Not making 90 degrees cut on MFT 1080

[fidelfs]

Hi,

I have been cutting with my MFT 1080 on and off.  I always comeback because it is more convenient to make crosscuts with long pieces than with my Table Saw (I will refer to Table Saw as TS to avoid confusion with the TS55 or 75).

I have always been disappointed not being able to have 90 degrees cuts and I move back to the TS.  Then after a few months later, I said I will try again and then I get disappointed again.

I used the standard fence and guides that came with the saw and after having so many problems and reading how difficult was to maintain square then I decided to buy the Qwas dogs.

So I disassemble the fence (following the way that Paul Marcel does it) and used the dogs to make a 90 degrees.  I made some cuts and measure the diagonals and they are not the same.

Hmm, I decided to use my Bosch miter finder (digital) to see what was going on.  The holes in my MFT are not at exact 90 degrees at each other (not all of them, but the ones I need to work with the fence and guide are).

I thought what could be more exact a CNC machine or my Bosh miter finder, I said well, the CNC machine it is a sure bet.  So I measure all the holes with all my 90 degrees rules (Starret, Home depot, other miter finders,etc) and there is always a little difference so they are not 90 degrees.

Am I looking to have something perfect that is not attainable ? of do You guys work with 89.8 ~ 90.2 degrees and you compensate later (I don't know how) of it is something wrong with my MFT top?
I know I am way out of warranty and I don't think that is covered because it is not the intended use, so no fault to Festool on this, but If my test is correct, I will have to give up the MFT for cutting all together and make some jigs for my Unisaw.

Am I doing something wrong?

I push against the dogs to maintain good contact, even some times I push so hard to see if that is the problem but no 90 degrees. In other words, I tried soft push, medium push and strong push without any difference.

Do you experience something similar?  I know there are a lot of posting about how to square the MFT, they don't work on mine.  I thought for awhile to buy the MFT3 but I said, will I have the same experience and waste $500? 

Please help!

The caveat as I always said, I am a hobbiest not a pro, but I tried to build my stuff as a pro.

 

[Alan m]

to be honest i never checked to see if the holes were square to each other or not . i just assumed  them were. i think your best bet to see if it is actually square is to use a vernier calipers and trigonomitry (remember that crap you said in school you would never use) that should tell you

 

[GhostFist]

how much out of square are we talking here? How difficult is calibration on the MFT? the next purchase I was planning was the MFT3/ TS75 package for cross cutting and the like. The film studios are starting to use track saws more and more though no MFT's to be found (and doubtful they ever will be). I've been using their track saw quite a bit, and encouraging others to as well when making difficult cross cuts by measuring both long edges of the board and dropping the track on your marks and the results have been very good for our applications, much better than the wonky way some people try to murder themselves cross cutting on our table saws.

none the less the issue has been brought up several times on this board regarding squaring the MFT and there have been numerous methods suggested for doing so. Not owning one I kinda pay half attention to it but with this being my next planned purchase my question is, is it worth it?

I would like an MFT as a collapsable portable workbench to be used for general work as well as in conjunction with a TS75 and later a router for cutting dados. How much finicking around am I constantly going to have to do with this thing in order to get the results I want?

 

[fidelfs]

It is between 89.8 up to 90.2 degrees.

I was cutting the drawer bottoms so I dont mind the out of square because they will be inside of a grove, and i can compensate.

The diagonal measures were 861 and the opposite 854, I use the bosh miter finder and it was 89.8 degrees.

The problem was when I cut the boxes for the cabinets.  I dont think it is acceptable that out of square, or am I wrong?

 

[mastercabman]

It is between 89.8 up to 90.2 degrees.

Good enough for me!

 

[ScotF]

Could it be that you are overtightening the rail where it pivots? The reason I ask that overtightening this can tweak the rail out of square to the angle head - at least this has been my experience on the mft/3.  The key has been to get the rail to drop right on the tab on the front without moving it side to side and hand tightening so that the rail just drops down.  Then square the fence to the rail without the black fence lock on the back and then tighten the lock -first to the mft and the to the rail. I find I can get repeatable and square cuts.

Scot

 

[Qwas]

If I'm not mistaken you're talking about an error of more than 1/16" over 24". I think you should test your holes and see what is going on.

Start with a visual look first. Make sure the holes don't have any glue residue in them. The dogs should feel the same as goes into each hole i.e. you should feel the same amount of play between the dog and the holes). Next bring your eyes down to where you can eyeball down a row of holes. Look for any hole where the edges aren't in line with the others. After doing the horizontal rows, do it with the vertical rows (or columns) also. I recommend circling the bad holes with a red magic marker but any way you want to mark  a bad hole is fine.

For more accuracy you can try using a straight edge. If you don't have one, use a level or a framing square. Use 2 dogs in holes, near the ends of the straight edge. Insert a 3rd dog into the holes between those 2 dogs. It should touch the straight edge. You can use a piece of paper as a feeler gage to test how close it is. Keep in mind a piece of paper is about .002" thick and I don't think that small of amount will cause this big of an error. If you can slide 2 or 3 pieces of paper in then I would be concerned about that holes's accuracy. Also move the straight edge around some to verify it's not a bad spot on the straight edge. Run this test both horizontally and vertically. You can also try to do it diagonally but I don't see where it would show anything different than the horizontal/vertical test. Again, mark any bad holes so you know not to use them with the dogs.

