TS 75 and MFT/3 squareness problems - I've tried IT ALL losing my mind now

[realpdm]

Hello! I have had my MFT/3 for several years and had fairly good luck with it. I've recently starting trying to be more precise with my building and noticing some lack of squareness issues when things don't quite fit together perfectly or flush when i've taken great care with the setup. I purchased a Benchdog fence system (mk2) and decided to try to get the thing square and proper.

Short summary: Some how the backside of the track is not matching what the saw is cutting on the blade side.

I've done the '5 cut method' to see how out of wack it is and it is pretty out of wack. Even with simply cutting a panel though I can see with my Woodpecker squares it is not square properly and veering off .001 even after 3-4 inches.

I have the giant 26" Woodpecker square and also their MFT specialized triangle. Both of them show the track and fence are absolutely square to each other. I can't even get a .001 feeler gauge in there. If I make a cut on a panel and place the squared up corner on the back side of the track with the fence it shows gaps.

Some how the backside of the track is not matching what the saw is cutting on the front side.

Here is what I've done so far:

* installed slop stop, absolutely no wiggle in track
* verified  Benchdog fence is straight and not deflecting (supported by 3 bolted in fence dogs and the low profile one behind the under fence extension
* I've also put the factory fence back on both the fence dogs and with normal protractor head
* cleaned and scraped any bumps off the MFT top
* moved the kerf over to fresh area 'just in case'
* supported the track with scrap to make sure there is no wobble to it when cutting towards the top
* adjusted the TS/75 so it is 90 degree cut is exactly 90 degrees
* verified there is no dust on reference surface of fence before each cut
* verified the track is straight on the backside and front side with Veritas 36" steel straight edge

Anyone have any ideas of something I haven't tried? How on earth could the TS/75 cut crooked when used on the rail?

As I type all this out, I note that when I complete a cut in all my testing I stop pushing the saw before the rear of the blade passes by the final edge. Only the front edge of the blade completes the cut.

Thank you for any ideas. I've been stuck for days starting over from scratch many times and repeating all the setups.

 

[tallgrass]

You are saying the backside does not match the front side? I am not sure what you are meaning. How are you interrogating your rail? Out of curiosity try marking lines, using a pencil. Draw using the clean zero clearance strip. Are you able to "draw the geometry" without using the saw? You should be able to "draw" your cuts. measure the lines.

 

[afish]

I think what he is saying is the blade side of the track is not parallel with the left side of the track (hard aluminum side, no rubber strip side)  I'm assuming he is checking for square between the fence and left side of the track.  Then when he makes his cut even though the the WP square says its square it isnt. 

A picture of the set up would help.  It seems many struggle with squareness issues with the MFT.  I had some issues when using dogs and a diy mft table until I switched to a very solid/straight 80/20 fence and a track hinge with no play. Any deflection will have you chasing the problem and pulling your hair out.  Another source of problems is the festool track hinge.  There seems to be problems with it staying perfectly plumb or square when being raised or lowered to adjust for different stock thickness.  so if you are checking/adjusting everything for square with the track on the table then raising the hinge to slide your stock under all bets are off with the festool hinge.   

 

[FestitaMakool]

Have you thoroughly checked the blade?
That it is not unevenly worn, ie; more worn on the teeth on one side. Actually anything that can cause the blade to pull/push in one or the other direction.

 

[Bugsysiegals]

I did not see any mention about adjusting the green tensioner knobs on the saw which eliminate side to side play on the track.

Have you removed the bench dog fence and checked square using some regular bench dogs to validate if there's some issue with this fence or specific holes you’re mounting it in?

Besides this, I agree with drawing a pencils line where you intend to cut and seeing if it moves during the cut. 

You may also try clamping the panel and guiding the saw slowly through the cut in case the blade is not sharp enough, or could be binding, and is pushing the panel forward thus deflecting the fence.

 

[realpdm]

So the saw is tight to the track, I forgot to mention that. I have adjusted it and there is no play whatsoever.

The track itself seems to be parallel on both sides.

