog post soon on how its done so I wont steal his thunder...

Cliff

[Pete1177]

21 Dec 2018 - I managed to fit SG1 onto my boat last Sunday while preparing the boat for the 2 club races, totally ignoring my self-imposed rule of not doing major changes just prior to a racing session. Luckily I didn't manage to launch as the gooseneck pin snapped fairly promptly as I rigged the sail and I had enough time to revert to the old pin and toggle.

Failed Gooseneck - MarkForged Onyx/Kevlar

IMG_0997_Low Res0005.JPG (17.55 KiB) Viewed 28994 times

This failure does show the major limitation of 3D printing technology. As an additive process, the material is built up layer by layer (maybe 0.1mm at a time). Most 3D printing technologies produce parts that are inherently anisotropic or not fully dense, with a weakness along the direction of the layers. The gooseneck is subjected to forces along all 3 axes, so maybe there isn't a solution with enough tensile strength using an additive process. The other limitation is that for 3D printed parts, the cost per part is more or less the same whether you make 1 piece or 25 pieces. I have begun to lean more towards using CNC which is a subtractive process. Subtractive manufacturing begins with a block of solid material (blank), and uses cutting tools to remove (machine) material to achieve a final shape. This gives a homogeneous material rather than the inherently weak bonds within 3D printing. However, the downside is it's more expensive to produce lower quantity parts, but as you approach a certain volume, CNC actually becomes cheaper.

I also realised that the quick and dirty CAD I used for SG1 (TinkerCAD) wasn't going to have the capability to do much more - in particular to export the formats required for CNC. Nor would it have the ability to check geometries for mesh, solidity etc. A new CAD modelling system was needed. The software that 50% of people use is Solidworks. Unfortunately it's a Commercial program and, outside of a free trial and student/academic use, it costs money. However, there is an excellent CAD-modelling program which is open source and totally free to use - FreeCAD. So I decided to use that. It has quite a steep learning curve, but it did seem to have all the requirements I needed.

After several hours learning how to drive FreeCAD, I started the SG2 design. SG2 has wider flanges to make it more rugged (now 6mm not 4mm) and a larger diameter pin. SG1 had an after-print diameter of 11.5mm which was a bit small for the boom-end female socket (13mm diameter). I have designed the pin at 12.60mm so it should be a nice fit into the boom. The vertical edges of both pin and toggle have all been radiused to 2mm to make potential CNC-machining easier and less costly. Another small modification is that I made the hole in the toggle 5.2mm so that it revolves easily around the 5mm dowel. The dowel is a neat solution (they only cost 10p each) but you could use a 3/16 inch clevis pin and ring (a 3/16 pin is 4.8mm).

Here is the design:

SG2_Complete_snip.JPG (21.91 KiB) Viewed 28994 times

Dimensional Drawing

SG2_Dimensions.JPG (16.75 KiB) Viewed 28993 times

SG2 is now at the 3D printers. I decided to do a 'space model' to check everything fits as an assembly. The part will be produced in Nylon-12 with graphic infill (which should make it stronger). I'm not expecting this to stand up much to normal wear and tear but it will serve as a prototype before I commit to manufactured parts. The Nylon part is around £10 per unit.

I've had a look at the options for manufacturing. I really would like to get the gooseneck manufactured in 316 Stainless Steel (marine grade), but Delrin is a possibility as it would give a 30% lower price point. A critical decision is just how many parts will need to be produced. For CNC there are economies of scale so that the more that are produced, the cheaper the unit cost is. I think the likely batch sizes would be 10 units at a time - if I take the experience of the tapered battens then this would be a typical batch quantity for a Class such as ours. For 316 Stainless Steel produced in the UK, produced 10 at a time, the cost is roughly £70 each. I have a quotation from a Chinese CNC service at around £60 per unit. However, this may be too high a price for general acceptance (remember the existing rubbish part is less than £20). For x25 units, the unit price is about £15 less (£45/unit Chinese).

I'll need to think the best way forward to bring the costs down - my target is £30 per unit as I think this is a reasonable price premium for a quality, long lasting part. I would be happy to pay that if I was certain it would do the job. I feel the only way to do this is to get higher volume, which means more people would need to commit to the upgrade or to start putting it on new build boats (at Hartleys).

