Tips on tiling z-axis

[relayerbob]

I am trying to level a board longer than my CNC table, but when I do, it's very difficult to avoid having a tiny lip/edge where the tiles meet. Anyone have any tips on how to get the z-axis to line up perfectly after re-aligning the board?

[Adrian]

I always zero to a fixed touch off point on my machine. Not sure if that is an option on your machine but I find that more accurate to using plates, pucks or bits of paper on top of the material.

[relayerbob]

Thanks, I do that, as well as zero off the material. The issue is getting the blank to line up precisely after moving it. I've tried re-zeroing, as well as leaving the zero as is, but I always get about .25mm-ish edge.

[Adrian]

I was confused about why you were re-zeroing it again so that answers that.

If it's changing like that then it would seem that the board is not lying totally flat when you've moved it.

[martin54]

Has the whole of your spoilboard been machined flat or do you have in effect a pocket where you have not machined completely to the edge of your spoilboard? That will cause the 2 parts to not meet correctly
Only other thing I can think of is what Adrian has said about the board not sitting correctly flat either on the first or second part you have machined
Actually it's the same thing really because a lip around the spoilboard means the board will not sit completely flat

[relayerbob]

The blanks are not exactly flat, that is why I'm trying to level/plane them. The spoilboard is fine. I try to level one side of a blank and then the next, but in any case, I can't get it to find the exact zero, hence the question on any tricks someone might have to get around it. It gets really close, but even after going back and forth on sides, there is still usually a very narrow lip. I can sand it out, as long as there's no pattern there. I wish I had a planer that would fit these, as it would be much easier, but the parts I am making are a little too wide (well a couple of inches) for that and a little too long to fit the CNC table, even at a 45 degree angle (which is how I make my parts in the first place). So I'm stuck with tiling and leveling on the CNC.

[adze_cnc]

You say that you are flattening both faces. When flattening the first face what are you using ensure that board doesn't rock or twist when moving to a new tile? If the first face is not flattened "perfectly" there's no way the second face can be either.

If I was to use a cnc machine to flatten both faces of a board I'd create sled for the board to be mounted to for the first face. See this 5 minute video for an example: https://www.youtube.com/watch?v=CiWnr5gsnHo

[relayerbob]

Thanks, that sled idea is good. I was thinking of something along those lines, didn't know what to call it, the video will help. Yes, it is almost impossible to align them perfectly. Some of the balnks have a slight twist, not alot, but about 2 mm over the ful length of the board (~760mm). Enough to be a pain in the butt

[relayerbob]

You say that you are flattening both faces. When flattening the first face what are you using ensure that board doesn't rock or twist when moving to a new tile? If the first face is not flattened "perfectly" there's no way the second face can be either.

If I was to use a cnc machine to flatten both faces of a board I'd create sled for the board to be mounted to for the first face. See this 5 minute video for an example: https://www.youtube.com/watch?v=CiWnr5gsnHo

The sled idea worked great! I found a board that was just the right size to fit my blanks, shimmed and glued like the video did, and while I still had a minor problem, well within the learning curve on this, I got the board right in a total run time of about 8 minutes!! Compared to fighting with it for half an hour plus, and still having to sand out the edge a little. Thanks!!