Use of heat in releasing machine screw

PabloPicasso said:
First heat is always copius amounts of boiling water. I mean loads and loads of it!!

It'll disolve years of salty detritus, and works in places like this amazingly often.

Really, it needs a lot if boiling water + + + + + +!!!

Only try more serious heat AFTER the boiling water trick has been absolutly exhausted as an option.

The plus sides are:
*Its easy to do
*No specialist tools or equipment needed
*won't damage anything
*USUALLY SUCCEEDS

Please please have a go and do report back.
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NO NO, boiling water isn’t hot enough! Doesnt usually succeed. It needs serious flame heat, in this case not possible. Tap, hit it, fiddle with it, penetrating fluid, try to get a flame on it but not at the expense of burning the surrounding. Then if that fails, drill it out. Specialist SS drills are available, I’ve got some on my boat.
 
Of course it’s not just the s/s screw contact with aluminium of the track itself but with the plate buried in the glass fibre which is a much longer journey for penetrating fluid/boiling water/freezing shock spray. Also wondered if the fact they (presumably) used machine screws with finer pitch than a bolt makes area of converted AI bigger and harder to shift?
Cutting through the machine screws between the bottom of the track and the deck not straightforward as angle grinder won’t fit - maybe Dremel will work
 
eddystone said:
Of course it’s not just the s/s screw contact with aluminium of the track itself but with the plate buried in the glass fibre which is a much longer journey for penetrating fluid/boiling water/freezing shock spray. Also wondered if the fact they (presumably) used machine screws with finer pitch than a bolt makes area of converted AI bigger and harder to shift?
Cutting through the machine screws between the bottom of the track and the deck not straightforward as angle grinder won’t fit - maybe Dremel will work
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Or a stainless blade for an oscillating multitool like Amazon.co.uk ?
 
Beneteau381 said:
NO NO, boiling water isn’t hot enough! Doesnt usually succeed. It needs serious flame heat, in this case not possible. Tap, hit it, fiddle with it, penetrating fluid, try to get a flame on it but not at the expense of burning the surrounding. Then if that fails, drill it out. Specialist SS drills are available, I’ve got some on my boat.
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The boiling water dissolves salty detritus, but you do have to use A LOT. Got to be worth a try before more aggressive methods that may caise damage to surrounding structure, no?
 
I have a Rothenburger blow torch attachment that fits a Mapp gas bottle. It is on the end of a flexible hose & the burner itself sits in line with the hose. The flame adjustment is a small wheel in front of the burner. It gives a very fine flame & I use it for soldering. The flame, whilst hot would be the size of the head of a 6mm countersunk set screw.
If one could find it online, ( I have had mine years but it was not expensive) one could just play the flame on the head of the bolt thus heating the bolt without necessarily applying too much heat to the traveller. Done carefully the heat should work its way down to the substrate. Certainly a better option than hot water- Which, frankly I would consider a waste of time unless one wanted an excuse for lots of cups of tea
But if one wanted to get the job done quickly, then just drill the heads off. Lift the track- if possible- then unscrew or shear the resulting studs with a set of mole grips. Travellers have spare holes, so if re fitting drill tap & re fit into new holes.
If you decide to bite the bullet & waste the track then just cut it into sections with an angle grinder & chuck it right from the start. save hours of poncing about.
 
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zoidberg said:
Should the above methods fail, might you consider using a bi-metal hole saw to drill around the heads of the machine screws, then lifting the 'destroyed' track away? With the m'screw heads exposed it should be somewhat easier to apply 'encouragement' to remove them.

You'll want some new track, of course, but that's not hugely expensive - especially if you ask in here and other boaty online sites.
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I'll have to remember this one, after everything else fails. And it really only takes 1-2 that won't move to create a 100% fail. With the track out of the way, the screws can be cut off flush or even drilled down to plug. Move on.
 
eddystone said:
One problem is that it is impossible to buy a 9.5/10 mm slotted bit for my (Milwaukee) impact driver. Managed to find a hand impact driver in Machine Mart with 10mm bit. I’m far from testing the solidity of the s/s-aluminium interface because not getting enough grip on the head. I wondered about drilling into the screw head to get a firmer grip - screws can be replaced.
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You could make a screwdriver bit out of an impact quality extension bar.

Then give up trying to get it undone and drill the screw out and retap it.
 
eddystone said:
Seeking some advice on usefulness of heat to help release machine screws attaching main sheet traveller track to bridge deck on Sadler 32. I’m assuming that the screws are threaded into aluminium plate embedded in lay up. This seems to be standard Sadler practice. After over 35 years of galvanic action between the aluminium plate and s/s screw assuming well corroded in. Not helped by slotted head on screw.
So far used ATF/acetone mix, Plus Gas and cold shock spray. My feeling is that heat wouldn’t penetrate as far as the aluminium plate so unlikely to create differential expansion between s/s and aluminium.
Correct assumption?
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I used the ATF/acetone and heat trick. In my intense concentration I forgot that they shouldn't be used together. Very explosive. The scars are fading now.
.
 
Take a picture of the location it might spark other ideas (but only if you post the picture).

Jonathan

I don't know the technical terms but

Find a drill bit, like a plug drill or small hole saw with toughened inserts. They usually have a centrall drill bit, part remove, as the screw will keep the hollow drill bit centralised but you need the central drill bit as it is locked into the drill with the chuck. Ideally it wants to be just larger then the screw head - then drill the screw out. Assuming you don't actually destroy anything, re-tap, and use a bolt to replace (with Duralac). It should not be difficult to drill as its simply aluminium and a hand, battery, drill will suffice.

I have the sort of drill bit I'm thinking of, for drilling HT steel and aluminium. If you want a picture - ask - and I'll take one tomorrow

Jonathan

Josepheline had the same aluminium inserts for the addition of tracks on the cabin roof. I added tracks and did as you imply Sadler did (except I did use Duralac). My tracks were 'embedded' in the roof, part of the layup - except my tracks were set on a layer of plywood - so when I drilled for the bolts - I knew when I had drilled through as I had sawdust. I then tapped the aluminium - but I fitted with bolts not screws.
 
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Yes, agreed about alu oxide & water.

I've found now on many occassions when it is an apparently lost cause like this, that the coipius amounts of boiling water trick worked.

No one's said "oh we've tried that and it didn't help at all" 🤣
 
I have done this job before several times, last time on an elderly Twister, A decent impact driver with a screwdriver bit ground to fit the slot exactly.
If you try & tighten & undo several times. I also used an air powered impact driver, You will snap bits & have to regrind them.
If that fails cut the track away, You can buy 1mm thin cutting discs for aluminium, Once cut you can put a spanner on the bit with the screw in it.
Mapp gas / oxygen is a good idea as it is nearly as hot as Oxy acetylene.
I seem to remember to remove the two tracks from the Twister took me a weeks work!
 
PabloPicasso said:
Yes, agreed about alu oxide & water.

I've found now on many occassions when it is an apparently lost cause like this, that the coipius amounts of boiling water trick worked.

No one's said "oh we've tried that and it didn't help at all" 🤣
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In my 60 years of maintenance work, in the early days trying boiling water on jobs such as this “we've tried that and it didn't help at all”
How’s that?😂
 
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