What practical accuracy is acceptable on MFT/3 for frameless cabinets?

[Kodi Crescent]

I'm working to square my MFT/3 to crosscut parts for frameless cabinets.  Using the 4 cut method, I end up with the error being 0.01 inches per cut from square.  This is over a 40 cm cut.  Is this level of accuracy acceptable for frameless construction?

(Units added per other comment).

 

[cpw]

I'm working to square my MFT/3 to crosscut parts for frameless cabinets.  Using the 4 cut method, I end up with the error being 0.01 per cut from square.  This is over a 40 cm cut.  Is this level of accuracy acceptable for frameless construction?

.01 what?  If you're saying .01cm/40cm; I think the largest cabinet you are likely to make is 96 inches or 243cm which is about 6 times 40; or .06cm ~= .023in or under 1/32.  You have about 2mm of adjustment in euro hinges, so I think you should be within tolerances.

Caveat: I've built a house full of cabinets, but am not a professional.

 

[lwoirhaye]

I think it's probably okay for many framless builds.  Make a sample cabinet with an inset slab door and see how the reveals look.  Once you start stacking frameless boxes things can get weird if the setup isn't dialed in really well, but single rows under counters and things like that are more forgiving.

 

[sancho57]

Wood will move more than that, your walls will out more than that and thats why they make shims

 

[Cheese]

Here's an earlier post, see reply 12.
http://festoolownersgroup.com/ask-festool/5-cut-calibration-method/

 

[Kodi Crescent]

I was able to get it down to 0.0055" over 335 mm.  That's about the same difference in offcuts for the crosscut sled on my table saw.

If I calculated the angle correctly, it's 0.024 degrees (?).  I'm assuming this means when I make a square cut on the MFT one side will be 89.976 degrees, while the other is 90.024 degrees.  Is this logic correct?

 

[Cheese]

I was able to get it down to 0.0055" over 335 mm.  That's about the same difference in offcuts for the crosscut sled on my table saw.

If I calculated the angle correctly, it's 0.024 degrees (?).  I'm assuming this means when I make a square cut on the MFT one side will be 89.976 degrees, while the other is 90.024 degrees.  Is this logic correct?

Both your calculation and your logic is correct.  [smile]

That's basically 1 1/2 minutes of angle...pretty small. I wonder how long that will last on an MFT?  It'd be interesting to do another check after you've used the MFT for a while.

 

[fshanno]

The accuracy you've described is about what I get.  It will work fine for frameless casework.  I've cut up hundreds of sheets of plywood for cases that go together well.

I'll offer a suggestion.  Unless you have access to outstandingly flat and stable plywood, I wouldn't go frameless for wall cabinets.

The narrower sides tops and bottoms are more susceptible to slight bowing.  You can take the bow out of the back edges of the sides top and bottom with stretchers or a solid back.  But since the front can't have stretchers the bow may still be there on the front edges.  You can't put stretchers across the front, obviously, and nobody goes with fixed shelves any more.  The face frame will remove the bow or completely hide it.  It also makes the wall cabinets a little stronger which isn't a bad thing.

Also you don't really lose storage space in wall cabinets with face frames.  You can go with full overlay doors and achieve the same 1/8" overlay just like your frameless base cabinets. 

 

[waho6o9]

" You can't put stretchers across the front, obviously, and nobody goes with fixed shelves any more."

I was going to suggest a middle fixed shelf with a 3/4" back and you're good to go. And if you use Blum

soft closing hinges you'll need a positive stop anyways and the fixed middle shelf will do that.

 

[Michael Kellough]

I'm working to square my MFT/3 to crosscut parts for frameless cabinets.  Using the 4 cut method, I end up with the error being 0.01 inches per cut from square.  This is over a 40 cm cut.  Is this level of accuracy acceptable for frameless construction?

(Units added per other comment).

1/100th off over 15-3/4” is pretty good and is acceptable for parts that size (probably a lot better than most places achieve) but if you working on setting up your equipment as best you can then a goal of .01” over 40 inches would be much better for the long term. If you do achieve than then you’re biggest problem in getting cuts that are that accurate will be keeping the edges of the material free of dust big enough to misalign the material to the sled fence.