Will this work? Flattening an epoxy table larger than my machine - 387

here we go with another fun cnc experiment can my 10 foot long cnc flatten a 12 foot long epoxy tabletop i do think that it can so let's begin my go-to bit for large surface flattening is this two and a half inch wide astra coated replaceable insert bit from bits and bits a non-affiliate link is in the description below each carbide insert has four cutting edges so i'll start by rotating the insert for a fresh cutting edge here's a quick tip for cnc work make a tray of some kind for swapping bits my cnc has an open front rail so i made the tray so that it straddles the rail this gives me a safe surface for bits to drop onto in the event that they fall out from the collet when loosening the collet nut and it's also where i keep the wrench's 4-bit changes here's another quick tip keep compressed air nearby to blow out the collet with every bit change this keeps the collet functioning as it should by eliminating dust packing between the grooves this will be the first task of the day so a quick spindle warm-up procedure is necessary for added support i'm cutting this edge jointed board into two so that i can carefully clamp it to the front and back rails where i do not have any horizontal table support a long level on top of the spoil board lets me know that i'm clamping it at the correct height finally the table arrives along with two strange dudes and the shenanigans can begin a rolling cart like this is super handy for moving tables around and there you go a 12 foot table on a 10 foot cnc we're primarily relying on gravity to prevent this from moving but i did take the time to add a couple of stop blocks to the sides of the spoil board here you can see the back edge of the table top approximately in line with the highest y value of the machine travel and here you can see the front edge of the table about two feet forward from the y zero location we added extra support in front with a cart and a few blocks the first file to run is a 49 inch by 124 inch rectangular pocketing tool path now on large slabs like this it's typically best to use a raster tool path so the bit is kind of parallel if at all possible with the grain direction however when epoxy is used i like to use an offset cutting direction this spirals out from the center which can create some sanding issues when the bit runs perpendicular to the grain but it also ensures that the bit will be cutting in a conventional direction at all times instead of alternating between climb and conventional directions with each pass if someone knows of a way to force a rapid movement between conventional passes with the raster setting please let me know the slab was pretty flat after the epoxy pour so only one pass was needed for the first file and that actually rarely happens so that was nice now the table can be pushed back so the front can be cut the reason why we're able to flatten this table that is larger than the machine capability is because it is secured to melamine with a constant thickness so long as the melamine is referencing off of the spoil board the resulting top face of the table should be flat with the z zero and cut depth unchanged the front section is flattened to match the rest of it and also i never got a good shot of the entire top surface so this is the best view to see how the table will look cedar with black epoxy flowing between the sap wood this should look pretty darn nice when completed now the really fun part we got the top surface nice and flat so we need to flip it over and repeat the process so i stood on the machine to support it the the table not the machine while it was vertical so that they could focus on doing the heavy lifting part with the top flipped the melamine backing can be removed now the freshly flattened face is referencing off of the spoil board and we can plane to final thickness in this case the final thickness is as thick as we can keep it after resetting the z zero height the same process is repeated on the back side starting with the full size tool path on this bottom side we had to cut a little deeper to get the bottom side completely flat and of course pushing it forward allows us to finish the rest of the area with that the job is done so yes you absolutely can flatten a 12-foot table on a 10-foot cnc machine so long as there's a little asterisk there so long as you have a flat reference face to start with in this case it's the melamine if the glue up was brought to me without the melamine underneath and the bottom was you know rough sawn lumber i guess there would be no way to ensure consistent thickness when repositioning the material on the spoil board yes you get a flat surface but once you reposition it if you don't have another flat surface to reference off of to get the first flat surface there's no way to maintain that thickness or that height all the way through the piece if you are in the north mississippi area and are interested in commissioning a piece be sure to hit up my friends at back 40 customs tell them that i sent you not because i make anything in their sales i absolutely do not but because as a small business i know it is valuable to know where your customers are coming from that's it for this video have a great day and i'll talk to you in the next one do