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Author Topic: New blade = kickback?  (Read 7584 times)

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Offline b_m_hart

  • Posts: 415
New blade = kickback?
« on: March 18, 2010, 02:16 AM »
Apparently one of the contractors currently working on my house thought that it would be a GREAT idea to use my saw to cut a nice clean line in the plaster walls.  Go figure, the old saw blade didn't work so well once they were done.

Anyway, I went out today and bought a new one.  I had a panther blade and the blade that comes with the TS-55 (yes, both were dulled on plaster walls), so I figured I'd get another panther blade, as I needed to cut some 2x4s and 2x8s.  I get the 2x4s cut, but only with an unusual amount of wrestling and fighting kickback (which I have never once experienced until now with my saw).  Finally, on the last board I needed to cut, it kicked back harder than I could handle, and it ended up munching one of my rails, and the blade itself is toast now.

Here's a pic:



Now, questions:

1) Is it possible that the blade was somehow damaged and that could explain the odd behavior?
2) Is it normal for the panther blades (or the TS-55) to kick back when cutting dry 2x4s?
3) There are multiple teeth damaged on the blade, but they're not consecutive (basically about one tooth each third of the blade).  How did that happen?

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Offline jonny round boy

  • Posts: 3227
Re: New blade = kickback?
« Reply #1 on: March 18, 2010, 05:18 AM »
Apparently one of the contractors currently working on my house thought that it would be a GREAT idea to use my saw to cut a nice clean line in the plaster walls.  Go figure, the old saw blade didn't work so well once they were done.

Did you give that contractor permission to use the saw? If not, I suggest you send them a bill for the damage they caused, and inform them that taking something without consent (even if you intend to return it) is technically theft.

1) Is it possible that the blade was somehow damaged and that could explain the odd behavior?
2) Is it normal for the panther blades (or the TS-55) to kick back when cutting dry 2x4s?
3) There are multiple teeth damaged on the blade, but they're not consecutive (basically about one tooth each third of the blade).  How did that happen?

1. If the plate of the blade was slightly bent, that could have caused it but there's no way of knowing for certain. It's also possible that it was something to do with the timber. It could have internal stresses that would cause it to pinch on the blade (the riving knife will help with that but may not eliminate it completely). I have a Panther blade, but I only ever used it once & really didn't like it - it didn't kick back, but it didn't feel 'right' either. I can't explain why, I just didn't like using it & haven't done since;

2. No, but it depends on the timber (see above);

3. It probably happened because the blade 'bounced' on the rail, and only a few teeth hit hard enough to do damage.


The blade is, as you said, is toast.

As for the rail - don't be tempted to try & bend or hammer it back into shape - you'll most likely cause it to buckle more. Simply file off the high spots & fit a new splinter strip, and it'll be fine in the future. Both of my rails have similar 'battle scars'!
Festoolian since February 2006

TS55R EBQ saw - CTL26 - CTL Mini - OF1400EBQ router - KS120 Kapex SCMS - ETS150/3 sander - RO90 sander - DF500 Domino - PDC18/4 drill - PSC420 jigsaw - OFK500 trimmer

Wish list (in no particular order!): Anything not listed above....

Offline RL

  • Posts: 3040
Re: New blade = kickback?
« Reply #2 on: March 18, 2010, 06:18 AM »
What a bummer of a story! I had to reread the original post because I missed the part where you wrote that a contractor took your saw in your house until I read Johnny's reply.

From the picture, it appears as if the damaged part of the rail is very near the start. If you are unable to fix it, I would epoxy a wooden block to the rail to act as a stop, and just use the remaining good part of the rail. You should only lose 4 or 5 inches or so.

The good news about the blade being damaged is that the brunt of the kickback seems to have been taken by the broken teeth and not the saw itself. A bit like the crumple zone on a car.

It would be fair if the contractor paid for a new saw blade.

Richard.

Offline Inner10

  • Posts: 191
Re: New blade = kickback?
« Reply #3 on: March 18, 2010, 07:47 AM »
Not trying to make you sound like a child or anything but was the stock supported and secured properly while you were making the cut?  Kickback occurs if the saw is forced away from its natural straight path causing the blade to bind or if the blade becomes pinched due to the material not being supported properly.

Offline Alex2

  • Posts: 44
Re: New blade = kickback?
« Reply #4 on: March 18, 2010, 08:02 AM »
Try the universal blade next time. it rips 5/4 and 6/4 hard maple without any problems... (the universal is NOT the default blade)

alex

Offline kosta

  • Posts: 25
Re: New blade = kickback?
« Reply #5 on: March 18, 2010, 08:35 AM »
Apparently one of the contractors currently working on my house thought that it would be a GREAT idea to use my saw to cut a nice clean line in the plaster walls.  Go figure, the old saw blade didn't work so well once they were done.

