So far I've been doing mostly large cabinetry sort of stuff, and in a house like mine if things are a little out of square, that's no big deal, it fits right in with the frame. However, I'm about to embark on doors for the cabinets I've built, and for that I want to cut miters that are good to fractions of a percent, and in general, making sure that I don't have to double-check my tools would be good.

A couple of people have mentioned that they have trouble keeping the fence and the rail on their MFT square, and I realized that maybe this is why I'm having trouble nailing my miters. I've been thinking about building a replacement fence that clips to the side rail, that'd not only give me a few more inches of width on the MFT, but would register to the frame rather than the top, but then I realized...

For those of you having issues with the MFT and squareness, have you tracked down the source of your error? Is it the top shifting relative to the frame? Wracking in the frame? Something else altogether? If I can put together an assembly that nails this and gives me 45.000° (as well as a good solid 90°), that'd be awesome.

You've identified the problem IMO. However, some people have less problems than others. Assuming everyone has the same level of interest in squareness the difference could be as simple as how tight the screws are that secure the MDF top to the frame.

The MFT3 attempts to solve the problem in two ways. First, the fence is attached to the frame instead of the MDF top. Second, the top is better secured with threaded inserts to hold machine screws.

You could add threaded inserts to your top and investigate Steve's Qwas Dog system. There is lots of info here.

Another option is to make a large 45 degree template (from 3/4" plywood) to add to the standard fence kept at 90 degrees. Calculate the thickness of shims needed to place between one end of the template and the fence to make angles slightly more or less than 45 degrees. You should already have made a dead-on plywood square to reset 90 degrees.

Dan, that is the $10,000 question. I have never been able to figure out why the fence comes out of square. I can tell you that since removing the Festool fence, I no longer have problems with things getting out of square so the problem lies in the fence. Michael has a good idea but I would still have problems keeping square using Qwas Dogs and I don't have that problem any more.

But your real question is how to cut good miters.

The first answer I have is an old trick. Cut a perfect 90 degree corner on a piece of plywood. This will become your fence. Insert that corner under the guide rail so the point comes right to the cutting edge and the plywood sides are at about 45 degree angle to the rail. Clamp it in place. For every corner of your door, one piece is cut against the bottom of the plywood fence and the other gets cut against the top of the plywood fence. Even though the miter may not be a perfect 45 degree miter, you will get perfect 90 degree corners.

The second answer is to use the table to it's full capability. Align the guide rail to the holes using Qwas Dogs (or some good bench dogs), then stick the dogs in a diagonal row of holes. Perfect 45 degree cuts every time.

Check out my You tube video to see the results. 6 minutes into the video you will see the set up for 45 degree miters.

__________________
Steve Adams, Qwas Products

I have not been able to get square cuts with my new MFT 3 and TS 55. The cuts are off 1mm per foot of cut.

My work area dictates that I have to put away the MFT at the end of the day. Each time I need to use it, I have to install the components and check for square.

I clean the fence and tabletop of sawdust before lining up my material.

I have used a 12" speed square and two different framing squares to lay out the fence and guide rail. I have checked that the squares themselves are square.

Is there an order that you follow to lock the components into position? I have tried different methods of lining components into position and locking them into place.

Stopped by my dealer to ask for suggestions in squaring up the unit and was told that it is supposed to cut square.

Qwas- Since you removed the stock fence, what did you use for a replacement fence?

Replacement Fence? I have several. 3 or 4 sit on some special bench dogs so I can place them where ever needed. Then I have a fence that is built on the MDF top.

I can use Qwas Dogs to align the rail or I can use any of my fences to align the rail. Since setting it up, I have discovered it stays aligned. I check it daily before use but It's never been off. I move my guide rail often and it only takes a few seconds to align.

As far as accuracy, my cuts are within .01 inches over 2 feet. If I spend a few more seconds, I can get accuracy of .005 inches over 2 feet.

You can check out my fences in these threads.

http://www.talkfestool.com/vb/showthread.php?t=104

http://www.talkfestool.com/vb/showthread.php?t=105

http://www.talkfestool.com/vb/showthread.php?t=106



http://www.talkfestool.com/vb/showthread.php?t=107

__________________
Steve Adams, Qwas Products

balrog,

Are you saying you align the fence and guide rail for squarness and your first cut piece is out 1mm per foot? Or does it work it's way out of square?

__________________
Les

lspencer98-

The first cut is off. I have tried cutting with and without a pair of festool quick clamps.

All of the connections are left loose during installation.
Slide the front and rear guide rail supports on the front and rear extrusions.
I slide the protractor unit along the back extrusion.
Connect the fence to the protractor.
Attach the angle stop (fence rail clamp)to the fence and left extrusion.
Install guide rail with two screws on the rear support- leave screws loose.

As I tighten each component, I recheck for squareness.

Set protractor to 0- tighten head and position on extrusion.
tighten knob on protractor to hold fence in place.
Set scrap (usually 1/2" or 3/4")under guide rail. Tighten front and rear supports
Set guide rail to rear support
Tighten angle stop to left extrusion.
Go back to the guide rail support and check again.

I only use one saw on this table. It is the same blade that cut the rubber strip for the first time about two months ago.

If I use the MFT guide rail without the fence and a pencil line, I can get a square cut. I can also get a square cut with another guide rail and a cutting table. Because of this, I think I can rule out the saw. The gibs are adjusted to let the saw glide on the rail without play.

I use the same mechanical pencil, tape measure and have tried with three different squares. Swept the work surface, fence and guide rail between each try.

Thank you for your help!

Have you watched this you tube video? Lots of good info.

One thing you also might try is when you set your rail onto the tab, either push or pull the rail sideways about 1/32". This will take out any play between the grove in the rail and the tab.

I also use 1-2-3 blocks to help insure squareness as described in this http://http://www.talkfestool.com/vb...aring-mft.html.

__________________
Les

Balrog,
It sounds like something is not getting tightened. I hope the video pointed something out that you haven't been tightening. I don't have an MFT/3 so I can't help much but I know many others have the MFT/3 and they get perfect cuts and report the fence stays squared once you get it there.

Only thing I know to do is to isolate what is causing the problem. Align your fence and rail. You can try to measure the fence relative to some holes and then do the same with the guide rail. I would start with the fence and measure each end with caliper something like this.

Measure 1.jpg

Then measure the guide rail.

Measure 2.jpg

Make a couple of cuts and then re-measure. Now we should know what moved and at which end it moved.

__________________
Steve Adams, Qwas Products

Hey Balrog,

One common error that will produce this kind of result is when the front Guide Rail Bracket is set a little too low. The tab on the top of the front Bracket fits into the slot on the underside of the Guide Rail to locate that end of the Rail. Set at the proper height, you may get a few thousandths of an inch play between the slot in the Rail and this ^ shaped tab -- but, set any lower you will get an increasing amount of play. Setting the height of the Guide Rail Brackets doesn't need to be difficult or time consuming, but it does need to be done correctly.

Let us know either way on the status of this situation.

Corwin