Speed switch and gears don't engage fully in T series drills

[buller]

The speed switch on my T12 drill often does not engage fully, stopping short of its final resting position at speed 1.  To get it to fully engage, I have to pulse the trigger, then switch back to speed 2, then back to speed 1.  If I try to drill with the switch not fully engaged, the gears grind horribly. 

I am now on my second drill with the same problem, the first drill having already been graciously replaced by Festool. 

Is this normal?  Should I send the drill back once again for replacement, or do they all behave this way?  Someone at Festool told me the switch not fully engaging is normal but the grinding gears is not.  But I have seen a video of a T15 drill doing the same thing.  And I myself have now owned two T12's that do it too.  I now suspect that this behavior may be ubiquitous among Festool drills (And perhaps all variable speed drills?)

So, is my drill defective or not? Am I doomed to pulsing the trigger and switching the speed back and forth whenever my gears don't engage fully, or will a replacement drill fix this issue?

Thanks for any input.

 

[Brice Burrell]

I've not had this issue with my Festool drills but it isn't uncommon among cordless drills.  Try switching the gears with the drill running, that usually gets the gears lined back up.  Maybe that's what you were saying you're already doing?

 

[buller]

Thanks, Brice.  I just tried switching speeds while running the drill slowly and the same thing happens with the switch and gears not engaging.  The switch ends up being about 2mm from reaching its full resting point.  I tried drilling with a 1/2" spade bit just now while the switch was 2mm from being fully engaged and it induced grinding noises again.  So I definitely have to make sure the switch is fully engaged when using the drill.  Kind of annoying, but if all variable speed drills do this then I can't really call it a defect.

AJ

P.S., I should add the problem only occurs about 1 out of 5 times that I switch to speed 1.  The other 4 out of 5 times the switch and gears engage fully.

 

[Ken Nagrod]

Send it back and tell them you're not happy with it.  The gears should be meshing up better.  Sounds like something is wrong in the geartrain or the selector actuation mechanism.

 

[Brice Burrell]

Thanks, Brice.  I just tried switching speeds while running the drill slowly and the same thing happens with the switch and gears not engaging.  The switch ends up being about 2mm from reaching its full resting point.  I tried drilling with a 1/2" spade bit just now while the switch was 2mm from being fully engaged and it induced grinding noises again.  So I definitely have to make sure the switch is fully engaged when using the drill.  Kind of annoying, but if all variable speed drills do this then I can't really call it a defect.

AJ

P.S., I should add the problem only occurs about 1 out of 5 times that I switch to speed 1.  The other 4 out of 5 times the switch and gears engage fully.

Try it again with the drill at full speed.  

Also, it's probably not fair to say all drills have this issue.  However, I've come across it on more than one drill.  If your drill is still under warranty why not send it in.

 

[buller]

Brice, sure enough, the same thing happens when running the drill at full speed, at least as often as when I don't pull the trigger at all. 

Ken, I think I will send it in again.  Sounds like something that happens with other drills but not so much Festool drills.  Maybe I just got unlucky twice.  I did notice the date of manufacture was 03/09 (I'm assuming that is a date on the sticker), so maybe the issue (if there is one) has disappeared since that time.

Anyway props to Festool customer service, as they've already offered to take the drill back again for replacement.

 

[Ken Nagrod]

I've used a lot of battery powered drills and maybe it's just luck, but the only one I ever had do that was a 3 speed Makita, but I was told by my friend at Makita service that it was normal in that drill because they don't have a design that constantly meshes the transmission gears.  He told me to just give it a light blip of the switch and then it would switch speeds easily.  His advice was never to switch gears (speeds) while the drill is running as that causes a collision of mating gear teeth -- wear and breakage.  I don't know the internals on the Festool drills so I can't say if his info applies.

 

[buller]

Yep, exactly: blip the trigger, switch to speed 2, back to speed 1.  That usually takes care of it.  It seems to be a matter of whether the gears happen to line up when I flip the speed switch, and they usually do.  It's when they don't that the switch doesn't quite fully switch over and I get grinding unless I perform the trick you just suggested. But it got old after a while when I built my lumber rack and had to switch the speed often when drilling and driving.  About every fifth time I'd have do the trick.

But from you guys' feedback, it sounds like my drill is not behaving normally.

 

[Rick Christopherson]

When you shift from 1 to 2, you are physically sliding the ring gear (shown as cutaway below) between two stages of the 3-stage planetary gearset. For high speed operation, this ring gear disables the 2nd planetary gearset by locking it to the 1st planetary hub. The 2nd planetary consists of the 6 pink colored planet gears and their (yellow) hub. The hub of the 1st planetary is the blue gear. Sliding the ring gear locks the blue hub to the pink planet gears.

There are a lot of teeth that have to mesh as this ring gear transitions from the engaged to disengaged position. That is why the ring gear can hesitate between shifts.
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If I am reading you correctly, it sounds as though you tried to operate the drill with the gear shift only partially engaged, and then the gears ground under load. If that is correct, it really isn't a warranty issue in my opinion. There is a good chance you broke the teeth off the ring gear and that is why it happens more and more. Festool would probably replace it anyway, but you shouldn't have operated the drill with the speed selector halfway between the two settings.

Yes, this is pretty much the same way that all 2-speed drill transmissions operate.

 

[buller]

Rick, I see what you mean about why there is sometimes hesitation between shifts.  Maybe my drill is not defective after all.  Great photo, thanks a lot.

And you are correct.  I did operate the drill with the gears only partially engaged.  But at first I thought only the speed selector switch wasn't fully engaged; I thought the gears themselves were engaged fully, as the switch was only 1 or 2mm from the end of its travel.  It wouldn't go any farther. 

In my ignorance I had to experiment by drilling to see if the gears were fully engaged.  I didn't continue drilling after hearing grinding--I immediately shut it off.  I don't think the drill is damaged, as it still functions like it always has.  But I learned that the switch has to be fully engaged before use--not just 1 or 2mm from fully engaged.  If the switch isn't fully engaged, I have to do the trick (pulse trigger, then flip switch back and forth) until it is. 

This is my first variable speed drill, which is why I had to post about this in the first place.  Thanks to everyone for their input so far.