Tablesaw making crowned cuts

[Shannon Vincent]

Hi,I am new to posting on this forum,and want to say thanks in advance to all of you for the great info you pass along,as it has helped me immensely already.
My issue is:I recently purchased the Incra 1000se mitre fence,and finally had time to dial it in today.(T/S is the ts3650)I was checking for square by cutting pieces at 45 deg,(using mdf)and noticed that the pieces were slightly crowned after cutting.What I mean is,the kerf was not flat after cutting(slightly high in the middle of the cut,more material removed at the start and end of the cut,than at the middle.Very minor,maybe .003"-.005",but visable when assembling the pieces.
What is causing this?Dirty or worn blade?Too fast of a feed rate entering the blade?(I tried different feed rates)Blade deflection?Just a downfall of MDF?The pieces were maybe 2" wide by 12" long.I was using the miter gauges stop and holding the wood against the fence,and passing the blade completely.The blade is square with the miter slot.
I have cut mostly mdf with this blade,but it doesn't visually appear to have alot of pitch buildup.Thanks in advance!

[Michael Schwartz]

Welcome to the forum.....

Sounds like it might be a technique problem, Try securing the peice with a clamp. Also, when you are holding the peice, hold it with one hand infront of the other, so as the line of force is a strait line back from the workpeice to the miter gauge.

[John Thompson]

Hi,I am new to posting on this forum,and want to say thanks in advance to all of you for the great info you pass along,as it has helped me immensely already.
My issue is:I recently purchased the Incra 1000se mitre fence,and finally had time to dial it in today.(T/S is the ts3650)I was checking for square by cutting pieces at 45 deg,(using mdf)and noticed that the pieces were slightly crowned after cutting.What I mean is,the kerf was not flat after cutting(slightly high in the middle of the cut,more material removed at the start and end of the cut,than at the middle.Very minor,maybe .003"-.005",but visable when assembling the pieces.
What is causing this?Dirty or worn blade?Too fast of a feed rate entering the blade?(I tried different feed rates)Blade deflection?Just a downfall of MDF?The pieces were maybe 2" wide by 12" long.I was using the miter gauges stop and holding the wood against the fence,and passing the blade completely.The blade is square with the miter slot.
I have cut mostly mdf with this blade,but it doesn't visually appear to have alot of pitch buildup.Thanks in advance!

I use a SCMS to cross-cut and do few miters, but the very first one I ever cut on my Hitachie resulting in the open ends you describe. Perfect cuts at 90 degrees, but open ends at 45 degrees. The machine was checked for pure 45* angle. Perfect!... TK blade deflecting?? No as a regular kerf blade did the same thing. Conclussion.... ???

I sought out 3 trim carpenters locally I know. They all gave me the same answer I needed as they laughed at my dilema. Considered sharp blade.. no excessive run-out.. miter bar tight in the slot with no slop... try this!

45 degrees on hard, abrasive material as MDF or hard-wood causes the blade to tend to shift the stock on entry and exit in a classic term used by southern trim carpenters as "Walking the Fence".

So.. may I suggest we check for a term we can make up on your TS called "Walking the Table". ha.. ha... Solution as I was directed to was:

Slow down your feed as a cross-cut puts no "side directional" force on the stock as an angle cut. And more important.. do whatever it takes to clamp that stock with a "death grip". Add a piece of self adhearing 150 grit sandpaper to the miter fence face for good measure. Solved the problem for me!

Regards and good luck...

Sarge.. john thompson

[Cliff Rohrabacher]

Sounds like your saw isn't tuned correctly.

When the blade and slots (& or rip fence) aren't lined up properly the blade's curvature is imparted to the cut.

Tune your saw.

[jim gossage]

pictures would help with this question. if i understand correctly, if you laid two 1x4" boards flat on the saw and cut them, and then butted the cut ends against each other (still laying flat on the table), the ends would rock back and forth like the simple figure below (with a perspective of looking down on wood and table):

[-----)(-----]

if this is correct, i can only think of two causes.
1. technique, as mentioned earlier.
2. part of the miter gauge is loose or the gauge is loose in the miter slot, and this allows the piece to rock through the cut.

i would not think that a poorly tuned saw could cause it unless #2 was also present; even if blade and miter slot were not parallel, that would only cause a taper cut and not a crown.

[Shannon Vincent]

Sounds like your saw isn't tuned correctly.

When the blade and slots (& or rip fence) aren't lined up properly the blade's curvature is imparted to the cut.

Tune your saw.

Thanks for all the quick replys!Well,the blade is aligned with the miter slot within .001",so there shouldnt be an issue there.The Miter fence also cuts dead on 90's(flat also,no crown).I should have a chance tommorow to mess with it again.I was planning to make a sub-fence with a sandpaper/griptape face anyway,so I will try it again after attaching that.I will also clamp it(JED) to the fence.If that doesnt fix the issue,I'll try some plywood and hardwood, as well as a different blade if there is no change.I will let you know how it goes!Hmmm.....maybe I just need a miter sled....;)

[Shannon Vincent]

Made a little auxiliary fence with some grip tape on the front,and..... problem solved.Beautiful, dead-nuts on,flat 45's! Didnt even have to clamp it.(But I will anyway from now on)Its strange to me,because I was sure that using a stop behind the piece would be enough to keep it from "walking the fence"(Thanks John!)but,I guess not. I now realize that I didnt have that problem previously because using the old crappy miter gauge and fence without a stop, I HAD to clamp the piece to it.Thanks again all!:D

[John Thompson]

Made a little auxiliary fence with some grip tape on the front,and..... problem solved.Beautiful, dead-nuts on,flat 45's! Didnt even have to clamp it.(But I will anyway from now on)Its strange to me,because I was sure that using a stop behind the piece would be enough to keep it from "walking the fence"(Thanks John!)but,I guess not. I now realize that I didnt have that problem previously because using the old crappy miter gauge and fence without a stop, I HAD to clamp the piece to it.Thanks again all!:D

Morning Shannon...

I had a feeling that would fix ya! When I had the problem.. I was rather embarrassingly be-fuddled as I know machinery pretty well. Every common sense approach to trouble-shooting the problem didn't solve the mystery and that included going to another blade on my 12" SCMS.

I fortunately went to the source of those that do miter cuts for their source of daily bread and discovered what they already knew was the problem and simple fix.

And now ya know what "Walking the Fence" is and the head-ache it can create solving the mystery which is no real mystery to a trim man! ;)

BTW.. I just go by Sarge as the only time I hear John is when I'm in trouble with the "First Lady".. ha.. ha.. ha..ha..ha..

Regards...

Sarge.. john thompson

[Shannon Vincent]

BTW.. I just go by Sarge as the only time I hear John is when I'm in trouble with the "First Lady".. ha.. ha.. ha..ha..ha..

Regards...

Sarge.. john thompson[/quote]


Thats better than what my "First Lady" calls me when I'M in trouble!!!:D

[Steve Clardy]

Glad you got that problem resolved :)

[Bill Wyko]

I'm not sure what would cause your problem but I use the Miter 1000SE for segmented cuts and i can make 24 segments to make a ring and be off less than a 10th of a degree.

[Shannon Vincent]

I'm not sure what would cause your problem but I use the Miter 1000SE for segmented cuts and i can make 24 segments to make a ring and be off less than a 10th of a degree.


I saw your recently completed vase in the turners forum.What a magnificent work of art!I suspect we will see that in one our WW mags soon!The time and patience it must have taken...WOW!:eek: I know you have been doing this a while,but you gotta tell me,after all the design time,cutting and assembly time,you had to still feel a little nervous when you chucked that thing up,right??