Bolts, and gudgeons

[Michael Rogers]

Hi, I'd be grateful for some expert advice please.

1) What's the best way to shorten a bolt and still keep it nyloc-friendly? Either measuring then cutting off (with a hacksaw) before putting a nut on, or screwing the nut on before cutting and then backing it off over the cut seems to chew up a nyloc nut something rotten. In my inexpert hands, even getting a nut on/off over the cut end of a bolt isn't easy. Would it help to cut off slightly long and then grind the last few millimetres back with an angle grinder? Is there a normal-nut-plus-a-drop-of-loctite school of thought/practice?

2) With my kit I've been supplied with Seasure gudgeons and pintles. The tolerances are surprisingly small, and after fitting them to rudder and transom with all the precision I can muster, the rudder head swings but not very freely. The holes in the gudgeons (on the rudder) really need easing - I would have thought about half a millimetre: I don't want them thumping around, but clearly free movement is important. What's involved in doing that? I don't have any metal-working tools or experience and I'm a bit daunted. Incidentally, the tiller passes from the rudder head into the boat through a port about 3/4 way up the transom, so once the tiller is in place there is no way the rudder could unship off the pintles.

3) Both gudgeons and pintles are (except for the pintle pins which are obviously bright stainless) finished in quite attractive matt dark grey. Overall the weight suggests steel. There's some suggestion (along edges) that the finish might come off in normal use. What about corrosion resistance, assuming the metal is not s/s? The various corners are uncompromisingly sharp, and were it wood I would round them off, not least from a safety point of view. I think the appearance might be compromised if I did that with the metal, but if I don't I shall get jabbed/scraped sooner or later. Does anyone know about this sort of finish? They are, incidentally, not cheap fittings - about £20 a throw.

Thanks, in anticipation.                  Michael

[Paul H (admin)]

Michael,

This is what I do:

1) Leave nut on bolt, gently clamp in vice then cut off waste. Use correct sawing action taught at school - blade, hand, elbow and eye should line up in a straight line. This is important to get a precise 90 degree cut, otherwise the nut will not fit easily.

Hold bolt in left hand, use a medium file at 90 degrees to flatten off the rough spots, turning a few times in the left hand. The aim is to get a smooth 90 degree end.

Then file at 45 degrees with gentle forward strokes only, continuously rotating the bolt in your hand. This gives a chamfer to the start of the thread to ease it into the nut. With gentle strokes you get a feel for how much material is removed and it prevents the file jamming at the start - when the surface gets smoother the sound and motion of the filing becomes smoother.

By now you should be able to remove the nut and replace it. If you can still feel sharp edges a final few strokes of the file will remove them.

I'll cut them for you if you give me an idea of sizes.

2) One trick is to drill the bolts holes 1mm larger to give some wobble room. I use it all the time to align fittings cosmetically vertical or horizontal etc.

-Paul

[Jeremy]

I tend to always shorten bolts in the lathe, as it gives a nice finish to the cut ends, but if doing it by hand the method Paul suggests is fine, but ideally use a plain nut, not a Nyloc just for the shortening bit.

My guess is that the pintles etc will be stainless, but probably just mill finish, rather than electropolished.  Either a gentle pass over the edges (at 45 deg) with a smooth cut file, or run over them with a deburring tool, would take the edges off.  If using a smooth cut file, then draw file the edges (move the file parallel to the edge) to avoid creating a rough edge.

The holes can probably be reamed out, but the tightness is most probably very slight misalignment, rather then the holes being too small.  You might want to try slackening off the fixings and seeing if the rudder turns freely.  If it does, then adding some thin packing under the parts fixed to the hull might help you get better alignment.

[Timmo]

I have tap and die set (less costly than a lathe). Spin a die onto the bolt before cutting, back it off (after cutting carefully and dressing with a file as Paul described below) to clean the thread. If you don't have that then put an ordinary (not nylock ) nut on and use that to tidy the thread. Strictly speaking Nylock nuts should only be used once. I'd go Nylock over Loctite personally.

If you're going to ease the fittings first (as suggested below) you can enlarge the screw holes a little so alignment can be fine tuned. If more is needed then a fine tooth round file in the gudgeons to enlarge them is possible but you'll want to keep the holes as smooth and polished as possible, perhaps finish with very fine wet and dry on a dowel.

Don't know what the make is of your fittings. Matt grey sounds like it could be an anodised finish which would be more likely on an alloy, some of which can still be weighty. The price also suggests alloy (but then they're for a boat, so obviously they cost more whatever they're made of!) I wouldn't go changing their shape if they are, alloy still corrodes if the finish is removed and you may affect their strength in ways you won't anticipate. Might be better to sell them on and buy a different design if you don't like them!

