Removing nylon plug from carbon fibre tube

[Sam SpoonsParticipant @samspoons83065]

Posted by Ed Duffner on 22/05/2020 17:08:20:

Edit: Just noticed I suggested the same as a previous poster (overlapped posting).

Edited By Ed Duffner on 22/05/2020 17:28:40

Great minds

[Sam SpoonsParticipant @samspoons83065]

Thanks John, The CF tube used in this application is pretty robust, roll wrapped pre-preg with walls in excess of 4mm thick so not prone to splitting.

[Sam SpoonsParticipant @samspoons83065]

Posted by Rod Renshaw on 22/05/2020 17:46:32:

Hi Sam

I noticed that the plug is thought to be stuck because it has absorbed water and swelled. Might very gentle heat over an extended period, perhaps several days, or even more, dry out the nylon, so that it shrinks, and thus loosens it? Perhaps use in conjunction with other methods of pulling it out. I am fairly sure this would help if the plug was wood but I have no experience of nylon.

Rod

Yeah, not sure about that, just seems the most likely scenario as it is extremely well stuck and nylon is known for absorbing moisture and swelling slightly. Difficult to apply a useful amount of heat for a long enough period (several days I'd guess as the mast is over 6 metres long and impossible to get indoors (at least without accelerating the divorce proceedings beyond what I'm prepared to risk…..)

Thanks for all the ideas, keep them coming

[John BaronParticipant @johnbaron31275]

Hi Sam,

When you mentioned how light the mast was, I thought that it was going to be thin, thinner than 4 mm anyway.

I would try my first suggestion since you now have a threaded hole there.

[old martParticipant @oldmart]

An even simpler way would be to shorten the mast by 40mm, just cut it off.

[Sam SpoonsParticipant @samspoons83065]

Yeah that would be easy….. But it's a strict one design so shortening the mast, even by a few mm is not allowed (strictly speaking even using a custom made plug is not legal as all parts must be sourced from the official supplier but I reckon I'll get away with that one).

The ally mast is 7.8 kg including rigging and fittings, probably about 5.7 for the bare tube. The carbon mast, with rigging and fittings is 5.3 so probably about 3.2kg for the bare tube, that suggests a wall thickness of around 2.5mm so I guess I'm wrong (just going off what I have been told) I cannot easily measure it without removing the damned plug……

Edited By Sam Spoons on 22/05/2020 18:33:32

[Rod RenshawParticipant @rodrenshaw28584]

Sam

Gentle heat ideas?

Leave out in the sun during the day, pack around with pre dried silica gel at night?

Or, pierce a hole for the end of the mast in a tin can. Add another hole for an incandescent lamp holder and leave the lamp on 24 / 7.

Or, wind the end of the mast in gardeners' soil warming cable, (borrow from a keen gardner who will not need it now it's nearly summer.)

Or, see if anyone you know still has an old electric blanket in the loft.

Others might have other ideas!

Or, cut off the last 40 mm, as suggested above, and make a new plug, with 2 diameters, and which is 40mm longer than the old one to make up the lost lenght .

Regards

Rod

[Sam SpoonsParticipant @samspoons83065]

Might wrap in in several layers of black bin bag and leave it 'till tomorrow evening then give it another go (I can move it so it gets the sun in the morning and back again after lunch). I like the idea of a longer plug but if I have to destroy it to remove it I may as well not alter the mast as well.

[TrevorhParticipant @trevorh]

Sam A simple but expensive option – Buy an Ent and come back from the dark side…

Hope you get it out without any damage to the mast Mate

cheers for now

Trevor

[old martParticipant @oldmart]

I'm surprised that the rules are so strict that a shorter mast would be banned, I can see how a longer one might be frowned upon as it might add some speed. Drilling a number of holes lengthwise near the edge would tend to loosen the grip a little. Careful cutting of the bottom of the nylon would expose the end of the carbon fibre to find out exactly how thick it is.

[Sam SpoonsParticipant @samspoons83065]

Posted by old mart on 22/05/2020 20:40:19:

I'm surprised that the rules are so strict that a shorter mast would be banned, I can see how a longer one might be frowned upon as it might add some speed. Drilling a number of holes lengthwise near the edge would tend to loosen the grip a little. Careful cutting of the bottom of the nylon would expose the end of the carbon fibre to find out exactly how thick it is.

