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Help with CAM on first project?

11 REPLIES 11
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Message 1 of 12
joearledge
576 Views, 11 Replies

Help with CAM on first project?

I'm brand new to this field and I'm trying to figure out the CAM for my first project, copying a simple bullet mold that I own. I have looked at a lot of videos and read a lot of stuff on CAM and the related subjects over the past few months. I've taken a stab at it(more like a scatter gun approach I'm sure) and I feel like it was a swing and a miss. I don't currently own a ton of tools for the CNC mill(compared to most of you) so I intend to try to use this CAM model to determine what I need to buy next in order to make this part. Anyone willing to help me learn and explain things to me so that I can logic my way through other projects would be greatly appreciated. Please see below for the project.

Thanks,

Joe

11 REPLIES 11
Message 2 of 12
Anonymous
in reply to: joearledge

I'd like to try and help you! Maybe we can have contact via the message option?

Message 3 of 12
seth.madore
in reply to: joearledge

First question that matters a great deal; what is your actual machine? The approach to manufacture changes significantly depending on the "robustness" of your machine (and budget, of course). Do you have one part you'd like to make, or were you thinking of making several?


Seth Madore
Customer Advocacy Manager - Manufacturing
Message 4 of 12
joearledge
in reply to: Anonymous

I would appreciate that. I'm not seeing another message option besides this one. If there is a different method of communication that you would prefer, that's ok with me, you just need to let me know where I can find it.

Thanks,

Joe

Message 5 of 12
joearledge
in reply to: seth.madore

Brand new Tormach PCNC440 in my garage. Some decent tools came with it, but I bought some El Cheapo Chinese Amazon tools to learn with also. I figure if I'm gonna break some stuff it's better to break a $5 tool than a $50 one starting out. The tools are held in ER20 collets with the TTS collet holders. The machine has been leveled and trammed to the best of my ability to measure currently. Backlash compensation was added for about 0.0005". The work will be held in a 4" Tormach vise. I'm just trying to make this mold currently. So it would be this part X2(a left and right half of the mold). My focus is on the highest quality surface finishes, I know the cheap tools limit that, but I'd like the highest possible quality I can get with them, which should be even better when I switch to the good tools. Machining time is not a major concern currently, maybe one day 20 years from now if I own some sort of machine shop, but today it's all about quality. There are other parts that go to it, such as a sprue plate, but I'm hoping to take what I learn on this part and attempt to apply it to the other parts to see if I can logic my way through the other ones on my own(the ultimate goal). If I'm not able to, then I'll be back for more tutoring. I thought it would be a nice project to learn on since it seems like it forces me to learn many of the basics without being overly complex starting out.

Message 6 of 12
leo.castellon
in reply to: joearledge

Looking at your toolpaths, you should research how to use containment boundaries and rest machining. Some of your toolpaths are machining areas that don't need to be machined with that specific tool. Also, if you are looking for the highest surface finish, your model mold will not look exactly like the male part of your casting due to your sharp corners in your mold because you are using ball end mills to machine the cavities, so those sharp corners will have small fillets, not sure if that is an issue or not. If you are not concerned with having the sharp corners, it is best if you modeled in some fillets there. When you are surface machining with those small end mills, they don't like sharp corners and they can break, or at minimum, flex and then you will have blips where the end mill has to change direction.

 

If you had a CNC lathe, you could bolt the halves together and machine the mold with boring bars and get much closer to your modeled shape. 

 

LeoC

Message 7 of 12
joearledge
in reply to: leo.castellon

Yeah I've seen some stuff on the boundaries and rest machining. From what I understand, "tool outside boundary" and "rest machining checked" are best practices unless it's going to cause a crash or mess up the part for some reason. I thought about adding fillets, just haven't done it yet, I'll go back and do that. Razor sharp corners are not critical and it'll probably help the solidified lead come out of the mold easier if they are rounded. As for the radius of the fillets, should I just use the radius of my smallest ball nose? If needed, I'm not opposed to buying more tools, I'm going to have to do that at some time. The only other ones that I thought might apply to this project are bull nose, tapered, and/or lollipop. Though there may be more that I'm not considering, and those I mentioned may not be useful, that's part of what I'm trying to learn. It also seems like the chamfers shouldn't be in CAD, only in CAM, since all I'm trying to do is break the edge. As to the lathe, I could always do mill turning, or I'm sure someone has devised a way to mount a boring bar in a spindle, which I may play with one day, but it seems a little advanced starting out. I guess one specific thing I'm looking at is the order of operations. My Idea was Face, 3D adaptive, Trace, then I'm not sure what strategies and tools would be best to cut out the cavity and the index pin holes and to finish them. What you see posted(after those 3 ops) was basically just me trying stuff. I noticed that even in the center of the cavity where it's nice and wide open, it still seems to be leaving material. I kind of expected that in the tight spots(since I've never done this before), but I may also be looking at the CAM simulated model wrong. What I'm seeing as "material left over" may be on the order of 0.00001" which doesn't matter here, but could be 0.010" which does matter. So I guess another thing I'm trying to learn is how to best analyze the CAM simulated model so when I try to cut the part, I have the best chance of not scrapping it, though I don't realistically expect the very first one ever to be flawless and perfect. let me know what you think about the fillet radius and the chamfers and I'll make those changes.

Thanks,

Joe

Message 8 of 12
joearledge
in reply to: leo.castellon

Here's what I have so far. It keeps giving me a "Kernal" error everytime I try to add another opp. Any advice on fixing that?

Message 9 of 12
joearledge
in reply to: leo.castellon

sorry file didn't upload

Message 10 of 12
leo.castellon
in reply to: joearledge

I tried multiple things on your latest model, and I could not get rid of that error. I wish when Fusion generated error messages, it would give you a better explanation. I even tried offsetting the surfaces .0001 and have it compute surfacing on that and it still failed.

 

Also, in your original post, you mentioned high surface finish was important, for your finishing operation, I would recommend that you only climb cut, so choose one way, not both. This is especially important since you are using high speed end mills. I see that you chose 40 for your feed rate, I don't think that will work very well, I would expect you to break a lot of end mills at that feed rate. Since you mentioned using a Tormach, which I am not familiar with, and having shown using a 5000 rpm spindle speed, I would expect a HSS end mill to work better at 4.75, this is based using FS Wizard with the material being aluminum. One of the premier small tool manufacturers, Harvey Tool, they list their .020 ball end mill with a .500 reach for finishing using a .00025 per tooth chip load, you have yours set at .004.

leocastellon_0-1687373701053.png

 

LeoC

 

Message 11 of 12
leo.castellon
in reply to: joearledge

3D contour works, see attached.

 

LeoC

Message 12 of 12
joearledge
in reply to: joearledge

Sounds good, I appreciate the help. While time is not my biggest concern currently, it's predicting over 20 hours of machining time. Is that normal for a part like this with a max RPM of 10,000? Just curious, I haven't developed an intuitive sense for a lot of this stuff yet.

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