2D contour with 0.5mm stepdown, is milling straight from -3.0mm

[ovisopa]

I found the 3mm endmill broken a few minutes ago, and I started to investigate why it broke, as I used this operation on other models too, with success. When I seen the part it seem very weird for me that the left side was milled correctly, stepping down from top do bottom, but on the right side of the model, the end mill touched the material while it was at Z -3.9mm, in that moment the 3mm endmill broke 😞

 

 

I have set from the begining MAXIMUM ROUGHING STEPDOWN of 0.5mm, a few weeks ago I also selected ORDER BY ISLANDS and ORDER BY STEP as I didn't like that the endmill was traveling very often from one side to another, but with the ORDER BY STEP enabled I think what it happen to me today, should not happen, as you can see in the screencast the endmill touched the material at Z -3.0mm , and I don't know if there is something wrong with my operation, or if this is a bug?

PS. Today it happen twice, Fusion 360 freezed after this action : 

1. Click File -> Save 

2. Click File -> Export .. when I tried to change the export folder, an error sound was played , and from that moment anywhere I tried to click the same error sound was playing , the only option I had was to close Fusion process from task manager.

[HughesTooling · Accepted solution]

Using just Order by step gives a good toolpath, not sure if the Island option is getting confused because the areas you want to machine are open rather than individual cavities.

[HughesTooling]

Didn't really explain the island option well above. The islands would be for individual boundaries forming cavities, you don't really have any islands, you're just maching the outside leaving 2 bosses.

Mark

[ovisopa]

Thank you. This was again an expensive mistake 😞 But I still think Fusion did not make a correct toolpaths, because it treated the areas as islands, it first milled one, and than the other, but why it started the other "island" at such low Z value, I can't understand 😞 

I'm curious guys, what is your average tool life when milling tool steel ? How many meters can you mill with one endmill? I purchased a 4 set (12mm, 10, 8, 6) RF100 speed Guhring end mills, and the 12mm one is already dull (will send it to be resharpend at their factory) , I made with it about 5 - 6 parts like the one attached, I milled with that end mill an average of 19meters / part, let's say a total of 100 meters and the end mill can't be use anymore, until resharpened.

I'm far away  from your numbers ?

[HughesTooling]

Fusion should really be able to deal with the settings you used. With 2d I'm not sure if the island option is for islands in the stock or islands defined by closed profiles but either way it should work better than it did with your file. @jeff.pek can you take a look as this looks like a bug.

Thanks Mark

[cj.abraham]

Note that order by step only applies if there are multiple stepovers for a contour. So in this example, enabling/disabling order by step has the same result. Also, "order by island" is not necessarily the same as "order by area." This particular situation has two islands near each other that create the appearance of areas because of how rest machining trims the passes. "Order by area" (found in adaptive clearing) would have been the ideal linking case in this situation.  

That said, there does seem to be a strange linking order when using order by island. Agree it seems like a bug.

[ovisopa]

@cj.abraham Maybe I don't understood what you mean by multiple stepovers, but in my case the end mills is milling that section at multiple depths, first at -1mm, than -1.5, -2, -2.5mm .. etc isn't this multiple stepovers, shouldn't the order by step option mill in this order -1, -1.5 ... -2.5, -3 ?

Today, another broken tool 😞 it was an 1/16" 2 flute endmill that I usually use with a very small DEPTH OF CUT, just 0.1mm at a time (slot). 

As you can see in the file attached , even with ORDER BY STEP activated, it still does not make the correct toolpath, I had to make another operation, a simple contour without the tapper angle, to clear that area, and than to mill using the tapper option

Can you guys give me other suggestions , what I can do to improve to brake less endmills, in those shallow areas? I mill those sections using small flat endmills to not brake the tip of the chamfering endmill, that will do the contour on the exterior and on the interior to make the blade sharp.

Thank you.

[cj.abraham]

Order by Step will only be applicable when there are multiple stepovers. See the tooltip for this option where there are 2 "stepovers." This setting determines whether, for a single contour input, The tool does all of one Z level first, or the outermost pass from top to bottom first.

In the toolpath for this thread, there is only one "stepover" and therefore "Order by Step" cannot have an effect. In fact, I have created a ticket to remove the option when it does not apply (CAM-8869).

The current issue is that there is a bug in order by island that causes passes to be linked in an incorrect order. CAM-8170 should fix this bug.

Until then, my proposal for a current workaround is to break this up into two toolpaths, one for each area. Then, disable both "order by island" and "order by step" (which has no effect anyway) and you should achieve the toolpath you want. It will complete one "area" from top to bottom, then move to the next area. See a video of the result here: http://autode.sk/2ycEy0J

[ovisopa]

And it happen again 😞 In the photo bellow check the fine stepdown in the right side - light brown color, it first milled right side than it moved to the left side where it milled right trough material 😞

I'm so pissed of I haven't checked the complete simulation at slow speed, I have only checked if it follows the correct order of the steps, and it did in the first section, and than I fast forwarded the simulation to the end, but didn't noticed it does some weird things when it moved to the other section.

I don't know how Fusion developers team are treating those bugs, but in my opinion the CAM bugs must have the highest priority, and should be fixed first, before anything else, having errors like this in generated code can lead to serious loss, the end mills are so small but unfortunately the price is quite high at ~40 - 50 Euro each, I started to look over cheaper endmills, at least those very small that will brake at the smallest mistake. 

@cj.abraham I'm not convinced that the main issue is related the Order by islands bug, I haven't checked that option this time, instead I had checked ORDER BY STEP, and I say again, my contour operations uses stepdown, very fine stepdown of 0.08mm. I don't know if stepover is the same thing as stepdown, but by looking in the POPUP help image when placing the mouse cursor over the ORDER BY STEP option, it shows exactly what I need - starts from top to bottom, than move to the next contour and starts from top to bottom.

I don't really know if there are other places, other than this forum to notify the team that there are serious bugs, also I don't know how serious this seem for you, but for me it really seems an huge issue. 

Also there was no collision detection red mark in the simulation, and I have checked it before starting the milling process.

Is there also a bug in the simulation module, or why that section was not picked up ? The operation was set to make small 0.08mm steptdowns, but the endmill hit the material at a depth of 1.2mm (slot cut with an 1.58mm diameter end mill in tool steel 1.2379).
 

PS. The model has many lines in the tappered wall because I have converted the initial spline to a polyline, using CamBam, as Fusion did again some weird things with the original spline 😞 I know the error is very small in this case, but on this model I had another extra issue, and I chose to convert the spline to by fix all those errors.

[cj.abraham]

@ovisopa Please read my last post very carefully. "Order by step" will have no effect on your toolpath because it does NOT have multiple stepovers. What you have are multiple contours with one stepover at multiple depths. It will not make any changes to this toolpath. The checkbox is being soon being removed because it is misleading to show it if stepovers are disabled (CAM-8869).

We know that the linking order is an issue. Ticket CAM-8170 was opened to find a fix.

In the mean time, Here is a solution to do your passes in the correct order. I broke the 1 operation into 3 to order the passes by area manually, as well as enabled "order by depth" for top to bottom linking.

[ovisopa]

Thank you CJ, now I won't confuse stepover (multiple passes on X and Y axis) with stepdown (multiple passes on Z axis).

Yesterday I did what you suggested in previous post, I splited the milling in 3 operations and I was able to finish my part, now I just started to mill again, this exact same model needs to be milled twice, very rarely I have to do a model twice.

Any ideea when CAM-8170 will be fixed? Judging by the number I think the bug is many months old 😞

Have a wonderfull weekend!