Negative angle surface wall

[Santa Fe]

What would be your prefered toolpath to machine a wall surface that has a negative angle and all you have is a 3-axis machine and a Lolipop EM or a specaial grinded EM to reach the end of that negative angled wall.

 

I wonder if anybody has a different approach than mine. In the past I have used toolpaths like surface flowline, wire frame ruled, lofted.

 

I would like to see other opinions and what has worked for other programmers.

 

Appreciate all inputs.

[Mgrenier]

Surface contour and surface flowline are your only options AFAIK

[Santa Fe]

Forget to mension Coons patch toolpath.

 

My issue with the Surface contour is that it is harder to control it or maybe I'm not checking the right settings. It is more propense to crash at plunge and retract.

[harleysport]

i used to use wire frame swept 3d on negative drafts. I now, 99% of the time, use surface finish contour and change colors of entities, lead-in lead-out and leave about .003 on check surfaces.

[Colin Gilchrist]

Sante Fe,

 

For Surface Finish Contour, you need to use Reference Points. These will be the start/end points of the toolpath. These reference point in combination with the "Direction" button, give you lead in/out moves on a surface.

[Santa Fe]

Colin,

 

I did a quick solid 1" tall to try your input above. The solid has three walls, one at -6.5° then a fillet radius of R.28 that transitions to a vertical wall. Regardless of whatever I do in the settings, the backplot shows the toolpath going down verticaly, it does not follow the negative angle wall. What am I doing wrong. I am attaching the sample I did.

 

Do you have a sample file so I can look at what setting you check.

[Colin Gilchrist]

I put a sample file on the Forum FTP site. It is located under 'Training Files' and the file name is SFC_UNDERCUT.MCX-6.

 

I started by creating some surfaces from the solid faces (I find it easier to drive the surfaces and I like being able to turn everything else off)

 

I used a containment boundary to prevent the tool from cutting on the outside of the surfaces. I defined a .500 Lolipop cutter, and turned off the check boxes for gouge checking in the "Gap settings".

 

Check out the settings in "Direction". This option provides Lead In/Out motion on the surface. Sometimes you need to play with the angle settings to get the right motion. (I usually just generate the path and check it visually, then adjust that angle number and regenerate the path until it is correct.

[Santa Fe]

The ftp is asking me for a username and password which I don't have. Colin could you email me the sample file you made.

 

or

 

how can I request a username and password for the ftp site?

[Chris Bloedorn]

See

 

'Important Topics - please read before posting' under FTP instructions...

 

That should give you the instructions you need.

[?Mark]

Adjust your boundary control...

hth

[Guest CNC Apps Guy 1]

You're usually going o need to turn gouge checking off too.