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between 'Tool dia', 'width', and 'pass overlap'

Bino Oetomo
Sat, 30 May 2015 02:24:10 GMT

Dear All, C/Q JP .. First I have to appreciate this really good software. Kindly please tell me what/how is the relation between that 3 parameter when generating CNC from geometry. Let's say my gerber is generated from eagle. The trace width is 0.4 mm, I want a Gap between trace and groundplane at +/- 0.4 mm The mill depth is 0.015 , since my bit is V bit (0.3 mm tip width, 30 deg angle) ... the final tool diameter is 0.39607996794969 mm. My Setting is (Units = mm): Cut Z = 0.015 Travel Z = 2 Feed Rate = 30 Width = 1 Pass Overlap = 0.15 When I generate the CNC , and export the G-Code ... run it on my router .. it eats the trace more than I want. Note : I also use Autoleveller (from autoleveller.co.uk ) before send gecode to my router. Kindly please give me your enlightenment for best calculation (or guess) methode. Sincerely -bino-

jpcaram
Fri, 05 Jun 2015 18:53:51 GMT

Those settings look okay to me. If you use width = 1, the pass overlap if ignored, because there is only one pass. Tool dia is the effective diameter, which depends on your tool. Assuming you did the calculation right, and the 30 degree tool with a flat tip width of 0.3mm at a depth of 0.015mm is 0.4mm wide, then everything is correct. If the CNC job looks okay in FlatCAM and is cut different in your machine, then you probably calculated the width wrong. I'm a little surprised by the 0.3mm V-bit. They are usually much narrower at the tip. Also, a depth of 0.015 seems very shallow. You mush have a very accurate machine. But I'm just guessing. Is the gap being cut 0.4 mm wide? Cheers, JP

gustavogmb
Sun, 04 Mar 2018 18:32:48 GMT

I have the same problem with some traces, it eats some traces more than I want. How can I calculate all those?

mikypolice
Wed, 09 Jan 2019 19:40:46 GMT

If you assume that the width is correct so you can try to reduce the feed rate (in the case SOME trace are faulty). If all trace are faulty than your width (calculated or declared from the productor) aren't reliable.