Routing Greenply

[jhowarth]

Hi guys,

I'm relatively new to using the shopbot and would really appreciate some feedback on two of the problems I am having.

I am trying to route a number of squares with pockets in them for a table I am building. I am having a problem with the material I am using. I am using 3/4Inch thick maple greenply http://greenply.net/ .

One of the internal layers of the ply seems to be getting ripped at the edges by my routing bit. Also, I have suffered a little bit of delamination (the top half of a square coming off) while routing. Photo of the edge attached.

I am using a 1/4 inch mortise compression bit from Centurion Tools (after doing some research on this forum).

Shopbot settings
- 16000rpm
- 4ips
- 0.25inch plunge depth.

Any ideas on how to overcome this problem?
- Is it material related?
- Do I need to change my tool path?
- Am I being to aggressive with my tool path?

Cheers
James

[zeykr]

Not familiar with greenply, but at first glance I think you're spinning the bit too fast - I'd try 10K or 12K. Are you cutting .25 per pass or .25 total? The upcut portion of the mort-comp bit is probably .25 inch so you are lifting your material by only going .25 deep, I'd increase it to .375 to get the downcut into play.

Which direction are you cutting, climb or conventional? Is the cut between the squares wider than your bit (i.e does it make one pass each way or just one pass)?

[bleeth]

As far as the lifting of the top veneer edges Ken is right on the mark. You need to deepen your first pass so you are cutting below the upcut part of the bit. For the fuzzies in the inner layer you are dealing with the wood they are using for the inner core and the grain direction there. Play with the speed of your router. Try slowing down first. If that doesn't work you may discover, contrary to normal expectations, that you can get a cleaner cut by going a little faster! This will result in your bit wearing faster as it will be getting hotter then under an ideal chip load but may cut your part cleaner.
If you are using a PRS standard I would slow my speed down to 3 to 3.5.
For an Alpha you are being conservative which is wise until you are more experienced with your machine.

[jhowarth]

All really good questions.

1) I am cutting 0.25 inch per pass. 0.75 inches total.

2) I am using a climb cut the whole way through.

3) The bit width is the same as the cut between the squares.

4) The exact bit I have is http://centuriontools.com/router_bits_toolcase/centurion_tools_showcase.html?page=full&__max=6&--eqskudatarq=14CR21.02.5FEM200&id1=374&id2=6&id3=734&

5) Dave, I believe I'm using an alpha. You mention that I'm being a little conservative. How fast do you think I can go? How about if I were to switch to maple appleply?

Cheers
James

[bleeth]

1) I am cutting 0.25 inch per pass. 0.75 inches total.
As we already said-Too shallow for your mortise. you have .200 upcut on that bit so if your z adjustment is off just a bit or your top veneer layer is in that range then you will get lift at the edges.

2) I am using a climb cut the whole way through.
Conventional leaves a cleaner edge.

3) The bit width is the same as the cut between the squares.
I have never cut this way. I leave a web between pieces. That way I am cutting each part the way I want instead of having the bit cut conventional on 1 part and climb on the other.

Your bit is a good one.

If it is an Alpha-and you should know-you can cut faster but regardless of speed set you will be slowed down in smaller pieces due to ramping constraints. Information about this is in your manual and lots of it here on the forum as well.

Appleply does have very nice tight inner layers (wish I could get it here in South Florida) but you should also be able to cut the ply you have well.

[jhowarth]

Thanks for the information guys.

I'll implement some changes tonight and see how I go.

Much appreciated.

Cheers
James

[jhowarth]

Hi guys,

I had another couple of sessions on the shopbot over the weekend.

Your advice really helped.

I increased my path depth to 0.375" and had good results + there was the obvious benefit of a speedup.

I separated my design where I could, so that I wasn't doing a conventional cut on one piece while doing a climb on the other.

Finally, on a couple of the large pieces I did a climb cut first, then went back over with a conventional cut. This really gave a nice finish.

I'm done with GreenPly. I'm sick of having it delaminate on the shopbot. I think I will have to try maple appleply next time.

Thanks again for all your help.

Much appreciated.

Cheers
james