New TS75 “Kicks Back”

S

SoonerFan

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Jan 27, 2014
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774
I got out my new TS75 today to use it for the first time.  Worked fine to trim a rail and on a practice cut in some MDF.  However, when I went to cut some 5/4 maple (reason I bought the bigger saw) the saw kicks back up very hard.  I attempted to plunge from the end of that maple 5 or 6 times with two different rails and it kicked back every time. 

After it kick back a few times I then tried another cut on the maple plunging in a few inches from the end of the board it was fine.  I used the rail same I used to plunge in the middle of the board to cut the 5/4 maple with my TS55 from the edge of the board and it worked fine. 

It’s almost like when the riving knife starts to follow the cut into the kerf it kicks back.  Not sure that is exactly what happens because it happens without warning.  It kicks back really hard.  I checked and nothing is obstructing the blade.  Neither the blade or the riving knife have any signs of hitting something or each other to cause the kick back. 

I checked the spacing before the cut and the gap to between the riving knife and the blade is within the specifications of 2-4 MM in the manual and so is the gap from the bottom of the blade to the bottom of the riving knife.  The gap between the riving knife and the blade is right at 2 MM but I thought I would ask the option if others before I adjust that. 

Any suggestions?  Is there something potentially with my technique?  I have had my TS55 for years and never had anything like this happen. 

I am still within the 30 days so I can send it back but before I do that I thought I would see if others have experience this and had a solution.

Thanks. 

Sent from my iPhone using Tapatalk
 
Just to be sure, are you plunging the saw to full depth before it enters the wood?  I used to plunge my 55 into the beginning of the workpiece all the time and that was fine for 3/4” ply and the small saw.  The 75 will kick back if you start cuts while plunging.  The reason is because technically the blade is climb cutting as you plunge the leading edge of the blade.

 
.....You are also using a tool with more umphhh and torque now.

Peter
 
It could  be something in the setup of the saw.  However, I have experienced kick back if I don't have the saw fully spun up and plunged before hitting wood.
On 1/2 or 3/4 ply it's not so much a problem, usually no kick back.  But when I stack 2 or 3 sheets or cut into thicker wood stock it will definitely jump back.  I either use the rail stop or(and much simpler) just leave myself enough rail at the beginning to have the saw fully plunged before contacting wood.

The 75 is a huge improvement over the 55 when cutting thick stock, I think you'll be super impressed.  With the stock 36t blade on the 75 I've powered through plenty of 8/4 and thicker walnut stock.
 
[member=64030]TinyShop[/member] - thanks fo the details.  Documentation was helpful.  I think my saw setup is correct.

[member=13462]live4ever[/member] [member=1674]Peter Halle[/member] and [member=65755]jarbroen[/member] - thanks for the comments.  I think you are on to something.  I think this issue might have been caused by longer board, not having the saw plunged completely down before entering the wood and the additional power.  I will test it out to confirm.

Thanks FOG
 
While I believe it's already been answered I just wanna back up the possibility. A TS55 will do the same thing if you plunge into the corner of your workpiece in my experience. In fact, when I'm showing anyone on my crew how to safely use a tracksaw - which they are STRANGELY loathe to learn - that's one of the first things I say. It's one of the only situations where I feel there is any issue of safety with these things. So as long as you have a good amount of rail hanging off the workpiece, and have ample room to engage the rear cam into the track so you can plunge full depth before you hit the workpiece, everything should cut smoothly.

Why oh why oh WHY can't we be supplied with a rail that is about 4" longer??? Most of us cut a lot of sheet goods, and it's worth stepping up to the next rail size, or cutting a custom one for plywood width. Sorry that's off track.

Oops, no pun actually intended...
 
[member=28223]SoonerFan[/member] be sure to leave enough room on the rail at the start of the cut so that you can plunge the saw to the full depth and let it get up to speed BEFORE contacting the workpiece.

Ron
 
I may be misunderstanding the situation but what is the point of a plunge saw if you can plunge into the material? I've never had this kind of consistent kickback with my TS55, only when doing a miter and realizing I was putting pressure on the wrong way. I've also had it stall using a cross cut blade doing a rip cut in a fairly thick door. I don't plunge a lot but I don't see why plunging in itself should cause kickback as cutting downward, from the POV of the circular saw blade, is identical to cutting forward. Always let the saw get up to speed before engaging the workpiece, yes, but you should still be able to plunge. I'm just a hobbyist though, feel free to educate me.

EDIT: To the OP, I know you said you checked your saw but you mentioned it seems to happen when the riving knife slides in the groove, to me that seems like a dog whistle for an alignment problem. If the riving knife is not in line with the saw blade it will push the saw blade sideways when it slides into the groove which could cause kickback. Just a thought. Perhaps it got bent a little somehow?
 
Sanderxpander said:
... I don't see why plunging in itself should cause kickback as cutting downward, from the POV of the circular saw blade, is identical to cutting forward. ...
Click to expand...

