Hedge Trimmer Problem

Motor brushes?

Worn bearings and brushes

Thanks. I did wonder about that. Looking at the motor, I'm not sure how easy they are to remove, but a quick search online suggests that they are at least still available, unlike many parts for that model.

Adrian

I would also checkout any wiring that you may have disturbed internally when swapping the micro switch, a loose wire may make contact if the trimmer is held in one position but disconnect when reorientated. That happened on a drill I once owned. Externally check the mains wire where it enters the tool which is an area where maximum flexing takes place often resulting in the conductors fraying. The latter is usually the point where domestic managements steam iron goes bang.

In message <v92jin$18n7$ snipped-for-privacy@dont-email.me, Tricky Dicky snipped-for-privacy@sky.com writes

I've had it apart again. The brushes appear to have plenty of meat left on them, so I think we can rule those out. The wiring still appears OK, I've rechecked all the connections (of which there are many), and there is a nice big clamp/gland where the cable enters the casing. I also double checked the plugs on the lead (normal 13A at the wall, and a two pin close to the body, which will move about as the trimmer is moved).

Put it back together again, and progress of sorts. It now stops working when the blade is pointing straight down, rather than at 3 o'clock.

Adrian

I repacked the main bearing on mine a couple times.

The gear house is open to the outside world. Material you are trimming, a tiny bit gets into the grease. The grease has to be stiff enough to stay inside the housing.

B&D used to have a store here, and DeWalt acquired it I guess. It's moved around the city a bit. I used to be able to get small appliance grease packs (toothpaste tube). And the trimmer had been repacked a couple times. That may give you sufficient power to withstand rotation of the machine in usage.

The brushes went on mine, and there weren't any more brushes. That was the end of the trimmer for me.

The gears inside the machine were excellent. Sharp as if they were new. Made from a very hard metal. As long as the machine friction is low enough, there should be power to spare to cut a hedging.

My electric mower was similar. You could feel the gear box load by moving the blade, and determine the gear box needed to be re-packed with grease. The grease they provide, they take a commercial grease and have someone put it in tubes. The last grease I bought was a "urea" grease. One of the problems with greases, is biological material gets into them. Some greases (even petroleum greases!), stuff grows in them and makes them stink. Urea grease is one of them.

Paul

Tim

In message <v92nru$2khi$ snipped-for-privacy@dont-email.me, Paul snipped-for-privacy@needed.invalid writes

On this model the gearbox is enclosed apart from the slot where the cutter bar goes in.

Adrian

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I saw a tool for checking this in a small appliance repair shop a long time ago: a test jig? tool? circuit? where a light bulb was in series with a socket. Plug in hedge trimmer, turn on, and wiggle the cable. Any flicker in the bulb means the cable is intermittent. The light bulb puts a bit of load on the testee, and keeps the current down if the testee is short circuit...

Thomas Prufer

That's how stuff gets into the grease. The cutter bar opening.

The cedar hedges I cut, the cedar isn't too much of an offense to the grease. I'm not replacing the grease because it is particularly "fouled". I'm replacing the grease to reduce friction.

I also oil the blade pair, at the beginning of each session.

This is likely the sort of thing, for a mains powered trimmer, where you would measure the current draw when the machine is new. And later, using your Kill-a-Watt meter, measure it again after five or ten years, and see how much the current draw has gone up. That would give some idea whether the unloaded level of friction in the machine is having an impact. I use this sort of testing, for my electric pumps, and for my roof heater (ice buildup).

My first suspect would be a fracture in the cable just past the flexible sleeve where it exists the trimmer. See if manipulating the cable can cause the stop and start.

If it does, then disconnecting it from the tool, chopping a bit off, and re-terminating will normally fix it.

That's precisely what I would have said, but several others beat me to it! I've had a couple of power tools which have exhibited this exact problem.

I've done that. At the terminal block inside the case, and with the two pin plug/socket on the lead. There is enough slack in the cable that the 13A plug isn't moving, so I've left that alone. It is now consistently operating in dodo emulation mode.

I think a shopping trip may be in order :-(

Adrian

It can be a good idea to buzz out between the live on the plug and the terminal on the switch, same for the neutral. Then pull the switch and buzz from the plug terminals to both brush holders, and also both connectors to the field coil (aka stator winding). If all those work and the brushes look ok, then bus out the field coil, and then look closely at the commutator bar on the end of the armature. Check for black or burnt looking segments.

In message <v9bk2r$2uluv$ snipped-for-privacy@dont-email.me, John Rumm snipped-for-privacy@nowhere.null writes

Thanks. I haven't had a chance to go shopping yet, so there is still hope.

The last time it ran, I could see it sparking a bit through the vent holes in the casing.

Looking at the wiring on the motor, there are three connectors on each side. The middle pair are clearly the brushes, I'm making an uneducated guess (I'm not an electrical engineer) that the other four are the field coils.

Last time I had it apart, I drew up a wiring diagram as it seemed a bit of a rat's nest (did I mention that I'm not an electrical engineer). Coming off the terminal block on the mains lead, one wire leads to one of the pair of micro switches (but to one of the switched terminals, rather than the common), the other seems to go directly to one of the coils, and to a capacitor (mains suppresser ?). If I had somewhere to post it, I'd tidy it up and scan the diagram and put it up.

"bus out the field coil". Resistance check ? and if so, where to where ?

Adrian

In message snipped-for-privacy@ffoil.org.uk>, Adrian snipped-for-privacy@ku.gro.lioff> writes

Busy afternoon, so no time to take it apart. However, I a thought crossed my mind. As I've mentioned before, there is a short lead (1ft ?) that comes out of the trimmer, with a two pin plug on the end of it. There is then a longer lead with a two pin socket on one end, and a 13A plug on the other. The two pin plug/socket isn't handed, so can be connected together either way around, so what is on the live terminal in the trimmer could as easily be the neutral. I turned the trimmer on, and no life (as before). With as little disturbance as possible, I reversed the connection on the two pin connector, and now the trimmer runs, sort of. Still rough and cutting out at the wrong angle.

This could of course be a complete coincidence.

Adrian

Have you checked out the 2 pin connector, is it moulded or can it be opened likewise the socket on the extension it is going into. As I said in my first post and many have repeated since it has all the hall marks of a bad connection somewhere which is making intermittent connection depending on orientation. A multimeter is useful for tracking down continuity problems, failing that a buzzer & battery and a few wires will do.

In message <v9dbke$3c9r4$ snipped-for-privacy@dont-email.me, Tricky Dicky snipped-for-privacy@sky.com writes

Thanks.

Yes they can be opened up, and they have both been checked several times, and the cable trimmed back and the connections remade.

Adrian

Sounds like you have a bad connection in that connector block. From memory replacement blocks are easy to source.

I have been having trouble with my mobile phone Sometimes I couldn't 'mount' it as a drive to transfer data.

Then yesterday it stareted to show errors whenever I touched the phone. I replaced the lead and normal operation has resumed

Reversing an AC lead has no electrical implications, but has many possible *mechanical* implications.