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Slingshot mast cap - damaged threads

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Created by TroyMcClure 6 months ago, 2 Jun 2021
TroyMcClure
12 posts
2 Jun 2021 3:46AM
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Having come away on holiday, I've just tried to reassemble my Slingshot foil and discovered the mast cap threads (that attach the front wing) are seriously worn, to the point where there is just a couple of bolt turns left on each one. I've ordered a new one and am just hoping it arrives in time, in the mean time I was wondering whether a temporary bodge might be drilling through the mast cap threads and simply sticking in a longer stainless steel bolt with a nut on the bottom or would terrible things happen?

KDog
158 posts
2 Jun 2021 6:38AM
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If you in a hurry and have to get on the water that would work might cause some drag but you might not even notice.I have had good luck with just threading the mast cap all the way through and using longer stainless bolts and grind them to fit flush,but that might take more time than you have. Also I also don't take the wing off the fuse unless I change to a smaller wing seems to help with thread wear on the cap.Other SS owners might have a better quick fix.

aeroegnr
386 posts
2 Jun 2021 7:10AM
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You mean that small removable piece that takes the two 6mm hexkey bolts in front of the 4mm hexkey bolt?I stripped one of the bolts out and ordered a replacement cap. Ended up sailing it with only one of the larger bolts in, as the second couldn't even be torqued at all, but the 4mm bolt still in there. The way it is shaped I wasn't that worried but be careful and don't go out too far if you sail on it regardless of what you decide on doing.

stehsegler
WA, 3250 posts
2 Jun 2021 8:02AM
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The mast cap primarily for show. The two bolts only hold the cap in place and nothing else. Myself and other people have overtightened them and stripped the thread thinking it the cap holds the front wing in place... but it doesn't. You can tape up the hole using electrical tape.

If wing wobble is a problem some people have drilled a second hole into the wing that lines up with the thread that's in the fuselage. This will result in a rock solid wing. I think this has been discussed in the forum here before.

Windbot
322 posts
2 Jun 2021 12:26PM
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Mast cap? You mean that teardrop shaped thing that goes on the top of the front wing. Those things are garbage, I am using a first-gen cap that is basically a crossection of a mast. It allows me to thread the bolts on way farther. Your idea sounds like it would work. Call the rider hotline and Slingshot will send you new ones, they did for me. I am keeping them as emergency spares but I know my current one is so much better it will never fail.

Bender
WA, 2201 posts
2 Jun 2021 1:17PM
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See the the pics below as to how I solved it. The best way i found was to sell my SS set up and buy Axis instead

search for this thread i cant seem to embed a link to it

Advise needed how to eliminate Slingshot wing wobble.

azymuth
WA, 1489 posts
2 Jun 2021 4:30PM
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Select to expand quote
Bender said..
See the the pics below as to how I solved it. The best way i found was to sell my SS set up and buy Axis instead



Agree - Axis has nice wing/fuse/mast connections.
However if you want superior freeride windfoil performance on the ocean I haven't seen anything that comes close to Slingshot Infinity76 & 65 wings and Wizard V3 114/90, V2 105/87 boards

There are various simple failproof methods to get secure wing/fuse and fuse/mast SS connections - all been covered many times in these threads.

JuriM
48 posts
2 Jun 2021 6:04PM
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I stripped the original FWind1 version with brass inserts and got a new aluminum version with my i76. Before I got the i76, I was using a 3D printed version that I made myself. Last year, I designed a new version that uses M6 countersunk bolts just like the stabilizer (+ some M6 nuts). The latest version of that is designed to be used with a bit of PTFE tubing (6mm ID, 8mm OD) instead of a 3D printed tube, but I haven't bothered trying it yet. The previous version worked fine, but was slightly difficult to remove because the screws compressed the.

The first 3D printed version didn't even have metal threads, so the M8 bolts were rather loose in there, but I didn't lose any bolts and the wing was secure.

If Slingshot doesn't mind, I could share the design so others can print it. They might have a patent on this stuff though. I sent the first M6 version to Wyatt Miller (Slingshot) and he also found it a bit hard to remove, but that it worked.

