Strange TS75 problem

[Kevin Stricker]

I was using the TS75 at my school last night and had a strange thing happen and am still trying to figure out the problem.  I was cutting some 6/4 Elm and was about 1/2 way through the cut and the saw just stopped moving.  The RPM's were still up but I couldn't budge it any farther.  At first I thought it was the blade, and switched it out and was able to finish the cut.  The thing is that the cut was very clean, with no burning or deflecting which I would expect with a dull blade.  The other blade worked better but did give me some trouble as i was finishing the three other cuts I made with it.  The first blade I was using was a universal blade, and I switched to the Panther for the rest of the cuts. 

I thought after the fact that maybe the rail was bent, and it was causing some binding at that point.  Now I am thinking it has more to do with the riving knife.  I would like to troubleshoot the problem so I can get the saw working for the school.

BTW I have a TS55 that I use daily so I do not think it was operator error.  At the same time I always use the same riving knife as my Tenru rip blade has the same kerf as my other Festool blades.

Thanks in advance for any input.

 

[Tim Sproul]

I've had the kerf close up on my and cause binding....but that results in the blade stopping.  I suppose it is possible for the kerf to close on the riving knife without closing on the blade too.

Were you crosscutting the elm or ripping?

 

[Kevin Stricker]

Crosscutting on a 15 degree diagonal. 

 

[WarnerConstCo.]

The 75 has a slip clutch, I do believe.

 

[Forrest Anderson]

The 75 has a slip clutch, I do believe.

Yes it does, and that's a very good point. This illustration comes from the TS75 brochure

Which naturally leads to a question for Kevin...

Although you said "The RPM's were still up but I couldn't budge it any farther", do you know if the blade was actually turning?

Forrest

 

[Michael Kellough]

Saw didn't want to go forward.

Possible causes,
1. obstruction on guide rail or inconsistent extrusion causes a thick spot
2. blade improperly installed and it slipped
3. dull/dirty blade couldn't cut through a knot
4. internal stress in lumber pinched riving knife
5. stringy fibers from wood causing drag on riving knife
6. riving knife crooked and catching on rough edge of wood
7. cord and or hose snagging on something (thanks Brice)
8. all of the above

 

[Brice Burrell]

Saw didn't want to go forward.

Possible causes,
1. obstruction on guide rail or inconsistent extrusion causes a thick spot
2. blade improperly installed and it slipped
3. dull/dirty blade couldn't cut through a knot
4. internal stress in lumber pinched riving knife
5. stringy fibers from wood causing drag on riving knife
6. riving knife crooked and catching on rough edge of wood
7. all of the above

Good list here Michael. Number 1 should be easy to figure out, #2 or 3 are the most likely on the list. $ and 5 would be the likely culprit if this was a rip cut and we know it wasn't. Number 6 would have caused the same problems with the other blades.

I'd add one thing to the list, don't know how likely this is since you aren't a new user. The hose/cord getting hung up. I've run into your problem before only to find some moron standing on the cord.  [unsure]

 

[Kevin Stricker]

No obstruction although an inconsistant extrusion will have to be checked tomorrow night.  Blade was very tight, i.e hard to unlock with allen when it was changed.  Blade hitting a knot would have left a broken kerf or burn marks in my experience, and there were no knots where I was cutting.  I have had internal stresses clamp the riving knife on a rip cut but never a cross cut with my TS55.  No chance the cable or hose were catching as they were off to the side and it was a 2 foot crosscut on a 1400 rail.

I am not sure that the blade was in fact turning before I shut her down, although I did back up the cut and push back into it.

The other cuts I had were fine until the end ( with the other blade) and it seemed that the blade tilted into the workpiece as I 'finished the cuts and was unplunging.

So on the TS75 do you need to change the riving knife between the universal and panther blade? 

Thanks again for your replies.

 

[Michael Kellough]

Kevin, I re-read your original post and the description sounds exactly
like a snagged cord or hose as Brice suggests. It happens to me a lot.
The hose snags on something and stretches subtly so you don't realize it's
hung and then the saw won't go forward.

I've gotten into the habit of hoisting the cord and hose over my shoulder
so I can feel when they hang. I wish I had one of those mesh sleeves
to go over the hose.

 

[tbellemare]

I've gotten into the habit of hoisting the cord and hose over my shoulder
so I can feel when they hang.

Michael:

I got in the habit a long time ago to do that so they don't hang up. If there'e no boom or equivalent involved, I find it pretty frustrating to cut any other way.

Tom

 

[PBS]

Tom:
That is just what was happening to me. I used two brand new blades and had the same problem with each.
If you figure it out let me know
Thanks, Pete

 

[WarnerConstCo.]

Wish you knew if the blade was still spinning when this happened.

 

[Kevin Stricker]

Like I said, I am 100% positive the hose was not caught up because there was no hose connected for the cut.  The schools CT22's are across the shop in the sanding area and the cable was in front of me. When the saw stopped that is the first thing I looked for. I backed up the saw, pulled up the cable(it was free) and pushed into the cut again.  I agree that that is usually the cause of a saw stopping, I have had that plenty of times. 

I will try to post a picture of the blade if I get a chance later today, it looked a bit worked.  The inside had circular burned looking grooves from about 2/3of the way into the collett.  Also there were two hot spots mid blade where it appeared the temper had been lost( discolored blue).  The blade was warm when I changed it about a minute later but not hot so I assumed that someone else had damaged the blade prior to my use.

When I switched to the Panther I finished the cut and made three more cuts.  All of them seemed to go OK until the end of the cut when the saw was leaving the workpiece and I was unplunging.  At that point it seemed the saw started to bind and it left kerf marks on the workpiece (inside) side.  I had the rail clamped for all four cuts and was careful to keep the saw from tipping.

Like I said I use the TS55 on a almost daily basis making cabinets and storage units.  I have cut up 10 sheets of 3/4 ply in the last week.  Something is wrong with the saw, not the operator, in this situation.

Still no answer if you change the riving knife with the blade on the TS75.  Also if the saw had been previously dropped and the housing was tweaked could this account for the problems.  I checked and the blade was square to the body.  I did not ( nor do I know how to) check to see if the blade is properly aligned front to back as I know it is slightly toed-in.

If someone from Festool could chime in that would be great.

 

[Administrator_JSVN]

Kevin,

Based on your description, David McGibbon (one of our application specialists), had seen your thread and believes that the problem is that the blade skew is not properly set.  The back of the blade, when properly adjusted, it slightly further out from the guide rail.  The process for correcting this is in Rick Christopherson's manual on page 12.  While this manual talks about the TS 55, the same procedure should be applicable to the TS 75.

I would like reiterate that, while the forum serves as a fantastic resource to its members, that you can always contact us directly using the phone number that's on the label on your tool for assistance with issues like this.

 

[Kevin Stricker]

Thanks Shane, I will check that this evening.

 

[Tezzer]

My TS75 has this as a reoccurring problem,  

Its easy to check. When you are ripping and the blade slows or stops, carefully lift the saw from the cut and slowly re-plunge it back down, if you are re-cutting some stock (probably around 1mm) then you know thats the cause of your problem so you will have to realign the saw to the plate. I dont think its a flaw, its just a heavy saw and being picked up and some times not placed down to careful can cause it to go of whack.