Before you start cutting your waste board there are some things to check. The X Carve is a great machine once properly setup. The first thing your should always verify is that the surface your machine rests on is FLAT. Notice that I used the word FLAT and not LEVEL. Your machine does not need to be LEVEL but it MUST be FLAT. The X Carve is NOT a rigid machine and will take the basic shape of the table ir rests on. If there is a deviation of 0.045" then it should be relatively easy to see with a good straight edge. A better way to check it is to use a Digital Angle Finder. Below is a link to one. There are cheaper ones available but this one reports a repeatability of 0.1 degrees. Most others are 0.2 degrees.
Digital Angle Finder on Amazon
First, lets verify that your machine is FLAT.
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Place the digital Angle finder on the front edge of your waste board where it is screwed down to the 2020 extrusions.
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Zero out the display so that it reads 0.00 degrees.
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Move the angle finder to the back edge of the waste board where it is screwed down to the 2020 extrusions.
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The display should read 0.00. If it does not then your table is not FLAT and MUST be fixed before you can truly get your machine dialed in.
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If it does read 0.00 then your table and machine are FLAT.
If it is not flat then you could place shims under the low corner(s). However, this is a temporary fix and will eventually lead to the center of your waste board to sag because the extrusions that support your waste board in the center will no longer be in contact with the table it is sitting on. You could remove the waste board and place supporting shims under the extrusions but in time that will probably not be sufficient either. If all you ever carve are V Carve signs then you could probably get away with it but any type of relief carving will begin to show tool marks as your waste board begins to take the shape of the table top.
A better way to fix a table top that is not flat is to add a piece of 3/4 inch laminated plywood. under your machine. Birch that has already been sanded is a good choice. Not Pine that is designed for exterior use, it is often bowed which will only add to your problems. If needed, you can shim the plywood rather than your machine as long as it doesn’t require a lot of shimming.
Next lets check to see if the Gantry is Parallel to the waste board.
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Move the Angle finder back to the front of the waste board and insure that it reads 0.00. If not then zero it out.
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Jog the gantry to the front of the machine
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Place the angle finder on top of the gantry and note what the readout shows. (Based on your original post, I suspect this is where you will find your error) If it does NOT read 0.00 then your gantry is NOT Parallel to your waste board. If it DOES read 0.00 then slowly move the gantry along the entire length of the Y axis. If it continues to read 0.00 throughout the length of Y axis travel then your Gantry is parallel. If it changes from 0.00 as your machine is moved from front to back then your Y axis rail height is not the same on each side meaning that they are NOT parallel. This will have to be fixed to proceed.
Fix out of parallel Y axis rails
(This works best if the belts for the Y axis rails are removed but can be done with then installed.)
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Cut a small block of wood that fits snugly under the front of one of your Y axis rails. Draw an Arrow pointing to the front of your machine and one pointing to the left or right. Also mark two lines, one on either side of the rail when it is under the rail so that you can insure that each rail sits on the same spot on the block
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With the block of wood under one rail at the front, loosen the screws where the Y axis end plate attaches to the bottom extrusions that support your waste board.
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Move the Gantry as far forward as possible to insure the left and right spacing is correct on the rail. The block of wood should be supporting the weight of the rail, then tighten the screws and remove the block of wood. You should use a hammer to gently tap the wood to slide it out. If it slides out too easy then it wasn’t supporting the weight of the gantry and you need to make a thicker block.
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Move the block of wood to the other rail at the front and repeat.
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Next do the same for both Y axis rails at the back of your machine. If you find that one end of either Y axis rail does NOT lower down to the level of the block of wood then you can loosen the screws that attach the top of the Y axis end plates to the rails for a little more adjustability. If that doesn’t work then your block of wood is too thin and you will need to start over with a thicker block. Just remember to keep the wood with the arrows always pointing in the same direction and that the rails are resting on the same spot on the block.
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Once finished repeat the steps for checking that the gantry is parallel.
At this point your X and Y axis should be running true and parallel to the waste board. The error of 0.45" should be either gone of greatly reduced. Next it’s time to consider adding a secondary waste board.
Secondary waste board Pros and Cons.
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Pros
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A secondary waste board should be cut to a size so that when it is surfaced there won’t be any lip around the perimeter which will affect carving on stock that is longer than the machine.
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It is easier to replace when it gets too many cuts in it.
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It allows you to utilize T-Tracks for work holding with small strips of waste board between the tracks.
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Cons
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It has to be screwed down to your original waste board
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It will reduce the travel of your Z axis unless you add aftermarket Y axis end plates that are taller than the stoick versions.
Once you decide on a waste board configuration and have one installed it is time to prep it to insure that it is FLAT and parallel with your X and Y axis. Before you do though, be sure to check that your spindle is perpendicular, also known as trammed. Check Youtube for videos on Tramming. Once trammed, you can safely surface your waste board and your 0.045" error will be resolved.
I hope this helps. If you have any questions let me know.
Charley Thomas
Triquetra CNC