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3D printed disc brake

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Joules:
Whilst waiting for my CNC controller to arrive, I had a rummage around in my junk box and found an old worm wheel gearbox....  Ahhh, CNC rotary table ?   I had a look on Youtube and found another guy had done this mod and he mentioned his issue with backlash and requirement of a brake.  I was looking round and spotted the hydraulic brake on an old mountain bike.  OK might be over kill for this, but the principle is sound.   How to implement this in 3D printed parts.

Body is easy, just a couple of blocks bolted together and attached to the gearbox somewhere.  Next came the brake pads, as they aren't stopping the disc from spinning they just need to clamp the disc.   Lets see see how contra rotating splined inserts will hold up, they can be operated from a small pneumatic cylinder/bellows or solenoid is my thinking.  Anyone got any thoughts on suitable bellows for simple operation, bit like in a barograph.

Anyhow, some sketching later and I have this as a starter.  Now it could easily be machined, but if the printed brake pads work it's such a quick solution even if they wear some.  The disc will most likely be a small circular saw blade machined down or hard drive disc.  As drawn the pads move 0.5mm with 45 degree movement on the arms, they will probably need a return spring to release the pads.

 

ddmckee54:
So if I am getting this correctly, the only part that you've got drawn that won't be 3D printed is the brake disc - right?  The brake body, the actuating arms, the splines, and the threaded/splined brake pads will all be 3D printed?

Sounds cool, let's see how it works out.

Don

Joules:
Cheers Don, the short splined shafts will be machined from 10mm perspex rod and 6mm rod between the brake arms.  I have also changed the threaded brake pads to M16 x 2mm, its a more standard size and I had a proper thread profile on record in CAD.  The left hand thread is then a mirror of the right, this is where the printing excels.  Whilst M16 taps are cheap (sparkplug etc) I can't say that for a left hand M16 tap and die, though not such an issue cutting the threads on the lathe.

I will probably need to broach the arms with some splined shaft as they need to be a slide fit rather than press fit.  Will have to see how the parts print out.  It's all good fun.

Joules:
Well that went better than expected.  I printed the splined shafts and forgot to compensate for exact fit, a little needle file work sorted them and they are a very snug fit, but easy to print the parts again.  I am trying some different filament from my usual and it has a bit of a learning curves with new compensations and slight increase in extruder temperature.





I'm very happy with how the threads printed this time, they are a good fit helped by using a course thread profile and I hope plenty of leverage.



In the open position.



And closed.

I have just tried a bit of 1.6mm alloy sheet between the pads and we go from sliding fit to gripped in about 10 degrees of travel, very little force required to lock the brake.  In this case the printed splines will be strong enough, and I can use much shorter arms.  I consider this one a big success.

 :ddb:

DMIOM:
Bravo !  :clap:  :clap:  :clap:

Dave

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