4th Axis - Internal Contour - Wrap - Not Reaching Corners

[redmond.limited]

Hello,

Apologies for all the posts on here but I am still very new to 4 axis machining in Fusion, without having the actual machine extension for it.

I am trying to machine the pocket in the attached Fusion file, using 2D operations with wrap toolpath but, as you can see from the picture below, the tool can't get all the way to the edge of the contour.

If I've understood correctly, this is because the centre of the tool is always perpendicular to the wrap cylinder, which means the edge of the tool isn't; which means the tool can't get right into the corners to "properly" machine the walls, if you see what I mean.

Is there any way around this?  I haven't got any of the machine extensions.  I've just got the "wrap toolpath" option in the 2D operations.

As ever, I would be very grateful for any advice or help that anyone can offer.

Thank you,

Clem.

[engineguy]

@redmond.limited 

Have you tried using the "Offset" function for the wrap ? Might work for you, see image below.

[redmond.limited]

Yes, I did try that but I got the result, below:

The tool gets into the edge of the pocket at the top but then goes too far at the bottom.

I suspect that what I want to do isn't possible without the machining extensions for full 4 axis machining but I live in hope that somebody may be able to tell me how to do it.

[engineguy]

@redmond.limited 

Have you tried making the angle of the walls of your pocket go to the center of rotation as that is where the tool is pointing to, agreed, the wrap facility is maybe not the best but if the angle of the walls is not critical and you can get them to match the line of the tool it may help ??

[a.laasW8M6T]

Hi,

Even with the extensions and rotary contour you cannot properly machine this geometry

the below picture is with rotary contour using a 6mm R1 bullnose cutter, it "generates" the walls but still doesnt get into the bottom fillets:

You could do as @engineguy suggests and modify your geometry so it is a true wrapped feature(bear in mind the endmill must match the corner rad of the walls for this to work properly)

Alternatively you can machine this feature using 3 axis non-extension toolpaths(not using any 4 axis motion) with a 2mm ball nose.

attached example uses a combination of Contour, Morph and Pencil to achieve the result(note all feeds/speeds are not correct as i don't know what material you are using)

[redmond.limited]

Thank you very much for your replies and advice, Engineguy and A.LaasW8M6T, and for taking the time to look at this.

Please correct me, if I have got this wrong, but I think the geometry is a true wrapped feature.  I created it by revolving a rectangle about the centre of the circular faces, by 40 degrees, to get that pocket, and then radiused the corners.

I think the problem is that the centre of the tool follows the radius of the wrap cylinder so, to really get into the corner, the tool would have to move so that that centre of the tool is right in that corner, and this would mean that the edge of the tool has gone past the edge into the surrounding material, which I don't want.

I shall have a look at your Fusion file, A.LassW8M6T, and try this.  Thank you, very much, for this.  It is very kind of you.

Luckily, it's only a test piece, so I can just accept what I get, with the toolpaths that are available to me.  I'm just trying to get used to using a 4th axis and how to adjust feed rates, etc. when doing so.  It also helps me to know what I can and cannot do, if I'm designing something to be machined on a 4 axis set-up

Thank you, both, again, for your advice and for taking the time to be so helpful.  It is very kind of you.

[a.laasW8M6T]

Have a look at this video/screen cast that should explain a bit more

[redmond.limited · Accepted solution]

Thank you very much for this.  That has explained it all very well.  And thank you for taking the time to help.  That is very kind of you.

I shall, hopefully, get this on a machine soon.