How Do I Make this Bracket?

[Wongster]

Hi guys,

I'm currently planning to start my build of a tiny bending brake based off a plan I bought from Mogen Kilde. I'd so far gotten the 3D model done to give me some visual of how things fit and work together. Gathering of materials will start after the the lunar new year. 

While going through the processes in my head, I couldn't figure out how the brackets are to be made. This is how one looks like:

   

I don't have a slip roll in the shop.  I was thinking of milling out the inner shape in aluminium and form a 3mm steel sheet over it.  Very little experience in processing sheet metal and I have no idea how accurate the brackets need to be. 

Any suggestion and/or help is greatly appreciated. 

Regards,
Wongster

[f350ca]

I hope it doesn't need the precision the drawing is implying Wongster. Probably doesn't as the note says to make a pattern and compare the part to it. Forming it over a mandrel as you suggested would require the pattern to be sized to allow spring back as the metal is bent. I'd try forming it with a hammer and a vice.

[Vinny]

Or depending on the size of the clamp, finding something at the store that would be close - like a conduit clamp.

[TomG]

I would bend them up in a vice, over a form, but it would be an internal form, not an external one. Start but working out the jog, and once that is correct, make a form roughly 17.5mm high, 17.5mm wide, with an 11.5mm radius. Clamp the form against the 5mm wide section after the jog and hammer the metal around the radius. the re-position the form on the 5mm section along the bottom and hammer the metal around it to create the second radius. This section should be left long and trimmed after the bend to get the 38º angle. Assuming you are using mild steel, springback will be minimal. For a 90º bend over an 11.5mm radius, the springback will be about 2º and the radius will grow to 11.68mm. You can compensate for both when you make the form.

OR, a way around the springback is to heat the steel red before bending it, if you have the means.

Tom

[Wongster]

Thank you all for your input.

Tom, may I know what's a jog?

[TomG]

(01-30-2017, 08:52 PM)Wongster Wrote: Tom, may I know what's a jog?

That would be the 159º section that "jogs" over 1.8mm.

You'll need to clamp the stock 21.8mm from the end and bend the 159º angle, flip the part and clamp it about 5mm farther, and bend it back vertical again. That will probably be the toughest part to bend up and get it right. Just be sure to write down your dimensions so you don't have to make too many trial pieces. You may have to heat the metal to get the sharp bends shown in the drawing.

Tom