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dfox1787
19-01-2018, 09:08 PM
Hi

hope someone can explain this to me.

i have a part that is 6mm in height. My stock is 6.45. i use a facing tool path that removes .45 making the stock 6mm in height.

I have a pocket that is only meant to remove 2mm but when i run the simulation its removing 2.45mm

Ive tried selecting the top height from the top of the model in the tool path settings but it still removes 2.45mm.

can anyone help?

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needleworks
19-01-2018, 10:00 PM
Hi

hope someone can explain this to me.

i have a part that is 6mm in height. My stock is 6.45. i use a facing tool path that removes .45 making the stock 6mm in height.

I have a pocket that is only meant to remove 2mm but when i run the simulation its removing 2.45mm

Ive tried selecting the top height from the top of the model in the tool path settings but it still removes 2.45mm.

can anyone help?

23625

23626
If I were doing that part, I would make the last setting on the heights tab as "Bottom Height" From > Model Top, and the "Offset" as negative 2mm Not saying that's the correct way to do it, just how I would do it.

magicniner
19-01-2018, 10:22 PM
Is the top of your part Z zero?
It's kind of an industrial standard thing that's worth working with until you know better ;-)

dfox1787
20-01-2018, 10:03 AM
Is the top of your part Z zero?
It's kind of an industrial standard thing that's worth working with until you know better ;-)Yes the bottom left corner is set to zero. I can send you the file to have a look.

Sent from my SM-N910F using Tapatalk

Clive S
20-01-2018, 10:21 AM
Yes the bottom left corner is set to zero. I can send you the file to have a look.

Sent from my SM-N910F using Tapatalk

This is confusing as magicniner asked "is the top of your part zero" and you said "yes" and then said left bottom corner is set to zero!!

The normal way to start is to use the top of the part as Zero and any movement below that becomes -ve

dfox1787
20-01-2018, 10:24 AM
This is confusing as magicniner asked "is the top of your part zero" and you said "yes" and then said left bottom corner is set to zero!!

The normal way to start is to use the top of the part as Zero and any movement below that becomes -veWell it's the top of the stock but in the corner. So it's still the top it's just I prefer my zero position in the corner.

Also the facing operating is removing the correct amount off the stock it looks like the pocket operation after isn't taking that into account.

Sent from my SM-N910F using Tapatalk

magicniner
20-01-2018, 11:41 AM
Well it's the top of the stock but in the corner. So it's still the top it's just I prefer my zero position in the corner.

Your Stock is not your Part, that kind of confusion will result in unexpected depths of cut when you incorrectly interpret the terminology in your CAM package :D

dfox1787
20-01-2018, 11:43 AM
Your Stock is not your Part, that kind of confusion will result in unexpected depths of cut when you incorrectly interpret the terminology in your CAM package :D

i know its not but ot shoudl take into account the stock is thicker than the part and the take .45mm off the pocket if the stock has been faced.

the first operating is a face to remove .45 and the next is a hole pocket and the operating after is to pocket 2mm not 2.45mm. On the simulation the z moves down to 2.45mm

http://a360.co/2mUUlN4

magicniner
20-01-2018, 11:57 AM
You are mixing things up and trying to make the CAM work the way you think it should.
It's obvious that you are taking .45 off your stock but referencing your pocket depth as it would be from Top of Stock but your CAM is taking it from the actual Top of Part.
Setting Top of Stock as Top of Part is the source of your issues, you'll have to work out how to juggle the numbers in CAM to deal with that, a spreadsheet would help in keeping track of the differences required ;-)

dfox1787
20-01-2018, 12:03 PM
You are mixing things up and trying to make the CAM work the way you think it should.
It's obvious that you are taking .45 off your stock but referencing your pocket depth as it would be from Top of Stock but your CAM is taking it from Top of Part.
Setting Top of Stock as Top of Part is the source of your issues, you'll have to work out how to juggle the numbers in CAM to deal with that, a spreadsheet would help in keeping track of the differences required ;-)

thats correct. i would it expect it to know i already removed .45mm from the facing operation. I have to add a offset of -.45 for the tool path to start at the correct depth but it still pockets -2.45 which is going to make the the pocket deeper than it should be. At the moment the only way i can see is to leave it cutting nothing but it adds machining time. . To me it should know have took that into consideration.