It's a SMOD (Single Manufacturer One Design)* the idea is that anything that is not supplied by the manufacturer is not allowed, simply so that everybody has exactly the same kit. The Laser is probably the strictest SMOD, the Blaze (my boat) is pretty flexible in comparison. If you want a long diatribe/discussion on the merits and otherwise of SMODs please ask….. Hmm, thought not You are right, a shorter mast may be slightly less efficient and a longer one more.

Drilling near the edge to introduce some flexibility is the plan if I do decide to destroy it so if nowt else works that will be the next step.

Trevorh, I need a singlehander mostly so that's not an option though I will probably end up with another Ent before I retire (I'm 67 so not quite finished with sailboat racing yet but can only go on so long). I would love a Rondar Mk3 (I've done wooden boats, not going back there…) But I have this as well as the Blaze so my two hander needs are covered for now.

Edited By Sam Spoons on 22/05/2020 21:20:36

[not done it yetParticipant @notdoneityet]

Posted by Rod Renshaw on 22/05/2020 18:53:36:

Sam

Gentle heat ideas?

Leave out in the sun during the day, pack around with pre dried silica gel at night?

Or, pierce a hole for the end of the mast in a tin can. Add another hole for an incandescent lamp holder and leave the lamp on 24 / 7.

Or, wind the end of the mast in gardeners' soil warming cable, (borrow from a keen gardner who will not need it now it's nearly summer.)

Or, see if anyone you know still has an old electric blanket in the loft.

Others might have other ideas!

Or, cut off the last 40 mm, as suggested above, and make a new plug, with 2 diameters, and which is 40mm longer than the old one to make up the lost lenght .

Regards

Rod

In addition to my previous post, I’ve located some actual figures for ‘wet’ and ‘dry’ nylon. Looks like it can/might expand by as much as 2 1/2% and needs about 80 degrees Celsius drive off the moisture. Here

Enclosed, in a lump, may need quite some time to dry it out. I declined from making any heating suggestion as the insulation (presumably required) will affect the internal temperature considerably.

Edited By not done it yet on 22/05/2020 22:14:10

[Sam SpoonsParticipant @samspoons83065]

Yes, on that basis I think I'll admit defeat and get the drill out. The effort to get the existing heel plug out undamaged compared to the cost/effort involved in fabricating to buying a replacement seems disproportionate.

Just to refer back to John Barron's concerns about the wall thickness and risk of splitting/damage. The mast is actually in three pieces (I knew this, can't think why I didn't occur to me when I answered your post John), two main sections, the upper being tapered (and possibly thinner walls at the top) and the lower being parallel and, presumably, equal wall thickness. The bottom few inches may be a repair where the base was damaged and a new section sleeved in* so all bets are off WRT it's inside diameter. Without being able to find out who the actual manufacturer of the mast tube was It's impossible to get any reliable info on older boats apart form the hulls. Add to that the 'builder/design rights holder**' has changed at least twice during the life of the class and it's fairly easy to get info on the hull (usually built in house by the 'manufacturer or, at least, farmed out to a specific builder) but finding info on the other bits is hard if the boat predates the current builder's tenure.

* Repairs are allowed to original components and carbon fibre masts are usually easily repairable, one of the selling points compared to aluminium masts which re pretty much impossible to repair successfully.

** The 'builder' is the guy who holds a licence to build and sell the boats, the design rights holder may be the same person or may be the guy who owns the IP related to the design and licences the 'builder' to build and sell the boats, but the 'builder' may not be the guy who actually 'manufacturers' the boats, he can subcontract that to another…. err, builder…. or…. errr…. manufacturer….. I give up……***

*** If you're still reading, google Laser Performance Europe vs Bruce Kirkby and 'International Laser Class Association' vs Laser Performance Europe. It's a long haul but you couldn't make it up…..

Edited By Sam Spoons on 22/05/2020 23:15:46

[John BaronParticipant @johnbaron31275]

Hi Sam,

Did you get the plug out ?

[Sam SpoonsParticipant @samspoons83065]

Hi John, No, It's not coming out intact and I haven't destroyed it until I have a new one made or sourced as it will still work. I'm waiting for a lump of 50mm Derlin round bar to fabricate a replacement before drilling it out.

Meanwhile I'm slowly removing the UV protective coating (probably two pack varnish given the difficulty I'm having sanding it off) as it's delaminating in places, but annoyingly stuck like a very sticky thing on most of the mast. Having spent the thick end of £200 on paint and consumables to refinish it I want to do a proper job So I won't have to do it again for a fair few years.

