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

 

[Anonymous Poster]

Fred, check the wire gauge size in your shop circuit, if it is 14/2 it might be a little light. I have a Dewalt chop saw and run it on 12/2 w/20amp. It has never tripped the breaker on startup or otherwise. I did have trouble once when I helped a buddy out on a welding project, the shed we were working from had 14/2 w/15 amp circuit, it was tripping on startup and I think we must have reset that sucker 20 times that day. It got to the point where he would just stand at the panel while I cut. I was a little dissapointed with the power of the Dewalt saw when I got it since I moved up from one of those $99 chinese jobbies from Harbor freight, there really didn't seem to be that much more power, maybe I was expecting a little much. One thing I did learn was the value of good cut-off wheels, those cheap import ones sometimes glaze up when cutting thick stock and just stop cutting to the point that I would have to throw in a piece of flat bar on edge and dig into it hard so it would give it some fresh cutting edge to work with and switch back to the heavy piece.

 

[DocHeb]

You didn't mention model numbers for your saws. I've used a Dewalt DW705 for woodworking over the past four years without problems on a 15 amp circuit. You said you were cutting metal studs. My owners manual said to not cut ferrous metals with my saw. Do you have a woodworking model that you are using for metal? I could see where the metal dust would short out the brushes/motor in a non-sealed, non-TEFC woodworking model.

The basic Dewalt 12" woodworking model is DW872

 

[Robert_in_NY]

Take it to a DeWalt repair shop and tell them the problem. They will either fix it or replace it as DeWalt is one of the top companies for customer satisfaction. I have quite a few DeWalt tools and have had minor problems with a couple of them, took them to be repaired at no charge and never had any problems again.

 

[gerard]

When you say Chop saw I assume you mean a METAL chopsaw since you're cutting metal studs?? If you have a wood chop saw and are using a metal blade and cutting metal you'll kill the saw. The metal filings get into places and can short things out. Metal chop saws are all sealed to prevent that. I have a wood (sears contractor) and a metal chop saw (milwaukee), both run on 15 amp circuits with no problem.

 

[cp1969]

Milwaukee would have replaced the on-off switch, which sounds like less of a problem than you are experiencing with the DeWalt.

Just my opinion, but I would not consider DeWalt (other than the old radial-arm saws) to be a 'premium' line of tools. To me, Milwaukee, Ryobi, Makita, and Porter-Cable all look like they're better built, and I once read an article on Black and Decker in Forbes magazine in which the CEO was gloating over the fact that the DeWalt line of power hand tools was just a marketing ploy; the tools were in fact little, if any, better than the Black and Decker line but commanded higher prices due to the yellow color scheme and the money put into advertising. My own experience with DeWalt tools is at work, where three of the four 12V cordless drills I bought are out of commission and one of the two 1/2" corded drills is also down.

Btw, Porter Cable looks to be going downhill as they have started to supply the Home Depot type market. These big buyers dictate to the tool supplier what the tool will cost, resulting in a downward spiral of quality along with price.

 

[Phred]

Ed,
I have the exact same unit.
<A target="_blank" HREF=http://www.dewalt.com/us/products/tool_detail.asp?productID=160>http://www.dewalt.com/us/products/tool_detail.asp?productID=160</A>

I also checked the voltage; 123.8 V. So that's not the problem.

Stephen;
I have this on a dedictaed breaker, nothing else on it.
I have changed the breaker in and out from 20A to 30A.
But the wire is 10 gauge in EMT connected up to a commercial grade 30A GFI outlet.
A 10 gauge extension cord (25ft) then connects it to the saw. So the circuit up to the saw is
good for 30A continous with very little voltage drop.

Chris;
This saw is designed for metal. It uses an abrasive blade that slowly wears away as you cut metal. Its great for EMT, metal stock, pipe, metal stud, etc... You can cut through a metal stud in a ~10 seconds. Sure beats the hack saw.

If you have never used one of these make sure you use a face shield, gloves, and long sleeves. These things throw hot sparks all over the place. A lot like a grinder only much larger.

Charles; Well I called Milwaukee and they said that I had to take it back to a particular center that would have been quite a drive.Probably two seperate trips to drop off and returm. My time is worth more than that so I returned it.
I have heard similar talk about dewalt. But I have a set of the 18V cordless tools. These things have been abused and work great without any problems. I even dropped the cordless drill of a ladder on to concrete and it still keeps running. I think this chop saw is just defective and its my bad luck to get two turkeys in a row.

Robert: Your right. I will call dewalt and see how hard it will be to get this thing repaired or returned.


Thanks for all the input guys.

Fred

 

[Robert_in_NY]

This link if it works will take you to dewalts service center search. There are a lot of them so you should have one somewhere close.
<A target="_blank" HREF=http://www.dewalt.com/us/service/center_finder.asp>http://www.dewalt.com/us/service/center_finder.asp</A>