Unless there is a setting im missing.

but if the fusion doesn't calculate it that it just adds more time for me creating paths. thank you for your response as always :)

magicniner
20-01-2018, 12:13 PM
Your time creating paths would be normal if you follow industry conventions.

Top of Part should be the top of your part, your stock should be defined correctly within the software and your CAM can then see what is required for a facing cut on the top of the part, without you defining the depth of material to be removed, because it knows the depth of stock above the part. You just tell it the depth of cut you want to use with your cutter and the CAM will work out if it needs one or more passes.

dfox1787
20-01-2018, 12:51 PM
Your time creating paths would be normal if you follow industry conventions.

Top of Part should be the top of your part, your stock should be defined correctly within the software and your CAM can then see what is required for a facing cut on the top of the part, without you defining the depth of material to be removed, because it knows the depth of stock above the part. You just tell it the depth of cut you want to use with your cutter and the CAM will work out if it needs one or more passes.

I should be able to tell the tool path to start the at 6mm and pocket -2mm. At the moment no matter what i change it always pockets -2.45mm.

here is the part if you want to take a look http://a360.co/2mUUlN4

magicniner
20-01-2018, 01:43 PM
It's a 2.5D part and you've modelled it in 3D and are using the 3D model in CAM?
There's your extra work! :D

To generate the paths you need in CAM for true 3D parts you will at some point need additional geometry as well as your 3D part, this geometry can be as simple as a perimeter to limit a cutting path to exactly the area you want or as complex as extending a compound curved surface beyond the edge of your model to allow a smooth finishing tool path to transition off and back onto the part for an axis feed rather than stopping exactly at the edge and creating machining artifacts.

Similarly for 2.5D parts you rarely need much if any part modelling and can control your tool paths with very simple, easily constructed geometry, this is why there are still people out there who think CAD/CAM for a single simple part is slower than manual machining, most often it's not ;-)

Just draw all your geometry at Z zero and generate paths to your required depths for
1. Facing cut
2. Rectangular Pocket
3. Through Hole

The geometry for your facing cut will be larger than the part perimeter by just more than your cutter diameter
The geometry for your rectangular pocket will be larger in two directions by just more than 1/2 your cutter diameter
The geometry for your round pocket will be unchanged.

In my CAD/CAM that takes me around 8 minutes to draw and tool-path

Modelling simple 2.5D parts in 3D is not required unless -
You need the part for a complex 3D assembly in CAD,
You can't visualise the part without pretty pictures,
The customer wants pretty pictures,

dfox1787
20-01-2018, 01:55 PM
It's a 2.5D part and you've modelled it in 3D and are using the 3D model in CAM?
There's your extra work! :D

To generate the paths you need in CAM for true 3D parts you will at some point need additional geometry as well as your 3D part, this geometry can be as simple as a perimeter to limit a cutting path to exactly the area you want or as complex as extending a compound curved surface beyond the edge of your model to allow a smooth finishing tool path to transition off and back onto the part for an axis feed rather than stopping exactly at the edge and creating machining artifacts.

Similarly for 2.5D parts you rarely need much if any part modelling and can control your tool paths with very simple, easily constructed geometry, this is why there are still people out there who think CAD/CAM for a single simple part is slower than manual machining, most often it's not ;-)

Just draw all your geometry at Z zero and generate paths to your required depths for
1. Facing cut
2. Rectangular Pocket
3. Through Hole

The geometry for your facing cut will be larger than the part perimeter by just more than your cutter diameter
The geometry for your rectangular pocket will be larger in two directions by just more than 1/2 your cutter diameter
The geometry for your round pocket will be unchanged.

In my CAD/CAM that takes me around 8 minutes to draw and tool-path

Modelling simple 2.5D parts in 3D is not required unless -
You need the part for a complex 3D assembly in CAD,
You can't visualise the part without pretty pictures,
The customer wants pretty pictures,

are you saying to make a 2d model and create tool paths from that? i cant see how it can know the depths i need to face and pocket from a 2d model. I thought i could make my own model within the model and the machine it out in cam.

magicniner
20-01-2018, 02:13 PM
are you saying to make a 2d model and create tool paths from that? i cant see how it can know the depths i need to face and pocket from a 2d model. I thought i could make my own model within the model and the machine it out in cam.

