3m saw guide rail. How straight is straight?

[Rorschach]

Did you test the flex as I suggested?

 

[Distinterior]

When I got my 1st track saw in 2003, I bought a 2 x 1400 rails + joining bars and during my very first long cuts I realised what a pain in the rear it was to keep joining and separating the rails, so I went and bought the 3000mm rail the next day. Mine came in a wooden box and I still store it in that today to keep it safe.

From habit now, if I need to do a long butt joint, I always use the technique I described earlier and then trim the large jointed panel to final size once its glued.....The longest joint I've done using this method is just over 3650mm and I obviously had to join my 1400mm rail to the 3000mm rail to achieve the cut with a router.

I have nothing else that long and "straight" to compare it with but it has always given me good service and seems to be accurate....

 

[sammy.se]

Is your blade sharp? and is it good quality blade?
I had an issue on my mitre saw, where the cut wasn't perfectly straight. Turns out that a very sharp blade, and a high quality blade that doesn't resonate and vibrate will improve the cut.

As well as the cams that grip the track, there are screws that allow you to adjust the blade motor in relation to the base plate (to adjust toe in, and toe out). Have you checked these?

 

[pe2dave]

Minor point, may cause tiny errors. If the 'rubber' grippy strips under the track are dusty, they'll move.
If you press the saw directly down (if needed at all), but not sideways, that will help, especially over
a long cut.
Advised to dust down the gripper strips regularly, and wipe clean every couple hours use.

 

[blackteaonesugar]

From habit now, if I need to do a long butt joint, I always use the technique I described earlier and then trim the large jointed panel to final size once its glued..

Yes it's a good tip that.
I've been woodworking for years and years but always around decent panel saws.

I'm actually relatively new to track saws since going self employed so am always learning more about how to get the best from them.
Cheers

 

[blackteaonesugar]

If you can, just to satisfy my curiosity. Can you clamp the ends and then test the flex in the middle of the rail?

Does this constitute a Rorschach test?

Yes, you can deflect it very slightly. It's very stiff though in that plane so only .5mm or so.

 

[C64]

I tend to leave a very small gap between my two Mafell 1600mm rails when joined up using the connector piece in case the ends aren’t square and butting up could cause a slight deflection. How do you put the rail on to your marks? I lower them onto the marks rather than sliding the rails to them. Which saw do you have? The Mafell MT55 has adjusters to take out any slack between the guide rail and the saw. My KSS40 don’t have adjusters and I can feel the slack between the rail and saw as I am pushing through the cut. But really useful when outside and breaking down sheets before hauling them in.

If the cut is really critical then I cut just outside of the marks and whip out the jack plane for a couple of passes to sneak onto the line. Helps to tidy up any saw marks especially if you had to stop cos the stupid cord or hose got caught up on something.

 

[Rorschach]

Does this constitute a Rorschach test?

Yes, you can deflect it very slightly. It's very stiff though in that plane so only .5mm or so.

lol!

So that deviation is about what you saw in the cut really and also around what I would have expected. I only have a 1400 track and I could only just about get it to flex when I tried, certainly less than 0.5mm.

 

[Alli]

Looking at the photo which shows the supports under your boards. It might be my eyes put it looks like the bottom piece of mdf, isn't flat and has a small belly half way along. I think I can see supports left and right under your work piece, is there anything underneath the middle? If the deflection is downwards rather than front or back, could that cause an error in a straight cut?

 

[RobinBHM]

I would test the straightness of the track as a starting point.

If you lay it on a long flat surface, do a pencil line on the non saw side, then turn the track around to the other side of the line, it will tell you if the track is straight.


I have a 3.2 metre panel saw, so I often do a long rip on that - which creates a perfect straight edge, easily good enough for calibrating machines etc with.

 

[johnny]

if the gap is in the middle of the length and everything checks out ok ......I'd suspect that the bench surface is out of true in the centre ....or is deflecting slightly during the rip.

 

[TRITON]

Here's an interesting vid.

Made from laminate flooring so pretty damn spot on dimensions wise and straight for joining.