No, this is not correct.
 
Corwin said:
Sanderxpander said:
... I don't see why plunging in itself should cause kickback as cutting downward, from the POV of the circular saw blade, is identical to cutting forward. ...
Click to expand...

No, this is not correct.
Click to expand...
To elaborate on this: then being plunged in when entering the material the contact surface between blade and kerf is oriented so the saw pulls itself down (or the workpiece up). When plunging into the material the blade is basically a fast spinning wheel (equipped with spikes) in the air that is lowered onto a surface: the moment the blade makes contact and gets initial grip on the workpiece the rotation direction (from back to front, at contact point) leads to the saw and the blade trying to move into opposit directions, as the saw is lighter (= has less inertia than the workpiece) it is suddenly being propelled (with interesting amount of force) toward the user holding it...

There is a spot on the baseplate of the TS 75 where you can attach a #491582 FS-RSP kickback stop, I suggest you put one there to have one at hand at all times - and actually use it on every plunge cut you do: put the saw into the position where you want the plunge to happen, slide the kickback stop in the rail and into contact to the baseplate from behind, then tighten it.

It will prevent both the saw from moving backwards (possibly gaining momentum into the wrong direction, or messing up the positioning in case you do a cutout) and also keep the back of the baseplate from lifting from the rail (as the little corner of the stop will hold it down), turning a plunge with the TS 75 into a safe operation.

It's also a good idea to clamp the rail on plunge cuts, to prevent the saw taking the rail with it in case it kicks against the stop.
 
What length rail are you using?  The TS75 comes with a longer rail than the TS55 for a reason.
 
I was using my FS 3000 rail.  I think the issue was not having the blade fully deployed.  Will check it out in the next few days to confirm.  Thanks all.

RobBob said:
What length rail are you using?  The TS75 comes with a longer rail than the TS55 for a reason.
Click to expand...
 
You didn't mention what blade you are using. Hardwood can have a lot of tension in it and not using a rip blade can create kickback if the tension is closing the wood around the blade and riving knife. Sometimes you can get away with not using the proper blade other times you can't.
 
I just bought a TS55 and have not even made a test cut yet. I read Festool’s manual the other night and I have been working my way through the Suplemental. The supplemental has a capitalized Caution item as the first words in the Plunge Cutting section that explicitly says that use of the limit stop behind the cut is absolutely required to prevent kickback. I was surprised to read it but it’s there.
 
I just realized that Tinyshop put the link to the TS55 supplemental on this thread. The paragraph that you want to read is at the top of page 18.
 
Gregor said:
Corwin said:
Sanderxpander said:
... I don't see why plunging in itself should cause kickback as cutting downward, from the POV of the circular saw blade, is identical to cutting forward. ...
Click to expand...

No, this is not correct.
Click to expand...
To elaborate on this: then being plunged in when entering the material the contact surface between blade and kerf is oriented so the saw pulls itself down (or the workpiece up). When plunging into the material the blade is basically a fast spinning wheel (equipped with spikes) in the air that is lowered onto a surface: the moment the blade makes contact and gets initial grip on the workpiece the rotation direction (from back to front, at contact point) leads to the saw and the blade trying to move into opposit directions, as the saw is lighter (= has less inertia than the workpiece) it is suddenly being propelled (with interesting amount of force) toward the user holding it...

There is a spot on the baseplate of the TS 75 where you can attach a #491582 FS-RSP kickback stop, I suggest you put one there to have one at hand at all times - and actually use it on every plunge cut you do: put the saw into the position where you want the plunge to happen, slide the kickback stop in the rail and into contact to the baseplate from behind, then tighten it.

It will prevent both the saw from moving backwards (possibly gaining momentum into the wrong direction, or messing up the positioning in case you do a cutout) and also keep the back of the baseplate from lifting from the rail (as the little corner of the stop will hold it down), turning a plunge with the TS 75 into a safe operation.

It's also a good idea to clamp the rail on plunge cuts, to prevent the saw taking the rail with it in case it kicks against the stop.
Click to expand...
I realized some of this when I thought about it some more. Thanks for the elaboration though. I will be careful doing my plunges. So far I've only had to plunge into softwood ply and I always do it slowly.
 
It was my technique that cause the kick back.  I must not have been fully plunging before entering the hard maple.  I made two passes through the same board with the same rail and made sure the saw was fully plunged just now.  No issue what so ever.  I guess my technique just got “lazy” using the TS 55 and cutting all those sheet goods. 

No harm to the wood, the saw, the rail or most importantly me from the kick back so I consider this a good reminder to fully plunge.  Thanks FOG for all the advice. 

The new saw BTW worked perfectly.  Could not be more happy.  Both cuts were burn free and ready to glue. 

Sent from my iPhone using Tapatalk
 
Great it worked out for you. yea these tools take some getting use to.

Always a learning curve
 
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