Makita combi drill burnt out motor?

[CaptainJack88]

I was trying to cut a hole with a hole saw through some solid timber earlier, and I got a bit greedy towards the end and just went for it.

Bad move, as my dhp456 started smoking, the noise went from that smooth whine to a rough spinning sound and there were some small pops.

I believe this is a brushless drill, so could it be that the motor just need replacing? The motor itself still functions and engages

 

[Deleted member 174758]

The DHP456 is an older design of brushed drill and whilst it is currently still available from one or two places for £65 to £70 (bare) it is an out of production tool AFAIK. TBH they weren't top of the range tools and they aren't the most powerful, so not really up to drilling large diameter holes with hole saws. I have one, but I restrict its' use to pilot drilling, drilling bolt holes up to about 10/12mm in timber and maybe up to 20mm with spade bits (for heavier/deeper stuff I have a DHP481 brushless combi).

From the sound of it I think it is highly likely that you've goosed the gearbox (i.e. stripped teeth, which I believe are nylon on this particular drill) rather than banjaxed the motor. To get a drill with a heavy duty gearbox capable of taking a lot of abuse you need to look at something like the DHP458 (brushed) or DHP481 (brushless) in the Makita range. These have powerful motors, heavy-duty all-metal precision chucks and heavy-duty gearboxes - but also have price tags to match and are noticeably heavier (although they will happily run 127mm hole saws through warm roofs).

Personally I'd be half inclined to bin it and buy a newer brushless such as the DHP484 (c.£88), or possibly a new heavy duty brushed model such as the DHP458 (c. £82), because a new gearbox will run you around £35 to £40 (see here - part 11), and then you need to fit it

 

[CaptainJack88]

Thanks for the detailed reply. A gearbox would actually make more sense.

I hastily ordered the direct replacement of the 456, the 482Z. I'm not in the trade, and I've finished most of the renovation in my home, so other than finishing stud work and building a desk in my office, it'll probably just be used for light work.

Do you think I'm best off getting the 484 over the 482 for the extra £20? I've got a 152Z impact driver so its prey much just for drillings etc

 

[Deleted member 174758]

AFAIK they both have metal gears but the DHP484 has a heavier gearbox casing (ally outer) which is designed for heavier duty use and it is brushless, so longer run time. Against that the DHP482 is a bit more powerful and quite a bit cheaper. but it has a brush motor so the run times will be shorter. Providing you aren't going to be running large auger bits or oversize hole saws (again) you'll probably be OK with the brush motored DHP482.

TBH anyone looking for the most bang for their buck in terms of power and durability might be better off looking to the DHP458 - it's £5 to £10 cheaper than a DHP484, but it is heavy and it doesn't give the battery life you get from equivalent brushless tools (which should really only be an issue in heavy trade use)

 

[CaptainJack88]

Thanks.

I took my 456 to pieces to see if I could see anything obvious. The carbon plates on the motor are fine, plenty in them.
Motor still spins.

In the gearbox, all of the gears still haven't plenty on them, none of them are worn or show signs of damage.

The sound must be coming from further down towards the chuck. I've got no idea how to get that apart to investigate though.

I also can get the damn case back on the drill, seems to be something stopping it going together near the motor

 

[Deleted member 174758]

In the gearbox, all of the gears still haven't plenty on them, none of them are worn or show signs of damage.

I've certainly come across DHP453s where the gearbox has had deformed or stripped teeth (generally cheapskate tradesmen who are buying the bargain basement drill then using it for drilling masonry and drilling out for mortise locks - nylon gear tools really aren't up to that)

The sound must be coming from further down towards the chuck. I've got no idea how to get that apart to investigate though.

Open the chuck jaws and shine a light in there - a screw inside the chuck holds it onto the gearbox shaft. The chuck on your drill is a plastic item. Could it be that your enthusiasm has put paid to it?

I also can get the damn case back on the drill, seems to be something stopping it going together near the motor

Maybe a wire - the casings are really tight on pretty much all cordless tools

 

[SammyInnit]

Bad move, as my dhp456 started smoking, the noise went from that smooth whine to a rough spinning sound and there were some small pops.

Faulty armature.

I'd imagine as you run the motor it sounds gritty, gives the impression it's a damaged bearing or faulty brushes but it won't be.

Easiest way to confirm would be with a multimeter; there are videos on YouTube of how to do this.

If it's as I suspect your drill is scrap. You can buy replacement armatures but the cost isn't worth it with such an old model.

I believe this is a brushless drill

It's brushed.

Unfortunately on brushless models it's even more complicated to repair and either has to be done by Makita or you buy a new tool, as it's not a case of swap the rotor or brushes but you have to swap the entire controller, motor stator and trigger assembly which isn't cheap.

 

[Deleted member 174758]

I discounted problems with the armature because the OP didn't complain about smoke, smell or arcing - and you'll generally get one or more of those in the case of a shorted armature, won't you?

 

[SammyInnit]

I discounted problems with the armature because the OP didn't complain about smoke, smell or arcing - and you'll generally get one or more of those in the case of a shorted armature, won't you?

Not always. Arcing is very tell tale but again not always a given.

I just find it very difficult to see that it's a gear box issue. Given the amount of reductions and there being two gear sets for a further reduction to low speed or would need one absolute killer snag for it to shear or damage teeth, nylon or powdered metal.

 

[Chud]

I discounted problems with the armature because the OP didn't complain about smoke, smell or arcing - and you'll generally get one or more of those in the case of a shorted armature, won't you?

Bad move, as my dhp456 started smoking