No, you don't need any models at all!
I'm saying that all you need is two rectangles and one circle drawn at Z = zero and use them to control tool paths.


i cant see how it can know the depths i need to face and pocket from a 2d model.

Autocad state that it is possible to 2d pocket from chained contours, that's lines to you and me, not solids, not 2d faces but lines.
One of the options for Bottom Height is Stock top: incremental offset from the Stock Top. so you set your depth as an offset from Z Zero, which is also top of stock, making things easy for yourself rather than trying to make it complicated then trying to make that work!

Here's a link to a relevant page on TFM, give it a read -
http://help.autodesk.com/view/fusion360/ENU/?guid=GUID67DC60DE-EE42-4BC4-B50D-B28D938D146E

dfox1787
20-01-2018, 02:27 PM
are you saying to make a 2d model and create tool paths from that? i cant see how it can know the depths i need to face and pocket from a 2d model. I thought i could make my own model within the model and the machine it out in cam.

sorry i dont understand why it cant be done the way im doing it and why its complicated. i've seen plenty of videos of people creating a model on fusion 360 and then using the cam to machine it. (https://www.youtube.com/watch?v=o-GBpUZ3piY&t=134s)

I know i can do the same operating in aspire where i can surface the stock first and then set the start cut depth. so if i remove .45mm from the stock i can start the cut -45mm but to me fusion seems to make the same operation more complex or not very easy to understand.

aspire is simple:

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Fusion does appear to have better tooling operations so i am keen to understand it more and use it for future projects. i am still new to it but something as simple as removing some materiel and then start the cut from the depth i want seems impossible at the moment.

magicniner
20-01-2018, 02:44 PM
Your work flow is illogical and doesn't work with the software you want to use.
You refuse to use a work flow which does work with the software you want to use.
You discount a quicker workflow which would achieve your requirements.
Good luck with that, you really crack me up :D
Roger & Out!

Clive S
20-01-2018, 03:08 PM
Fusion does appear to have better tooling operations so i am keen to understand it more and use it for future projects. i am still new to it but something as simple as removing some materiel and then start the cut from the depth i want seems impossible at the moment.

This is one of the best places to learn Fusion360 https://www.youtube.com/user/cadcamstuff/playlists

magicniner
20-01-2018, 03:10 PM
This is one of the best places to learn Fusion360 https://www.youtube.com/user/cadcamstuff/playlists

Got a link for people that don't like how it works, haven't read the manual or tutorials and expect it to be changed to suit them? :D

m_c
20-01-2018, 08:30 PM
Nick, in Fusion360, you can create a model, then use 2D toolpaths on that model by picking chains.

The only real benefit over using just a 2D drawing, is it allows you to see how the toolpaths are in relation to the model, which is handy for highlighting any issues (usually operator caused!). Regardless of 2D/3D toolpaths, you still have to ensure heights are correct for each toolpath, and you've set the part zero at the correct place.

Industry standard is you set Z zero on the surface and work downwards, but in Fusion you can set part Z zero wherever you want and adjust heights accordingly. If you're unsure about the heights, you should be able to go to a side view, and when altering any of the depths, they should be shown on the model.
Not all the settings may make sense if you're unfamiliar with the settings though, as there are options to alter where the heights are relative to.

Neale
20-01-2018, 08:50 PM
thats correct. i would it expect it to know i already removed .45mm from the facing operation. I have to add a offset of -.45 for the tool path to start at the correct depth but it still pockets -2.45 which is going to make the the pocket deeper than it should be. At the moment the only way i can see is to leave it cutting nothing but it adds machining time. . To me it should know have took that into consideration.

Unless there is a setting im missing.


First of all, You haven't given us quite as much information as I would like - a screenshot showing the CAM model with the various heights shown would help, along with a copy of the setup/operations list on the LH side of the screen. So what I say here is guessing at what these might show but this is based on my own use of F360 (which I use a lot for design and CAM).