Tim.

On 27 May 2012, at 15:44, Michael Rogers [via UK HBBR Forum] wrote:

Hi, I'd be grateful for some expert advice please.

1) What's the best way to shorten a bolt and still keep it nyloc-friendly? Either measuring then cutting off (with a hacksaw) before putting a nut on, or screwing the nut on before cutting and then backing it off over the cut seems to chew up a nyloc nut something rotten. In my inexpert hands, even getting a nut on/off over the cut end of a bolt isn't easy. Would it help to cut off slightly long and then grind the last few millimetres back with an angle grinder? Is there a normal-nut-plus-a-drop-of-loctite school of thought/practice?

2) With my kit I've been supplied with Seasure gudgeons and pintles. The tolerances are surprisingly small, and after fitting them to rudder and transom with all the precision I can muster, the rudder head swings but not very freely. The holes in the gudgeons (on the rudder) really need easing - I would have thought about half a millimetre: I don't want them thumping around, but clearly free movement is important. What's involved in doing that? I don't have any metal-working tools or experience and I'm a bit daunted. Incidentally, the tiller passes from the rudder head into the boat through a port about 3/4 way up the transom, so once the tiller is in place there is no way the rudder could unship off the pintles.

3) Both gudgeons and pintles are (except for the pintle pins which are obviously bright stainless) finished in quite attractive matt dark grey. Overall the weight suggests steel. There's some suggestion (along edges) that the finish might come off in normal use. What about corrosion resistance, assuming the metal is not s/s? The various corners are uncompromisingly sharp, and were it wood I would round them off, not least from a safety point of view. I think the appearance might be compromised if I did that with the metal, but if I don't I shall get jabbed/scraped sooner or later. Does anyone know about this sort of finish? They are, incidentally, not cheap fittings - about £20 a throw.

Thanks, in anticipation.                  Michael

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[Port-Na-Storm]

Michael

I agree with everything said so far. If you don't have a non nyloc nut, try putting it on the wrong way round so that the metal end is cleaning the thread.
I've used the Seasure gudgeons and pintles and was quite pleased with them. They shouldn't need reamed out. As Paul suggests leave everything finger tight at first, and let them find their own best position by moving the rudder from side to side, and up and down. Tighten everything gradually, and not too bloody tight, Stainless is soft.

I wouldn't tamper with the coating. I think they are an alloy casting, and as Timmo says the finish is anodised or something similar.  If you try to file it down the coating will come off and the alloy underneath will corrode. I don't find mine are a problem.

Good Luck.
Graham  

[momist]

Pintles and Gudgeons:
If they are the ones I've just looked up on t'internet,
http://www.guildfordmarine.co.uk/ebuttonz/rudderfittings/seasurepintleandgudgeons/index.htm
they are "Made from heat treated black anodised aluminium".  I would strongly suggest not interfering with them at all.

Considering your problem, the tiller has huge leverage on the rudder, as does the waterflow.  I really don't think a bit of stiffness in the movement is a bad thing, as long as it doesn't interfere with getting them on and off.  How easily do they slide up and down?

Ian

[Michael Rogers]

Paul, Jeremy, Tim, Graham, Ian

Apologies for the delay in getting back to you, to thank you all for your collective words of wisdom, which I will apply as best I can. Very grateful.

As you will have gathered from this request and my other about keel band, managing 'big' metal is a bit of a closed book to me, which I'm sure seems strange to all you proper workshop types. On the construction side (as opposed to sailing which I've done most of my life), I came to boat building late after lots of self-taught model making which was almost all in wood and involved a minimum of metal (stuff like thin aluminium sheet). Some model ships, but mostly around my 16 mm to inch garden railway (currently in storage) - and I wasn't up to building the locos.

My fit of the rudder etc was the dry run prior to painting, and has now been dismantled again. I'll follow up your suggestions (eg a possible bit of packing out) when I do final assembly. I've been back to the gudgeons/pintles though, and am still surprised at the rather uncompromising tolerances. The rudder did swing, Ian, though not as freely as I was brought up to believe is a Good Thing, but I take your points. Thanks for the chandlery link - not one on my radar hitherto, but I've bookmarked it on my Mac: I like background info on what I'm buying! On the basis of the info about the metal used, I will (rather gratefully) forbear to muck it about.

I've been following the CCC threads with great interest. Can't make Beale this year, sadly. The beer tent was, and doubtless still is, a high spot - lovely stuff on offer. May the best boat win the CCC, and I hope the following Raid is a success.

Michael