In any event, the next stage is to develop a working prototype - watch this space!

PS: I have another project in mind - to design a better luff guide for the sail entry at the bottom of the mast. Low friction, flared entry ... but that's for the future.

Pete
SN1177

[Pete1177]

26 Dec 2018 - An update in between the Christmas festivities ... I have now received the SG2 prototype. This build uses a 3D printing method known as 'Selective Laser Sintering' (SLS), which is a polymer bed fusion technique. A CO2 laser beam is used to fuse (or sinter) the pre-heated polymer powder granules together layer by layer (50 microns deep) to form the part, resulting in the part being encased in powder which needs to be removed in the post processing. In this case, I have chosen a graphite-loaded nylon 12 polymer which promises to be stronger than SG1. It is possible to create 'hidden' structures with this technique - so one development might be to design in the connecting pin as an integral joint instead of using an interference fit stainless dowel. I prefer to use dowels as they are more 'elegant' than clevis pins (which require a retaining cotter or split ring to keep in place).

Here is the part as received. Dimensionally it is very good. The claimed tolerance is +/- 0.3mm. I designed the pin at 12.6mm diameter and the actual diameter is nominally 12.45mm. The distance between the 'cheeks' is 23.85mm (design value 24mm). The toggle height is 15.98mm (design value 16mm - this is critical to allow the toggle to fit the mast bracket and still allow room for a bearing washer). So I'm really happy with the tolerances. The only bit of further engineering I needed to do was to ream out the slightly undersized 6mm hole for the mast bracket clevis pin (1/4 inch). The part does have a cast-finished look, but of course it is not cast in any way. I have joined the two parts together with a 20mm stainless dowel (slightly short) but that's all I have at the moment (24mm dowels are on order). These 5mm diameter dowels are a tight interference fit on the pin 'cheeks' but since I made the toggle hole 5.2mm it rotates nicely. It would be a end-user choice to substitute a 3/16inch clevis pin in place of the dowel if you were unsure of using dowels. Although it's not important, the nylon part weighs 18g versus 28g for the standard assembled pin and toggle.

Nylon Laser Sintered Pin and Toggle (assembled)

IMG_1005-3.jpg (4.41 KiB) Viewed 28894 times

The next stage is to fit SG2 to my boat and see if it will withstand normal rig stress in the short term, I think long term I am preferring a CNC-manufactured approach as it eliminates any doubt about the material strength. For reasonable quantities, 3D printing is more expensive than CNC'd parts but I now have a quotation from a Chinese manufacturing operation for 316L Stainless Steel pin and toggle for less than £30, even with VAT and import duty added. The downside is that the MOQ is 100 units and I would need to be sure I could sell 100 units through the fleet and be assured they will be suitable for both new build boats and retrofit.

The slightly modified SG2 for CNC (which will be SG3) has a 1mm chamfer where the pin meets the body (it's impossible to mill a sharp angle) and I had to export to STEP format - for some reason the Chinese couldn't read my IGES format files properly as it threw up a few inconsistencies.

I will keep you posted and a Happy New Year to you all.

Pete
Class Secretary
SN1177

[Pete1177]

7 Jan 2019 - A quick update - still waiting for some decent wind to test out SG2. I did plan to get out racing yesterday but 2 things put paid to that. Firstly there was little wind (if any) making the 1 hour trip to the Sailing Club a waste of time, and secondly, I came down with a bad cold and didn't have the motivation to make the trip. I do need a decent blow to test the gooseneck fitting properly and the wind picked up to a decent northerly breeze today. So I'm hopeful I can work through this cold and get sailing at the weekend.

I do have one further design change to make (SG3 which is CNC-optimised), keeping with a 3D printed sintered nylon 12 part I can increase the tensile strength by about 30%. There is one company in the UK that can do a carbon fibre reinforced polyamide and I plan to order a few samples in the next week. This is the strongest 3D printed 'plastic' material on the market today. Sintered metal (e.g. 316L stainless - marine grade) is possible but the unit cost is in the region of £150 each

I'll keep you updated.

