Chop Saw Blues

[Phred]

Hi guys,

I bought a milwauke electric chop saw from home depot. After two weeks and a few 20 gauge metal studs the turkey stopped working. More acurately it would not stop working. If you plugged it in it sawed away even if you did not pull the trigger! Clearly the trigger switch was shorted out.

Returned that unit and got the dewalt instead. I normally buy dewalt and cheaped out on the saw and paid the price in the inconvience.

The dewalt is rated at 15amps. I figured that a 20 amp breaker would be needed since the start current on these motors is significant. However, after about three weeks of use it started tripping the 20 A breaker during the initial startup. Called dewalt and they said that some of the units had problems with the brushes and that the would pull as much as 26 amps for a very short time at startup. The fix; a new set of brushes. I installed the new brushes that look exactly the same as the set it came with. Solved the problem for about 20-30 studs and then back to the old problem.

My current solution is a 30 amp breaker. But the EE in me is not happy about a 15 amp motor on a 30 amp breaker!
Its a great saw but it dosen't even have a gound wire!


Anbody else have similar problems?

Fred

 

[TWINKLE_TOES]

Fred,

I think the <font color=blue>. But the EE in me is not happy about a 15 amp motor on a 30 amp breaker! </font color=blue> is right on. . You might want to check the voltage at the outlet to the motor with the motor underload, maybe you have a low voltage problem. If that checks OK I would give the saw back to Mr. DeWalt.
Al

 

[EdKing]

Fred,
I have a Dewalt chop saw, and I haven't had any problems running with a 15 amp breaker. I would contact Dewalt again.

Ed King

 

[JJT]

Sounds like a fire hazard to me. Is this 120v or 240v? I believe the max amperage for 12 gauge wire on 120v is 20Amps, 14 gauge and the max drops to 15Amps. I have a 12inch Dewalt power miter that has 100's of hours on it - it's rated 13A and I've never had a problem, (on a 20A circuit). I'd return it.

 

[Anonymous Poster]

Fred...

They say the third time around is a charm...

I should own stock in this Ryobi company... I really like them... I don't remember any problems with any number of their tools I own... /w3tcompact/icons/smile.gif

 

[Phred]

Al,

The voltage is 120. You may be on to something with the low voltage. I will check on this. The electrical service is new and I am out in the sticks, so this would not supprise me.

Your also right about the 12 gauge wire. Thats why I put it on a 30 amp breaker with 10 qauge wire, a 30 amp industrial outlet, and a 10 gauge extension cord. So the circuit upto the saw is not a problem.

What worries me is the saw itself. I am 99% sure that the start current is the problem (maybe a few milliseconds) so fire is probably not much of a problem. What worries me is what if something goes wrong with the saw (motor burns out, etc..) ? You end up with as much as 30 amps dumped across a shorted motor before the breaker trips! Not a pretty sight.

Ed: How old is your chop saw? Do you happen to know the model?


Fred

 

[Anonymous Poster]

<font color=blue>...However, after about three weeks of use it started tripping the 20 A breaker during the initial startup...</font color=blue>

Fred,

Do you have a dedicated circuit for just this device...?

Is it possible "something else" is sharing this circuit...?

Even a 15 amp breaker shouldn't trip during initial motor startup... the way they are normally designed... they should handle true circuit overload conditions while still avoiding any nuisance tripping... /w3tcompact/icons/smile.gif

Either the breaker is "trigger happy" and needs replacement, something else is on and sharing the same circuit {then the breaker is doing its job as expected}, or you truly have "rotten luck" with two bad saws in a row... /w3tcompact/icons/frown.gif

 

[Phred]

John,

Its a dedicated circuit. Nothing but the saw on the breaker.
I am pretty sure that its the saw.
I still need to check the voltage, although the power folks checked this out when they did the install a few months ago.

The dewalt guy I talked to indicated on some units the brushes casued current spikes as large as 26 amps. He was not supprised by my problem and had replacement brushes ready to go.

I wonder how many folks have a similar saw and if any have seen this problem?

You may be right about the ryobi. I have a table saw / router setup from ryobi that I am very happy with. Its just supprising that the dewalt has this problem since my past expereince ( 5 seperate tools) has been that dewalt is top notch.

Fred

 

[Anonymous Poster]

I needed something more portable and bought this Ryobi a couple years ago… then sold my 12” Craftsman /w3tcompact/icons/shocked.gif… I have a couple routers and needed a hefty unit for the bench and got a Ryobi, something like this one pictured about 3hp {they no longer make}…

I would try using your DeWalt cutoff at a friend’s place on a dedicated circuit… if it acts up there… then return the saw… otherwise back to the drawing board and check out your wiring again…

DeWalt was idling along just making their radial arm saws until Black and Decker bought them… someone there in marketing turned DeWalt into a premium tool line and the rest is history… /w3tcompact/icons/smile.gif

 

[EdKing]

Fred,
It is a DW871, I've had it for about 6 months. I have it on the same circuit as the lights in my shed, when I run it up the lights dim down for a second, but no breaker trip.

One thing you could try is put it on a 30 amp breaker and put a 15 amp "slow blow" fuse in line. If it blows the fuse, the saw is definitly bad.
Ed King