hot enough?

need to bend a bike frame rear triangle as in link will a plumbers gas torch be up to it?

https://sites.google.com/site/recycledrecumbents/rear-triangle-jig

want to use idea for different project to on site.

Edited By mick70 on 28/05/2018 16:51:17

Looks like this guys using oxyacetylene or oxypropane to get the heat in a local point. A large propane torch (Sievert type) may get it hot enough. I personally would attemp it with a plumbers torch. A Map gas torch will give you a higher temp but it not a good as the genuine MAPP gas.

All disclaimers and errors and omissions included! 😳

John

I would use a BIG contractors gas blow torch with plenty of 'refactory' brick to conserve heat. heat both tubes at the same time, add heatsinks to the brazed joints you don't want to disturb. A cheap torch could be the sort used for killing garden weeds straight from a big propane bottle - for the burner go BIG and wear heatproof gloves, nothing worse than nearly up to temp and frying your hands.

can we see a photo of the finished project ?
Bob H

when i get it finished will put pics up.

got another project under way at min but thinking ahead.

it's for a tadpole style bike

I have done a bit of lampworking.

Here is an extract from Wiki re glass forming:

‘The transformation of raw materials into glass takes place around 1,320 °C (2,400 °F);^[16] the glass emits enough heat to appear almost white hot. The glass is then left to "fine out" (allowing the bubbles to rise out of the mass), and then the working temperature is reduced in the furnace to around 1,090 °C (2,000 °F). At this stage, the glass appears to be a bright orange color. Though most glassblowing is done between 870 and 1,040 °C (1,600 and 1,900 °F), "soda-lime" glass remains somewhat plastic and workable as low as 730 °C (1,350 °F). Annealing is usually done between 371 and 482 °C (700 and 900 °F).’’

Lampworkers typically use propane burners - either ‘hot-heads’, which are propane /air mixtures or oxy-propane burners (often surface mixed burners). Hot-heads are just satisfactory for soda glass but not borosilicate. Smaller oxy-propane burners will soften the glass much more effectively and are the preferred type. For soda glass a 5 litre/minute oxygen concentrator is sufficient for the oxygen supply, but pure oxygen is noticeably better (the less gas dilution with inert gases, the better). Those that regularly use borosilicate glass use at least a 10 litres per minute oxygen supply with a larger burner.

I have only a 5 litre/minute oxycon. (The above may help you decide on whether you want to braze with air/propane). Bending requires less temperature and needs the heat in the right place - or the bend may not occur at the expected point. If it is a precision job, I think I would be preferring an internal mixed torch for better flame control.