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Hi Stefano
I'm having an issue with the wing slot option using a MH42 airfoil. The chord length is 169mm but when I cut it comes out smaller at 145mm. I've checked on both Mach3 and LinuxCNC and both produce the same. I've made everything else OK all the blocks have come out perfect and match the print outs. I exported the cut path to a dxf and loaded into Draftsight and that confirms its only 145mm. Am I doing something wrong or is there a bug. I cut the tail slot and that worked fine but that is only rectangular.
As a test I changed the wingslot to a rectangle of 8mm and when exported to a dxf that comes out at 166mm, I supect 3mm is in the kerf. So it looks like there is an issue using a dat file. I exported the dat file from Profili2 Pro and aslo tried one from http://airfoiltools.com/airfoil/details?airfoil=mh42-il
Hope you can help
Keith
Edited by keith howlette - 5/11/2018, 09:01
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Guru
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I suppose this is a kerf problem. A kerf error of 1mm can give some cm of difference in the length, cause the sharp shape of the airfoil
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Hi Stefano
Yes you were right. I removed the kerf setting and the size came out correct. But if I cut with no kerf the slot will surely come out larger. I tried a 1mm kerf and got 159mm which is still to small. Is there any way around this ?
Thank for your help
Keith
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Yes, you must set the right kerf value...
But, if you have a sharp TE in the wing, then thinner part can never be cut, as the wire has finite diameter.
Adjust that by hand with a blade if required, the hot wire cannot make sharp concave cuts
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3 replies since 4/11/2018, 17:54 486 views
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