TS55R not cutting square with MFT/3 guide rail

[cliffp]

I realise this may well be a problem with my technique but when I cut using the MFT/3 and attached guide rail (I haven't tried without the MFT/3 attached guide rail for comparison) I get a non square cut. The error is what you would expect to get if you set a small negative angle on the saw. When I investigated the way the rail sits in the work piece I could see that the two rubber strips that run along the length of the rail appeared to be lifting up the rail relative to the edge of the rail where the cut is made. It occurred to me that if this allowed the cutting edge part of the rail to droop, there would be a negative cut angle. I am suspecting that this is the problem but wonder how to avoid it? I can't imagine the user is expected to put a spacer under the right hand edge of the rail. I have tried applying some pressure over the left hand side of the rail to squash the rubber flatter but this does not eliminate the problem, probably because I didn't press hard enough (and I wouldn't have thought this was a very good solution anyway). Maybe I shouldn't be putting any pressure on the work piece (with the rail) at all since it is firmly against the top and the fence.

Any suggestions as to where I am going wrong would be much appreciated

 

[Nigel]

There was a recent thread on this :

http://festoolownersgroup.com/festool-tool-problems/ts55r-not-cutting-square/

 

[cliffp]

Nigel, I have read that thread and think that possibly the issue is different. I am thinking that the error comes about because my guide rail is ending up at an angle to the workpiece. If the guide rail is supposed to be at an angle to the workpiece and the calibration of the saw is supposed to take that into account then clearly I need to adjust the calibration of the saw. My question is: am I doing something wrong in the way I use the saw or not?

 

[Stone Message]

When you place the guide rail on the surface of the wood to be cut it is important to ensure that you apply some downward pressure to the guide rail to keep it in contact with the work piece prior to doing up the front and rear clamps. That should ensure that the guide rail will remain flat throughout the cut.

If your stock is narrow (perhaps half of the guide rail is unsupported) then it helps to place some scrap wood of the same thickness as your stock to support the rail. Do this before your clamp up as described above.

If this fails then post a picture and I will look more closely at the problem.

Peter

 

[cliffp]

Thanks Peter, The stock is about 18" long, 2" wide and 3/4" thick. The cut was to shorten the stock (ie the csa of the cut is 2 x 3/4). I imagine your comment about supporting the stock relates to making a cut along the length of  a narrow piece. I was applying downward pressure across the guide rail to try and make it lie flat. I will post a photo later if needed for clarification.

 

[Nigel]

It seems from what you say you are crosscutting a 2 inch wide piece. In this case the thickness doesn't matter much but the width does as you have little support and the guide rail is likely to rock or bend under the weight of the saw unless you have a scrap piece or two the same thickness to place before and after the cut. Or the MFT...which has rail supports fore and aft.

 

[cliffp]

Nigel, I am using the fore and aft supports of the MFT. I think the saw needs adjustment as per the thread you kindly provided a link to.

 

[peter halle]

To add another thought, you might want to take a look at this video - especially the first 2 minutes and see if this situation could be happening to you:

Setting up the MFT/3 part 1 of 3

Peter

 

[cliffp]

Thanks Peter. I had seen that (excellent) video but I think I am doing it right according to that. What I have just noticed is that there is some rotational play in the guide rail supports (particularly the front one) when they are unclamped. By this I mean that when I unclamp the support and raise it to the correct height, there are a range of angles the support can be set at. If this was set in the wrong position with the splinterguard side of the guide rail drooping, it could cause the problem.

 

[Nigel]

Nigel, I am using the fore and aft supports of the MFT. I think the saw needs adjustment as per the thread you kindly provided a link to.

OK that's fine.

I only flicked through the video Peter posted and didn't see it but when you set the height of the supports you really need the wood under the rail to get them square. As you say there is some side to side movement. The guide rail should be perfectly flat to the workpiece and not at an angle. If the rail is flat and square then there is something wrong with the saw. Another thing when you set the rail supports they can move up a bit under the clamping action potentially affecting the flatness.

 

[cliffp]

Nigel, I have placed the wood under the rail when setting the support but since the two rubber strips on the rail lift up that side of the rail, it would be easy perhaps, for the splinterguard side to be allowed to droop if the guide rail supports could rotate to accomodate this. If the supports could only be level, the only way you could make the splinterguard come into contact with the wood, would be to compress the rubber strips. I'll have another play with it tomorrow (bit busy today) and report back.

