Kapex KS 120 REB widely unprecise

[karellm]

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.

 

[Birdhunter]

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.

 

[ChuckM]

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.

 

[MaineShop]

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.

 

[Birdhunter]

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.

 

[Cheese]

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.

 

[semenza]

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

 

[Michael Kellough]

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.

 

[ChuckM]

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.

 

[madjalapeno]

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.

 

[Birdhunter]

I also use the blade deflection technique to make “whisper” cuts. Works great.

 

[Mini Me]

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.

 

[tigger]

All I can say is that I've personally never experienced these issues with my Kapex. Maybe I'm just lucky. However, a bit of a giveaway in the comments is "fine cutting on one side but out when cutting on the other side". I can say with 99.9% accuracy that this will be user error. Not picking a fight with anyone [embarassed]
I used to train end users in power tools and with any mitre saw, this is an issue. Festool has attempted, through design, to negate this by placing the handle in the vertical position above the blade. If your stance is correct an your left hand/arm matches your right arm/hand action, then you cuts should be identical.
Logically speaking, if your fence is straight and your left and right cuts differ, its a mathematical impossibility to "out". The only variant, is the user.
The best advice I can give is to set up the Kapex with set squares and practice your biomechanics when using the saw from either side.

Sorry if my reply is a bit direct  [embarassed]

 

[ChuckM]

User error is a possibility, so is stock not being truly straight and flat.

 

[Gebones]

I have the same/similar problem. I thought the fence was flat until I placed my straight edge across and then used feeler gauges. I found with the flat edge spanning across both fences that at the inner tip on the right side I could easily get about a .003 inch feeler gauge in-between the fence and the straight edge. The left side allowed for a .003 feeler gauge in with ease and a .004 inch feeler with a bit of force. For my final test I moved the the flat edge from the left fence pushing it right until it mated with the right fence and there was no stoppage. Then I ran the flat edge the opposite way from the right fence to the left fence where it bumped and stopped. It got hung up on the left fence right at the tip and wouldn't continue on that plane without lifting it. As others have stated, I can get the left or the right to be dead 90, but then the opposite side is less than 90. I've spent all day reproducing all of the results over and over. The fence is not flat. The saw is perfectly reproducing the same cut time and time again. If the fence was flat my issue would go away. My saw is 7 days old. I'm very irritated for this price.

 

[Gregor]

Contact festool service, explain how you diagnosed the issue. They'll fix it for you.