The top of the project is clean the backside is breaking out?

Hello all,

The top of my sign projects are clean but the backside is breaking out? I am relatively new to this and I have had my 1F since November. I am wondering if there is anything I can use on the backside of my signs that I am making to stop the wood from breaking out. I am using a whiteside bit which is amazing and the top side is a very clean cut. I am making these signs out of birch plywood. I thought about using painters tape on the back however someone told me that will wear out the bits much faster. Any advice would be greatly appreciated.

Use a compression bit

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Hello and thanks for the reply! I looked up the bit you recommended and don’t see a difference between that and the one I am using now. I have also tried an up cut version of what I have and it did not work as well as the down cut.

A good video to look at on Youtube he explain the difference between bits

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A compression bit has an initial flute geometry that is Upcut (often the first eighth inch) but then the flutes switch to a down cut. So the first pass (if greater than the upcut section length) will cut through the top of your material with a downcut spiral. That will eliminate the tearout you get using an upcut bit.

The upcut portion of the bit comes into play as you’re making the final pass for the cut out. Since it’s an upcut profile it will pull the fibers of the bottom face of the material up and eliminate tearout on the bottom face.

If you’re not through-cutting and are just cutting down into the material but not through it, you can use a downcut end mill but you have to take it shallower as the flutes won’t eject the chips up & out. Your vacuum/dust collection has to suck them out of the cut so they don’t pack in.

If you’re getting tearout on the top surface, you’re either using a dull bit or an upcut one.

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Yes I am cutting all the way through with a very nice Whiteside downcut bit. I am going to get one of their compression bits and try it out next and that should take care of this. Thsi stuff is so fun!!! Thanks for the reply!

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Depending on the software you use, you may be able to specify a different bit to be used for the final pass (the one that cuts through the bottom). If you can and you have an upcut bit, then you can add that as your final pass bit while you wait for your compression bit to come in. It’s an extra tool change but works to prevent the tear out on the bottom.

Yeah Unfortunately I do not have a 1/8 inch up cut bit. One thing I do have is plenty of patience though ha ha and I thank God for it too! I think one needs plenty of patience with this hobby! Thanks again for the reply this forum is awesome!