Order of operations

[Scott Wayne]

Hello everyone. I’m a CNC machinist that’s just starting to learn mastercam and I’m getting hung up on what is the “right” way to create objects. I almost always get the regeneration error when making parts. Here is the example I’m working on right now. 
 

it’s a stepped washer with a slot in the bottom. I made the part and got an error when I tried to save and after regenerating it changed everything and I had to start over. It’s hard for me to specify what’s going on because I don’t understand why it’s not working. So if anyone could break down as if I’m 5 what order you would create this simple part I would love that. I started with the widest part, made parallel lines to create the slot, used extrude to cut a body for the hole and repeated the process for each layer. Should I draw circle and extrude them or use cylinder? Extrude cut or hole? There’s just an overwhelming amount of choices that it makes it very confusing. Thanks for any help in advance!

[#Rekd™]

It depends on a few things such as make and model of machine or machines you are going to use, type of tooling available and the material you are cutting.

[Scott Wayne]

I’m using a Haas VF2 and it’s made out of aluminum. Solid carbide Garr tools. 

[#Rekd™]

Starting with round stock cut into discs? You will need to create a second operation to mill the slot. If you can use a 5c collet to grab it on the 0.9 diameter. 
 

How it is being held will impact on how aggressive you can cut that slot. 

[Scott Wayne]

I was asking more about how to correctly draw it in mastercam, but I ended up figuring it out. 
 

We have acrylic beds on top of the machine bed and we use double sided tape to hold down aluminum plate, no coolant, just air, so we take small cuts. We have a lathe too but our smallest drill is 1” so we decided it would be easier to do this on a mill. We’ll mill out the slots and profile the plate, then flip it over and mill the rest. Using an acrylic bed and double sided tape allows us to mill all the way down to the tape. 

[#Rekd™]

Sorry I miss read your initial post!!! 

[Thad]

Personally, I would draw the three diameters and extrude them. Boolean-Add them together to make one solid. Extrude cut the hole thru and extrude cut the slot through. 

13 hours ago, Scott Wayne said:

I made the part and got an error when I tried to save and after regenerating it changed everything and I had to start over.

Based on your description, here's what I think happened. You created wireframe and extruded it. Then you modified that geometry to make another extrusion (or for some other reason). Your error was something like "this geometry is used in a solid, are you sure  you want to modify it?" You said OK. Then when you regenerated the solid, that's why it changed everything.

Once you create a solid body from geometry (extrude a circle for example), that circle wireframe shouldn't be touched because your solid is associated with it. If you change the diameter of the circle, your solid will go dirty and need regeneration...which will update the diameter of your solid. See how that works? It kinda sounds like you found out how that works.   At the same time, that's how you intentionally edit a solid. Say you wanted to change the thru hole size. You edit the wireframe circle diameter and then regen the solid. Done!

[Jobnt]

I would create this in a side view and use a revolve function then cut the slot out the bottom.

 

[Thad]

1 hour ago, Jobnt said:

I would create this in a side view and use a revolve function then cut the slot out the bottom.

 

To expand on that, you could move the "center line" over .255, but sill revolve around the same axis, and it will create the .510 diameter thru the center all at the same time. From a modeling fundamentals perspective, I wouldn't use revolve to create this though. I have been taught, and I believe, that modeling things so that they are easily modifiable is the best way to go. Probably splitting hairs on this particular example, but I try to be consistent. 

[#Rekd™]

I made a video of how I would do the solid model. Many different ways to do it as the others have talked about.

https://www.dropbox.com/s/nls8xuj18adunh0/Solid.mp4?dl=0

[cncappsjames]

There's always MANY ways to skin the CAD cat. Like Thad I try to be consistent as well. Makes for easier troubleshooting if something goes wrong.

I would start with the largest diameter and extrude up from there, adding to the existing body as I go. Once all the diameters are done and it's a single body, then I would extrude cut the thru hole. Finally I'd create a rectangle to cut the center slot either from the front view of the bottom view. There's probably 5 or 6 different ways to do it that doesn't break any rules.

Something helpful for future CAD work; draw everything sharp, then add fillets. If you draw in the radii you'll have a tougher time blending things. When blending radii, create the largest radius first then work your way down.

[Thad]

7 hours ago, cncappsjames said:

Something helpful for future CAD work; draw everything sharp, then add fillets. If you draw in the radii you'll have a tougher time blending things. When blending radii, create the largest radius first then work your way down.

Not to mention, create "vertical fillets" first. Then the other fillets.

[Thad]

9 hours ago, #Rekd™ said:

I made a video of how I would do the solid model. Many different ways to do it as the others have talked about.

https://www.dropbox.com/s/nls8xuj18adunh0/Solid.mp4?dl=0

Nice video, John. Thanks for taking the time and the trouble! (Good to hear your voice!!)

For those non-Canadians out there, "Zed" = Z. 

[JoshC]

most of these titan of cnc parts have videos on how to make them in CAD, and even a video on how to then toolpath them in cam. titans team did a good job with these videos and even made them free https://academy.titansofcnc.com/category/mill-building-blocks

i would suggest you review those to get familiar with some solid modeling processes, and once you get your feet wet maybe branch out into some caminstructor training or perhaps training with a local reseller. but many online free resources like this are available if your willing to watch some videos. Just remember there is always more than one way to do just about anything, so keeping an open mind is always best!

[Thad]

@JoshC I like how they broke the videos down to CAD, CAM, CNC and showing in different softwares. That's brilliant! Thanks for sharing!!