# How Tight Is Home?

I’m beginning to appreciate those who have said that spoilboards - especially for beginners such as me - are surprisingly tough. I’m laying out toolpaths using Vcarve Pro.

My spoilboard is in two pieces - a more or less permanent base with threaded inserts and t-tracks, and sacrificial slats on top with corresponding bolt and dog holes. I plan to put down an oversized panel of mdf to machine the base. The first toolpath will mark out permanent screw-down positions within the field of this panel. After screwing down at those locations I will finish the other milling cuts and lastly trim the base panel to final size.

If I lay out a square toolpath 32.25 x 32.25 inches, chuck in a 1/4 end mill, and tell the cutter to cut ON the toolpath, I theoretically end up with a 32.125 x 32.125 panel. But that supposes I can get away with setting my x,y for the job at HOME. Can I get away with this, or do you think I run a good chance of hitting the soft limits?

You’re kind of crossing terms there. Homing has nothing to do with the cut. Homing keeps it from bashing into the stops at full speed in any direction.

The zero position will determine within the “homed space” available to cut. In theory, if you have a 6 inch diameter cutting bit, and you zero to the left front as far as it will go, you would cut 3 inches bigger than the 32.125 by 32.125. The zeroed position is to the center of the cutter.

Oh, and if you have a 6 inch cutter…stand way back!!!

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I guess I worded that awkwardly - what I meant was if I send the machine to home (as in at the left front stall position), and set that position as 0,0 for the ensuing cut, I’m I likely to have trouble

John - I’ll have a new video out tomorrow morning on the accuracy of homing. I hope you watch the whole video, but in summary, homing is repeatable to ~1mil. So, in reference to your question, you will likely get 32.124 to 32.126 +/- 0.002 – based on my tests. YMMV.

-Tom

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Thanks Tom, and of course I’ll watch the whole video

You can absolutely start your cut at absolute 0,0 (home) without worry. Did that for surfacing my spoilboard.

Home is as accurate you can get on a machine less than \$20K. I have never had an issue with repeatability using the same Home setting.

-Alex

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