The drill press let some sparks out


(Paul Harvey) #1

I turned it on (on about hole 16 of 20), sparks came out of the switchbox thingy (on the drillpress) and tripped the breakers.

Does anyone know how these fail? Is there a starter circuit that could be repaired? I’ll be giving it a look if I can, tonight…


(Paul Harvey) #2

@Rurik went over the drill press and determined that the bearings in the motor are shot. It still does actually run, but apparently occasionally stalls, which might explain the breakers tripping.

I’ll add it to my personal TODO list but other suggestions are welcome


(Derryn Harvie) #3

I’ve got a small shop press which is normally required to get the bearings in and out of the housing. Bearings are normally cheap.

Having not seen it, I’m assume it’s just got a smallish induction motor on it?

I’m happy to have a crack at sorting it out.


(Paul Harvey) #4

That’d be great @Harvs, yeah it’s a small induction motor, ?/4 HP. Did you want to come in on Tuesday again? I can bring @CarlosPeco’s analyzer to finish off your helical build - we can take the motor off and I’ll get measurements to see if it can be bought outright for replacement or whether it’s feasible to replace the bearing.


(Derryn Harvie) #5

I should be able to make it in Tuesday. Don’t get too worried about bringing in the analyser, it would only be an out of interest thing.

Are there any tools we need that aren’t at the space to at least get the motor off?


(Paul Harvey) #6

I’m hopeful we have everything - I’ve just bought a couple more screwdrivers for the space, we’re down to a single #2, #3 Phillips screwdriver I think. Should probably do an alibaba order for small handtools. Pretty sure we have socket sets and other bolt-turning stuff.


Tuesday 4 April: Maker meet cancelled
(Paul Harvey) #7

Hi @Harvs, turns out I can’t make it tomorrow night - feel free to take a look on Wednesday night or whenever you’re there next.

Cheers


(Derryn Harvie) #8

I’ll probably delay until Wednesday then, thanks for letting me know.

Cheers


(Derryn Harvie) #9

I pulled the motor, stripped it and cleaned it last night at the space. I have left it laid out on the bench for others to have a look and weigh in on the diagnosis.

I don’t think it’s the bearings (at least not in the motor), they feel ok and there’s no evidence of the rotor striking the stator.

I also inspected the switch assembly on the press and it seems fine.

The only thing that I can see might be the issue is the starter cut out contactor looks a quite burnt (more than normal for it’s age, who knows?) So possibly the starter cap might be internally shorted. I didn’t have a meter on me to check it at the time, but it will be the next task.


(Paul Harvey) #10

Did you turn the motor before removal? It did seem pretty noisy - I’ll annoy @Rurik next time I see him around :smiley:


(Derryn Harvie) #11

I didn’t fire it up, but I did just spin it. Made some horrible squeaking sounds but that wasn’t the bearings, it was the centrifugal switch for the start circuit.

I can still replace the bearings, the rear bearing felt like it had some wear (i.e. it span quite freely). But I just don’t think that’s going to solve the problem.


(Ben Paton) #12

I did not pend more then five minutes looking at it but then the motor is in place it is it making the noise and the shaft feel very crunchy. I disconected all the pullies and had cranked them all and the only one that did not spin freely and made noise was the motor. There was audible crunching sounds when hand crancked and a high pitched sound when turned on with no load on it.


(Ben Paton) #13

My question seems to have been answered.


(Ben Paton) #14

I just picked up a new bearing for the motor. I think it is worth the try replacing it rather then going a new motor at this stage. Does someone have the tools to pull and press it back in?


(Paul Harvey) #15

@Harvs ? We think perhaps the bearing feels mostly fine but perhaps under lateral load it’s binding.


(Derryn Harvie) #16

Sure, I’ve been away a lot lately so haven’t had a chance to finish it. I’ll do it this week if the bearing is around somewhere?


(Ben Paton) #17

The bearing is currently in my glove box of my car. I can leave it with the motor next time I am in the shed. Which should be tomorrow


(Chris Small) #18

I was thinking about this…What condition are the points in the centrifugal switch for the excitor winding in? (From what I could see, the motor is an induction type with an excitor coil that is switched off once the motor is running). If there’s a build-up of oxide/slag then that can cause the thing to spark more that it otherwise might, without leaving the excitor-winding damaged.
Cheers, Chris.


(Derryn Harvie) #19

Drill press is back together with the new bearings. Seems to run ok, I guess we’ll see how it goes.


(Paul Harvey) #20

Thanks heaps @Harvs :smiley: I’ll try not to break it again :slight_smile: