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Author Topic: Kapex is dead !!!  (Read 14026 times)

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Offline luke1984

  • Posts: 146
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Kapex is dead !!!
« on: May 25, 2016, 06:00 PM »
My kapex died today ,in style I may add. Cutting some hand rail for a job I'm doing and all was good. Had 1 cut left to do so pulled the switch on my kapex and there was sparks and smoke from the motor. And that was that , Was not happy. Emailed a repair form to night as its under warranty hopefully get it back for Tuesday as iv got oak flooring and 10" skirting to install. Will be lost with out it  [mad]

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Offline bobfog

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Re: Kapex is dead !!!
« Reply #1 on: May 25, 2016, 06:07 PM »
Another one bites the dust...!

Offline Brandon

  • Posts: 217
Re: Kapex is dead !!!
« Reply #2 on: May 25, 2016, 06:42 PM »
Sorry for your loss.
I know this subject has been beaten to death but this really is a problem. As I've posted before mine died a couple years ago in similar fashion. Sad that the best saw made has the worst motor. Maybe Festool should give Bosch or Hitachi a call and ask for some motor tips.

Offline mac west

  • Posts: 17
Re: Kapex is dead !!!
« Reply #3 on: May 25, 2016, 09:02 PM »
my new kapex.  399.00 price matched at Lowes with free stand. Its a beast cuts spot on out of box . Dust collection not as good but I will work on improving. Mac
.
« Last Edit: May 25, 2016, 09:04 PM by mac west »

Offline TomE

  • Posts: 131
Re: Kapex is dead !!!
« Reply #4 on: May 25, 2016, 09:30 PM »
What's with the yellow tape or whatever it is all over the Hitachi?

Offline mac west

  • Posts: 17
Re: Kapex is dead !!!
« Reply #5 on: May 25, 2016, 10:38 PM »
What's with the yellow tape or whatever it is all over the Hitachi?
Its a personal problem i am very disturbed individual. Mac

Offline Rick Christopherson

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Re: Kapex is dead !!!
« Reply #6 on: May 26, 2016, 02:06 AM »
Had 1 cut left to do so pulled the switch on my kapex and there was sparks and smoke from the motor. And that was that

Given this description, I am beginning to think the root problem might be something related to an effect from PWM speed controls. Sometimes the power from a PWM controller into a motor can have very large voltage spikes--much larger than the supply voltage, but very short duration. If these spikes are larger than the insulation rating on the motor windings, the tiny spike will put a tiny hole in the winding insulation. A couple of holes in the insulation isn't a problem, but over time the effect becomes cumulative until you have a catastrophic short circuit. That's kind of like what these failures sound like.

Offline live4ever

  • Posts: 835
Re: Kapex is dead !!!
« Reply #7 on: May 26, 2016, 02:27 AM »
Had 1 cut left to do so pulled the switch on my kapex and there was sparks and smoke from the motor. And that was that

Given this description, I am beginning to think the root problem might be something related to an effect from PWM speed controls. Sometimes the power from a PWM controller into a motor can have very large voltage spikes--much larger than the supply voltage, but very short duration. If these spikes are larger than the insulation rating on the motor windings, the tiny spike will put a tiny hole in the winding insulation. A couple of holes in the insulation isn't a problem, but over time the effect becomes cumulative until you have a catastrophic short circuit. That's kind of like what these failures sound like.

Hmmm interesting....given that, would you expect there to be any difference in failure rates between folks who use the saw at max speed all the time vs those who use the saw at different speeds?
Current systainer to productivity ratio:  very high

Offline Rick Christopherson

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Re: Kapex is dead !!!
« Reply #8 on: May 26, 2016, 02:29 AM »
No, I'm not familiar enough with it to make that distinction.