The "new" full aluminum Slingshot version seems to be more durable, but the bolts become loose over time, so it's a good idea to check them frequently even if you leave the fuse+wing assembled.

P.S. We're still in the "wild days" of product development for foils. I'm sure that eventually we'll have what becomes the "Tuttle" or "PowerBox" of mast-fuse and foil-fuse connections. In terms of engineering, I feel the mast-fuse connection Slingshot has is the equivalent of the venerable US fin box...adjustable and simple, but it relies almost entirely on the bolts not breaking (which they will eventually as they are heavily loaded).

Bender
WA, 2201 posts
2 Jun 2021 8:00PM
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Select to expand quote
azymuth said..

Bender said..
See the the pics below as to how I solved it. The best way i found was to sell my SS set up and buy Axis instead




Agree - Axis has nice wing/fuse/mast connections.
However if you want superior freeride windfoil performance on the ocean I haven't seen anything that comes close to Slingshot Infinity76 & 65 wings and Wizard V3 114/90, V2 105/87 boards

There are various simple failproof methods to get secure wing/fuse and fuse/mast SS connections - all been covered many times in these threads.

I'd like to provide some balance to JJ's comment.
I have owned and windfoiled the SS kit and now use the Axis set. The axis 750 LA wing rides very similar to the infinity76 in both windfoil/wingding and sup foil mode. It carves/turns just as good as the 76. Even better to use is the HA 900 wing. Its faster and handles high speed carves better and the glide is sensational. Yes the SS are good to ride but i feel there are better made set ups out there for e.g. that dont need mofifying to stop wing wobbles etc. For me AXIS wins hands down and they are alot lighter. Just my opinion, I'm out. Cheers Bender.




TroyMcClure
12 posts
3 Jun 2021 3:02AM
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stehsegler said..
The mast cap primarily for show. The two bolts only hold the cap in place and nothing else. Myself and other people have overtightened them and stripped the thread thinking it the cap holds the front wing in place... but it doesn't. You can tape up the hole using electrical tape.


Yes absolutely this. I thought those two bolts held the front wing on. If they don't what does??

When I have the time I think I will just helicoil the two mast cap holes all the way through and grind off longer bolts as suggested above.

Also just how tight should I be doing these bolts up. The only instructions I've seen on putting the foil together are a video by Wyatt Miller and he seemed to just say something like 'do them up tight'. I do a lot of cycling and they are always pretty specific about the torque settings required in Newton Metres. Does anyone have these figures for Slingshot foils? I see there is a previous thread but nothing specific to SS.

azymuth
WA, 1489 posts
3 Jun 2021 5:42AM
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Select to expand quote
TroyMcClure said..

stehsegler said..
The mast cap primarily for show. The two bolts only hold the cap in place and nothing else. Myself and other people have overtightened them and stripped the thread thinking it the cap holds the front wing in place... but it doesn't. You can tape up the hole using electrical tape.



Yes absolutely this. I thought those two bolts held the front wing on. If they don't what does??

When I have the time I think I will just helicoil the two mast cap holes all the way through and grind off longer bolts as suggested above.

Also just how tight should I be doing these bolts up. The only instructions I've seen on putting the foil together are a video by Wyatt Miller and he seemed to just say something like 'do them up tight'. I do a lot of cycling and they are always pretty specific about the torque settings required in Newton Metres. Does anyone have these figures for Slingshot foils? I see there is a previous thread but nothing specific to SS.


The single M6 bolt will keep the wing tight if the wing is a good fit on the fuse. The mast cap is used to fill the A position insert (used for SUP foiling). It marginally helps keeping the wing tight - you can safely foil without it.

If you tighten the M6 bolt as tight as you can with the correct size hex tool and the wing still moves I'd add tape to the fuse and jam it on before retightening. It'll get you through your holiday. Leave the mast cap off - you won't notice the drag.

When you get back from holidays;
Drill a new hole in your wing to make use of the existing extra hole in the fuse so you're tightening with 2 M6 bolts - a 5 minute good solution.
or
I installed Helicoils and use 2 cut-down M8 bolts - filling the wing mast cap void with glassfibre filler. An overkill but works for me.