Pete
Class Secretary
SN1177

[Pete1177]

13 Jan 2019 - Having largely got rid of the cold I have been suffering for 10 days I finally plucked up the courage to go racing today. Winds were gusting to F4 - so a good chance to try out SG2. I now have the 24mm dowels for the connecting pin and these hold the toggle with a nice interference fit on the cheeks.

However, as this is a prototype and never tested before, I didn't want to brave sailing 2 races with it. I kept the usual gooseneck for the racing, then late afternoon fitted SG2 and went out for about 20 minutes with a lot of trepidation (the rescue boats had packed up for the day). The boom pin fit is excellent - not too loose. I did a lot of fast reaches with a lot of pressure in the sail, did some gybing and tacking, and an intentional capsize to see if it would hold up (the water was too cold to try more than one ducking). My initial reaction was that you could feel it was smoother without the usual creaking and noise you get with the standard gooseneck.

Back on the shore, I removed SG2 for a close inspection. There is no visible deformation and the part looks good - no cracks etc. Early days yet with more testing needed, but so far, encouraging enough for me to try it out for real in the racing next weekend.

Since the fit is excellent, I've ordered parts in carbon fibre loaded nylon which should be in my hands in early February. If anyone is coming to the Winter Championships on 23 February at Bowmoor you will be able to see it there. I'll also have a couple of spare Dynaflex tapered battensets with me if anyone fancies a set (£80). As these are from France, who knows what the price will be after Brexit! (Update 18 January - sorry but these have all gone).

SG3 is a very slightly modified design optimised for CNC but will also suit 3D printing. This will be printed in a specialised carbon fibre+graphite filled nylon and is ideal for functional components that need to be light and strong. It has the highest strength-to-weight and stiffness-to-weight ratios of any 3D printed plastic. I've ordered 2 parts so that another can be tested in parallel with mine on another boat. The carbon fibre material has a tensile strength of 76 MPa (MegaPascals) compared to 58 MPa of the graphite-only loaded part (SG2) i.e. 30% stronger. It costs the same, being around £10 per unit cost price. The tensile strength of the existing gooseneck (aluminium) could range from around 90 MPa but it could be as high as 200 - 300 MPa if it is an annealed alloy.

There is some merit in using nylon as it is relatively cheap and shouldn't wear out the boom socket. One concern might be that a stainless component might wear the socket too much. However, some Supernova owners have replaced their gooseneck with the Allen stainless one, but of course this needs the modified mast bracket as well (total cost £80). In any event, the boom inboard end could be replaced easily at modest cost (about £10) if needed, as this a readily-available spare part.

Happy days .

Pete
SN1177

[Pete1177]

25 Jan 2019 - Absolutely no wind last Sunday, so we aborted any idea of racing and instead did some Cunningham dyneema splicing on a couple of boats, then home for the afternoon.

SG3 (two samples) arrived in the post this morning, as did some bits from Hartleys for my boat SN1177. I needed a new mainsheet and I ordered a new boom inboard end and a complete existing Superspars assembly (including mast bracket) so that I could create a 3D model of the mast bracket in FreeCAD. It seems that my preferred mainsheet (Marlow Excel Fusion) is becoming hard to get, so I ordered the standard Supernova mainsheet from Hartleys - a bit 'slippery' in comparison. Hopefully they shipped 8 metres as I haven't checked yet (26 January - just checked it and it's a touch under 9 metres, so I'm happy with that ).

If anyone needs a new complete gooseneck assembly then let me know as I have a spare one. I'll be at the Winter Championships at Bowmoor on Feb 23rd so you can have it for £20 (they are £26 new).

SG3 in the new carbon fibre/polyamide material looks great - good surface finish and no extra finishing required, except for reaming out the toggle hole to 5mm diameter and assembly. 3D printing does tend to print vertical holes slightly undersized (this is a consequence of the 100 micron layering deposition and sintering process). I also reamed out the mast bracket pin to 6mm, although I notice that the clevis pin on the new mast bracket from Hartleys is oversized (0.25in or 6.3mm). Maybe they have run out of 6mm pins. The new mast bracket hole has been supplied reamed out (post manufacturing) to 6.5mm to compensate.