Here is what I found after I wondered about not pushing the back of the blade all the way through the cut. I don't think I physically can with this size track I have that came with the MFT/3

I just made a fresh cut on my test panel. What I see is that the fresh cut edge is NOT parallel with the splinter guard. Towards the back of the cut (closest to the reference edge on the fence) it protrudes further out. With my calipers I measured the front edge of wood vs splinterguard to be .001". On the back side near the fence measured .014" Now this is hard to measure with the measurement pin coming out the back of my micrometer but it was visibly different as well.

So I am now wondering if my blade isn't aligned properly. When I plunge the blade on the fresh cut it seems to be flush front and back. I think I would expect the back to have a hair gap.

Here are some pictures of my setup. Thanks for all the suggestions. Really appreciate it.

Overview of setup

Image Cut line not straight

For some reason it wouldn't let me attach images to the post. Links to pictures above.

 

[FestitaMakool]

Try one pass as Bugsysiegals suggests, don’t push hard, go real slow and let the saw eat slowly.
Only feed the saw light slow and steady through the cut.
It could be pushing too hard/fast and/or dull blade. Pushing too hard and a dull blade is the worst combination.

 

[Bugsysiegals]

I would say measuring from the splinter guard is not a reliable way of measuring.  At least for me, mine is not a smooth linear cut and has different areas which the blade must have caught and made it thinner.  For a pure measurement, I would measure from the edge of the rail to the edge of the panel just to be sure.  For this same reason I never align the track to any pencil line based on the strip.

A longer length on the top makes sense if the wood rotates CCW because you're pushing hard, or binding on the cut.  It also makes sense if the Right side of the fence is being pushed backwards from deflection which also results in the panel rotating CCW thus it cuts less off the top.

Do you still have the issue if you use a few bench dogs, clamping the panel, and making sure not to cut slowly so there's no way the panel is deflecting the bench dogs and thus rotating?

 

[Mike Goetzke]

[member=15078]realpdm[/member] I'm thinking measuring distance between the anti-chip and cut is not a good reference. Can you measure from the guide rib? Also, do I have this correct: you have maybe 0.013" drift over maybe a 2' cut? This translates to less than 1/16" over 8' - doesn't seem terrible to me.

As mentioned above I have had issues with squareness of my cuts and it was 100% related to a dull blade.

 

[realpdm]

Thanks folks for this. I did find that if I pushed the saw all the way through as far as I can it was 'more square'. I think maybe the back of the blade is cutting further into the stock than the front is.

I'm going to order a new blade and see where that gets me and work on pushing all the way through the cut in the mean time.

Also some other WW friends suggested I try cutting off more than a sliver of stock, so the blade is fully supported on both sides. I guess it is possible the blade is deflecting a little on such trimming 1/8" cut.

Thanks!

 

[Bugsysiegals]

Perhaps this video will help you confirm if the blade is tracking correctly.  Also, maybe you can take the blade off, check it's not bent on a flat surface (table saw if you have one), re-install, and try once more in case something happened in the way it was mounted with dust behind it.

 

[tallgrass]

Make a shallow cut , lets say 1/8th deep, in a 3/4 sheet. Making it a very low load cut. What does that look like? Pressure applied to the saw can affect the outcome. So make a "scoring cut.

 

[realpdm]

Ok! I ran to Woodcraft and got a new blade. Mine was like 8  years old probably time for a new one anyway. I also checked the blade reference to the splinter guard and found that it was not setup per the recommendations in the supplemental manual. My saw was cutting like /, less in front, more in back. Now the front is cutting flush with the splinter guard and the back is .006" offset as the manual suggests.

..drumroll...

It is.. pretty square now! 

I went from about a .02" gap over 24" to .004" gap now. I can still see a teensy bit of light with my 26" square at the very end but I can only get a .004" feeler gauge in there. I think I'm going to call this good enough.

I really do like the Benchdog fence. Feels very secure supported by screwed in from below dogs and the low profile dog right behind the under the track extension. No flex in that thing at all.

Thank you all for the suggestions!

 

[Bugsysiegals]

Glad you got it worked out!  0.004” over 26” is 0.002” over 13” and WoodPeckers guarantee their squares to within 0.001” over 12”.  If I recall correctly 0.002” is half the thickness of a single sheet of copy paper so this should be very acceptable for wood working.

I’m pretty sure you can get the blades resharpened several times ... if that’s true, I’d send it off and have it ready in the future and not wait 7 years.