Creating CAD files for free

[chickenStripCharlie]

I understand your frustration but like everything there is a learning curve, that why there are whole industries dedicated to these programs. Typically the more powerful the program the more difficult it is to learn. think MS paint vs Photoshop. If you want a very simple CAD program that is really easy yo use check out Sketchup. I dont think its free anymore but its cheap. However its not parametric, and not precise, but you will be able to generate simple drawings with it.

STL files are lossy. I would not use that file type AT ALL except exporting final output for 3d printing or machining a very complex curvature. You can cheat it by increasing the triangle count but its still not great.

I know its not what you want to hear but this is why you draw it yourself correctly the first time. Lol. Take the time to learn a one of the CAD programs and learning others will be easy. I started with Alibre about 10 years ago and now I am well versed in Rhino, Solidworks, Fusion, Alias, AutoCAD and Sketchup. I use sketchup everyday for work becuase its incredibly fast for ideation. Once the design intent is solidified I will move to Solidworks or ACAD.

If you don't want to take the time to learn a CAD program just draft this part by hand. Its really not that complex.

View attachment 226358

Funny, I came across that very diagram while googling how to do that conversion. Which makes sense, once you understand the basics of how each file is created.

I would have had that diagram drawn by hand a long time ago, if the machinist would take it. Lol. I agree, it's not complex.

I talked to a different machinist and he told me that the setup time for CNC would take longer than it would take him to do this on a manual lathe.

Does any CNC aficionado here know what he means? It was my understanding that you set a price in the machine, load up the tools needed in the tool head and press start *shrug*

I watched some YouTube videos but they all skip over the setup process. Is it as complex as the other machinist made it seem?

(I'd really like to invest in a small hobby lathe. I think one of those 7"x14" units would be awesome to have in the garage. I cant justify the cost and shipping right now, but hoping one pops up for sale used locally. I'd really like that)

 

[doc_rot]

The tool paths are not arbitrarily created by dropping the model in a program and letting the program make the part. Although that is where the industry is currently heading. Someone has to program the different types of cutting operations, specify how they are done, and with specific tools. this can be quite time comsuming because you also have to accommodate work holding and other factors.
Loading and calibrating the tools and machine before cutting is critical and time consuming. There is a tipping point where a manual machine is faster. it depends if he has a lathe with live tooling or if hes cutting the entire part on a mill, what kind of work holding hes anticipating doing, etc. too many variables to guess. I frequently use Fictiv.com as a resource for ballparking part costs. Its really interesting how secondary operations, and certain dimensions can influence cost. it can be surprising.

 

[sav0r]

Machining in a meaningful way isn't as easy as many might think, but with determination it's possible for just about anybody to learn. We are a long way off from sending a model to a machine and pushing go. Well, 3D printers more or less do that, but the vast majority of 3D printed stuff ins't all that useful. The closest I have seen with subtractive manufacturing is the replication of repetitive tool paths (meaning the same path is used on similar features on different models) are automatically applied to new models in the CAM stages. It automates the CAM process to degree, but the good tool paths and strategies have to be developed in the first place. For most (definitely including hobby level) we are faced with measuring, squaring stock, measuring again, programming, measuring some more, setting up, then finally hitting go. If you did your homework, the part comes out in some usable form. If you are still learning, it might take a few tries.

That said, I could probably machine that hub fairly cheap, I'd do it on my CNC mill because I don't own a lathe. The cost of material would make up at least 30% the cost of the hub. It won't be as round as a lathe made hub, but concentricity isn't particularly important for a brake rotor. One of the first things I ever machined on my CNC mill was the brake hub for my RD350, that was like 5 years ago and it's still working great.

 

[chickenStripCharlie]

The tool paths are not arbitrarily created by dropping the model in a program and letting the program make the part. Although that is where the industry is currently heading. Someone has to program the different types of cutting operations, specify how they are done, and with specific tools. this can be quite time comsuming because you also have to accommodate work holding and other factors.
Loading and calibrating the tools and machine before cutting is critical and time consuming. There is a tipping point where a manual machine is faster. it depends if he has a lathe with live tooling or if hes cutting the entire part on a mill, what kind of work holding hes anticipating doing, etc. too many variables to guess. I frequently use Fictiv.com as a resource for ballparking part costs. Its really interesting how secondary operations, and certain dimensions can influence cost. it can be surprising.

Great info! Thank you! I will check out that website and play around

 

[chickenStripCharlie]

Machining in a meaningful way isn't as easy as many might think, but with determination it's possible for just about anybody to learn. We are a long way off from sending a model to a machine and pushing go. Well, 3D printers more or less do that, but the vast majority of 3D printed stuff ins't all that useful. The closest I have seen with subtractive manufacturing is the replication of repetitive tool paths (meaning the same path is used on similar features on different models) are automatically applied to new models in the CAM stages. It automates the CAM process to degree, but the good tool paths and strategies have to be developed in the first place. For most (definitely including hobby level) we are faced with measuring, squaring stock, measuring again, programming, measuring some more, setting up, then finally hitting go. If you did your homework, the part comes out in some usable form. If you are still learning, it might take a few tries.

That said, I could probably machine that hub fairly cheap, I'd do it on my CNC mill because I don't own a lathe. The cost of material would make up at least 30% the cost of the hub. It won't be as round as a lathe made hub, but concentricity isn't particularly important for a brake rotor. One of the first things I ever machined on my CNC mill was the brake hub for my RD350, that was like 5 years ago and it's still working great.

Thanks for the great info!
The machinist has a cnc mill (and cnc lathe) I believe. I was quoted $260 cad (or about $190-200usd) for the part. That sound reasonable to you?

I might have to play with that site doc posted and see how much I could save doing certain things myself, like chamfering, maybe even the threading.

Edit: not sure why I said threading. I meant tapping threads. Lol.