Table, Tool, or Technique?

[Bikewreck]

I just started working with my MFT and I'm having a problem.  Square cuts just aren't happening.  Tonight I was cross cutting some  6" x 3/4" oak to length and could not get a square end to save my life.  I had the same problem last week  cross cutting some 3/4" melamine for a cabinet side panel.  I've checked the squareness of the rail to the fence with both a Swanson speed square and a Starette combination square - it's square.  The rail is  supported for its entire length so there's no deflection, and I also checked it for straightness as soon as I took it out of the box (I've been reading here for quite a long time).  I've used 2 different blades on my TS75, with both yielding the same result.  The cut starts out on the mark, but by the end, it can be off by as much as 1/16" on a wide piece.  I'm not real sure what the next step is because I haven't had this problem until I started using the MFT.    Any ideas would be appreciated.

Mike

 

[tbellemare]

Mike:

There are a couple of things that come to mind...

Did you use the device that is designed to secure the end of the fence, the "Fence Clamp"? - Over the length of the fence, there is a potential for deflection. Even though it is a relatively rigid extrusion, when secured in two places, it makes the whole assembly significantly more rigid.

You don't say how big the work piece is or what you are cutting. Considering you are talking about the TS 75, I am going to assume it is a significant piece (that could be a silly assumption) and it makes a difference how to secure it. Also, as with any cut, feed and speed are critical to a clean cut and the work piece working with you and not wanting to walk away.

The previous thought leads to the fact that your work piece might be moving relative to the table and the fence. The guide rail, with its gripping strips on the bottom, tends to hold the work piece securely beneath it so this isn't normally a problem. However, if there is some dust, sawdust, or other detritus between the gripping strips on the bottom of the guide rail and the work piece (or the work piece and the table), the work piece can move. It's best to dust or blow it off between cuts. I tend to keep a $1.99 bench brush around on site. In the shop, I can just give it a squirt of air.

You also have to be sure that your guide rail is flat on the work piece. This means that you have to balance the "elevation" on both sides of the table. It's pretty easy to do but can take 2 coarse adjustments and 2 fine adjustments. It's worth making all four adjustments in my opinion.

If you have set up the MFT and it's hardware that is designed to hold the guide rail in place properly, it isn't likely to move. I have an easy method for set-up and you can find it here.

I use the MFT's, both old and new, with the 55 and 75 plunge cut saws and they cut clean and square. If I stick a 30 lb chunk of beef on the table and jam it against the fence to get square, I better have something to back up the fence other than the pivot. Even then, I have to be certain that I'm not moving things I don't want to move.

Once these tables and their gear (guide rail and angle mechanisms) are set up (which is easy using the holes in the table), they don't go awry easily unless abused. If you set your stops on the side t-tracks, you can return to the previous position easily also.

Tom

 

[Bikewreck]

Tom,

Thanks for the reply and the link.  I did everything that you had mentioned, and that's part of the reason why I'm scratching my head on this one.  The fence was secured with its respective clamp, and the work piece was secured to the table with 2 clamps.  It was pushed tight to the fence, but not tight enough to deflect it.  The rail was supported front to back with both the piece I was cutting and some scrap of the same thickness.  The board was red oak, 6" wide and 3/4" thick, and had been planed on both sides and jointed on one edge.  Those three edges were all square to one another and it wasn't long enough to hang over the edge of the MFT.  I double checked the fence and rail for square before and after the cut and they were fine.

I'm starting to wonder if it's a problem with the saw.  Is it possible for the base to move in relation to the blade over time, with the end result being that the saw won't track correctly?

Thanks again,

Mike

 

[EcoFurniture]

As it is only 6" wide, can't you cut it on the miter saw?

 

[greg mann]

Did you take the play out of the two pads on the bottom of the saw that run on the guiderail? They are usually loose when you first get the saw.

 

[johnsonri]

Are you sure that the piece being cut is has parallel sides that are square to the ends? If the peice being cut hasn't been squared, the cut piece will likely not be square or parallel either.

 

[counterfix]

so I've had this issue on my ts 75 the blade track can be off. you should lock out the blade with fastfix  and measure both sides of the 75 blade to the guide slot  if there's a conflict you can adjust it  by loosening the two screws on the opposite side and its best if you use a flat rule.

