Domino XL 700 Mortise not Cutting Parallel to Fence

[808]

My Domino XL doesn't cut mortises parallel to fence/reference surface, so when the opposite pieces are joined using a single domino (which shows how well the mortise is aligned to the reference surface), the error is doubled and the pieces are skewed/twisted from one another on the referenced surfaces.

I had tried all suggestions, lock height before locking fence, plunge slower, use new bit, etc. I finally was able to send it in for repair, but the response was very disappointing.

I got a call from Festool service and they said the machine was within spec. They asked about the problem and I described that I was using the Seneca domi-plate. They said they can't be responsible if I was using another product with the domino and that the domino XL was not designed for stock thinner than 1". Ok, fair enough.

I did, however, describe that I had the same problem mortising material thicker than 1" and had the same problem. The response was that maybe I was plunging too fast or not holding the tool flush to the surface. I insisted that I was very careful and made sure I plunged carefully and slowly and that the fence was flat on the reference surface. The response I got was that wood is a natural material and not always flat or square. Clearly not what I wanted to hear. I then asked how the tool was tested. It sounded like it was put in a rig that could test tolerance precisely. I asked that they just have someone use the tool normally and just try to join two pieces of stock with a single domino and if the pieces were aligned perfectly, then I could accept the user error explanation. He said he'd try and make the request.

I don't hear anything after that and I get the tool back. However, nothing changed and I still consistently get skewed pieces. So to ensure it wasn't the unevenness of the wood causing the issue, I cut and planed new stock greater than 1" thick to test. I also used a new 8mm bit.

The pictures show the stock is square (first picture with reference surface facing down) so there shouldn't be an issue with an uneven wood surface. I get a skew of almost a quarter inch 9.5" out from where the single domino is. I tried many times and continue to get skew. I even tried holding the fence handle with my opposite hand to see if it was something to do with my more dominant hand. I still got skew in the same direction. The only thing that seemed to result in a small improvement (i.e., less skew) is if I put near zero pressure on the fence handle. I can only guess that there is some flex somewhere in the tool when the fence has to support some amount of weight from the back of the tool.

Normally, I'm guessing I use a 50/50 to 60/40 weight distribution on the front handle/back handle when making plunges. I assume this is normal to ensure enough weight is placed on the front handle to hold the fence square. In any case, would be interested to hear how others distribute weight for the front/back and whether you get similar skew with one domino. Also, just to be clear, I am being very careful and verifying that the fence is flush to the reference face no matter what the weight distribution is on the front and rear handle, but the weight distribution seems to change the accuracy.

I also got skew when using the base to reference the mortise, although the amount of skew was a little less

Anyway, pretty disappointed in what should be a well-calibrated tool from the factory.[attachimg=1][attachimg=2][attachimg=3]

 

[Gregor]

Normally, I'm guessing I use a 50/50 to 60/40 weight distribution on the front handle/back handle when making plunges.

After aligning the machine to the workpiece only hold it at the fence handle, pressing it down on the reference surface with slight force in the direction of the cut.

Then just push in the machine from the back to make the plunge, do not hold it up (or whatever direction) on the back handle at all.

The fence handle as holding point will make sure that both reference surfaces stay in perfect contact with the workpiece, not holding it at the back removes the (very possible) error of using the machine as a lever to twist it out of alignment.

PS: for setting the fence - always set and lock the height with the fence in storage position first, then set the angle. Else you might twist the fence a little bit out of horizontal.

 

[drax]

Try a cut on the widest setting with the correct plunge method as suggested. Then align your square as shown and measure the cut dominos height at each end. If there is too much difference then when the pieces are mated the misalignment or skew will be doubled. This will tell you the sliding fence is also skewed or too much play or maybe.

 

[808]

I have tried holding the machine on the workpiece by holding the fence handle only, but I get the same results with the mortise not parallel to the workpiece reference surface/fence. I also made a mortise on the wide setting and measuring from the reference surface to the top of the mortise on the left side and the right side there is a about a 0.12 mm difference. That means when joining opposite pieces, the error is doubled to 0.24mm over the mortise length, so over 9.5" from the domino mortise, the faces are about 3/16" different. Is such a difference normal? I can't believe such a difference would be within spec. I borrowed a friend's domino 500 and I can get flush faces across the workpiece using a single domino.

 

[Gregor]

I have tried holding the machine on the workpiece by holding the fence handle only, but I get the same results with the mortise not parallel to the workpiece reference surface/fence. I also made a mortise on the wide setting and measuring from the reference surface to the top of the mortise on the left side and the right side there is a about a 0.12 mm difference.

Asking since you didn't explicitely mentioned this:
Did you set fence height with the fence being fixed vertically and only after that the fence angle?

Procedure would be: loosen both levers, put fence vertical (storage position), tighten angle lever, set height, tighten height lever, loosen angle lever, set angle, tighten angle lever, reference, make plunge.

Just to make sure that you don't accidently twist the fence when setting it up - while it sounds unlikely it's the only thing (apart from not putting the fence flat onto the workpiece) that could possibly go wrong. Apart from that I'm at a loss at what else might happen, or what you might do wrong handling wise that we here overlook while remote-diagnosing your issue.

I can only suggest to have someone else (like your dealer) do such a cut. In case he manages to reach a correct positioning you should be able to compare techniques to find what you do differently in a face-to-face situation, in case he also fails the tool can be sent in for service directly.

To prepare for the latter: Document your error description (in the style you did here) to tape a printout of it (or this topic, with the measurements in your last post visibly highlighted) onto the domino with a big red 'FESTOOL TECH: READ THIS FIRST' on the visible side, to make sure the one servicing it will see it so he knows where the problem is.

