outline breaks mortise shoulder for blind tenon

[Gerry A Brown]

Hi everyone,

This has been a infrequent problem for us for some time but lately it seems it is happening on almost all top and deck pieces. When we do the outline cut on our tops or decks the shoulder on the mortise breaks off.

We have a CS45 and are cutting our outline in conventional direction with a .5" compression cutter at 16,000 rpm and 600 ipm. This happens on drawer boxes and cabinets.

If anyone has found a method to eliminate or minimize this problem I would appreciate your input.

TIA,
Gerry

[Forrest Chapman]

It would help tremendously if the dado stopped short of the back edge.

Forrest

[Gerry A Brown]

Forest,
On the gables they stop short and we have no problems with those of course. I could shorten the tenon but then you see daylight through the corners.
We have just changed melamine suppliers so maybe that is what is causing the increased problems.

Thanks,
Gerry

[Stuart Douglas]

...We have just changed melamine suppliers so maybe that is what is causing the increased problems...Gerry

This. We have found a tremendous variability in the quality among manufacturers of PB and TFLPB (mel). The more expensive materials generally have a finer, more dense core matrix or use more glue in the board to keep things together. All this is moot if you are doing production work, because cost is king when you are ordering units of board a half dozen at a time. revisit your feeds and speeds for these cuts and maybe reorder the cutting operations if you can't stomach the higher cost of quality materials.

[Jeremy Schiffer]

Another option is to make the tenon thinner, if your construction and tooling will allow.

[Gerry A Brown]

I have shortened the tenon so it closes the mortise on the ends . We will see how this works out. Making the tenon thinner is something I had not considered.

Thanks,
Gerry

[Brad McIntosh]

Since it started happening more frequently, I too would think "core material adhesion" (less glue/resins holding board together).

You mentioned 16000 RPM at 600 ipm. Perhaps try increasing the RPM to 18000. Smaller bites might result in lower forces on the material.

[Gerry A Brown]

Brad,

I will try that also.

Thanks,
Gerry