Based on what I think you are doing, two quick answers. First of all, F360 is doing exactly what you told it to. No more and no less. Secondly, it will cut your pocket to exactly the correct depth as you have it; the simulation shows the pocket depth being 2.45mm deep. That's not an error - in the operation tab, you told it to work with top height equal to stock top - and the pocket is 2.45mm deep from stock top. Best way to fix this is just to change "top height" to reference model top, not stock top. That should work OK.

What I am not sure about because I can't see exactly how you have set up your operations is whether it will start cutting from stock top (so cutting air for 0.45mm) or from model top. I would create one setup and then under that create two (or more - not sure what else you are doing) operations. The first is to face the stock and second is to cut the pocket. I've just thrown a quick F360 model together and tried the CAM operations. I used facing and pocket under 2D (you can use 3D pocket clearing but this just complicates things when you are really cutting a 2.5D feature) and running the simulation it seems to do exactly what you want - the pocket cut starts at the top of the model, not the stock.

I would disagree with Nick - you might only be doing 2.5D operations (that is, essentially 2D but with a single defined depth of cut) but I don't see any issue in putting the 3D model together. It takes a minute or two to do, gives you all the F360 advantages (although this depends on what you are comparing it with) such as being able to go back to the drawing and change a dimension and have everything dependent on that automatically change or be marked to be recalculated. Nick is much more experienced than I am, as I always assume that I am going to make mistakes and F360 gives the best chance to go back and make changes without redrawing. In addition, of course, this might be just one component of a more complex 3D design in which case designing in F360 and then applying CAM to individual components for CNC manufacture is a sensible way to go. Practising on individual components makes this a good training exercise anyway.

My model took only a few minutes to generate; it can be edited trivially, can be rotated on screen for visualisation, etc. I, personally, like working with a relatively simple-to-use 3D tool like F360, but there's plenty of scope for other views and a lot depends on what you are used to. I've been at a model engineering exhibition today, talking to quite a few professional engineers from various backgrounds from aerospace to watch-making, and everyone has their own favourites. Largely determined by what their employer has bought and standardised on, but not many people buy their own Catia or Solidworks!

magicniner
20-01-2018, 08:55 PM
Nick, in Fusion360, you can create a model, then use 2D toolpaths on that model by picking chains.

Once you've got the model there's little point, I was pointing out that simple outlines at Z zero would allow him to easily do what he was asking, unfortunately he wants the software modified to work with his ideas of how it should be! :D



Industry standard is you set Z zero on the surface and work downwards, but in Fusion you can set part Z zero wherever you want and adjust heights accordingly. .

Clarity is everything, Part Surface or Stock Surface?

In all decent modern CAM/CAM they can set Part Zero where they like, but unless they have good reason then by busking it before they can walk the inexperienced can end up on their butt by trying to run ;-)

Rules and conventions are there for those who don't know enough to do their own thing. Those who do know enough to do their own thing don't have to ask how to do it :D

EDIT - The OP hadn't even read the guide on the parameters and options on the paths he wanted to use? RTFM!

Neale
20-01-2018, 09:08 PM
Once you've got the model there's little point, I was pointing out that simple outlines at Z zero would allow him to easily do what he was asking, unfortunately he wants the software modified to work with his ideas of how it should be! :D


That seems a little harsh. I don't think he was asking for software to be modified, and did accept that he might have missed a setting - not difficult with the plethora of settings in F360. In this case, I think it was as simple as not spotting that the top of cut was set referenced to stock top, not part top. I think he can be forgiven this as no-one else seemed to have spotted it either. At least F360 allows you to visualise the part, refer to contours, pockets, and other features by clicking on them, making them very visible, and then simulating the cut(s), and all without leaving the package. I've used a 2D drawing package (TurboCAD) and separate CAM application; I found it clumsy by comparison and more likely (for the beginner?) to make mistakes by making them visualise what they are doing rather than being able to double-check by seeing a 3D model on screen.

As for industry conventions - not easy unless you are actively working in the relevant industry and probably professionally trained into the bargain. As far as reference zeros, which way X and Y go, etc, I'm a firm believer that for an amateur working purely for themselves then only important convention is that you use a right-handed coordinate system with Z vertical. You can stick your zero where you like :smile:! Seriously, doing a lot of woodwork on a router rather than mill, it makes a lot of sense sometimes to have the reference on the bed/spoilboard (less sensitivity to material height when doing full-depth profiling) and sometimes on the work surface when doing, say, engraving. I can't guarantee that the board material I buy will be sufficiently accurate from batch to batch that I could afford to assume consistency.

