clean cut on 3/4" plywood

[Larzag]

Trying to get a clean cut on 3/4 plywood.
1. the edges in the direction of the grain are clean, whereas the cross grain edges leave material.
2. occasionally get splinter pieces ripping away in the cross grain direction only.

Have tried many speeds and feeds while using a 1/4 straight ball nose two flute.
thanks for any inputs.

[steve_g]

Larry...
The issues I'm seeing from your photo will go away with a down cut bit. Is there a reason you're using a ball end bit?

SG

[dlcw]

Trying to get a clean cut on 3/4 plywood.
1. the edges in the direction of the grain are clean, whereas the cross grain edges leave material.
2. occasionally get splinter pieces ripping away in the cross grain direction only.

Have tried many speeds and feeds while using a 1/4 straight ball nose two flute.
thanks for any inputs.

On plywood I always use a compression bit. Up spiral on the bottom, down spiral on the top. Gives a super clean cut top and bottom. Make sure the bit is SHARP.

Don't attempt to resharpen a compression bit as the resharpened bit has less then half a factory sharp bit and resharpening is not cheap to have done.

Another thing about a compression bit is you have to plunge it into the plywood before you start moving the spindle/router so the up spiral on the bottom of the bit is below the veneer on top of the plywood. Otherwise, if you do a standard ramp, the first part of the ramp will have a lot of split and chewed up veneer because the lower up spiral is not down shearing the veneer. It is up shearing the veneer tearing it up and making a mess. Don't ask how I know this.. :eek:

[steve_g]

Larry...
From your photos, I thought you were pocketing, If these are indeed through cuts than as Don has suggested, a compression bit is the appropriate bit. Ball end bits are generally used for 3D carving. If you need suggestions for a source for down cutting or compression bits please ask. These are not bits you will find at a big box store or most woodworker retail establishments.

SG

[dlcw]

Also, if you are going to do ANY milling into plywood, use a down spiral bit otherwise you will tear up the veneer.

[BTP]

On my standard. For veneer plywood I use a compression bit 1/4". 2.9 inches a second feed rate. any faster i do not get the perfect edge I need.
any slower, the bit will go out faster.