KemppiFrog
Member
- Messages
- 4,274
- Location
- Aquitaine
Heres the bender I use for square section tube. The motor is 2hp (ex pool pump) driving a 40:1 reduction ( off a Do-Nut machine) the chain and cogs are from small motorcycles.
It originally was bench mounted and hand turned. But that was seriously hard work and needed several passes, so when the gearbox was spare due to a bent shaft, I reworked it for power, and free-standing. The only machining I farmed out were the rollers, the motor/g box mating plate and coupling were turned on my old Sphere. It was set up for 40x40 box until much later, when I got an order for some 'Monet' pedestrian bridges from a big landscapers, so I upped it to 50x50mm. The rollers are a snug fit on the tube to avoid distortion.
The top tube of the gates is a single pass. There is always a bit of wastage, as one sets it up with the tube on the rollers, switches it on, then quickly turns the screw to get the pressure on, so the first bit is not the same curve. A couple of people have asked how one gets the curve right. My usual answer is 'experience', but often the reality is to get it about right then build the gates to fit. If it matters, like the bridges, then multiple passes at low settings until the curve is correct.
The gates are a bit spartan, but that was the order.
KF
And a coat of paint would improve it
It originally was bench mounted and hand turned. But that was seriously hard work and needed several passes, so when the gearbox was spare due to a bent shaft, I reworked it for power, and free-standing. The only machining I farmed out were the rollers, the motor/g box mating plate and coupling were turned on my old Sphere. It was set up for 40x40 box until much later, when I got an order for some 'Monet' pedestrian bridges from a big landscapers, so I upped it to 50x50mm. The rollers are a snug fit on the tube to avoid distortion.
The top tube of the gates is a single pass. There is always a bit of wastage, as one sets it up with the tube on the rollers, switches it on, then quickly turns the screw to get the pressure on, so the first bit is not the same curve. A couple of people have asked how one gets the curve right. My usual answer is 'experience', but often the reality is to get it about right then build the gates to fit. If it matters, like the bridges, then multiple passes at low settings until the curve is correct.
The gates are a bit spartan, but that was the order.
KF
And a coat of paint would improve it
)