The Slingshot HG switchfuse is super popular because of its adaptability to optimise the wing centre-of-lift across different foiling sports - especially with Tuttle box boards

michaelpaf
81 posts
14 Jul 2021 11:15PM
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I solved the mast cap issue with replacing the m8 23mm with m8 25mm. Now I can use also my just damaged Mastcaps.

The option to use a secon m6 hole is also good. But in case of selling my foil one time I didn't wanted to put an extra hole in it. Never the less I'm wondering why they do not deliver the wing with two m6 bolts.

mulligat
3 posts
25 Jul 2021 11:44AM
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I had the original brass version strip out, switched to the new version but still experienced thread wear. I now use Blue threadlocker...I probably have 50-75 sessions on it without any loosening, but can still take it apart if I want to.

bigdaz
NSW, 303 posts
25 Nov 2021 8:01AM
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michaelpaf said..
I solved the mast cap issue with replacing the m8 23mm with m8 25mm. Now I can use also my just damaged Mastcaps.

The option to use a secon m6 hole is also good. But in case of selling my foil one time I didn't wanted to put an extra hole in it. Never the less I'm wondering why they do not deliver the wing with two m6 bolts.


I've just had same issue stripped cap. I thought longer bolts might bottom out in the cap and not be a tight fit. I've got a new cap on the way from slingshot. Do the 25mm bolts create a tight fit?

KDog
158 posts
25 Nov 2021 8:44AM
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Just drill through and tap threads all the way and make a couple of custom length screws stainless 316.The mast cap does not really hold the wing on the fuse just that small 6mm does the job ,no need to overtighten the mast cap.

KDog
158 posts
25 Nov 2021 8:48AM
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Oh and might as well replace the two that join the mast to fuse with 316 stainless

bigdaz
NSW, 303 posts
25 Nov 2021 1:55PM
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Select to expand quote
KDog said..
Just drill through and tap threads all the way and make a couple of custom length screws stainless 316.The mast cap does not really hold the wing on the fuse just that small 6mm does the job ,no need to overtighten the mast cap.


Cheers

MrA
QLD, 109 posts
26 Nov 2021 9:15PM
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As a former slingshot owner, I have a slingshot mast that I bent at the top. Most of the mast is fine. I am happy to donate it for someone to cut up to make lots of caps and pay it forward. PM me if you have the equipment to do this and share the love. The ss caps are very easy to strip out and are probably hard to source now.

azymuth
WA, 1489 posts
26 Nov 2021 8:03PM
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The simplest and cheapest modification (that's also an improvement) is to ditch the mast cap, fill the void in the foil with cheap auto body-filler and drill a second hole in the neck of the foil so you can screw another M6 into the forward existing (and unused) threaded hole in the fuselage.

bigdaz
NSW, 303 posts
27 Nov 2021 8:52AM
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Select to expand quote
azymuth said..
The simplest and cheapest modification (that's also an improvement) is to ditch the mast cap, fill the void in the foil with cheap auto body-filler and drill a second hole in the neck of the foil so you can screw another M6 into the forward existing (and unused) threaded hole in the fuselage.


So do you ditch the other two bolts completely and just run the two m6's?
Any pics of this mod u can show?
Cheers

azymuth
WA, 1489 posts
27 Nov 2021 10:48AM
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bigdaz said..So do you ditch the other two bolts completely and just run the two m6's? Any pics of this mod u can show?



I went a stage further and inserted Heli-Coils in the mast cap holes and used two M8 bolts to secure the wing (didn't use the M6 holes), but that's time consuming to install and probably overkill.

Using the two M6 bolts works well - takes only 15 minutes to fill the wing void and drill/countersink the second hole (measure carefully with a paper template). Yes, ditch the mast cap bolts.
I've sold my Hoverglide foil but still got the old modified wing below to show the simple fill.


BTW - the original mast cap works fine if you're careful - Mr. Cool managed to use the same mast cap for a couple of years.



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"Slingshot mast cap - damaged threads" started by TroyMcClure