(Apologies to earlier posters - I managed to miss some early posts which did comment on using the correct reference plane for the second cut. However, an inexperienced F360 user seemed to need the specific parameter to be pointed out)

magicniner
20-01-2018, 09:15 PM
Sadly not harsh, repeated explanations ignored culminating in-


thats correct. i would it expect it to know i already removed .45mm from the facing operation. I have to add a offset of -.45 for the tool path to start at the correct depth but it still pockets -2.45 which is going to make the the pocket deeper than it should be. At the moment the only way i can see is to leave it cutting nothing but it adds machining time. . To me it should know have took that into consideration.

Unless there is a setting im missing.

but if the fusion doesn't calculate it that it just adds more time for me creating paths. thank you for your response as always :)

Fusion 360 should know he's taken .45 off the stock (the top of which he's set as zero) and compensate for him but unfortunately Fusion 360 has the same problem as me, it's Crystal Ball is in for repair! :D

Neale
20-01-2018, 09:39 PM
Sadly not harsh, repeated explanations ignored culminating in-



Fusion 360 should know he's taken .45 off the stock (the top of which he's set as zero) and compensate for him but unfortunately Fusion 360 has the same problem as me, it's Crystal Ball is in for repair! :D
One of the reasons I wondered what was in the LH side of the screen is that F360 works in terms of setups, each of which can contain multiple operations. I believe (but have not checked) that some operations can be instructed to use the "as machined" rather than "raw stock" as the starting point, but only for multiple operations within the same setup group. I further believe (but have not checked) that typically this applies to 3D operations which tend to be rather more complex but not 2D but I'm happy to be told I'm wrong. So here we have someone either using 2D operations or using 3D operations without specifying that this operation should use the "as machined" state as starting point. Combined with the fact that the OP actually and very specifically told F360 to use the stock as starting height (by missing this one parameter in the operation definition) I'm erring on the side of user error rather than stupid software.

Actually, I'm sympathetic to the OP because it took me quite a while to figure out what a lot of the CAM settings were for (and I still don't understand all of them, but usually enough to make it do what I want) and missing the significance of this one is understandable. Mild "tut, tut" rather than making him stand in the corner with his back to the class :smile:

magicniner
20-01-2018, 10:05 PM
Mild "tut, tut" rather than making him stand in the corner with his back to the class :smile:

I have strong doubts that someone not bothered to read the reference for one of the tool paths he's using has the slightest clue about any of that, he should read around the subject some ;-)

And yes, RTFM and re-engage, I ate a big slice of Humble Pie over at the BobCad forum early in my inexperience and was generously helped, now I help out others where I can.

But repeatedly telling others what the software should do without having read the documentation isn't just unproductive, it's lazy, and it's rude! :D

m_c
20-01-2018, 10:19 PM
It's probably worth mentioning, 2D and some 3D operations rely solely on user entered heights, and it's up to the user to decide what has/hasn't already been machined, and set heights accordingly.

Some 3D operations give the option of REST machining, whereby Fusion will base the toolpath of remaining material, not the original stock, and will handle heights automatically within the tolerances set.

It all depends on what you're trying to achieve. Basic 2D is better for some stuff, 3D is essential for some stuff, some stuff 3D makes life a bit easier/better (I.e. adaptive and trochoidal), and some stuff 3D just overly complicates things for no/marginal gain.

dfox1787
21-01-2018, 08:53 AM
First of all, You haven't given us quite as much information as I would like - a screenshot showing the CAM model with the various heights shown would help, along with a copy of the setup/operations list on the LH side of the screen. So what I say here is guessing at what these might show but this is based on my own use of F360 (which I use a lot for design and CAM).

Based on what I think you are doing, two quick answers. First of all, F360 is doing exactly what you told it to. No more and no less. Secondly, it will cut your pocket to exactly the correct depth as you have it; the simulation shows the pocket depth being 2.45mm deep. That's not an error - in the operation tab, you told it to work with top height equal to stock top - and the pocket is 2.45mm deep from stock top. Best way to fix this is just to change "top height" to reference model top, not stock top. That should work OK.