 

[Nigel]

OK cliffp, if your rail is tilted due to the rubber strips being thicker than the splinter strip then you have a very strange situation indeed .Is this what's happening?

The splinter strip should contact the wood for it to work correctly but the rail should be flat as you lay it on a flat surface not tilted. Perhaps you could take a photo as Peter Stone message suggested?

 

[cliffp]

I established that the problem was nothing to do with the guide rail usage. What I found was that if I set the angle to 0 deg looking at the scale dead on (by which I mean placing my eye at right angles to the "0" rather than having my head above the saw and looking down) I got a non square cut. I then found that by setting the angle to around 0.6-0.7 deg (using the method described above) I got a square cut. It then occurred to me that maybe you are supposed to set the angle looking down at the scale?  If you do this, it is pretty much dead on. Any comments?

 

[peter halle]

Cliff,

I guess i never really thought about that, but i do set me bevel while looking straight down.

Peter

 

[cliffp]

Peter, it will be interesting to see what others do.

I phoned up Festool and they offered to check it out. Very good service (not sure I'll do it yet) - they send a courier to collect and return free of charge. Can't ask for more than that.

Cliff

 

[Michael Kellough]

I established that the problem was nothing to do with the guide rail usage. What I found was that if I set the angle to 0 deg looking at the scale dead on (by which I mean placing my eye at right angles to the "0" rather than having my head above the saw and looking down) I got a non square cut. I then found that by setting the angle to around 0.6-0.7 deg (using the method described above) I got a square cut. It then occurred to me that maybe you are supposed to set the angle looking down at the scale?  If you do this, it is pretty much dead on. Any comments?

Set the angle according to the actual cut.
The scale is just a rough guide but if you establish a consistent way of looking at it you can get good results.

The 0 degree (or 90 degree) position should be set dead-on via the set screws in the mounting blocks so reading the scale cam be a non-issue. Adjust the set screws (if need-be) until the resulting cut is truly square. Then you can adjust the pointer so it looks right from the vantage point you will consistently use to read it.

 

[cliffp]

Michael, thanks for that. I will take your advice and adjust the set screws so that the saw gives a square cut. I can't see how to adjust the pointer - is it the scale that is adjusted?

 

[Michael Kellough]

I just scanned the full thread and see that a large part of the problem (maybe the whole problem) is that the wood you were cutting was narrower than the guide rail. As Nigel said, you need to fully support the guide rail to get reliable results.

When you prepare to adjust the set screws for a square cut first test the existing setting by cutting a piece of ply or MDF at least as wide as the guide rail. It's probably pretty good right now.

Another thing that requires consistency is where and how much pressure you put on the saw as you guide it down the rail. As you know, the sponge rubber on the left side can be compressed much more than the splinter guard. If you compress it for part of the cut the cut edge will have a wave and depending on where you test it may not be square.

On the MFt you need to set the guide rail so it lays evenly on the wood. If the mounts are set too low the guide rail will rise up over the work and as the saw comes along it will deflect inconsistently. If the mounts are too high you can also get poor results.

Also, you can torque the saws plunge mechanism out of square if you apply to much pressure to the handle.

These are few reasons you need to measure the actual resulting cut and adjust to that and use consistent methods.

I try to avoid unevenly compressing the foam by applying steady forward pressure with my right hand to the top of saw blade housing which is right over the un-compressible splinter guard. With my left hand I apply only enough pressure to the saw handle to keep the saw plunged.

If you are cutting very homogenous material like MDF you can easily push the saw and keep it plunged with the same hand. I've found that when cutting natural wood with knots or other areas of varying density that when the cutting slowed down I pushed the handle harder which sometimes changed the angle of the cut so I adopted the two hand approach.

 

[cliffp]

Michael, thanks for your extremely detailed reply. I had already repeated the test with a larger piece of wood though not as large as you recommend. I think I had also got my technique pretty good but I will try incorporating your much more advanced methods and see how I get on.

One thing I did was take a piece of wood I had cut (this was probably around 4" by 2") and matched it up to the fully plunged blade and it matched perfectly. The wood had the 0.7 deg error. Since I was matching it up without the guide rail I concluded the the error must have been in the saw. I did notice a bit of variation in the error along the length of the cut which indicates that some of the problems you specified might have occurred.

I'll try your tips next time I use the saw.

Cliff