Can heat be used to soften epoxy resin?

[Scooterman]

Hi,
This is a question regarding the camber tube on my manual wheelchair. I don't use the chair much nowadays for a variety of reasons and am currently looking into getting a powerchair. BUT the manual chair does come in handy sometimes.

It's a little wider than need be and I worked out I can reduce the overall width of the chair by shortening the camber tube by 1" and then re-centralising it. I.E. Bring the rear wheels in by 1/2" either side. This can be done without the wheels fouling or rubbing against the backrest uprights.

The camber tube is aluminium and the camber plugs I assume are steel? My theory is to scribe the alignment of one of the camber plugs to ensure correct orientation when refitted. Then to ring round the aluminium camber tube with a hacksaw (lathe would be better but I haven't got one) and cut to depth of the camber plug. Then heat that end of the tube with a heat gun, grip the camber plug with Mole grips and wiggle out. Then using a cold chisel cut off the 1" section of aluminium camber tube left on the the camber plug after removal, and remove roll pin. Then realign and re-fit camber plug using expoxy resin. Then drill through aluminium camber tube and refit roll pin.

I hope all this make sense I've given it a lot of thought BUT do you think it will work? The accurate re-alignment of the camber plug is crucial as the chair has 4 degrees of camber?

Will a heat gun melt cured epoxy resin?

If WD concensus is don't do it you'll f*** it up, then I'll leave well alone! Lol

[Burgerman]

No.

If you could get it hot enough it either burns or turns to white hard dusty stuff thats weaker.

[LROBBINS]

Expanding on what John said. He was referring to the specific question of whether you can melt epoxy with heat, not to the broader question of whether it's advisable to change the camber. I'll do the same - I know little to nothing about camber on manual chairs.

He is quite right about melting epoxy. It is not a thermoplastic, but a thermoset. Heating it will, as he says, weaken and/or destroy the epoxy, so it can be used to break the bond. And for most epoxies it doesn't have to get all that hot; 130oC will usually be more than enough. You then would have to clean carefully and use fresh epoxy to re-glue it.

As far as cutting the tube, rather than a hacksaw and not having a lathe a very handy tool for this is a pipe/tubing cutter. They don't cost an arm and a leg and will make a nice right-angle cut. You do have to clean up the cut a bit afterwards with a de-burring knife and/or file, especially on the inside.

You can use this for steel and stainless-steel tubing as well but be careful to tighten it only slightly every few turns, especially on stainless because it work hardens, or it's easy to dull or break the cutting wheel.

[Scooterman]

Expanding on what John said. He was referring to the specific question of whether you can melt epoxy with heat, not to the broader question of whether it's advisable to change the camber. I'll do the same - I know little to nothing about camber on manual chairs.

He is quite right about melting epoxy. It is not a thermoplastic, but a thermoset. Heating it will, as he says, weaken and/or destroy the epoxy, so it can be used to break the bond. And for most epoxies it doesn't have to get all that hot; 130oC will usually be more than enough. You then would have to clean carefully and use fresh epoxy to re-glue it.

As far as cutting the tube, rather than a hacksaw and not having a lathe a very handy tool for this is a pipe/tubing cutter. They don't cost an arm and a leg and will make a nice right-angle cut. You do have to clean up the cut a bit afterwards with a de-burring knife and/or file, especially on the inside.

You can use this for steel and stainless-steel tubing as well but be careful to tighten it only slightly every few turns, especially on stainless because it work hardens, or it's easy to dull or break the cutting wheel.

Thankyou, you're correct in guessing that I didn't understand John's reply, that's why I didn't reply his post! Lol. It's probably because I don't understand the difference between a thermoplastic and a thermoset. But it's better knowing that being a thermoset heat it burns or turns into powdery substance rather than a gooey mess. Do you know if a DIY heat gun reaches 130 celsius? I guess it must as 100 celsius is the boiling point of water. The pipe cutter is a good suggestion, and as you say will make a much neater job than a hacksaw.

[LROBBINS]

Oh yes, the usual heat gun reaches >1000oC. For better control in small spaces I've taken to using my surface mount re-work hot-air pistol and I set it a lot lower than that.

[Burgerman]

I don't understand the difference between a thermoplastic and a thermoset.

Thermoplastic melts when hot, sets as it cools.
Thermoset is cured by heating. In the same way they spray cars with a 2 pack paint/laquer which has a hardener, then put it into an oven to make it go off hard. It decides to set once warm enough.

[Scooterman]

Oh yes, the usual heat gun reaches >1000oC. For better control in small spaces I've taken to using my surface mount re-work hot-air pistol and I set it a lot lower than that.

Thankyou, this is my heat gun.

EDIT: I could do with getting one of them heat focusing nozzles that fits on the end.

[Scooterman]

I don't understand the difference between a thermoplastic and a thermoset.

Thermoplastic melts when hot, sets as it cools.
Thermoset is cured by heating. In the same way they spray cars with a 2 pack paint/laquer which has a hardener, then put it into an oven to make it go off hard. It decides to set once warm enough.

Ah thankyou at least I know now. Funnily enough I have heard of 2 pack paint/laquer but I didn't know it needs to be cured in an oven. I've heard it can be dangerous to work with?

[LROBBINS]

That heat gun is more than sufficient, and yes, a reducer nozzle would be a good idea. Even then you'll have to take care not to get too much heat where you don't want it.

