Question about cutting plywood

[Rob Frenette]

Hi All

We have not cut very much plywood in the past but have a fair size job to cut using 3/4 inch birch ply by Norboard. We are using a 3/8 comp cutter for our outline cuts and was wondering if anyone else is having a similar problem we are having. The problem is when cutting this plywood the edge is not totally smooth so when we go to edgeband with 1/4 inch solid edging we get get a gap between the panel and the edging. I have tried cutting a sample on the saw and do not get the gap. Is there something that I am missing maybe faster cutting speed? different type of cutter? Or is this the norm when cutting ply with a router bit. Any help would be greatly appreciated.

Our cutting speed is 700 inches at 18,000 RPM

[Ryan Hochgesang]

Rob,

It sounds to me like your getting cutter deflection because your feeding cutter to fast. You can either slow cutting speed to approx. 500 IPM or increase Spindle speed closer to 20,000 RPM. Eitherway, 700 IPM seems a bit fast for this diameter cutter and depth of cut.

[Joe Soto]

Rob, I cut mostly 5/8 maple ply with a poplar core using a 2 flute 3/8 comp bit, 500 IPM but @ 120% so 600 and @ 18500 RPM. My plywood likes a conventional cut also.
Joe

[Jody Wilmes]

My plywood likes a conventional cut also.
Joe

This is key to prevent "fuzzing" of the plywood...which would cause edgebanding/applied edge issues. I've been running 3/4" thick walnut plywood at 600IPM @ 18000 RPM's with FeedRate over-ride turned all the way up to 120%.
This means 600ipm x 120% = 720ipm
Hope this helps.

[Michael S Murray]

Jody,
Is Ken pushing that hard on that office furniture that you have to run at 120%????

[David Hall]

Hi Rob,
Norboard's aspen/birch core is more problematic than poplar core material (Columbia). We get good results with a new tool (one that has never touched PC or MDF) at 500IPM and 18000 RPM, conventional cut, but shorter tool life than normal.

Regards,
Dave

[Jody Wilmes]

Jody,
Is Ken pushing that hard on that office furniture that you have to run at 120%????

Nah. We're getting towards the end of it though.

[Rob Frenette]

Hi Guys

Thanks for all your help. We slowed down the cutter speed and changed to a new bit and that worked for a few sheets and then got worse as the bit got duller. I think David got it right on, the birch layers in the core are sitting proud of the aspen layers which is causing the 1/4 inch edging to not go on tight. To rectify the problem we had to resort to the saw and rip a few thou off This problem would probably not show with regular edge tape but with solid edging it is definitely a problem. There was a thread at one time asking about an option when double cutting to over size the cut on the first pass and then cut to finished size on the second pass. I think this might achieve a couple of things. First it would probably eliminate the problem the small lip cause by deflection in the bit, and second it would probably give us a better quality cut. On one other note I had a conversation with a tooling manufacturer one time and he asked if on the second pass does the cutter take any material off ? I said no it only cuts through the skin left from the first pass. His thought was that we would probably get longer tool life if on the second pass the cutter actually cut the panel to the finished size. His reasoning, if the main body of the cutter is rubbing on the material as it is cutting through the skin that could shorten the life of the bit. Just some food for thought.