Help With Pattern Please...

[c6craig]

Hi All,

Can someone please double check my thinking here?

I am trying to cut out an insert 9.5 inches long by .600 deep in 3/4" board. The goal here is to be able to insert another 3/4 inch board into the void so it stands at 90 degrees from the base.

When I tried to do a .750 rectangle carve region it is at a taper because of the carving bit so of course the insert board wedges immediately.

I saw in another post where someone mentioned you could just use the 1/8 straight cutting bit to make a final pass to clean up the edges and make them square but I'm not sure I am doing it right.

So I changed my pattern from .750 wide and 9.5 long (.600 deep) down to .500 wide and 9.25 long, then used "tools-outline pattern" and did a cut path .600 deep choosing the 1/8 straight bit.

Will this give me the .750 width I need in a nice square carvout?

Thanks in advance,
Craig

[AskBud]

c6craig,
Since all bits are round, you will always have rounded "inside" corners (the radius of the bit).

There are several things to consider.
1) What bits do you have?
2) If you have a 3/8" Straight bit, you could assign that bit and do the bit cut. You would subtract (.375) from both dimensions of the rectangle. You would, also, use a chisel to square the corners If/as needed. If your other piece of wood will extend past the end cut(s), you may not need to do much extra work on this slot.
3) If you only have the 1/8" Cutting Bit, you will just assign several rectangles nested or mirrored to clear out the area.
4) Your original Raster and Cutting bit shows a carver time of somewhere between 38 and 52 minutes. The 3/8" bit concept times out at about 5 minutes of machine time.
AskBud

[c6craig]

Hi AskBud,

Thank you for your reply.

I do have the full bit set, and would like to try the 2nd method you mention. I had considered it before on another project but was concerned about how the 3/8 straight bit would do making a line without some kind of pilot hole.

So as I understand it, I just make my rectangle .375 wide by 9.125 long and .600 deep, assign the 3/8 straight bit, then use a chisel to square the corners? That should get me my .750 x 9.5 square (with curved corners).

I will try this on a test board tomorrow before I add it to my actual pattern.

Thanks a ton!! I will post results.

Craig

[AskBud]

You may also set a "Max Pass depth", as you assign the bit, if you like.
AskBud

[c6craig]

AskBud,

I will definitely do that, I have set it to .200 so it will make 3 passes. I am sure it could do deeper with ease but I am always jittery on that part since the only bit I have ever broken was a 1/8 cutting bit trying .300 on red oak...$40 lesson :)

Thanks again!

Craig

[Dan-Woodman]

Craig
It will accually make 4 passes as it automaticaly includes a final "cleanup" pass
later Daniel

[c6craig]

Thanks Daniel,

The day went sideways on me today and I wasn't able to get to the garage to give it a try. I have my pattern all loaded up and a board ready for the morning though.

Good to know about the cleanup pass, I would have been scratching my head when it started the 4th pass...

Thanks,
Craig