[Scooterman]

That heat gun is more than sufficient, and yes, a reducer nozzle would be a good idea. Even then you'll have to take care not to get too much heat where you don't want it.

Thankyou. One thing that concerns me is that the aluminium camber tube is anodised. Do you know if anodising is very heat resistant? The idea is just to heat the end part of the tube that the steel camber plug inserts into, and wiggle is out with grips. The camber plug has two flats that I will be able to clamp the self-gripping grips onto (Mole grips).

[sad_vampire]

Worry about the melting point of the aluminium alloy (460-670C depending on the type) rather than the anodised surface (alimunium oxide melts at 2072C & protects the aluminium metal from further corrosion).

[Scooterman]

Worry about the melting point of the aluminium alloy (460-670C depending on the type) rather than the anodised surface (alimunium oxide melts at 2072C & protects the aluminium metal from further corrosion).

Thankyou. I hope I'll be able to do the job okay. I'm probably over-worrying and although it's a manual chair I think it's best to ask WD members first because i always trust you guys.

[Burgerman]

I suspect you wont be succesful with heat.

Also annodising is just aluminium oxide. And heating metals cause them to oxidise... So thats not your issue. Everything else is!

[Scooterman]

I suspect you wont be succesful with heat.

Also annodising is just aluminium oxide. And heating metals cause them to oxidise... So thats not your issue. Everything else is!

perhaps I should leave it alone for the sake of gaining an inch, I can't afford to mess it up. I might do better seeing if i can buy a shorter camber tube. It would cost probably circa £150 incl int shipping but might be the safer option?

[Burgerman]

As an aside, to anodize something you just drop it into sulfuric acid, and stick an electric current through it. It oxidizes a thick layer of very porous oxide layer all over. You then dip it in a dye of whatever colour you want, and let it sit for a minute. They you seal it forever by boiling it in hot water, and then giving it a shine!

[Scooterman]

As an aside, to anodize something you just drop it into sulfuric acid, and stick an electric current through it. It oxidizes a thick layer of very porous oxide layer all over. You then dip it in a dye of whatever colour you want, and let it sit for a minute. They you seal it forever by boiling it in hot water, and then giving it a shine!

Thankyou I never knew that! When you say oxide is that the white powdery stuff that you get on bare aluminium? And the sulphuric acid and electric current just produce a more severe form of it? Or am I barking up the wrong tree?

[Burgerman]

Correct. But because aluminum oxide doesn't conduct electricity then coating it in such a way automatically puts down a complete even layer. And bits that are misses are the only bits left that conduct. So you cannot help but get an even layer as long as the part was clean to start with.

And I mean really clean!
And the acid dilution, amount of current and time is all a bit of an art to get right. And the dyes need to be colorfast and ultra violet proof. Ever seen red anodizing that has faded in sunlight?

And because it's just dyed oxides, you can spray dyes with an airbrush. And get colour fades!

Yellow, red, purple and blue and black here.

[Burgerman]

https://www.ebay.co.uk/sch/i.html?_saca ... kit&_frs=1

[rlnguy]

A bit late to see this, but are you sure the camber plug is just held with epoxy, and not theadlock?
Heat will work on both, but most of these I have seen had threads inside the aluminum tube, and the camber insert was also threaded.
Cutting it might put you in the market for a new one.
good luck

[Scooterman]

https://www.ebay.co.uk/sch/i.html?_sacat=0&_nkw=anodising+kit&_frs=1

Good grief! I would never have believed you could buy an anodising kit online, and at such a cheap price. Wheelchair manufacturers are such rip-off merchants. I had to pay another £100 for the red anodising option on items like castor forks, etc, as opposed to the the free standard black anodised finish.

[Scooterman]

Correct. But because aluminum oxide doesn't conduct electricity then coating it in such a way automatically puts down a complete even layer. And bits that are misses are the only bits left that conduct. So you cannot help but get an even layer as long as the part was clean to start with.

And I mean really clean!
And the acid dilution, amount of current and time is all a bit of an art to get right. And the dyes need to be colorfast and ultra violet proof. Ever seen red anodizing that has faded in sunlight?

And because it's just dyed oxides, you can spray dyes with an airbrush. And get colour fades!

Yellow, red, purple and blue and black here.

I understand what you mean by the oxide being an insulator so any untreated parts are a conductor and automatically get treated. You can't but help get an even coat providing as you say the whole item of completely clean cos any contaminates, dust, grease, etc would act as insulators and you wouldn't get a nice even finish.

I didn't know you get fades, that's quite cool actually!

[Scooterman]

A bit late to see this, but are you sure the camber plug is just held with epoxy, and not theadlock?
Heat will work on both, but most of these I have seen had threads inside the aluminum tube, and the camber insert was also threaded.
Cutting it might put you in the market for a new one.
good luck

You may well be right! I don't know see. I know it's also secure by a blind roll pin (see lower 1/4 of tube in piccy). I read somewhere in a forum that it's epoxy'd in but you know what some forums are like, they were probably just guessing. It seems a logically method of fixing the camber plug in place (epoxy and roll pin) but I don't know for sure. Especially after what you say I will err on the side of caution and leave well alone. It'll be a right f*** up if I cut it only to find out it's threaded .