after figuring out that my previous problems all came from broken or incorrectly printed plastic parts, I ordered the full set from V1 and rebuilt the whole rig from scratch. While all axis now seem to move absolutely fine, I have a problem leveling the CNC correctly. On the X and Y axis there seem to be +/- 1-2mm inclines or declines that come from either the rails not being perfectly level with the ground board or the board I screwed everything to simply not being completely level. I measured as much as I could, but when drawing the infamous crown with a pencil, the pencil tip usually brakes off somewhere during drawing and in some areas it hardly touches the paper.
Now my question: I have seen some youtube videos where people simply put a milling bit into the mill and mill a big squart at, for discussion sake, 2mm and thus level out the base board by simply cutting an even surface into it. Is this a recommended method? If so, how deep would you cut? Also, is it a problem to this as now the “0” that was previously calculated is potentially 1-2mm deeper in some places than before?
Just asking this before I ruin my otherwise nice base board or have a thinking error in this.
Anytime I rebuild the machine I use a spacer block to set the heights of the outer rails. Put it under the lower rail at the corner and tighten the corner nuts, then move it to the next lower corner and continue to the other two corners. After that the spoil board should be fairly parallel to the X Y rails. You can check this by dropping your end mill to a known height above the board and move it around to see if the height changes. If it’s less than a couple millimeters I wouldn’t worry about it. When I resurface mine I usually cut down about a half millimeter. If it cuts the whole board, cool, if not I drop it another half until it does. 0 is arbitrary, it’s wherever you start, so it doesn’t matter if it’s lower than before.
But the 1-2mm make the it already impossible to get the crown nicely drawn I guess it would not matter that much in simple milling though. Maybe I try that next. The rails are parallel and I have used a pretty good measure to make sure they are aligned as much as possible. With the very tight fit of the metal tubes into the printed stands it is hard to make mm adjustments.
But I guess that is a “not recommended” on milling the base-board on which everything sits?
I rip a board to the same width as the measurement from the bottom of the Y tube to the table then cut it into 4 pieces. Place one under each corner, push down or lift up the rails untill they are all the same.
Yeah, there are two tings that can typically cause this type of issue. the rails are bent or the table surface (or spoil board) isn’t flat. Sambuka’s suggestion will help discover if the rails aren’t straight (and should be used on all six). If they are straight then it’s time to look at surfacing the work surface. discover if it’s the table or the spoil board (or both) by moving the head around and watching for changes in the surface height. If there is issues with the table, surface it. I used a 1" surfacing bit on mine where I needed to take a curve out of the spoil board, that gave me 1/2" past the edge or my work space. Like Barry suggested I did mine at 0.5mm each pass until the whole thing was being touched.
I guess it would not matter that much in simple milling though. Maybe I try that next. The rails are parallel and I have used a pretty good measure to make sure they are aligned as much as possible. With the very tight fit of the metal tubes into the printed stands it is hard to make mm adjustments.