 

[Lbob131]

I've just examined my own  XL 700.
When you plunge  the cutter 20mm  place a metal  spacer between  cutter tip  and the  fence.
Then plunge  the full  depth  and make sure  the  spacer  fits exactly  at that point also.

I'm pretty sure  the  90 degree  stop is adjustable  by loosening the  stop  fastening screw. I think it has an elongated  hole.
Mine is dead accurate  so I won't  be loosening the  screw to  find out. The manual  probably has a section on this adjustment  and how to calibrate it  properly.

 

[Gregor]

I've just examined my own  XL 700.
When you plunge  the cutter 20mm  place a metal  spacer between  cutter tip  and the  fence.
Then plunge  the full  depth  and make sure  the  spacer  fits exactly  at that point also.

I'm pretty sure  the  90 degree  stop is adjustable  by loosening the  stop  fastening screw. I think it has an elongated  hole.
Mine is dead accurate  so I won't  be loosening the  screw to  find out. The manual  probably has a section on this adjustment  and how to calibrate it  properly.

Issue isn't that the fence isn't 90° - looks more like the fence rotation axis and the plane the cutter moves on not being parallel, leading to the mortices not being parallel to the referenced edge.

 

[Lbob131]

Ahh I see now.
The plunge rods  position  in relation to the ossicilating  action  will determine that accuracy. No way of calibrating  that afaik.
The plunge rod accuracy  on the fence  could have an affect  also.

I wonder if a variance in the  thickness  of the domino would throw it that much?

 

[Lbob131]

With my XL 700  placed  flat  on  the machined surface  of  my table saw  and using digital  calipers  I'm getting  1.191"  from the table  to the fence  on one side  and 1.196" on the other.
I then  set  a block  of  walnut  (with the reference surface  machined flat)  on the machined table  and  plunged a cut.
With the digital calipers  I'm getting  0.303"  and  0.301"  measuring  from the inside  surface of  each  side  of the domino hole  to the reference surface  of the walnut block.

I think these tolerances  are pretty accurate  for my machine  and would be well  inside  festools  limit.  And a good way of determining the  parallel  cutting accuracy.

 

[Holmz]

So what are the options for the fellow?
Tape on one side to hold the machine canted over?
Or filing, or grinding the surface to align it with the cutter?

And what are the specs that the machine fell within?

It seems like it should be able to be repaired to zero error by the repair department, if it was possible to have them do that (?).

 

[Lbob131]

I think 808  should try  those measurements  I suggested  and see  how much deviation  there is.
I just tried  joining two pieces  of pine as in  his  image above  and I'm getting no skew.

 

[Holmz]

He already did them and got 3/16 over 9.5"...
This seems somewhat similar to the Pro5 reports where 1/2 dozen people say that their sanders work correctly...
All that says is that there is manufacturing variance, and that it is possible to have a good unit. It doesn't say how to make the bad unit good.

He either need a bigger hammer or clamps, or some method of shimming/grinding/adjustment to get it parallel to the fence.
Personally, and since it is Easter, I would use some scotch tape and see if it can be raised up on the low side.

 

[Lbob131]

I mean  placing  the  machine on a flat surface and checking  how parallel  the  fence is to the base  and then  checking  the skew in the actual  domino  mortise cut relative  to  an accurate reference surface. That cut being made  with  the machine  placed on a flat machined surface.

Or perhaps I've missed  that in 808's postings. Apologies  if that is the case.

I think the first thing to be determined  should be ...  from  what surface is the inaccuracy manifesting itself?
Is it from  the flat base  of the  unit or from  the  fence?

Logic would say the fence though,  assuming  its being held flat.
The 0.12mm should  magnify  into at least  0.6mm across  the width  of  fence. Sliding on a new  fence would let you  know  a little more. But I realise  that's  not possible  unless you knew someone local  willing  to let  you  do a temporary swap  with their  fence  component. 
If its not aligned  then  the  component  was  probably  not machined correctly  during the manufacturing stage.

As 808 correctly states, any inaccuracy  across  the fence  multiplies X 2 when  you do the opposite mortise.

 

[Gregor]

I think the first thing to be determined  should be ...  from  what surface is the inaccuracy manifesting itself?
Is it from  the flat base  of the  unit or from  the  fence?

As far as I got it the reference surface to use is the fence, not the bottom of the machine.

 

[Lbob131]

The fence  or  the base can be the reference  surface  when doing mortises.

 

[Birdhunter]

With the base and the wood resting on a truly flat surface, make a cut. You can see if the mortise is canted relative to the base. If the mortise is canted, the machine itself is suspect.

Using the fence as the reference, make a cut. You can see if the mortise is canted relative to the fence. If the mortise is canted, the fence is suspect.

 

[Gregor]

Just looked again through the manuals, the base of the machine isn't intended as a reference.

Use the fence or the vertical alignment marks (https://service.festoolusa.com/media/pdf/Domino_XL_DF700.pdf page 12 bottom) on the machine.

 

[Lbob131]

The base is used as a reference.
When your doing  mortises  in sheet material  or larger  pieces  that  the fence  cannot extend too  then you have no other option.
And the centre line is  on the base  for the alignment.
The images on page 17 show  the method  I'm referring too.

 

[Holmz]

In that case, then one could also measure whether the fence is parallel with the base.

 

[Gregor]

The base is used as a reference.
When your doing  mortises  in sheet material  or larger  pieces  that  the fence  cannot extent too  then you have no other option.
And the centre line is  on the base  for the alignment.
The images on page 17 show  the method  I'm referring too.

True, I stand corrected. /me scheduling appointment for new glasses