Jetbrake on a pillar drill??? Why?!

[astro_al]

Hi guys, I have acquired a Meddings A10 'radial type' drill (slightly different to radial arm in that the head is on a double jointed swing arm to change distance from post, not on a geared track).

It has a Jetbrake which is attached to the body of the head, with a trigger arm pointing directly downwards to the table.

I'm struggling to see how it could be of use, since neither the table nor the head move while you are drilling, what could possibly trigger it to stop the motor? I'm sure I'm missing something obvious! Or is it just there in case something starts flying round on the end of the drill (which would trigger it)?

Cheers, can get a pic if needed, Al.

 

[gavuk]

You got it ,workpiece or vice movement ,"helicoptering".triggers the brake

 

[Paul.]

30 years ago I was caught up in a pillar drill, a working Jet brake would have saved me from a dislocated finger, (Which could have been torn off) a load of stitches and a lot of pain, they operate by firing a dc voltage into the motor to stop it dead when the switch is triggered, the wand is usually telescopic like a car antenna and can be set in length to clear the workpiece, but will catch sleeves, spinning workpieces etc, they can also be wired to a trip cable running round the machine table so that you can lean on it to stop the motor, although they can have some nuisance value with accidental tripping, the safety aspect far outweighs it.

 

[astro_al]

Ahhhhhh! Brill, ok thanks guys, that solves it.

That's exactly like it - a downwards pointing car aerial.

Yes, its weird to see a 'brake' which is all wiring! (Curiosity made me open it up for a look). I'm going to otoally rebuild the drill anyway, but I'll keep the brake then when I put it all back together.

Cheers chaps! Al.

 

[Luke]

Yes, its weird to see a 'brake' which is all wiring!

Inverters/variable speed drives work in exactly the same way, injecting a DC voltage rather than an AC waveform when braking the motor

 

[Hitch]

We have one on our radial drill, if something comes loose on there you'd want it to stop asap.
They can be a pain, big swarf will trip it, so you need to break the swarf off every now and then.