Anyway, I went out today and bought a new one.  I had a panther blade and the blade that comes with the TS-55 (yes, both were dulled on plaster walls), so I figured I'd get another panther blade, as I needed to cut some 2x4s and 2x8s.  I get the 2x4s cut, but only with an unusual amount of wrestling and fighting kickback (which I have never once experienced until now with my saw).  Finally, on the last board I needed to cut, it kicked back harder than I could handle, and it ended up munching one of my rails, and the blade itself is toast now.

Here's a pic:



Now, questions:

1) Is it possible that the blade was somehow damaged and that could explain the odd behavior?
2) Is it normal for the panther blades (or the TS-55) to kick back when cutting dry 2x4s?
3) There are multiple teeth damaged on the blade, but they're not consecutive (basically about one tooth each third of the blade).  How did that happen?

A1. Yes.
A2. Yes if you start the cut as pictured.
A3. Because of A1 and A2.

Read the directions and if you feel unusual behavior...stop the cut.
 

Offline b_m_hart

  • Posts: 415
Re: New blade = kickback?
« Reply #6 on: March 18, 2010, 11:13 AM »
From the sound of some of the replies, it seems as though I need to address a few points:

1) the stock was supported on a torsion box consisting of 3/4" MDF skins with 2x4s that were cut down to 3" wide, placed every 8" with blocking every 12" or so
2) the rail that I was using was clamped to the 2x8 that I was cutting with festool clamps, with roughly 3-4" of rail before the start of the board
3) not sure how I'd force the saw out of line with the cut
4) the picture was taken where it was because that's the best lighting I've got in my work area (there are 4 lights around the area so there would be fewer shadows for the picture)


To those of you that offered constructive advice, thank you. 

Offline WarnerConstCo.

  • Posts: 4080
    • Warner Mill Works
Re: New blade = kickback?
« Reply #7 on: March 18, 2010, 11:31 AM »
So you started the cut by plunging the saw into the piece?

Offline Jesse Cloud

  • Posts: 1741
  • Festooling at the end of a dirt road in New Mexico
Re: New blade = kickback?
« Reply #8 on: March 18, 2010, 12:21 PM »
I've never used a Panther blade before, but it seems odd that cutting into the aluminum rail would damage the blade...  I suspect the blade got dropped on the floor at some point or ran through some nails cutting that drywall.

Offline bruegf

  • Posts: 797
  • Michigan
Re: New blade = kickback?
« Reply #9 on: March 18, 2010, 12:22 PM »
From the picture it looks like you may have started with a plunge cut without a stop in place on the rail which would easily lead to kickback or you started cutting w/o the saw being completely on the rail which would allow twist leading to kickback.   You need enough rail that the entire saw base is on the rail at the start and end of the cut.   If you need start w/ a plunge cut you should use one of the stops.

Fred
Fred

Offline Inner10

  • Posts: 191
Re: New blade = kickback?
« Reply #10 on: March 18, 2010, 03:40 PM »
Quote
1) Is it possible that the blade was somehow damaged and that could explain the odd behavior?
2) Is it normal for the panther blades (or the TS-55) to kick back when cutting dry 2x4s?
3) There are multiple teeth damaged on the blade, but they're not consecutive (basically about one tooth each third of the blade).  How did that happen?

1) Unlikely, look at the blade does it look bent?

2) No idea, but saws just don't kick back, they kick back when the bind.

3) It jumped on the rail and skipped a few teeth, I've cut through many a nail and this happens.  Think about it like this, when the blade first hits the rail it breaks off the tooth then launches itself up, the blade is still spinning so it has time to rotate a quarter or half turn until it hits the rail again breaking another tooth.  Think about it bouncing against the rail.

How far did you cut until the blade bound up? Is that the piece you were cutting under the rail in the pic?


Offline WarnerConstCo.

  • Posts: 4080
    • Warner Mill Works
Re: New blade = kickback?
« Reply #11 on: March 18, 2010, 03:44 PM »
You have to watch the 55 if you are plunging to start the cut.
I have had it jump a couple times.  If you must plunge to start a cut, let the blade reach full speed and go slow.

The 75 has a slip clutch to help with this issue.

