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Author Topic: Kapex KS 120 REB widely unprecise  (Read 834 times)

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Offline karellm

  • Posts: 6
Kapex KS 120 REB widely unprecise
« on: May 03, 2021, 05:14 PM »
I recently bought a Kapex after debating for years whether it was worth the price. I've now spent over 6 hours trying to get a square cut and I wanted to see if I'm the only one finding this saw to be widely unprecise.

The list of things that seem good:
- Table flatness within .004
- Fence is straight within .002
- Fence is perfectly square

That basically leave me with the detent plate to play with. I've tried everything and I can't seem to get a square cut. If I get it square on the left side, the right side is off by .02 over 12". The best I got the double cut test is a .04 over 12". This is a lot and not acceptable for a tool that expensive. This kind of error will compound very quickly.

I've barely touched the mitters adjustments but they are both off by about 1 degree. Which again is not acceptable.

I love everything else from the tool but I'm really wondering if I'm expecting too much of a mitter saw or if the unit is defective. If it is to be expected, I think I will return it and get a cheaper tool that will likely do better.

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Offline Birdhunter

  • Posts: 3446
  • Woodworker, Sportsman, Retired
Re: Kapex KS 120 REB widely unprecise
« Reply #1 on: May 03, 2021, 06:00 PM »
I get a really good 90 degree cut with the wood on the left side and the cutoff on the right. Not so perfect in reverse. The great dust collection offsets the accuracy issue. If I want perfect accuracy, I use my big SawStop.
Birdhunter

Online ChuckM

  • Posts: 2620
Re: Kapex KS 120 REB widely unprecise
« Reply #2 on: May 03, 2021, 07:04 PM »
I can't remember the exact tolerance of the Kapex. If what you found is within tolerance, returning the saw seems to be the logical choice. If it's outside the tolerance, ask the merchant to get it back to Festool to fix it since you've already tried yourself without success.

Offline MaineShop

  • Posts: 90
Re: Kapex KS 120 REB widely unprecise
« Reply #3 on: May 03, 2021, 11:29 PM »
To me when I read this it sounds like you may have unrealistic expectations for a miter saw. A portable miter saw like the kapex is going to have some variation in the hundredths of an inch. Mostly due to the motion of you arm applying force to bring the saw down. I have a kapex and really find it a good tool for what it is. I use it mainly to cut hardwood stock for face frames and door parts. But at work I use large digitally controlled panel and jump saws that offer the kind of accuracy it sounds like you are looking for. However that kind of accuracy comes at a premium and those machines cost tens of thousands of dollars and require much greater power then a 15 amp outlet.

To help with getting a square cut on the kapex I can only suggest making sure your two referencing edges are parallel for the test, and make sure you are letting the blade spin up to speed before entering the wood so that you are not dealing with any deflection in the blade.

And if you are having buyers remorse simply return it.

Offline Birdhunter

  • Posts: 3446
  • Woodworker, Sportsman, Retired
Re: Kapex KS 120 REB widely unprecise
« Reply #4 on: May 04, 2021, 08:29 AM »
I think MaineShop is correct in saying even moderate  lateral pressure on the saw head can produce a measurable deflection in the Kapex.

My SawStop Industrial model is massively built and is dialed in with a micrometer. Even so, I’ve seen grain in hard woods produce a deflection in the cut.

For extreme accuracy cuts on the Kapex and the SawStop, I make the first cut slightly proud and then take a “whisper” cut.
Birdhunter

Online Cheese

  • Posts: 8430
Re: Kapex KS 120 REB widely unprecise
« Reply #5 on: May 04, 2021, 09:59 AM »
For extreme accuracy cuts on the Kapex and the SawStop, I make the first cut slightly proud and then take a “whisper” cut.

For my "whisper" cuts, I use the deflection of the blade on the Kapex, to work to my advantage. If I need to remove .002"-.003" from the end of a board, I lower the Kapex arm, push the stock against the blade so that there is some interference, clamp the stock down, raise the Kapex arm and make the cut. You'll remove just a "whisper" every time. It's also fairly repeatable & consistent.

Offline SRSemenza

  • Global Moderator
  • *
  • Posts: 9587
  • Finger Lakes Region, NY State , USA
Re: Kapex KS 120 REB widely unprecise
« Reply #6 on: May 04, 2021, 10:11 AM »
I would be curious to know if the error is evenly distributed across the full 12" width?  Or if it is mostly on the outer portion of the cut when the saw head is extended further.

Maybe try a 6" cut and see what the deflection is on that to help isolate the problem?

Are you measuring single cuts, or the four / five cut method?

Are you clamping the work piece for the test cuts?

I don't know if you are right or left handed, but it is the error worse when using your offhand to make the cut on one side compared to the other?

        Just some thoughts to consider in order to help sort things out.

Seth

Online Michael Kellough

  • Posts: 5190
Re: Kapex KS 120 REB widely unprecise
« Reply #7 on: May 04, 2021, 11:15 AM »
Even if the fence was a Vee shape from left to right you can still get a square cut if you move the blade to the right position. The right position is the place where it cuts square regardless of where the curser lands on the miter scale.

“I've barely touched the mitters adjustments but they are both off by about 1 degree. Which again is not acceptable.”

One degree off is HUGE. You don’t have to move the miter scale much to make it read way off. If you can’t get it back where it should be return the saw a try another.

Online ChuckM

  • Posts: 2620
Re: Kapex KS 120 REB widely unprecise
« Reply #8 on: May 04, 2021, 11:37 AM »
My experience with the Kapex EB has been all positive in all aspects from table flatness to accurate square AND bevel cuts since day 1 it was bought and tuned (using the 4-cut method). The saw has the best hold-down clamp, dust collection and bevel control feature. (The motor issue with the old EB model is a separate matter, and i have had no experience with that.)

However, for its price, I cannot accept that in the absence of user errors, one has to resort to workarounds to make it work. Anyone can get a miter saw at half the price of a Kapex, if not less, and use workarounds to achieve accurate cuts! Festool needs to step up and look into its Kapex manufacturing/QA process to deliver a machine that's consistently up-to-spec and reliable. Consistent reliability is a key factor I take into account when I buy any high-end product.
« Last Edit: May 04, 2021, 11:39 AM by ChuckM »

Offline madjalapeno

  • Posts: 30
Re: Kapex KS 120 REB widely unprecise
« Reply #9 on: May 04, 2021, 04:05 PM »
I bought the Kapex to replace a Bosch unit that would never cut square. Drop cuts or sliding cuts would be square, but never both. It could well have been my technique, but I suffered for years with never getting it consistently square.

The Kapex is a dream in comparison and giving me much nicer cuts. There is a tiny variation, but nothing for me to worry about.
TS55C ◉ CT15 ◉ Kapex KS 120 REB ◉ Domino DF500 ◉ PS 420 EBQ ◉ RO 125 FEQ

Offline Birdhunter

  • Posts: 3446
  • Woodworker, Sportsman, Retired
Re: Kapex KS 120 REB widely unprecise
« Reply #10 on: May 04, 2021, 08:43 PM »
I also use the blade deflection technique to make “whisper” cuts. Works great.
Birdhunter

Offline Mini Me

  • Posts: 28
Re: Kapex KS 120 REB widely unprecise
« Reply #11 on: May 04, 2021, 09:21 PM »
A very quick and easy method to measure how square the saw is cutting is to do a cut then leaving one half of the cut where it is then flip the other half over and see what sort of gap you have if any. Keep in mind this doubles the error and for that reason is easy to see.