Dewalt electric drill motor question?

[Vineyardmanager]

I need to solve a question. I have the Dewalt Dwd450 1/2” right angle corded drill. It’s being tested in a pretty harsh environment where we are are in a field with a 3” soil auger and drilling 16” deep holes in the dirt. We are trying to drill 1000 (100 per hour)holes a day. Any thoughts on if it can take this kind of work load? Second part is as I was testing it I had one guy that would trigger the drill on/off repeatedly to kind of feather his way down making the hole. I think he should just pull the trigger and hold it until the hole is complete and just regulate downward pressure but keep the motor running. Can anyone tell me if the excessive triggering will lead to any problems or will it damage the motor more that the single pull method over the course of the work? My theory is that the frequent trigger pull will wear internal motor components out much faster than the single pull and hold…just need an expert to weigh in. Thanks!

 

[LittleInch]

Yes you are right. Starting electric motors creates extra heat each time. Also your switch is lifed on number of operations.

Running an electric motor at no load is relatively low current and keeps the fan running to cool the motor down.

But will it last? No idea. De Walt have a decent reputation but that's a fairly brutal workload. Everything wears out eventually, but go for continuous operation, even between holes. 100 per hour is basically 30 seconds each. Doesn't sound feasible to me.

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Also: If you get a response it's polite to respond to it.

 

[wayne440]

Adding to the previous- use the low gear range of the drill, and plan on buying more than one drill.

 

[Vineyardmanager]

thanks for the comments and advice! I'll try to upload a short video below to give you a glimpse of what we are doing.


[URL unfurl="true"]https://res.cloudinary.com/engineering-com/video/upload/v1652371816/tips/IMG_9667_avqs2q.mov[/url]

 

[LittleInch]

OK, maybe feasible, but I would keep the drill running continuously unless you are in danger of drilling your foot....

And try not to stall the motor - that gets you some seriously high temperatures.

See how it goes, but maybe drill 10 to 20 then let the drill run unloaded for maybe 15 to 20 seconds to get some cooling air into it.

Or buy 2 or 3 drills and when one starts smoking or sparking you know its time to get another one....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[3DDave]

I'm betting the workers will wear out the fastest. There are post hole digging attachments for small tractors that will meet that production rate, driven from the PTO.

You are drilling roughly a quarter mile of hole.

Dewalt recommends, among other things "Auger bit applications in wood up to 1-1/2" as a limitation.

 

[wayne440]

Consider buying an electric earth auger that is designed for your work.

 

[jraef]

Portable drills use Universal type motors, basically series wound DC motors modified to accept AC input. As such, the speed / torque / current relationship is not the same as other types of AC motors. As load increases, speed decreases, current increases and torque increases as the SQUARE of the current increase (because current is increasing on both the armature and the field at the same time). So motor heat (I²r losses) then also increases very rapidly. In addition, Universal motors have brushes and commutators just like DC motors, so they can burn and fail much more rapidly if the duty cycle is too high. I would expect the drill motor to fail before your project is complete, but you may be able to swap out brushes to extend the life, so have some spares on hand and learn how to replace them (it's usually simple).


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[3DDave]

jraef - right you are - the brush holder and brushes are in the exploded parts diagram. Item 2 on the breakdown is Brushes so they must be a top item. Curiously, there is no item 1. Also the favorite items include the chuck key. It might be handy to have a spare if one of those goes missing in the dirt.

Seems a shame with all the electronics available that they aren't using a brushless motor.

It does have a low-speed gear box with a clutch to prevent overload, so there's that, but if 1.5 inch diameter into wood is a limit 3 inches into dirt might be too much.

I don't recall cooking a motor, but the electrics in the switch have melted before.

 

[jraef]

Brushless motors increase the price. You can find them if you look long enough, but the only advantage is that there are no brushes and most people don’t use them enough to make the added cost worth it.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden