erratic starting circular trim saw

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Forum topic by snakejeep posted 03-06-2013 05:00 PM 1025 views 0 times favorited 8 replies Add to Favorites Watch
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6 posts in 1955 days

03-06-2013 05:00 PM

I’ve got this porter cable 314 trim saw and the other day it stalled during a cut.I released the trigger
and removed the saw from the cut.Now sometimes it does not start when pressing the trigger.You
can move the blade a small tad and press the trigger and it will start.Sometimes it will start on its own
without any movement of the blade.I’ve been told that when a circular saw stalls during a cut you should
keep the trigger pressed and quickly remove it from the cut and then release the trigger.could my
problem be caused from not doing this when the saw stalled.Any opinions greatly appreciated.

8 replies so far

View woodbutcherbynight's profile


4866 posts in 2436 days

#1 posted 03-06-2013 05:06 PM

IF you are electrically inclined you could take the trigger apart and check to see if it is working correctly. Be advised this is 110vts @ a min of 10 amps so it stings if you do so plugged in. (Not reccomended as it can kill.) Use a electrical meter on the ohms scale check the feed into the trigger and the output as you squeeze the trigger. If it reads 0.01-0.50 ohms all the time no matter the trigger position then this is NOT the problem. If it shows out of range then the trigger is most likely bad. These do go bad and a replacement can be bought and all will be well. Again be careful if you are not familiar with electricity or a meter and how it works “call a friend”. (laughing)

-- Live to tell the stories, they sound better that way.

View MedicKen's profile


1615 posts in 3489 days

#2 posted 03-06-2013 05:13 PM

By moving the blade you are turning the rotor inside slightly which tells me it could possibly be a brush issue. As mentioned above check the trigger switch but I would also remove the cover to the brushes and use LOW PSI air pressure to blow any sawdust from the brush assembly.

-- My job is to give my kids things to discuss with their

View muleskinner's profile


896 posts in 2463 days

#3 posted 03-06-2013 07:17 PM

Could be brushes as mentioned above but it sounds more like you have a bad (burnt) spot on you’re commutator.

-- Visualize whirled peas

View Loren's profile


10476 posts in 3675 days

#4 posted 03-06-2013 07:21 PM

Those saws have a rep for developing problems.

View SCOTSMAN's profile


5849 posts in 3612 days

#5 posted 03-06-2013 07:27 PM

Also check theres no dirt/dust build up in the switch I have known this to be a problem! Alistair

-- excuse my typing as I have a form of parkinsons disease

View Loren's profile


10476 posts in 3675 days

#6 posted 03-06-2013 07:32 PM

You can take apart the handle and bypass the switch.

If you have to cut wires to bypass the switch, you can
get these little crushable connectors at a hardware or
auto parts store to put the wires back together if
bypassing the switch doesn’t solve the starting

I’d take the blade off, personally.

View Tennessee's profile


2873 posts in 2541 days

#7 posted 03-06-2013 08:42 PM

Since you can start it by moving the blade a little, it is almost certainly a brush to commutator issue. Sometimes you have the brushes on the commutator slots properly, sometimes not. It either needs stronger brush springs, clean the brush slots, put on new brushes, or a commutator dressing. It might have a dead coil in the motor, but I doubt that.

-- Tsunami Guitars and Custom Woodworking, Cleveland, TN

View snakejeep's profile


6 posts in 1955 days

#8 posted 03-07-2013 08:01 PM

Thanks a million for all these helpful hints.From looking over all the responses,I’m leaning toward
maybe a burnt spot on the commutator.The saw will start for a bunch of times,then all of a sudden
not start.I’m guessing it has landed on the burnt spot on the commutator and by turning the blade
it makes electrical connection on both brushes.Does anyone know what I should do now to take
cure of a burnt spot on a commutator.I’ll first clean the brush holders,install new brushes,and electrically
check the switch,but still I’m leaning toward a burn on the commutator because of releasing the trigger
when the motor stalled,although I don’t understand how that would spot burn a commutator.Thanks
guys for any help.Love this forum for the concerned members!

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