Edit: By the way, I rarely use my Kapex at full speed. Even though that doesn't apply, I should mention it. I'm typically set at about 4 for most cuts. It's a personal preference, and I like the results. My Kapex pre-dates even the European models. I can't remember when I got it, but it was the early spring before Kapex was announced in Europe. It's 240-volt.
« Last Edit: May 26, 2016, 04:39 AM by Rick Christopherson »

Offline bobfog

  • Posts: 839
Re: Kapex is dead !!!
« Reply #9 on: May 26, 2016, 03:37 AM »
Had 1 cut left to do so pulled the switch on my kapex and there was sparks and smoke from the motor. And that was that

Given this description, I am beginning to think the root problem might be something related to an effect from PWM speed controls. Sometimes the power from a PWM controller into a motor can have very large voltage spikes--much larger than the supply voltage, but very short duration. If these spikes are larger than the insulation rating on the motor windings, the tiny spike will put a tiny hole in the winding insulation. A couple of holes in the insulation isn't a problem, but over time the effect becomes cumulative until you have a catastrophic short circuit. That's kind of like what these failures sound like.

Hmmm interesting....given that, would you expect there to be any difference in failure rates between folks who use the saw at max speed all the time vs those who use the saw at different speeds?

I think that it's a pretty universal truth that any electromechanical device is going to have a lesser life and more wear and tear if it has a higher average operating speed than a lower one, if all other factors are equal. I.e. drive 500 continuous miles at 70mph is going to cause less wear vs doing the same journey at 140mph.

However I think this would be a very small aspect of the tools potential longevity  compared with a far more important factor being the stop start cycles. If you spend 20 seconds doing a continuous cut on a piece of 8/4 oak vs 20 seconds making 5 separate cuts in thin picture framing material, the 5 x increase in stopping and starting the motor will cause far more wear given the same time spent at the saw.
« Last Edit: May 26, 2016, 03:40 AM by bobfog »

Offline Rick Christopherson

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Re: Kapex is dead !!!
« Reply #10 on: May 26, 2016, 04:21 AM »
Had 1 cut left to do so pulled the switch on my kapex and there was sparks and smoke from the motor. And that was that

Given this description, ...

Hmmm interesting....

I think that it's a pretty universal truth that any electromechanical device is going to have a lesser life and more wear and tear if it has a higher average operating speed than a lower one, if all other factors are equal. I.e. drive 500 continuous miles at 70mph is going to cause less wear vs doing the same journey at 140mph.

No. Sorry but this is a completely different aspect that is not related to tool loading. It is related to a mathematical phenomenon of the wave signals sent to the motor. It's a topic that is slightly over my head, and I'm actually an electrical engineer. I know about it, but I haven't done that kind of mathematics in 30 years.

The good news is that if I'm correct, Festool could pull out a fairly simple fix with some filtering circuits.

Offline rizzoa13

  • Posts: 587
Re: Kapex is dead !!!
« Reply #11 on: May 26, 2016, 05:55 AM »
Would your theory flow down to broken armatures and worn out brushes? The main things needing replaced on y saw were the armature and brushes and it seems thoss are the two common major items for the saws when they stop working like this.

Offline geoffshep

  • Posts: 156
Re: Kapex is dead !!!
« Reply #12 on: May 26, 2016, 07:19 AM »
I have seen a few threads on Kapex problems - is this mostly (or entirely) with 110v saws?

Offline Holmz

  • Posts: 4010
Re: Kapex is dead !!!
« Reply #13 on: May 26, 2016, 08:16 AM »
Would your theory flow down to broken armatures and worn out brushes? The main things needing replaced on y saw were the armature and brushes and it seems thoss are the two common major items for the saws when they stop working like this.

Probably... If @Rick Christopherson is correct, then then the spikes would not only be tough on the wiring, but it would be hammering the motor mechanically like a solenoid. Some of that hammering could affect the armature, but the bearing maybe not so much.
He has impressed me this morning.

Offline pettyconstruction

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Re: Kapex is dead !!!
« Reply #14 on: May 26, 2016, 10:30 AM »
Would your theory flow down to broken armatures and worn out brushes? The main things needing replaced on y saw were the armature and brushes and it seems thoss are the two common major items for the saws when they stop working like this.


Probably... If @Rick Christopherson is correct, then then the spikes would not only be tough on the wiring, but it would be hammering the motor mechanically like a solenoid. Some of that hammering could affect the armature, but the bearing maybe not so much.
He has impressed me this morning.


