Thread: BobLs bandsaw brake

Bob, how do you actuate the brake?

The manual systems I've seen, have a foot pedal on the right hand side.

Have I missed that small bit of information?

Originally Posted by Pat

Bob, how do you actuate the brake?
The manual systems I've seen, have a foot pedal on the right hand side.
Have I missed that small bit of information?

Yep - still need to do that bit.

Can't decide on a foot pedal or maybe a cable driven hand brake lever from a bicycle.

Pedal means taking a foot off the ground - not sure if I want to be doing that all the time.

Hi Bob,
The large BS and spindle moulder i used to use both had foot brakes, as does one of my lathes (metal-just to be clear to all the woodies). You get really used to using a foot to stop the machines, and it also means if you get in a pickle and you need both hands to hold on to whatever to stop it/them being damaged etc you can stop the machine safely.
I have gotten so used to it i try go looking for the foot brake on my mill regularly....
It also makes sense that since you generally brake your car with your right foot it comes fairly naturally to do it with a machine. Best to put in a micro switch of course so you cut the power to the motor too....

Ew

Thanks for the feedback ideas Ueee. I didn't think of using it as THE regular stop mechanism, but now that you mention it why not?

I think its best to leave both options open-you will soon find yourself using one or the other though. The only thing that may be an issue would be the life of the friction material if you are using it all the time.
Even if you set the foot brake up so that just a touch will cut the power to the motor, that way you can turn it off with a foot (hook up a relay before the no volt cut out switch so it stays off!) and walk away or stand on the brake and stop it quick smart.

Ew

Edit, For anyone else thinking about it a cable actuated handbrake from your local wreckers is a good place to start.

Originally Posted by Ueee

I think its best to leave both options open-you will soon find yourself using one or the other though. The only thing that may be an issue would be the life of the friction material if you are using it all the time.

Thanks, I will keep both switches active.

Before I started I did back of the envelope calculation and worked out that my bandsaw needs at most 1/30th of the energy needed to stop 1 wheel of a one tone car travelling at 60 km/hr.
I estimate I use my bandsaw on a daily basis at a lower frequency than I stop at traffic lights.
And I go around 4-5 years per set of brake pads.
So I figured I should get around 120 years from a new set of pads on the bandsaw, which would well and truly outlast the life time of the bandsaw given it is already 6 years old.
This is why I settled for an old set of pads, they look like they are about 50% used.
And this does not take into account stop start driving in traffic and braking from higher speeds (e.g. exiting a freeway) which use much more energy.

You could scab a rotor and mechanical caliper from a gokart or even a hydraulic system as the latter would be more flexible for installation. The pedal could then be moveable to where it is needed at the end of a flexible line.

Originally Posted by Chris Parks

You could scab a rotor and mechanical caliper from a gokart or even a hydraulic system as the latter would be more flexible for installation. The pedal could then be moveable to where it is needed at the end of a flexible line.

Yeah I'd thought of that. I also saw a disc brake from a trail bike at a MC wreckers that would have done the job but the wrecker wanted $50 for it!

I've been working on the auto off feature, the linkages and the pedal and it's just about done - I should be able to post pics later today.

I've got this thing to the point where it is working nicely but I want to work with it before I spend any time tizzying it up in case I have to get the angle grinder and welder back onto it again.

Here's what it looks like. S
Since the first post I have added
Pedal and associated linkages
A back pressure/return spring (the calliper springs are not strong enough to drive all the linkages back firmly enough)
A micro switch to automatically turn the motor off when the pedal is activated - Cheers Ueee!


It's pretty obvious how it works but in case you cannot fathom it, here is the sequence
1) Pedal pushed down
2) this pivots the pedal arm
3) a short metal rod pulls the main lever #3
4) and an axial cam inside the calliper pushes the calliper onto the disc
5) is the return spring that pulls the pedal back when the operators foot is removed


Adjustments are down as follows - see diagram below
A) adjusts the tension on the return spring
B) sets how far back the main activating lever can go and also the maximum degree of pressure on the microswitch
C) These 4 bolts sets the disc to pad gap for the front caliper
D) These two bolts sets the disc to gap pad on the back fixed calliper
E) sets the free rotational distance of the main lever after the microswitch has activated and before the internal cam pushes on the brake pads to make contact with the disc
F) is a semi-knurled knob that adjusts the spacing between the main lever and the pedal lever - it effectively sets the pedal height. The rod on which F is mounted is LH threaded at one end and RH at the other which makes it really easy to assemble and adjust the pedal height.
To adjust the brake D-C and E are loosened.
A piece of paper is slid between the rear (fixed pad) and the disc, and fixed calliper/pad position (D) is adjusted so that the paper can just be removed.
Then the piece of paper is transferred to the gap between the front pad and the disc and the 4 bolts at C are adjusted until once again the paper can just be removed.
Finally E is adjusted so that the main lever drives the internal axial cam after the microswitch is activated.




The microswitch comes from an old X-ray machine and it says it is 15A capable.
The bandsaw already has a no-volt switch fitted, and it also has a keyed lockout switch, a cabinet door microswitch, and a push and lock type safety switch, all are in series, so I just wired the brake microswitch in series with the last of these.
When the cabinet door is opened it kills the power to the brake microswitch making it safe to change blades and clean up etc

The micoswitch is mounted on an aluminium bracket which can be adjusted and fixed in in several directions.
Initially I had the switch in a horizontal position but that put the AC connections ~5mm from the disc which was too close for comfort so I moved it to the vertical position like this



Here is how far the pedal has to be pushed to stop the saw.
You can also see how far the return spring stretches and how it rides around a small brass wheel.
I could fine tune the adjustment a bit more so that a much shorter pedal action is required but what I have now will be fine for the moment.
The linkage on the top of the main lever looks very close to the DS wheel but there is about a 10 mm of clearance which is fine, and when blades are being changed the linkage is well out of the way.



So far I am very pleased with the way it works - I will add some more locking nuts and then just use it and see what bits come loose, how long it takes to go out of adjustment etc.
What really pleases me is that I did not have to go and buy anything particular for this project, everything was already in my shed.
Some of the steel is a tad on the chunky side but it was all leftovers or scrap ($1 a kg) - Actually the guys at the steel place always price it for a less than this.

Very ingenious ! A useful addition to a piece of kit that makes operation much safer.

Nice work there Bob. It will be interesting to see how the sawdust affects the mechanisms in time, and how the mechanisms affect the dust extraction.

Originally Posted by dai sensei

Nice work there Bob. It will be interesting to see how the sawdust affects the mechanisms in time, and how the mechanisms affect the dust extraction.

Good point and I have thought about it. I have 3 x 100 mm flexies sucking on the BS. 2 go to the cabinet and one gets hooked up under the table. The latter seems to grab most of the dust because if I remove it more seems to end up in the cabinet. I also cut a breather in the side of the door to the bottom cabinet so that it breathes better and I no longer see any dust in the bottom cabinet except in the corners.

One thing I'm still thinking about is what to lube the moving parts with. Grease will just attract dust so I'm thinking some powdered graphite in the first instance although that will be sucked away by the DC.
The main thing that needs lubing is the internal helical cam so I might just grease that.

Try something like this

BobL, I would be a bit wary of Dry Glide - have a look at this thread, and the comments from the manufacturer