intermod said:
Hello,
I'm using the 118" guide rail for the first time. I'm getting uneven cuts on 3/4" MDF. The way I would describe it is it's bowing outward in the middle and touching on the front and end of the cut. I'm attaching a photo. I've clamped the MDF and the guide rail and the results are the same. I'm a little alarmed this is happening. Any suggestions?
Check to make sure that you have taken all the play of your saw base to the rail. Any slop will let the saw wave a little and can cause uneven cuts.
When making long cuts like this the board being cut has to sit flat. If the support underneath allows the sheet to be bowed up or down it will translate into a bowed cut. This is the culprit most of the time that I have seen.
On long cuts if you do not have the ability to make the cut in one even move, i.e. have to change hands along the way, or are reaching in to the middle of a sheet you can be pushing the saw sideways as well.
If the cuts are thin sometimes there is tension in the wood and it will just spring after cutting, move the rail over a little and make a second cut to take out the bows and see if they line up now.
The rails are aluminum and precision extruded. Temperature can have a slight effect and cause the rails to tweak sometimes as well.
If you still have problems and none of these help, the rails may have a slight bow to them. Have them replaced. If you have access to another long rail even a 2700 try putting them back to back and see if it bows a little between them.
One other thing is to put a stick somewhere in the middle of the sheet behind the rail and clamp it down so the rail cannot flex in laterally. I find this very helpful on cuts 8 to 16 feet long.
Hope these help.