Me to





EDIT> fixed quote box
« Last Edit: May 26, 2016, 10:32 AM by SRSemenza »

Offline Rick Christopherson

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Re: Kapex is dead !!!
« Reply #15 on: May 26, 2016, 02:38 PM »
Probably... If @Rick Christopherson is correct, then then the spikes would not only be tough on the wiring, but it would be hammering the motor mechanically like a solenoid. Some of that hammering could affect the armature, but the bearing maybe not so much.
He has impressed me this morning.

No, the spike durations are too short to have a mechanical impact on the motor. But yes, it absolutely translates to damaged armatures. The armature is the rotating motor winding. The stator is the stationary motor winding. But the armature is the more delicate of the two because the wire needs to be finer and wound into the small slots of the metal rotor.

The brushes could be impacted, but just because the service department replaces them doesn't mean they were damaged. They should be replaced simply because the armature is replaced.

This is a topic that is common for VFDs. Even though it is usually from long wires, it can also be caused by higher carrier frequencies. My guess is that Festool raised the carrier frequency on Kapex so it didn't growl like the TS saws do. Here's a generic oscilloscope screen for a VFD output to a motor I found on the internet. It's supposed to be a square wave, but the fuzzy parts are the spikes.


Offline Tinker

  • Posts: 3740
Re: Kapex is dead !!!
« Reply #16 on: May 26, 2016, 03:43 PM »
What's with the yellow tape or whatever it is all over the Hitachi?
Its a personal problem i am very disturbed individual. Mac

Purely psychedelic.  Better for your fix than other avenues I can think of   [bite tongue]
Wayne H. Tinker

Offline jmbfestool

  • Posts: 6632
Re: Kapex is dead !!!
« Reply #17 on: May 26, 2016, 04:10 PM »
Oh junk this reminds me I need to reply to Germany about kapex.

Totally forgot!  Just had a baby so been busy doing other things.

Well its interesting another kapex bites the dust.
Atleast yours is within the warrenty.
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Offline luke1984

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Re: Kapex is dead !!!
« Reply #18 on: May 26, 2016, 04:31 PM »
Yeah still in warranty but a huge pain in the  because iv got loads of work booked in and I could do with my kapex on most of it
« Last Edit: May 26, 2016, 04:36 PM by luke1984 »

Offline GarryMartin

  • Posts: 1854
Re: Kapex is dead !!!
« Reply #19 on: May 26, 2016, 04:42 PM »
Just had a baby so been busy doing other things.

@jmbfestool Congratulations! Best news update on a Kapex thread *EVER*  [big grin]

Offline tomscf

  • Posts: 41
Re: Kapex is dead !!!
« Reply #20 on: May 26, 2016, 05:17 PM »
Just had a baby so been busy doing other things.

@jmbfestool Congratulations! Best news update on a Kapex thread *EVER*  [big grin]

Yes, congratulations! Mine's due in about a month and a half. Train them well - my 2 yr old is already very good with a cxs  [smile]

Interesting thread also. I wonder if any of it (and I understand very little) has any weight. If it does, then I would be bemused as to how the engineering minds at Festool had overlooked such possible issues - especially as the symptoms of such oversights started to raise their heads.

Let's hope this remains as constructive and informative as it is currently and that it doesn't degenerate into chaos as much as a certain other related thread  [unsure]

Offline T. Ernsberger

  • Posts: 885
Re: Kapex is dead !!!
« Reply #21 on: May 26, 2016, 07:22 PM »
my new kapex.  399.00 price matched at Lowes with free stand. Its a beast cuts spot on out of box . Dust collection not as good but I will work on improving. Mac
.

I looked at the same Hitachi saw the other day.   The one I looked at did not glide smoothly.  It felt like all the movements were rough. 

