Cheap (Chassis Folding) Thrills

[tubeswell]

I have, until now, bent my chassis with a bit of 4 x 2 on my workbench in my garage. But in contemplating my latest build which calls for a 65cm (2'6") wide chassis, I have been pondering how to get a cleaner bend. The cheap Chinese Junk doesn't quite engender my complete confidence.

So feeling in an experimental mood I took all of about 6 hours (including driving around to buy the materials I needed; $8 worth of 2nd-hand 5cm x 5cm (2 x 2) angle iron, a couple of brass hinges ($20), and about $7 worth of bolts) to come up with this.

I tested it on a couple of short pieces and it seems to hold out okay. I'll work up to something more ambitious tomorrow and report back on the results.

(Oops! - News Flash - sitting down to write this, we just had a wee shake-up here (I thought about 5.5 on the MM scale, but it was only 4.1 - Aw Shucks, but the epicentre was all of about 4km away - Hope it doesn't happen again tomorrow when I am testing out my new jig - what the heck? it'd give me the perfect excuse if it turned out all crooked 8-)

http://www.geonet.org.nz/earthquake/quakes/latest.html

FWIW This page will quickly become outdated)

[Sir Cuitous]

I 'd love to hear how well that bending jig works. I want to start making my own chassis. 65cm sounds very long!

Looks like the epi-center was right on Wellington. You can check on quakes here.

[tubeswell]

1st chassis off the press

Well not exactly all of it - I had to revert to hammering the lips because there wasn't enough power in the brake (or in me) to easy handle 1.2mm Ally over 65cm long fold with a 1cm wide lip. With wider widths, like the tope and the bottom (which were 7cm wide) it works better. With shorter fold lengths it should work well too. But today's effort was a monster length, because it is designed to hold 7 pre-amp tubes (and three octals), and 11 knobs on top, and now I am too knackered to do any more today. Nevertheless it was a help in getting reasonably straight edges. I'll try a shorter chassis next time. I may have to revisit the hinge system to get the apron closer to the brake. It takes a helluva lot of force to bend stuff and as far as I can tell so far, the hinge position is critical

(Chassis in pic is 65cm wide, 13cm high and 7cm deep. It still has the protective film on the outside because it has yet to go to the engraver)

[defaced]

Very nice. I'm always a fan of simple but effective solutions.

I wonder if using C-clamps (the real cast iron kind) between the wing nuts will help get enough clamping force to allow you to bend the lips.

Looking at how your hinges are mounted, I think if you were to slit your apron so the pin of the hinge were in the center of the angle you'd be able to get the apron tighter to the brake. This though depends on if your hinge can accommodate the thickness of your apron's angle.

[tubeswell]

I found out that I can do the lips better if I turn the metal around so that the lip is in the brake (duh!). However be that as it may, 65cm was just too long for this folder. Nevertheless I have worked a few lesser lengths in there just a few moments ago and they came out good. I could probably do something between a 5E3 and an ordinary 5F6A chassis without needing to mod it further. However you are right about the hinges defaced. I had the same thought, and yes there is plenty of mass in the iron to grind out some hinge space (I just have to borrow a grinder from one of my M8s.)