[John BaronParticipant @johnbaron31275]

Hi Sam,

Thank you for your reply.

I did wonder. Unfortunately I don't have any large diameter Deralin bar or I would have offered you some. Sanding varnish off something is a right royal pain, particularly when you can't get a sander on it. Anyway I'm interested in how you get on.

[Sam SpoonsParticipant @samspoons83065]

Thanks John, It helps to talk the process through. I'm trying scraping the varnish off as sanding it seems to be more uneven but I'm also trying an oscillating multitool sander head which works as well. Whatever I do it seems to take ages.

I have a 90mm offcut of 50mm round Derlin on it's way, just need to figure a way to fix it to the topslide* so I can use a router bit** in the chuck to machine the tenon, then I hope it'll be long enough to turn the stepped section and part the finished part off the waste (which, hopefully, will be enough to turn a 50mm x 8mm sheave for the masthead halyard block.

* I'd love a vertical slide with a decent machine vice but I'll be improvising for this job.

** I think, used with care, a router bit will be sufficiently beefy to machine Derlin?

[Grindstone CowboyParticipant @grindstonecowboy]

Try and get hold of some of the open mesh type sanding sheets, they don't clog up in seconds like the ordinary ones do with paint and varnish. Like these maybe. Other sellers (and makes) are available…

Rob

[John BaronParticipant @johnbaron31275]

Good Morning Sam,

Be careful machining plastics ! The plastics are quite abrasive and will cause the tool to get hot very quickly. The danger is that the hot tool no longer cuts but starts to melt the plastic. A flow of water based coolant helps tremendously.

I've used router bits many times to mill steel and brass. The problem with those is that because there is no rake on the cutting edge they shear the material off. This is fine for brasses and alloys, it works on steel but to get a good finish requires fine cuts. I've never cut plastic with one but I imagine you would need a fairly high speed and fine cuts.

Deralin/Acetal machines quite well when turned.

HTH.

[Sam SpoonsParticipant @samspoons83065]

Thanks clogging is a problem with abrasive paper but the stuff on the multitool seems much less prone, scraping is probably the way though (and perseverance).

The first job I did on the Boxford after re-comissioning was to turn some nylon sliding bungs which had, presumably, absorbed some water and I experienced the overheating/melting issue slightly. Gut feeling that sharp HSS tools with some rake would work better than carbide inserts (which were the only functioning tools I had at the time). Now I have a working bench grinder I can probably clean up some of the rusty old tools that came with the lathe so advice on sharpening for turning Derlin please?

[John BaronParticipant @johnbaron31275]

Hi Sam,

You've got it about right ! Really sharp tools, about 350-400 rpm, maybe a bit less for that diameter and a nice steady feed. I usually go for about 6 thou per turn. If you do it by hand watch out for the tool biting in and dragging the saddle.

[Sam SpoonsParticipant @samspoons83065]

Well the plug is out, I drilled three 8mm holes each side of the tenon and had a bash with the slide hammer and it came out fairly easily. It's probably still usable TBH. It's about 60mm into the tube with about half being hollow and the rest solid (will add pics and measurements tomorrow). I now have plenty of 50mm derlin so attempt to fabricate a new one with a couple of sneaky refinements safe in the knowledge that the old one will still work if required. Wall thickness is, from a quick eyeball, around 2.5mm for the bottom section and the inserted part of the plug looks unmolested so probably standard.

I'm still suffering from a total lack of motivation WRT removing the old varnish (which I've now decided is either epoxy or two pack so especially resilient). I'd guess I've got around half done, scraping with the side of an old chisel seems most efficient but it's bloody tedious, even though I can finish up with a rub with the 'vibrating multitool' (ooh er missus). Even watching my buddies sailing on the club webcam didn't get me jumping off the sofa…..

Edited By Sam Spoons on 08/06/2020 21:32:24

[old martParticipant @oldmart]

Was the old one fitted at the wrong angle?

[John BaronParticipant @johnbaron31275]

Hi Sam, Guys,

Nice one ! At least you can now move on and get things sorted. I'm watching with interest.

[Sam SpoonsParticipant @samspoons83065]

Posted by old mart on 08/06/2020 21:34:55:

Was the old one fitted at the wrong angle?

Yes, slightly twisted so the sail track on the mast was slightly off centre. The original plan was to just realign it and refix.

 

Edited By Sam Spoons on 09/06/2020 10:38:35

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