The assembly uses a 5mm Stainless Steel dowel (316L marine grade) which costs 10p. It's a nice interference fit to the cheeks and shouldn't fall out. The 16mm high toggle allows two 1.5mm thick stainless washers top and bottom to be used as 'bearings' - I note that you don't get any washer/s with the Hartley Supernova gooseneck assembly and this is a shortcoming, in my opinion, as they are cheap and prevent the bracket being chewed up.

With the new boom inboard end (which is plastic with an aluminium insert for the gooseneck pin), I tried coupling my used regular pin and compared it with the new pin. Since the regular Superspars pin is cast and not very round, it's noticeable how rough the thing rotates with a degree of friction and binding. Even the new Superspars pin feels very rough. SG3 is very much smoother - the pin is a true cylinder. I'm hoping this will translate to a very smooth boom linkage with less grinding as the boom rotates about with the rig
Here are the pictures:

SG3 side view with new standard mast bracket attached

SG3_side_01.JPG (48.83 KiB) Viewed 27611 times

There is a right way up for the bracket - the lower bearing flange is thicker - worth bearing in mind if you change your bracket.

SG3 top view again with a new standard mast bracket attached

SG3_top_01.JPG (51.18 KiB) Viewed 27611 times

I'll be testing out on Sunday which is forecasted to be challenging - gusts to 35mph in a cold Northerly. Might need the small sail

28 January - didn't get sailing as the forecast was 36mph gusts. I went walking instead on the Wansdyke on the North Wessex Downs - in the event all but 3 of the fast handicap fleet Did Not Finish and three rescue boats had to be launched to help extricate the boats embedded in the reeds at the east end of the lake.

Pete
SN1177

[Pete1177]

6 Feb 2019 - I decided to take the Supernova out for a sail today as we lost the snow and ice and I haven't been sailing for several weeks (racing cancelled over the last 3 Sundays - no wind, too much wind, and a frozen lake last Sunday). I re-rigged the rudder uphaul/downhaul to eliminate the random rudder uncleating problem which has been a real nuisance. I wanted to see how this worked out and of course, to see if the new carbon gooseneck (SG3) would stand up in use.

As it happened, the wind was not as strong as I had hoped (F1 - F2), but at least it was from a relatively warm SW direction. I managed about 2 hours on the water, with speed over ground between 4 and 6 knots. Plenty of tacks and gybes. SG3 worked really well, giving a virtually frictionless boom connection with none of the creaking and grinding you get with the standard gooseneck. I did attach a short safety leash to stop the boom falling away if the gooseneck broke as I was the only person at the Club (with no rescue cover).

As it's all good so far, I'm going to leave SG3 on the boat now till it fails.

Pete
SN1177

[Pete1177]

10 Feb 2019 - Today was a real test for SG3. F3 gusting F4 winds NW. Race 1 went really well - nice and smooth gooseneck and no problems with one capsize on an involuntary gybe sailing by the lee, but I did notice the 5mm dowel starting to move (it is an interference fit) when I had finished the race.

Race 2 was a bit of a disaster. On the first beat an impossible 40-50mph very rapid gust came through on the back edge of a front, just before a heavy squall that lasted 10 minutes. This took out most of the racing fleet, with about 15 boats capsized at once with several needing rescue. This included me where I suffered a broken gooseneck. Another Supernova also lost it's gooseneck - on this boat the boom inboard fitting came away from the boom. I left my boat to drift into the reeds and took a rescue boat back to shore to pick up another gooseneck part. Back to the boat in the reeds, I replaced the gooseneck pin with a standard aluminium one and sailed back - race over.

I did have a bit of a problem with the new rudder uphaul/downhaul arrangement as a bunch of reeds became entangled in the rudder. Usually a quick up and down on the rudder would have sorted it, but my gloved and cold hands made hard work of it as it's no longer a 2:1 purchase. I made a mental note to improve the rudder system before the Winter Championships in a couple of weeks.

The nylon SG3 failed with a shear through the pin, about 5mm from the front face. This is probably where the pin entered the boom inboard end. It does beg the question that if I had been sailing with a standard pin, would I have suffered the same fate as the other Supernova? Maybe the failing of SG3 did some good by prevent more significant (and costly) damage to the rig.

