I have laminated 3 different coloured woods and need to carve down to each others height or depth.The 3 woods carve great so no problems there.It is a Bison and bear with the base material being silver beech.Would I get better results from setting the zeros top or bottom?
Top is best unless thereâs a reason to use bottom â the usual reasons for bottom are:
- concern about cutting into MDF
- joinery where the bottom will be the outside of the box
Either place would work. You must measure your material very carefully. I use bottom mostly if I am going to cut through. That method saves my spoilboard from being cut up. I use top for vcarving which will not go through the material. As I said earlier measuring your material is very important if you want to cut the exact distance for your project. Just pick a depth that will barely go through to the colored material below and just a little bit to get a good color and not leave the layer above with splinters along the edges.
Zero top or bottom really depends on what surface you âcare aboutâ the most.
For example, when doing a VCarve, you want to very accurately know where the top surface is, since a VCarve is so sensitive to even small changes in cutting depth. So, zero to top-of-stock, and then getting the material thickness super accurate just isnât a real concern.
On the other hand, when cutting all the way through the stock, you usually donât want to mark-up your spoilboard very much, so measuring from bottom-of-stock makes sense. If your material thickness isnât exactly right, then that just means that the first layer of cutting is a bit deeper or shallower, no big deal.
Or, say you are surfacing several pieces down to the same thickness, but they start at different thicknesses. Then you donât really care about how much your are removing, you care about how much is remaining, i.e. a measurement from the bottom-of-stock. Then you could Z Zero from the bottom of stock, and say that the stock is as thick as your thickest piece. Then you can run the same surfacing paths on all the pieces, and you donât have to re-zero between pieces - for the thinner pieces, there may be some air-cutting at the start, but thatâs harmless.
You may find in one project that you really need to do both - in that case, I would use two different design files, one for the features that are best with top-of-stock, and the other for bottom-of-stock. Right now CC doesnât allow having toolpaths with different Z Zeros in a file, itâs a setting global to the whole file.
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Iâm baffled by this too right now. It seems that this matters in other software, but does it matter in CC or CC Pro. Since all cuts are calculated from the top of the stock, setting your reference to the bottom or the spoiler board doesnât actually do anything, does it? Itâs good practice maybe, or something to think about, but does it do anything?
It changes whether a surface height is a reference height (i.e., specifically measured on the machine), or a calculated height.
When you use bottom-of-stock, then the top surface is calculated as being âstock thicknessâ higher, regardless of where it is in reality.
Surfaces with a calculated height are as accurate at the stock thickness you entered in the Job Setup. For some bits, even extremely small inaccuracies can make a large visual difference, for example wide V Bits.
Reference surfaces are always accurate, no matter how (in)accurate your Stock thickness is. You could tell CC that your stock is a meter thick, and a VCarve will still be correct when using top-of-stock as your Z Zero.
This means that a lot of the time, you can be very sloppy with the stock thickness, so long as you have chosen an appropriate reference surface.
âOh, the stock is about 20mm, good enoughâ - VCarve, top-of-stock.