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[OldBoy67]

The light of my life has a new NEFF oven so I’m now banned from using the oven to heat up crankcases for removal of bearings, bushes, spindles etc. So I’ve been looking at alternatives. I don’t trust myself using a propane torch on an old Enfield aluminum crankcase, and boiling water seems a bit hit or miss. I think that the purchase of a heat gun might be the way forward, but I’m concerned that this would provide heat only to localised areas of the casing. Also I was suprised that some of the guns I’ve looked at have a very limited number of heat settings. For example, a couple of expensive De Walt’s provide a choice of only 2 temperature settings of either 50C or 600C. That is way out of the required temperature which I think should be about 100-150C. Does anybody here have any experience of using the heat gun approach? Did it work and what are the problems (if any)? Thanks in advance.

[Wheaters]

Or you join the WI and use THEIR oven...
As far as the heat gun goes, rather than direct heat, why not build a cabinet from ply or chipboard and use the gun to heat up the inside of that?
I kept our old electric fan oven and it's now used for jobs like this. I also invested in a DIY powder coating kit and the old ovens's ideal for that, too. 20 mins at 180C - perfectly cooked.

[Leon Novello]

Usually a heat gun will work, no need to heat the whole case,just heat the case around the bearing and trickle ice-cold water on the bearing to control expansion. Same when fitting a new bearing, heat around the seat while the bearing in the fridge.

[ChrisD]

OldBoy. I use a trusty old Black&Decker gun with only one heat setting; on-and-off. I use it to start barbecue’s so I guess it puts out LOTS of heat when localised. But, as others have said, you want the area around the afflicted part heated not localised and no higher than ~150C and that’s plenty (put bearing in freezer, disguised as a steak then she'll never know). The spray test is a good way to know if the heat is right – if the droplets spit and roll off the casing, that’s good. If you can, set it up so that the item to be freed is under tension – then when the heat gets to the critical level, it automatically separates. Cheers, ChrisD

[stinkwheel]

You'll get a second hand electric oven for local collection on gumtree for less than the cost of a heat gun... Just saying. You'll always have wanted a 30A spur in your workshop anyway? Or just run a 30A extension from the cooker socket when you want to use it.

[OldBoy67]

Thanks for the replies and ideas. I had thought about a used oven, but there are practical (and cost) issues over provision of an adequate power supply. I've only got a 12A double gang socket in the garage. So looks like I will be investigating heat guns in more depth over the weekend!

[OldBoy67]

Sorry - meant 2 x 13 Amp!

[Mark M]

OldBoy, get an old oven and install it. A 13 amp socket is quite adequate to power the oven section alone (do not try and run the whole thing though!) and you are protected by the 13a fuse in the plug anyway. I have been using an old Creda Cavalier for years. Happily it has a big enough main oven to take a whole Bullet or Twin crankcase half with studs. A heat gun is fine for small jobs but when doing main bearings I prefer to heat the whole case progressively increasing temperature over about 20 minutes. In the meantime you can get on with something else rather than hold a heat gun. And if a domestic situation should get out of control you can always cook your own dinner in peace!

REgards, Mark

[stinkwheel]

Aye. Hot pies and pasties in the workshop.



Mind you, you haven't seen apeshit until you've put a set of brake callipers with a fresh coat of VHT paint on in the oven to cure! Even I'll admit the smell was somewhat pervasive with a tendancy to linger.

[Wheaters]

Powder coating is worse - it can apparently give off Cyanide gas whilst curing. One more piece of advice...NEVER use the kitchen dishwasher to clean engine parts. I once tried it with a car cylinder head. It took two washes to start shifting the carbon and about four more to get rid of the smell before the missus came home and found out what I'd been up to.