Consistent width with parallel guides

[MTbassbone]

I was cutting strips with my parallel guides and noticed the middle of each strip is about 1mm wider than the ends.  What gives? I checked the play adjustment on my ts55 and it seems to be in check.  Kind of confused.

 

[Naildrivingman]

Are you using one rail or two?  If one, do you know that your rail is dead straight?  I've seen a few posts here on FOG about rails not being straight. If you using a two piece rail and you rails are not perfectly mated, you will have a bow in your cut.

 

[semenza]

Perhaps you are tending to push the saw to the side in order to ensure the guide stops stay tight to the piece? This could result in a small deflection in the middle of each strip but not at the ends where the stops will keep that from occurring? Maybe, just a thought.

Seth

 

[MTbassbone]

Just one rail (1400).  I bought the rail used, and am using the parallel guides made by Precision Dogs/Incra.  Not sure how to verify when its true or not.  The only thing I have done to it is replace the splinter guard.

 

[ear3]

Take a piece of plywood a little smaller than the rail. Trim the edge. Then make another cut to make a 3 or 4 in strip. Flip the strip so that the first and second cuts are mating and check to see if there's a gap in the middle.

When doing the cuts just be conscious about minimizing side ward pressure.

 

[Bohdan]

With multiple cuts off the same sheet any errors that are caused by a bent rail will be cancelled on the second cut.
The strip might not be straight but it will be the same width.

This would also apply to pushing the rail over a slight amount. It wouldn't disappear the error due to inconsistencies in sideways pressure but it would be significantly reduced on the second cut.

 

[Gregor]

Just one rail (1400).  I bought the rail used, and am using the parallel guides made by Precision Dogs/Incra.  Not sure how to verify when its true or not.  The only thing I have done to it is replace the splinter guard.

Take a larger sheet good, put the rail on it, draw a pencil line against the splinter guard. Rotate the rail 180° and align on front and back to the line from the other side, draw another. In case they're spot on the rail is straight.
Basically like flipping a square to check for 90°, but without the right angle.

 

[MTbassbone]

Ok, I had a chance this morning to check out the rail.  It appears to be straight, so I tried to cut a new piece with the parallel guides.  I was careful not to push side to side, and it came out much more consistent through the entire length.  I would almost say perfect, but I don't know if that is possible. Good enough for my purposes.

 

[Naildrivingman]

Thanks for sharing your experience. We can all be better together.

 

[Bob D.]

I wonder if you pulled a small diameter string or wire from end-to-end
if would you be able to detect of the rail was not true.

If Radio Shack still existed you could get small diameter wire used for
winding coils from them for cheap. Most likely available from other sources
but they would have been easiest.