Pencil box cutting strategy?

[myxpykalix]

I have a special request to make a pencil box for one of my granddaughters and my thought was to make the inside curved like my drawing (forgive my artistic abilities) and wondered what would be the best way to make the toolpaths for something like that? Would i need to use a ballnose bit? I have a tray cutting bit with the bottom edge curved but i've never used it.


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[scottcox]

Jack,

In turbocad v15 pro, I created a 12" x 6" x 3" block, then in 2d, took your arc shape, created a solid, then subtracted that from the block and saved as a .3ds file. Using this 3d model, I can use Cut 3D and do a raster toolpath to get your desired result.


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I've emailed you the cut files. Spruce up the sides and top and post a picture!

[myxpykalix]

Thanks scott that design is pretty much what i had in mind..

[davidp]

Jack

Use a ball nosed bit or even a cove cutter, just watch the depth of cut, your tray cutter will leave steps unless you use a very shallow depth of cut and small step over. You will still end up with a flat on the bottom.

Even with a ball nose bit it will be a fairly significant cutting time.

Good luck
David

[myxpykalix]

david,
It doesn't matter if the bottom is somewhat flat. I just wanted the sides a little curved so that when she goes to grab a pen it doesn't get rolled into the corner. Not that it makes that much of a difference I just thought this might be better than a plain old flat bottom box. I need to make a nice top and am thinking about some kind of design on the sides also.

[ryan_slaback]

jack,
In terms of time savings, it might be better to area clear most of it with a flat bottom and then do the final area clear in the corners with something like a 1/2" radius cove bit.

It will give you the rounded corners without the 6 hour machine time of a ballnose.

[phil_o]

Could you design the project so that the end pieces are glued on? That would simplify the machining process of the pencil tray and allow you to use a large bit that would make the cut fairly quickly.

[myxpykalix]

Scott made me 2 toolpaths the roughing pass was with a 1/2" endmill so it probably won't take long to do with a 1/8th ballnose to clean up the curve on the finishing pass.