Acceptable amount of deflection on Kapex 45 degree bevel cut -- now with pics!

ear3

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Just continuing to put my new Kapex through its paces.  I might end up swapping/returning the saw anyway because of some issues with the bed being out of plane, but I wanted to ask what people's experience is with the amount of deflection they get on a 45 bevel cuts.  The laser shows that the weight of the saw at that tilt produces some amount of deflection.  The first test cut I did on an 11 1/2" board produced maybe a 16th of an inch in deflection.  On the second test, though, I found that if I kept my hand pressing outward (to the right on a left hand tilt) I reduced the deflection to between 1/64th to 1/32.

I know that some blade deflection is just the nature of things on a miter saw when tilting -- if I need a perfect cut I'll reach for the TS or my table saw.  The Kapex certainly deflects less than my Bosch CMS, but I'm wondering if others have experienced less (or more?) deflection with their Kapexes with these sorts of cuts?
 
I've cut a 3/8" piece of plywood at 45 degrees that spanned the full Kapex surface. The cut was dead on its full length. I needed several pieces like this for a jig. They all were perfect. No errors from deflection.

I've never measured table flatness. My theory is that if my cuts are perfect, I don't want to know any minor faults the tool might have.
 
Edward A Reno III said:
  On the second test, though, I found that if I kept my hand pressing outward (to the right on a left hand tilt) I reduced the deflection to between 1/64th to 1/32.

I think that would indicate that the board was not secure and moved on you during the cut.
 
I rarely clamp when mitering but usually clamp when beveling - especially if it is a wide workpiece.  I also prefer the Festool 60 tooth blade when beveling.  My results are acceptable for high end carpentry.

Peter
 
Meaning you experience some deflection on yours?

WarnerConstCo. said:
Its a portable miter saw, not a dewalt GP, GA, or GE RAS.
 
Interesting.  So if I am experiencing deflection then -- assuming there is no user error -- there might be an issue with the saw?

Birdhunter said:
I've cut a 3/8" piece of plywood at 45 degrees that spanned the full Kapex surface. The cut was dead on its full length. I needed several pieces like this for a jig. They all were perfect. No errors from deflection.

I've never measured table flatness. My theory is that if my cuts are perfect, I don't want to know any minor faults the tool might have.
 
Edward A Reno III said:
Meaning you experience some deflection on yours?

WarnerConstCo. said:
Its a portable miter saw, not a dewalt GP, GA, or GE RAS.

Never had the need to check it in 6 years.  The things i cut fit together nicely. 

It is however a tool that you move around a lot, not a heavy stationary saw.
 
After some more test cuts I've found that if I'm very careful and torque my hand to the left on the (left tilt) 45 degree bevel cut, it comes out straight -- I wouldn't be able to do it without the laser though, since the laser shows me whether or not I'm parallel to the scribe line.  But the motion feels weird and unnatural.  Plus I won't always be able to get a scribe line, like if I'm beveling a large piece of moulding.

Just some pictures to illustrate -- again my sole objective is to find out whether my saw is like everyone else's, or whether there is some engineering issue that requires it to be sent back.

So just to preempt questions about user error or improper setup, I went through all the procedures in terms of squaring the saw and aligning the lasers.  I drew a scribe line with my Woodpeckers square, and double checked that the lasers ran parallel with the line:

[attachthumb=1]

You'll see that the cut is dead straight, just shaving the line:

[attachthumb=2]      [attachthumb=3]

Drew another scribe line with the Woodpeckers and set the saw to 45 degree bevel, left tilt.  You can see now how the laser skews slightly to the left at the front of the board:

[attachthumb=4]          [attachthumb=5]

But applying the torque so that the laser followed the line, I was able to come out with a more or less straight cut.  Once I tilt the saw back to the 0 bevel position, you can see how the laser again runs parallel to the scribe line of the completed cut:

[attachthumb=6]

So, should there be zero deflection of the head/laser when the saw is tilted at a 45 bevel?  Or when you guys cut do you use the same torquing method when pulling the blade down into the workpiece?
   

 

Attachments

  • 90 degree straight cut setup.JPG
    90 degree straight cut setup.JPG
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  • 90 degree straight cut completed.JPG
    90 degree straight cut completed.JPG
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  • 90 degree straight cut completed, front edge.JPG
    90 degree straight cut completed, front edge.JPG
    2.5 MB · Views: 393
  • 45 bevel, board top.JPG
    45 bevel, board top.JPG
    2.7 MB · Views: 447
  • 45 bevel, board bottom.JPG
    45 bevel, board bottom.JPG
    2.7 MB · Views: 387
  • Completed 45 bevel cut with saw at 90.JPG
    Completed 45 bevel cut with saw at 90.JPG
    2.8 MB · Views: 356
Usually i try to not to torque a SCMS with my hand when making any kind of cut to get the best results.
If you lock the head down and push the handle gently-moderately side to side is there any play between the head and the slides?
 
WarnerConstCo. said:
Cheese said:
[member=3891]WarnerConstCo.[/member]
WarnerConstCo. said:
Its a portable miter saw, not a dewalt GP, GA, or GE RAS. 

My thought is that you own a GP, am I close?

Along with an MBF, GA and a 925.

He's actually got machines you can use to mitre cut a six lane bridge in one pass and a tenoning machine to join them back together [blink]
 
Cheese said:
[member=3891]WarnerConstCo.[/member]
WarnerConstCo. said:
Along with an MBF, GA and a 925. 

How come so many? Different jobs for each one?
  some of us lust after Green,  Darcy lusts after 'Old Arn', and lots of it.... ;D ;D ;D ;D
 
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