Re: [rp-ml] circular interpolation

From: Caleb at Chinook Sailing Products (purchasing@chinooksailing.com)
Date: Thu Mar 15 2007 - 17:43:07 EET


Jeremy,

Thats what I meant - except I didn't mention the G-codes for CC or CCW circular interpolation(G3-G4). You are right about needing the centerpoint & radius values, that's why I suggested he would need CAM to write the code on complicated profiles. I was theorizing that the code he was writing might be using G0 - rapid point to point moves instead of the more fluid G1 linear interpolation. I have seen this happen in home-grown code & it makes for awefully jerky machine motion & funky profiles. It may be that he is using G1- linear interpolation & the motion could be improved by tweaking some of the controller parameters to achieve better move blending. The last idea of spline mode(G1.1) would probably also need to be programmed via CAM & would require, of course a controller that supports this type of code.

sorry if I confused anybody...

-Caleb Walker
-Purchasing/Product Development
-Phone (541) 374-5005
-Chinook Sailing Products
-HiFly America

-
  ----- Original Message -----
  From: Jeremy Pullin
  To: Caleb at Chinook Sailing Products
  Sent: Thursday, March 15, 2007 12:47 AM
  Subject: RE: [rp-ml] circular interpolation

  Slight error there buddy. G0 is rapid interpolation move in standard G code. You need to use G3 or G4 for circular moves but for that you need to know the centre point and radius value of the curves that you are trying to produce.

  Jez.

------------------------------------------------------------------------------
  From: owner-rp-ml@rapid.lpt.fi [mailto:owner-rp-ml@rapid.lpt.fi] On Behalf Of Caleb at Chinook Sailing Products
  Sent: 14 March 2007 16:14
  To: fintan mac cormack; rp-ml@rapid.lpt.fi
  Subject: Re: [rp-ml] circular interpolation

  Fintan, your controller if it supports "standard" G codes may be using G0 point to point moves instead of G1 linear interpolation. Depending on you controller settings this can be relatively smooth motions. To properly program circular interpolation or Arc moves, I would use a "CAM" program especially if you profiles are of any real complexity. You can get stripped down 2 - 3 axis CAM for free many times. I know SurfCAM was offering such a version recently. Alternately, you may investigate the possibility that your controller supports Spline interpolation G1.1 in some code.

  HTH

  -Caleb Walker
  -Purchasing/Product Development
  -Phone (541) 374-5005
  -Chinook Sailing Products
  -HiFly America

  -
    ----- Original Message -----
    From: fintan mac cormack
    To: rp-ml@rapid.lpt.fi
    Sent: Wednesday, March 14, 2007 2:53 AM
    Subject: [rp-ml] circular interpolation

    Dear List this could be a little off topic but i have been working on a home project where i made a simple CNC router that can cut out material and allow me to manually build up a 3D model. I have also written some software that slices a 3D model to generate the 2D layers. The question i have is when i generate the 2D layer it ends up producing a profile made up of a set of points, which the controller then converts into a set of straight line motions. I was wondering if there is a better way of doing this, the controller i have can do circular interpolation but how would you convert these set of points into circular motions. Any help would be greatly appreciated

    regards
    fintan

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