Lance

 

[Bikewreck]

As it is only 6" wide, can't you cut it on the miter saw?

Actually, it was slightly more than 6".  Just wide enough so it wouldn't fit in the miter saw.

Did you take the play out of the two pads on the bottom of the saw that run on the guiderail? They are usually loose when you first get the saw.

The gibs on the saw are just loose enough to allow it move freely across the rail.  I've had it for 3 or 4 years I think.

Are you sure that the piece being cut is has parallel sides that are square to the ends? If the peice being cut hasn't been squared, the cut piece will likely not be square or parallel either.

The piece of melamine I cut first was completely square, the oak board went through the planer, then over the jointer on one edge.  The other edge was unfit for use.

so I've had this issue on my ts 75 the blade track can be off. you should lock out the blade with fastfix  and measure both sides of the 75 blade to the guide slot  if there's a conflict you can adjust it  by loosening the two screws on the opposite side and its best if you use a flat rule.

I'm still thinking that there might be a problem with the saw versus the MFT.  I'll have to take a closer look at the relationship between the blade and the guide slot later in the week when I have more time to devote to this.

Thanks to everyone for their feedback.  I appreciate it.

Mike

 

[tbellemare]

Mike:

It is possible that the base of the saw is moving relative to the motor (and therefore the blade). If you know how to tighten/loosen that relationship it should be easy to determine that's the culprit or eliminate it from your analysis. If you don't, give me a call (512-428-9140) or call the service people at Festool (800-554-8741).

You don't want to randomly secure the base of a Festool plunge cut saw. They should always have a prescribed amount of toe-in.

Tom

 

[fshanno]

I don't think it's the saw.  I don't see how it could be.  Even if the blade is wobbling around relative to the guide wouldn't that just yield a bad still square cut if the guide is square to the fence?  You might see valleys of daylight between the cut and the square but the absolute high points on the cut, where the inside of the kerf wobbled to it's farthest point from the guide, would touch the square.  Sort of like using a very accurate crosscut sled on a table saw which had terrible arbor runout.

When I'm cutting panels on my MFT I bump the panel to the fence, get my mark lined up, get everything lined up.  Then I clamp the panel to the fence at the far end away from the guide.  Try that and see if it helps.

 

[romlee]

I have a 75 and had what sounds similar to the problem you're currently experiencing.  However, my cuts were longer (12" was the shortest compared to your 6" cuts) so none of my suggestions may be applicable.

Using a 1900 (connected to a 1400 attached to the end of the 1900 for ply sheets), I had been ripping and crosscutting rough stock and ply for a cabinet when I noticed the cuts were off by at least 1/16".  I double checked everything and could not get a square cut.  The cuts would start right at the cut mark then it seemed to wander about a foot from the end of the cut.  I checked the rail to see if it was square to the marked line and it seemed to be fine. 

Then I checked the width of the 1900 rail along the its length from its back to the edge of the rubber strip and found that it was the same width along the length.  But when I checked the 1400 the width was fine right up to the point where the cut seemed to wander (about a foot from the end of the rail).  From that point to the end of the cut the rubber strip gradually narrowed about 1/16".  When making cuts I always line the rubber up to the cut mark so it follows that if the rubber strip is inconsistent in width, the cut will deviate even though visually it's lined up with the cut mark.  Bottom line was that a cut using the 1900 plus the 1400 was true right up the point on the 1400 where the rubber narrowed.  My cuts on narrower pieces had been off by 1/16" too and this was because I used the 1400 for those cuts.

I repositioned the rubber strips on both rails and ran the saw through (I used my blue foam underneath) to make fresh edges on both the 1900 and 1400 .  I then made test cuts (with each rail separately and then connected) in ply and solid wood to check the results.  The cuts were now nice and square.  I've finished two cabinet jobs since "the fix" and haven't had any problems with square cuts. 

I had been using the rails quite a bit and I think the rubber may have moved somehow between jobs or I had applied a little much lateral pressure while making cuts for a previous job.  I am now in the habit of checking the rubber strip to make sure the width of the rail is consistent along the length.

I don't know if this helps or not.  Like I said, my cuts were longer than yours.  But if you've checked and tried everything else it might not hurt to check your rubber strip even if it looks OK (and especially if you're in the habit of lining up the rubber to the mark), reposition the rubber and make a fresh edge.

Rom