Mold cavity sloping edges toolpath advice

[zebraautodesk]

I wanted to ask for some advice on toolpaths for a sloping edge section of this mold I'm making.

[url=https://postimg.cc/34NHmMns][img]https://i.postimg.cc/34NHmMns/Cricket-mold.png[/img][/url]

Most of it is straightforward and comes out fine when I tested it in wood using 3D adaptive + parallel toolpaths (and scallop for the ball keys around the edge).

[url=https://postimg.cc/BPc9GkMQ][img]https://i.postimg.cc/BPc9GkMQ/20220301-190243.jpg[/img][/url]

The exception is this small section at the front where I get an awful surface finish with every toolpath and tool I've tried.  

[url=https://postimg.cc/5YrWmPr6][img]https://i.postimg.cc/5YrWmPr6/problem-area.jpg[/img][/url]

This is how it looked in wood.

[url=https://postimg.cc/HVd1tWkJ][img]https://i.postimg.cc/HVd1tWkJ/20220301-190411.jpg[/img][/url]  

The other vertical and sloping edges come out smooth. The only difference with the problem area is that the vertical edge and slope don't run parallel to my X axis. 

I tried parallel and parallel with additional 90 degree passes. I've tried various attempts with contour, smaller and larger stepover, square and round tools etc  but they all come out the same.

What finishing toolpath would you guys select for a 3d vertical + sloping edge of a mold cavity (or pocket) on a 3 axis machine? 

[kieran.gill]

Hi @zebraautodesk,

The image url  you have attached is resulting in an 404 Error. PLease can you attach them directly to the post please ?

Next, are you able to upload the F3D data ?

Kind Regards

[zebraautodesk]

Here are the pics dropped in directly. Not sure why my links don't work here.

1) the mold I'm making

2 How it looks tested in wood (the final will be aluminum).

3) The problem area.

4) The problem area in wood

 

 

 

 

 

[zebraautodesk]

Just in case the shape / geometry of my problem area is not clear from the pics, here is a pic of the part I'll be making in this mold. My issue is the female mold of that front portion of this air rifle stock with multiple vertical, sloping and 3d contours run in different directions / angles.    

[kieran.gill]

@zebraautodesk ,

So I would love to tinker with the toolpaths in your mould (F3D) if your willing to share it ? That way I can have a stab at a few toolpaths for you.

Secondly, lets break down the strategy that your using, Parallel and Scallop are really good for shallower areas and produces great results but doesn't do as good of a job when it comes to vertical walls. Contour, on the other hand, is the opposite, great for vertical walls but not as good for vertical walls.  

I would recommend having a stab with the Steep and Shallow strategy. Have you ever used Steep and Shallow ? Steep and Shallow is part of the Machining Extension and you can use the functionality as part of a trial for 7 days to see what you think. 

Steep and shallow is a combination of Contour (for the steep areas) and either Scallop/Parallel (for the shallower areas), HOWEVER Steep and Shallow brings with it a number of added benefits over the singular toolpaths your currently using. This post isn't long enough for me to type all the benefits but I've got a number of videos I would like you to watch which may help convey to you, a better idea of the benefits of using Steep and Shallow. One of the items which come to mind is certainly Optimized Perpendicular Passes option alongside overlaps between steeper and shallower areas which blend the steep and shallow areas together for a better surface finish, which is something you don't get on the singular toolpaths that your currently using.

Now, I have to say that I have not seen your model data and this may not solve your problem but its definitely worth investigation when there is a free trial available to you, to investigate it with. Hope the videos help below.

Look forward to hearing how you get on

https://www.youtube.com/watch?v=LTW5PH8EaVg&t=11s

https://www.youtube.com/watch?v=Twq8ZTHCFSE

https://www.youtube.com/watch?v=iBTm7NnuNQA

Kind Regards

[zebraautodesk]

I don't have any issues with the vertical or sloping surfaces where they run parallel or perpendicular to my X or Y axis. The surface finish issues are just where the angle changes. 

You can see in the pic below how drastic the difference is. The wall and slope on the right is identical to the problem area on the left except they run at 0 degrees to the X axis. The problem areas are at an angle of approximately 25 degrees, 40 degrees and 70 degrees. 

The parallel finishing toolpath leaves deep irregular grooves on those problem areas that I can't seem to fix with larger or smaller stepovers, or different size tools. Contour was worse.

I am currently using the hobby version so I have to work within it's limitations for now. I'm working on a start-up but I'm not making money yet...

[Steinwerks]

I would suggest trying Contour for your mold walls and Parallel for the floor. These can be constrained using the Slope option on the Geometry tab, something like 1-90° for Contour and 0-1.5° for Parallel to induce a little overlap. Think of it as the basic user's Steep and Shallow combo.

[zebraautodesk]

Does it matter if the angles you specify in the geometry tabs aren't exact? 

I have no good way of measuring angles with any precision in the corner of a mold cavity. I can guestimate though. 

I was hoping to avoid running a new program for each face ( the angles change for each one) but if there's no other way I guess it's the only option.

[Steinwerks]

No the angles have more to do with your needs than anything on the model as you the programmer are the final arbiter of what makes for a good toolpath.

There's no [obvious] reason two toolpaths have to be in a separate program. You can use the same tool, post them together, and have them run sequentially. In your case in a wood part I would be tempted to rough very close to my floor, then run the parallel pass first before Contour, but I generally machine metals so wouldn't take this advice as being very informed,  just a gut feeling.

FWIW I have made molds from steel and aluminum so I do have insight into the needs of those materials and what surface finish at transitional areas needs to look like for a successful result. I use Steep and Shallow almost exclusively for high finish requirements though as I find it excels in that regard.

[zebraautodesk]

There is no steep and shallow option in the hobby version so it's not an option for me yet. I'll upgrade when this business starts making money. 

The mold I'm making will be aluminum. I only use wood to test toolpaths because it's cheaper to practice on.  

None of these issues matter much for wood because a poor surface can be fixed with sandpaper quickly. It's too much to sand out of aluminum though. 

I haven't had issues with other molds with simpler geometry. 

[zebraautodesk]

I managed to (mostly) fix the problem areas by creating a separate program for every bit of geometry. I've gone from 7 toolpaths to 37 but I seem to have created a new problem. 

It has missed small ridges across the part. I can see gaps in the cutting moves in the simulation and I can't find a reason. For example, the first pic below shows some of the leftover material that It won't generate cutting moves for with any toolpath.    

The areas are not in enclosed spaces or corners where the tool can't reach. I've tried with both the "machine as computed" and the "machine cusps" options. I have no "stock to leave" or any additional offsets. 

The 3rd pic below shows an example of an unwanted gap in the toolpath cutting moves that seems to be there for no reason. What would cause Fusion to leave gaps like this (with every finishing toolpath)? 

Also, I now have unwanted cuts in the mold surface at random points that were not there when I used fewer toolpaths. I attached an example in the 3rd pic below. 

I am not sure if this is something I am doing wrong in Fusion or simply additional positioning inaccuracy that gets added with each extra toolpath. 

Any ideas of how I can stop it leaving small areas unfinished and also stop it cutting little chunks out of the part in random areas?

[Steinwerks]

Can you share your file? Seeing the machined part isn't all that clear and it'd be much better to try and demonstrate with an example.