Hi.
I just had a problem with my Dewalt chop saw (DW705). At first, I
noticed the brake was not catching all the time when I released the
switch. Then, a little while later the saw just quit working. So, I
pulled out the brushes and cleaned them up (I have been doing alot of
MDF cutting) and then the saw started working again. After a little
while, it stopped working again. So, off I went to get two new
brushes. Installed them and the saw is back up and running great. But
now, there is no electric brake at all. I am wondering if I installed
the brushes wrong or if something else needs to be replaced.
Can anyone explain how these brakes work, and what would cause it to
stop working?
thanks in advance.
bob
--
Check the switch and it's wiring first. Some brakes work by
shorting the brushes together(with the power completely removed
from both of them). Some also add a very low value resistor to
the shorting path so that it is not truly a dead short. The switch is
the common element with this method and it is usually the faulty
part.
Other braking mechanisms are mechanical.
Art
"Bob" <[email protected]> wrote in message news:[email protected]...
> Hi.
>
> I just had a problem with my Dewalt chop saw (DW705). At first, I
> noticed the brake was not catching all the time when I released the
> switch. Then, a little while later the saw just quit working. So, I
> pulled out the brushes and cleaned them up (I have been doing alot of
> MDF cutting) and then the saw started working again. After a little
> while, it stopped working again. So, off I went to get two new
> brushes. Installed them and the saw is back up and running great. But
> now, there is no electric brake at all. I am wondering if I installed
> the brushes wrong or if something else needs to be replaced.
>
> Can anyone explain how these brakes work, and what would cause it to
> stop working?
>
> thanks in advance.
> bob
>
> --
>
Mine had the same problem the blade was loose. VERY VERY scary.
The brake worked again after the blade was tightened.
> "Bob" <[email protected]> wrote in message
> news:[email protected]...
>> Hi.
>>
>> I just had a problem with my Dewalt chop saw (DW705). At first, I
>> noticed the brake was not catching all the time when I released the
>> switch. Then, a little while later the saw just quit working. So, I
>> pulled out the brushes and cleaned them up (I have been doing alot of
>> MDF cutting) and then the saw started working again. After a little
>> while, it stopped working again. So, off I went to get two new
>> brushes. Installed them and the saw is back up and running great.
>> But now, there is no electric brake at all. I am wondering if I
>> installed the brushes wrong or if something else needs to be
>> replaced.
>>
>> Can anyone explain how these brakes work, and what would cause it to
>> stop working?
>>
>> thanks in advance.
>> bob
A brush type motor will generate electrical current if the armature is
turning and no electrical power is being applied to it. The electric brake
designs take advantage of this by using an additional contact in the switch
to connect the 2 motor leads together whenever the switch is in the off
position. The generating effect of the coasting motor driving it's output
into this electrical short circuit will cause a significant braking force on
the motor. Worn brushes, a damaged commutator, or this extra contact in your
switch can cause the brake function to fail if they are defective. Since the
braking current develops significantly lower voltages than the normal power
line input, worn or damaged electrical contacts are more likely to cause
brake failures before they become bad enough to cause a failure of the saw
to run. You may need to clean up the commutator and replace the switch in
addition to replacing the brushes.
--
Charley
"Bob" <[email protected]> wrote in message
news:[email protected]...
> Hi.
>
> I just had a problem with my Dewalt chop saw (DW705). At first, I
> noticed the brake was not catching all the time when I released the
> switch. Then, a little while later the saw just quit working. So, I
> pulled out the brushes and cleaned them up (I have been doing alot of
> MDF cutting) and then the saw started working again. After a little
> while, it stopped working again. So, off I went to get two new
> brushes. Installed them and the saw is back up and running great. But
> now, there is no electric brake at all. I am wondering if I installed
> the brushes wrong or if something else needs to be replaced.
>
> Can anyone explain how these brakes work, and what would cause it to
> stop working?
>
> thanks in advance.
> bob
>
> --
>