Another "last resort" test would be to insert your calipers into the holes and measure the distance between the holes. All the holes should have the same reading, and it should be the same reading for horizontal spacing as the vertical spacing. I don't like this test which is why I saved it for last. I trusted several holes on my MFT and differences of .005" on holes I know to be accurate.

These test should identify any bad holes. After that, if you still have errors, you need to look into how well the guide rail is secured to the MFT (any loose screws or excess play with the brackets), be sure the MDF top is not sliding in the aluminum table frame, be sure the TS-XX has the gibs adjusted for no play but able to slide, and be sure your blade is tight, not bent, or has excess play.

 

[greenMonster]

push comes to shove, can always replace the top

 

[Corwin]

I have this same issue with one of my MFT1080s, and in my case it is due to table sag.  Since gravity has taken its toll on this table, the holes are no longer in perfect alignment -- or more precisely, the holes are no longer plumb since the table sags slightly.  I can place dogs along a row of holes and clearly see how the ones towards the center lean out of plumb.  The amount of  sag isn't all that great, but it makes a big difference on how well these dogs work -- or, rather it makes it so the dogs don't work.  If this is what is affecting your MFT too, I suggest getting a new top and add some bracing to prevent your new top from sagging over time.

 

[nickao]

I just flip the top once a month or so seems to keep it pretty flat, not perfectly flat but darn near.

 

[fidelfs]

I know for sure that not all the holes are identically.  I remember when I bought it that I tried to use the wonder dog from Veritas and I couldn't make it fit in some holes.  I even tried to move the fence some rows and the festool own dogs didn't fit in all the holes.  That was since day one.

I didn't care because in 2007-2008 when I bought it I had no intention to use the holes to square the fence or the guide. I used them only to hold the clamps.

Qwas, there are some holes that your  dogs don't fit either.  I think that table was a lemon.
I remember when I bought it I had to ask for another rail (one of the long ones) because it was damaged (it looks like it was hit and bent badly, I couldn't move the fence clamp).
So, probably the top was bad as well, but like I said I didn't care at that time.

I tested my guide and fence following the advise from ScotF, I set the guide to pivot and rest on the oposite tab perfectly, without worrying if it was 90 degrees to anything. Then I set the fence 90 degrees with my Bosh miter finder in relation to the guide, and voila, my cuts were 90 degrees.  So, at least I know the fence and guide are ok, not bent or anything like that. It is just the top.

Now, the question to myself is, should I buy a new top or keep squaring only between the fence and the guide.

??? ??? ???

P.S.

I am able to square the guide and fence without any other reference like the rails or holes, because I disassemble  the fence, remove the miter and the dogs. so It is a free fence that I have to support using the back clamp and one festool clamp. 

 

[Corwin]

Sounds like you are able to square your fence to the rail just as the MFT1080 was designed to do.  So, as I see it, you have no reason to get a new top until you really need to replace the original one, or, unless you really want to use the holes to use your Qwas dogs to align the fence and rail.

 

[Qwas]

I suspect a bad top. My MFT is from 2007 and that time frame has some of the largest holes, 20.17 mm. But all my holes were consistent in size, except the one that had some glue dumped in it.  [embarassed]

I haven't heard of a bad top before but there is always a first. If you decide to go with the guide and fence aligned to themselves, please remember that there is an issue with some of them not staying square. Mine would go out of square within 10 cuts, but yours may be perfectly fine.

 

[fidelfs]

Corwin,

Not quite, I am probably at 92 degrees in Relation to the rail.  I dont have the festool dogs.

I was not able to have square cuts with the standard config from festool.

My guide is not square to anything, the fence is square to the guide.

 

[PaulMarcel]

That's a strange problem you're experiencing. The fact that the dog holes aren't even a consistent size is strange.  I had a workbench top recently CNCed by a friend and the first 4 rows are too tight for a Qwas dog while the last 2 are perfect; he later said his CNC has drift issues.  I wouldn't expect that Festool's supplier for the tops would be running on a ShopBot; I'd actually expect a CNC that just plunges the holes with a properly sized bit.

Anyway, my table is square; I've checked it many times.  Even check for sag, but I don't leave anything on it for long.  My guide rail stays square so it seems like the tables you and Qwas got were less than spectacular.  Too bad since I know you were looking to use the CNCed top and Qwas dogs to your advantage for calibration.

If you end up ordering a new top from EKAT, explain to them the problem with the top.  Maybe someone can verify the top before sending  a new one.  Or, get a top cut.  Check out 100kGarages.com to find a CNC workshop in your area and see if someone would mind doing it.  It's a trivial cut-path.  If they could use an 8mm shank bit for plunging, see if you could bring along the Festool 20mm hole-boring bit.  I bought one for my friend to use on his ShopBot, but for some reason couldn't...  [blink]

Let us know the outcome!

 

[nickao]

Actually, using CNC I highly doubt it is one bit that just plunges the exact size and suspect it is a bit smaller and it runs a circular pattern to the exact size. Maybe someone from Festool who knows for sure can comment, but in my experience with CNC you can not do as you suggest because even bits made in the same run can be off in size, plus large industrial places resharpen their bits which can make them smaller. Running a smaller bit and cutting a circle ensures the bit size is irrelevant, you just put the exact measured bit size and the finished hole size  in the software, Relying on the bit to be the exact size is near impossible. I have never come across a bit that can be counted on to be the EXACT stated size.

And his shopbot is messed up then because a tuned shopbot can certainly make every hole so close in size the difference is not measurable. Heck my home made machine cuts perfect tops every time(better than a shopbot though).