INSTRUCTIONS FOR USING THE USEFUL-TOOLS HAND TUBE BENDER
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Grip Hand Tube Bender in a sturdy bench vice.
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Fit main mandrel for tube size. This involves removing the pivot pin/drive key assembly and fitting to new mandrel.
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Select the appropriate size alloy backing plate.
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Fit the correct size "bullet" to the threaded rod and adjust the position of this bullet until the machined faint line (denotes the end on the parallel portion of the "bullet") is opposite the centre line of the mandrel, with the mandrel at right angles to the work.
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Lubricate the “bullet” well with grease or oil.
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Slip the tube to be bent over the "Bullet". The tube should slide easily and not have to be forced .
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Slide the profiled "keep" plate over the protruding end on the tube and slip over the locating pin to snug against the side of main mandrel. (allow tube to protrude at least 1/4" past this plate).
- Fit backing plate over tube until end touches "keep" plate and screw in pressure adjusting knob to bring rollers up to the back of the backing plate. Apply a gentle"nip" to bring the backing plate onto tube/main mandrel. Slide crank arm into place, apply a little pressure and adjust the "nip" pressure so that the bullet threaded rod exits the rear of the tube as centrally as possible.
- Tube will then pull over the "bullet" and wrap around the main mandrel forming bend to desired angle. It may be found when bending steel tube that fitting an extension to the operating lever will reduce the effort considerably.
- Once desired bend radius is achieved, back main crank handle a trifle to ease pressure, remove "Keep" and backing plate & remove tube from machine. (sometimes a gentle tap with a hide mallet on the open end of the tube will help free the tube.)
Information
If the “Bullet” position is not adjusted correctly (see point 4 above) then you may have a condition where:-
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Excessive force is needed to pull the bend. This is usually caused by the “bullet” protruding a little too far with the faint line being out past the centre line scribed on the mandrel.
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Tube distorting and flattening slightly. This is usually caused by the “bullet” being screwed in too much with the faint line being behind the centre line of the main mandrel.
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When bending aluminium tube it may be that the tube necks and/or cracks. This is usually a result of the aluminium material being too hard and/or the silicon content too high. In most cases it is possible to overcome this problem by annealing the material immediately before use. We would also recommend 6063 aluminium as being a relatively easy to bend material, but that may still require annealing before use.
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Tip 1 - Aluminium anneals at about 320/340°C. Before heating the aluminium , rub a smear of soap along one side of the tube. Use a soft propane-type flame to heat the tube keeping the flame moving to avoid local overheating. When the smear of soap turns black, then the tube should be annealed. Deceptively, aluminium stays the same colour when hot so beware.
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Tip 2 - When bending steel we found a considerable difference in the quality of the steel tube supplied to us. One supply of 3/4" x 16SWG ERW was so 'hard' it would not bend properly, but after being heated to dull red and allowed to cool, bent perfectly. One answer to this problem is to use CFS tubing to the following specification: BS 3602 (PTI) CFS 360 NBK. This is a seamless tube that performs flawlessly and allows for perfect bends.
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Tip 3 - Bending 16SWG steel tube on a 1.5" or 2" centre line radius is technically very difficult and because of the high loadings generated, the steel tube being bent will sometimes slip back a little inside the "keep" plate as the bending process is carried out. To overcome this, we have designed a simple clamping arrangement into the "keep" plate that will stop this happening with steel tube. It will generally be found not necessary to tighten this clamp fully when bending alloy tubing.
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Tip 4 - When bending, say, 7/8" or 1" alloy or steel tube and you experience a slight rippling on the inner surface of the bend, then ease the "bullet" out a little (1 or 2 mm) to remove this effect. Continue to ease out until rippling effect ceases.
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