Hi, question to everybody who have MDF top table on CNC workbee, lead etc. machines. OpenBuilds Control software. Did you use a wizard for flattening table? Or, did you flattening table on youre CNC machines before starts using IT? I have CNC with MDF table. X and Y moves correctly (measure with calipper) 100mm. But when I try milling PCB with 0.5mm traces..it is tragic.. some traces are milling below 0.5mm - I don't knows why... I'm using bit V 0.2mm 20 degrees.. FlatCAM.
How are you ensuring that your pcb is perfectly flat to the spoilboard? Personally I wouldn't use screws to hold the pcb down, I'd use masking tape and superglue to make sure it was held down across the whole surface and couldn't flex. You also need to bear in mind that pcb materials are often not perfectly even in thickness. Alex.
Yeah I second Alex's observation 1) Surface the spoilboard first 2) Then hold the PCB using the CA glue and Blue Tape method: docs:tips:ca-glue [OpenBuilds Documentation]
I'm using double sided tape like this one from AliExpress. I haven't use tabs in ages because of it. I haven't tried it on metal cutting but on wood and PCB I did try and it works like a charm. Actually, almost too good, it's almost a struggle to get it off the table.
that is why the masking tape and CA glue method was invented, it holds just as well but is easy to remove and leaves no residue, and is generally cheaper too.
to cut PCB's you really need to probe the surface of the PCB and then let the software correct for the warp. They are never flat. The reason the warp makes a big difference is that that tool is tapered, this means the deeper it cuts the WIDER it cuts, and then the trace is too narrow and may even be broken. Sadly, OBControl cannot do the probing and correction for you, but bCNC can.
Ok, I try today surfacing wizard in OpenBuilds Control. Bit 30mm - on pictures. Why I have this lines on table after surfacing? Table is not smooth when I touch it with fingers...
That indicates your machine is not trammed. Seehttps://openbuilds.com/threads/tramming-a-generic-guideline.19481/ to learn more If the machine is not tram, the bit is not perfectly square to the plane of travel - and thus one side digs in deeper. Tramming the machine will resolve that
Possibly. Consider the High-Z mod. That could roll the beam itself due to the large amount of weight, offset quite forward
Ok, flattening wizard. 95% (on 30% that's same effect) step over on attached image. 200x200mm. Z -1mm. Always when changing direction on X Axis stairs are formed. On middle no stairs, surface is flat. Any ideas what to check? Yesterday I corrected X Axis.
If the bit digs in deeper on one side or the other - its not perfectly square to the machines XY motion plane
I found what's wrong! My stupid brain.... not enough cutter inserted to spindle. I pushed deeper and there is a perfectly flat surface! Thank's a lot!
Ok, but...how to flatten top table when spindle X/Y Axis cannot Reach full size of table? For eg. Top table size is 700x600mm but max travel is 650x560... How to do this?
One of two things that I do. 1 - Think of the uncut sides as a square way to line up my stock. 2 - Only make the spoilboard as wide as the cutting area. That's how mine is now. I have t tracks, for clamps, on either side where the bit cant reach.