What I am not sure about because I can't see exactly how you have set up your operations is whether it will start cutting from stock top (so cutting air for 0.45mm) or from model top. I would create one setup and then under that create two (or more - not sure what else you are doing) operations. The first is to face the stock and second is to cut the pocket. I've just thrown a quick F360 model together and tried the CAM operations. I used facing and pocket under 2D (you can use 3D pocket clearing but this just complicates things when you are really cutting a 2.5D feature) and running the simulation it seems to do exactly what you want - the pocket cut starts at the top of the model, not the stock.

I would disagree with Nick - you might only be doing 2.5D operations (that is, essentially 2D but with a single defined depth of cut) but I don't see any issue in putting the 3D model together. It takes a minute or two to do, gives you all the F360 advantages (although this depends on what you are comparing it with) such as being able to go back to the drawing and change a dimension and have everything dependent on that automatically change or be marked to be recalculated. Nick is much more experienced than I am, as I always assume that I am going to make mistakes and F360 gives the best chance to go back and make changes without redrawing. In addition, of course, this might be just one component of a more complex 3D design in which case designing in F360 and then applying CAM to individual components for CNC manufacture is a sensible way to go. Practising on individual components makes this a good training exercise anyway.

My model took only a few minutes to generate; it can be edited trivially, can be rotated on screen for visualisation, etc. I, personally, like working with a relatively simple-to-use 3D tool like F360, but there's plenty of scope for other views and a lot depends on what you are used to. I've been at a model engineering exhibition today, talking to quite a few professional engineers from various backgrounds from aerospace to watch-making, and everyone has their own favourites. Largely determined by what their employer has bought and standardised on, but not many people buy their own Catia or Solidworks!

Hi Neale

Thank you for your reply.

Sorry i am still new to fusion and current use aspire which i know functions totally different.

You are correct in staying the the pocket operation does hover over the part if it has already been faced. I have tried to set the tool path to the top of the model which does work on the simulation. The thing that is confusing for me is that on the simulation the pocket z height still cuts to -2.45mm. (maybe this is correct)

I did look at how to do the simple outlines function as nick asked but couldn't see how to set the cut depths but again that is probably me still not sure how the software works. With the little time i have. I spent watching online videos showing how to use fusion but i haven't yet found one where the stock is set to a fixed size because the material i will be using has these fixed dimensions.

One thing i did notice is if i set the facing operation the last thing i did and selected the one face that would be left after the previous tool paths then there are no issues. Perhaps this is the way the software is designed and the facing is meant to be the last thing you do?. Again still learning how to use the software.

heres a copy of my fusion file if you want to have a look.

http://a360.co/2mUUlN4

magicniner
21-01-2018, 02:15 PM
It sounds as if you have your Part Zero set as the top of the stock and the program is detecting the depth for the pocket as the difference between Part Zero and the bottom of the pocket on your solid model, are you choosing the top of your pocket as the top of your solid model without adjusting the pocket depth manually?

dfox1787
21-01-2018, 03:38 PM
It sounds as if you have your Part Zero set as the top of the stock and the program is detecting the depth for the pocket as the difference between Part Zero and the bottom of the pocket on your solid model, are you choosing the top of your pocket as the top of your solid model without adjusting the pocket depth manually?That would make sense.

I'll see if I can set a new z position at the top of the part rather than the stock.

After the facing operation the z psoisition would no longer be at the stocks surface but that of the part.


Sent from my SM-N910F using Tapatalk

dfox1787
22-01-2018, 12:19 PM
I think i have resolved this now.

the issue has been my lack of understanding the "heights" within the tool paths.

thank you to everyone who has had any input on this.

Neale
22-01-2018, 12:44 PM
That's great. I had a feeling the problem was lack of understanding of a bunch of parameters around heights. They make sense, but it does take a while to get to grips with what they really mean. Now you can move on to interpreting all the rest of the CAM parameters and settings - good luck with that! You do eventually reach the point where you know the ones that are important and the ones where you can happily leave the defaults.