Having played around with steel tins a few days ago, and come up with my Mk II attempt at a robust, screw top, alcohol/meths stove, it was time to try out a couple of tweaks.
Other than using a slightly thinner section of ceramic wadding, therefore not compressed so much, I did wonder if I could lose another gram or two by using a more open wire gauze. But found that this uses a thicker gauge wire and actually came in at two and a half times the equivalent weight. So it was back to using my first choice.
My second tweak was to include a choke in the top of my stove. Mk III had a very thin 1g copper sheet disc cut and fitted beneath a wire gauze cap, while Mk IV stove had .016 aluminium sheet cut into a disc with a small square of wire gauze beneath it. The circular cut out in the copper measures 33mm diameter and was created simply by running the point of a penknife round a bottle cap placed in the centre. The hole cut in the centre of the aluminium sheet was a very different affair. Hacked rather than cut might be a better description! Having no way to hand to create this, I simply folded the disc in half and cut a half moon approx 25mm diameter in the centre with a pair of Leatherman Raptor shears. The disc, sans centre, weighs 2.4g.
- Mk II- Tin, lid, ceramic wadding, wire gauze: 30.7g
- Mk III- Tin, lid, ceramic wadding, copper sheet choke and wire gauze: 29.3g
- Mk IV- Tin, lid, ceramic wadding, aluminium sheet choke, wire gauze disc below: 29g
|Burn times- all stoves brim full with fuel|
|Mk II||No choke||22min 50sec|
|Mk III||Copper sheet choke||27min 55sec|
|Mk IV||Aluminium sheet choke||25min 5sec|
It was a fairly cool evening at 18° with a slight breeze. In common with my last trial with a home made stove, I didn’t use any form of windshield. Next up is to get some boil times rather than burn times.
As it is, it is looking as though my Mk III is coming in as most effective in burn time and almost as light as the lightest.