Mandrel Tube Bender.

[Blackjack]

I've been adding some "random" workshop videos on my You tube channel, except that they weren't that random...

All of them related to building this...

http://www.youtube.com/watch?v=eofUqgM3FNA

so I can build an extractor 4-2-1 for a Reliant engine by bending up some tube.

Sadly lacking in details, because in the first place I was just making it up as I went along*, and in the second, while it's just about good enough, it can be a lot better, so no point in going into detail at this point.






*That's to say making it up as I went along having read quite a voume of manual, brochures, and treatises on mandrel bending and benders...

 

[wyn]

That looks like good stuff Blackjack, Could you use something like a ratchet head for the end of the bar.
What are you using as the former ?

 

[Blackjack]

The former was laminated up from plywood, shaped on a wood turning lathe, and then drilled 1" for some 1/8" wall tube, and sandwiched between some 1/4" plate to add strength and provide somewhere for the clamp to weld to.

Though, that's one bit that needs a rethink.

Yeah, you could use a ratchet, but is quite a lot of strain to put on one. Another 3:1 chain reduction and a big hand wheel is one idea I'm toying with.

 

[chedz]

I enjoyed watching you make "the egg"... I've not got a clue what it does but it looked good to me ! I've often used my drills as very very basic lathes to smooth and shape round things.
Graham

 

[Blackjack]

The "egg" bit, is the mandrel.

There's a rod sticking out of the tube tha'ts located by the two "fingers" welded to the far end of the base,

The egg is on the end of that rod and positioned just a little past where the tube starts bending. That supports the tube and helps to stop it from collapsing and kinking.

If you run it without the mandrel, it does make some fairly impressive kinks in the tube.