Offline jmbfestool

  • Posts: 6629
Re: New blade = kickback?
« Reply #12 on: March 18, 2010, 03:58 PM »
I've never used a Panther blade before, but it seems odd that cutting into the aluminum rail would damage the blade...  I suspect the blade got dropped on the floor at some point or ran through some nails cutting that drywall.


I agree!!! I cut through my rail and it cuts like butter cuts easier than wood! I didnt even know I actually I did the cut.
« Last Edit: March 18, 2010, 04:00 PM by jmbfestool »
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Offline b_m_hart

  • Posts: 415
Re: New blade = kickback?
« Reply #13 on: March 19, 2010, 12:50 AM »
You have to watch the 55 if you are plunging to start the cut.
I have had it jump a couple times.  If you must plunge to start a cut, let the blade reach full speed and go slow.

The 75 has a slip clutch to help with this issue.

Good to know, maybe I'll save up my allowance and pick one up one of these days.  The part of the rail that was chewed up was directly behind where the end of the wood was, you could see where it hopped back up (it didn't move entirely laterally up onto the rail).

Offline b_m_hart

  • Posts: 415
Re: New blade = kickback?
« Reply #14 on: March 19, 2010, 12:51 AM »
I've never used a Panther blade before, but it seems odd that cutting into the aluminum rail would damage the blade...  I suspect the blade got dropped on the floor at some point or ran through some nails cutting that drywall.


I agree!!! I cut through my rail and it cuts like butter cuts easier than wood! I didnt even know I actually I did the cut.

No - that was the blade that I had purchased a few hours before.  It didn't touch any plaster and lathe or other such bad-ness that I'm aware of.  The board that I was cutting did have a nice warp to it, I'm wondering now if that was one of the primary contributors.

Offline Corwin

  • Posts: 2644
Re: New blade = kickback?
« Reply #15 on: March 19, 2010, 02:21 AM »
From the picture it looks like you may have started with a plunge cut without a stop in place on the rail which would easily lead to kickback or you started cutting w/o the saw being completely on the rail which would allow twist leading to kickback.   You need enough rail that the entire saw base is on the rail at the start and end of the cut.   If you need start w/ a plunge cut you should use one of the stops.

Fred

I have to agree with Fred.  It does look as if the saw was not properly engaged on the guide rail before starting your cut -- the rear gib must be fully on the guide rail before starting the cut.  Also, as Fred stated, you really should use a stop behind the saw before starting a plunge cut.  Both these issues are crucial to prevent the kind of result that you have encountered.

One can have a similar issue at the end of your cut if the saw is allowed to travel so far forward that the front gib goes off the end of the rail.  This may not happen, but the potential is certainly there as the ability for the saw to travel askew is not contained  So, before beginning your cut you must position the guide rail such that the rail extends a sufficient amount past either end of your material and then make sure you don't exceed those limits during the cut.

Another thing to consider is checking the saw after such an incident.  While you are aware that your blade has been damaged, the saw has also sustained a significant amount force due to the kickback that may have knocked some of the adjustments out of alignment.  I would suggest at least checking the toe-in setting and readjust the gibs.

Hope this helps prevent future mishaps.

Offline Taos

  • Posts: 227
Re: New blade = kickback?
« Reply #16 on: March 19, 2010, 12:07 PM »
Lets quickly talk about sawblade geometry while I wait for my connecting flight.
The Panther sawblade should be removed from the market by Festool for liability reasons. Not being at my desk right now I cannot clarify the hook angle of the Panther but it appears to be at a minimum 18 degrees, probably 20 and a Z=14 (tooth count). I tried one of these blades last summer and it destroyed my guide rail as well. This blade is NOT a free hand manual feed blade. You wouldn't even find a blade this aggressive on a Mereen Johnson rip saw. Stick with Festools 36-48 tooth ATB's and slow down your feed rate...not too slow though. Besides, isn't the TS series and guide rails really intended for breaking down sheet goods? Please for safety use your table saw for ripping lumber.

Offline WarnerConstCo.

  • Posts: 4080
    • Warner Mill Works
Re: New blade = kickback?
« Reply #17 on: March 19, 2010, 01:30 PM »
I rip stock all the time with mine.
I straight line a lot of roughcut lumber
with my 55.  You just have to pay attention
when you ripping something very dense or
in the OP's case, wet treated lumber.
I have ripped a lot of tapers on pt lumber
and ripped a bunch 2x12.  One just needs to
pay attention when you start your cut.
It's a good heads up so others can make the mental
note. I am more guilty of hurry up short cuts and
generally not paying full attention to the task, then
a lot of people here.