Offline mac west

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Re: Kapex is dead !!!
« Reply #22 on: May 26, 2016, 07:55 PM »
there are two knobs on top of rail. one of  them you can see in picture of my saw, the knobs lock the rails up to limit the space the saw needs if you have it against a wall like the Kapex , If you didn't have them adjusted you will feel binding in the movement . For 400.00 dollars its a bargain. Mac
« Last Edit: May 26, 2016, 07:59 PM by mac west »

Offline Brice Burrell

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Re: Kapex is dead !!!
« Reply #23 on: May 26, 2016, 08:41 PM »
Yes, congratulations! Mine's due in about a month and a half. Train them well - my 2 yr old is already very good with a cxs  [smile] ....

Wait, you're expecting a baby in a month and a half, or for your Kapex to die. [tongue] [big grin]

Congrats to you and JMB both.
Check out my new blog, The Green and Dark Blue Blog.

Offline tomscf

  • Posts: 41
Re: Kapex is dead !!!
« Reply #24 on: May 27, 2016, 02:10 AM »
Haha - both outcomes will cause me a great deal of stress and sleepless nights [blink]
My Kapex has just handled a house of 18 oak frames and doors and skirting throughout and was a pleasure to use. Not wishing to rub it in to those who've had trouble  [sad]

Offline Tinker

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Re: Kapex is dead !!!
« Reply #25 on: May 27, 2016, 04:18 AM »
@jmbfestool Boy?/Girl?  no matter  great news  congrats   [big grin]
Wayne H. Tinker

Offline Jeremiah9675

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Re: Kapex is dead !!!
« Reply #26 on: May 27, 2016, 10:26 AM »
Lol, I'm reading this thread and I laughing a little. I feel bad for you brother that your saw died but Pulse width modulation on a saw that has self commutates? Back Emf or Harmonic filters? On a brushed motor? Really? I have a worm drive skill saw that's from 1996 that still has the same motor. If your making a living with these tools and you have to have a KAPEX I'd suggest getting a back up saw because these saws do this a lot. It's a known unresolved problem. If your a dealer or a hobbyist it's probably no big deal but if your counting on this thing to make your living you better have a back up. Sorry Man dead saw sucks!
I love to watch FOG members fawn over new people to the FOG by saying Welcome and putting up the emoji. It's very pretentious. No one really cares. Imperial sucks. Go metric.

(Just imagine I typed out all my Festool tools here. Imagine it's a lot of them. Also imagine your the kind of person who is impressed by it.)

Offline Holmz

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Re: Kapex is dead !!!
« Reply #27 on: May 27, 2016, 11:07 AM »
@Jeremiah9675 - That is a funny looking didgeridoo that the little one is playing in the avatar.
They stick to using cordless didgeridoos in the bush.


Back to the motors, the windings should look like inductors, so I am not sure what happens with the spikes in terms of torque and current...
I suppose at this point it is either a simple mod, or make it brushless if there is some stuff to fix.
« Last Edit: May 27, 2016, 11:09 AM by Holmz »

Offline Jeremiah9675

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Re: Kapex is dead !!!
« Reply #28 on: May 27, 2016, 11:19 AM »
Hahaha! That didgeridoo is the most expensive one in the book! Haha! [tongue]
Yeah brushless would solve the problem. If they did that hopefully they incorporate some conductive polyurea lube so stray emf current doesn't pit the bearings. Maybe a Agis brush to draw the current away. Oh good grief the cost of the saw went up $300 dollars lol! [tongue]
@Jeremiah9675 - That is a funny looking didgeridoo that the little one is playing in the avatar.
They stick to using cordless didgeridoos in the bush.


Back to the motors, the windings should look like inductors, so I am not sure what happens with the spikes in terms of torque and current...
I suppose at this point it is either a simple mod, or make it brushless if there is some stuff to fix.
I love to watch FOG members fawn over new people to the FOG by saying Welcome and putting up the emoji. It's very pretentious. No one really cares. Imperial sucks. Go metric.

(Just imagine I typed out all my Festool tools here. Imagine it's a lot of them. Also imagine your the kind of person who is impressed by it.)

Offline Drich

  • Posts: 198
Re: Kapex is dead !!!
« Reply #29 on: May 27, 2016, 04:53 PM »
So Glad I sold mine and bought a bosch. $550 bucks no tax and free ship.