Here is a picture of the failed gooseneck.

Failed part

SG3_fail.JPG (36.56 KiB) Viewed 27454 times

I think SG3 as it stands would not stand up to severe lateral stress loading on the pin where it connects to the boom fitting. Furthermore I am uncomfortable with the thought that it might not be robust enough for dealing with an occasional high stress incident such as a bad capsize. Although the carbon fibre has added extra strength, the part is compromised insofar as the material is more brittle.

I'm beginning to think now it needs to be manufactured in metal (Stainless steel 316 grade) but of course this is a significant increase in price for 3D printed low volume parts (about £130 per unit in the UK). My next idea is to design a composite part with a metal (stainless) dowel longitudinally down the axis of the pin. This should make the gooseneck substantially stronger against lateral stress forces. I'll redesign the part with a 3D printed hole through the centre of the pin to allow insertion of a 5mm pin post printing.

This will be SG4. Drawing to follow.

Pete
SN1177

[Pete1177]

11 Feb 2019 - After a night's sleep I decided to go down a different route to make a composite part. The idea of a stainless pin through the nylon centrally along the axis of the pin is an elegant solution, but one that involves a degree of machining to insert the pin after printing.

I decided that another approach might be better. This is to try and marry up the Allen gooseneck pin (as some have fitted to the extended gooseneck), to the carbon fibre/nylon toggle. This would be a good retrofit to the standard mast bracket, yet have a relatively high degree of tensile strength where it is needed most - where the boom pin meets the toggle cheeks. The toggle itself is not under undue stress, and even if it breaks after a 'impactful capsize', this might provide the means for a sacrificial piece to avoid a bent mast - after all, something's gotta give in such an event (like a downwind broach).

Although the toggle itself could be manufactured from 316 Stainless Steel, the cost per part would be in the region of £25 per toggle in the 25x quantity.

So I'll try the Allen pin + nylon composite set-up as SG4. At least this would give me more assurance that the part will stand up to a few capsizes. The Allen gooseneck is around £22, but of course this is supplied as a complete gooseneck with pin, toggle and radiused mast bracket (not for the Supernova).

Here is the picture of the complete assembly:

SG4 Composite Assembly

SG4_Composite003.JPG (30.35 KiB) Viewed 27453 times

The nylon/carbon fibre toggle is spaced with a stainless bearing washer top and bottom. I have used 5mm clevis pins for the pivots. The complete assembly cost is around £25 in reasonable volumes. It may be possible to reduce the cost by obtaining only the Allen pin, but this is a discussion I'll need to have with Allen Brothers once I have determined the nylon toggle stands up to some abuse. All the parts are demountable, so in-service replacements will be possible at low cost.

The next test will be this coming weekend, hopefully, with no more disasters.

Pete
SN1177

[Pete1177]

14 February 2019 - I now have a response from Allen Brothers who are able to supply me with the stainless pin only.

The composite part looks very good as a retrofit to the existing mast bracket. It is virtually frictionless and removes the strength issue using a 3D printed pin. Of course the toggle bit is carbon + graphite loaded nylon which gives a good solution as the toggle is not subjected to as much tensile stress.

I am going to order 25 pins and toggles in order to make up assemblies that can be retrofitted to existing (standard) mast brackets. On the basis that these are demo parts for beta (field) test, I am hoping to offer these for a discounted £10 each (+P&P) to anyone who wants one. This is substantially less than the standard gooseneck (£18 from Hartleys) for what is a much better product. These should be available from early March. Let me know if you want one.

If anyone wants to see the part first, I will be at the Winter Championships at Bowmoor on Saturday 23rd February. Also there to give out the tapered battens to those who are collecting.

In a spare moment, I had a look at the direct 1:1 rudder uphaul/downhaul, trying to figure out a way to make it easier. I discovered there is an optimum way to thread the lines though the stock which makes it easier (less force needed).

Pete
Class Secretary
SN1177

[Kevin]

Hi Pete,

I like the idea of a stainless pin, can your set up be retrofitted to the ‘updated’ gooseneck.

Thanks

Kevin
1226