Offline Forrest Anderson

  • Posts: 1072
Re: New blade = kickback?
« Reply #18 on: March 19, 2010, 01:42 PM »
The Panther sawblade should be removed from the market by Festool for liability reasons. Not being at my desk right now I cannot clarify the hook angle of the Panther but it appears to be at a minimum 18 degrees, probably 20 and a Z=14 (tooth count). I tried one of these blades last summer and it destroyed my guide rail as well. This blade is NOT a free hand manual feed blade.

The facts are that the Panther blade which is the subject of this thread is the 439685, and it has the following specifications:

Designation 160x2,5x20 PW14  
Diameter  160 mm  
Cutting width  2,5 mm  
Hole dia  20 mm  
No. of teeth  14  
Chip angle  35 degrees
Tooth shape  PW  


The above Panther blade is being replaced in the UK by a newer Panther, Order No 496301, with the following specifications:

Diameter  160 mm  
Cutting width  2,2 mm  
Hole dia  20 mm  
No. of teeth  12  
Chip angle  20 degrees
Tooth shape  PW  


The new Panther has a reduced hook angle and kerf, and less teeth.


Tenyru also make blades which fit the TS55, and are well-regarded. Their recommended ripping blade is the PSW-16012CBD2 with the following specifications:

Diameter  160 mm  
Kerf   .087" (2.2mm)
Plate thickness .063" (1.6mm)
Hole dia  20 mm  
No. of teeth  12  
Chip angle  20 degrees
Tooth shape  ATB


As regards "NOT a free hand manual feed blade", the TS55 manual confirms that rip cutting should only be done along a guide rail or similar straight edge, and states:

Specific Safety Rules for Circular Saws
When ripping always use a rip fence or straight edge
guide. This improves the accuracy of cut and reduces the
chance for blade binding.



The manual also offers advice on avoiding kickback, which I'll reproduce here for reference:

Causes and Operator Prevention of Kickback:
- Kickback is a sudden reaction to a pinched, bound or misaligned saw blade, causing an uncontrolled saw to lift up and out of the workpiece toward the operator.
- When the blade is pinched or bound tightly by the kerf closing down, the blade stalls and the motor reaction drives the unit rapidly back toward the operator.
- If the blade becomes twisted or misaligned in the cut, the teeth at the back edge of the blade can dig into the top surface of the wood causing the blade to climb out of the kerf and jump back toward operator.
Kickback is the result of tool misuse and/or incorrect operating procedures or conditions and can be avoided by taking proper precautions as given below:
a) Maintain a firm grip with both hands on the saw and position your body and arm to allow you to resist kickback forces. Position your body to either side of the saw blade, but not in line with the saw blade. Kickback could cause the saw to jump backwards, but kickback forces can be controlled by the operator, if proper precautions are taken.
b) When blade is binding, or when interrupting a cut for any reason, release the trigger and hold the saw motionless in the material until the blade comes to a complete stop. Never attempt to remove the saw from the work or pull the saw backward while the blade is in motion or kickback may occur. Investigate and take corrective actions to eliminate the cause of blade binding.
c) When restarting a saw in the workpiece, center the saw blade in the kerf and check that saw teeth are not engaged into the material. If saw blade is binding, it may walk up or kickback from the workpiece as the saw is restarted.
d) Support large panels to minimize the risk of blade pinching and kickback. Large panels tend to sag under their own weight. Supports must be placed under the panel on both sides, near the line of cut and near the edge of the panel.
e) Do not use dull or damaged blade. Unsharpened or improperly set blades produce narrow kerf causing excessive friction, blade binding and kickback.
f) Blade depth and bevel adjusting locking levers must be tight and secure before making cut. If blade adjustment shifts while cutting, it may cause binding and kickback.
g) Use extra caution when making a "Plunge Cut" into existing walls or other blind areas. The protruding blade may cut objects that can cause kickback.



As regards plunge cuts, the manual states:

B) Plunge cuts:
In order to avoid kickbacks, the following instructions absolutely must be observed when plunge cutting:
- The machine must always be placed with the rear edge of the saw table against a fixed stop.
When working with a guide rail, the machine must be positioned against the kickback stop (13.4, accessories), which is clamped on the guide rail.
- The machine must always be held securely with both hands and only plunged slowly.
Procedure: place the machine onto the workpiece and position it against a stop (kickback stop), switch the machine on, slowly press it down onto the set cutting depth and push it forward in the cutting direction.
The markings (13.1) display the absolute front and the absolute rear cutting points of the saw blade (dia. 160 mm) at maximum cutting depth and using the guide rail.


Forrest

« Last Edit: March 19, 2010, 01:44 PM by Forrest Anderson »
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