[Newbie] Cnc Questions

[TomS]

+1 on what Jim said about a stepper driven system. For reference my conversion cost about $2,000, not including the price of the mill. Your cost should be a bit lower as I have a NEMA 42 4200 oz. in. motor and driver on the Z axis. Properly set up a stepper system will produce very accurate parts. You just need to realize you are converting a hobby manual mill into a hobby CNC mill. Adding CNC components doesn't make it more accurate.

Good luck with your project and keep asking questions. We are here to help.

Tom S.

 

[JimDawson]

The machine that I was looking at converting is the PM727M milling machine. It's basically another Rong-Fu- 7x27, about 700 pounds etc.

Nothing wrong with that. It's a good base for a home sized CNC platform. You can run anything on that as a CNC that you could as a manual machine. Adding CNC is not going to increase it's capacity, but it will certainly increase it's usefulness.

I take it that with CNC instead of learning to manually machine and go a little bonkers from that, it's CAD that makes you a little bonkers with CNC?

Once you shift your thinking from manual feeds and speeds and get comfortable with the machine running itself, then you get to go bonkers figuring out the process. Workholding, order of operation, tool selection, etc. As you gain experience with both CAD and your machine, the parts you make will become more complex, and you will probably spend more time figuring out how to machine the part than actually machining the part. I did a 4 axis part the other day that I spent hours working out order of operation and tool selection, and about an hour doing the actual machining.

 

[jbolt]

I have had both manual and CNC mills, my current mill is CNC only, no hand wheels. I have become very comfortable running the machine as CNC or manually with an xbox controller as a pendant.

As for the lathe I have never found a reason to convert one to CNC as I don't know what I would use it for. Then of course there would be the problem of wanting an auto tool changer, air chuck and bar feeder!$$$

 

[bpratl]

The only reason that I converted my lathe to CNC was to be able to cut metric/ASE threads with out changing gears and have the ability to machine tapers/balls without special fixtures.
I started with an ELS conversion on Z axis only and then converted the X axis for full two axis CNC.

 

[HEAVYMETAL87]

Thank you everyone, I really do appreciate it.

The reason that I wanted to do CNC was for repetitive stuff mostly- or things that I would value being precise and what not. Part of the reason why I didn't want to break the bank on it too much. At the same time though, if I decide to go full Kool-Aid (as my old Drill Sergeant used to say) with this whole thing, then I would have at least gotten my feet wet enough to know what I was doing. I would love to build a router at the bare minimum, I had an idea with a friend of mine who is a programmer to make custom tool trays where someone would just select the tools on a website, lay out how they wanted them arranged through Flash, and then if they ordered it some how convert the order into a format the CNC software would recognize.

I take it that the bells and whistles like tool changers and the like is where the DIY realm ends and the nightmare begins?

I wonder if it would be possible to attach a 3D printer head to an R8 taper some how- and use a CNC mill as a monster 3D printer.

 

[JimDawson]

I had an idea with a friend of mine who is a programmer to make custom tool trays where someone would just select the tools on a website, lay out how they wanted them arranged through Flash, and then if they ordered it some how convert the order into a format the CNC software would recognize.

I'm a little confused about what you are suggesting here. But in software almost anything is possible

I take it that the bells and whistles like tool changers and the like is where the DIY realm ends and the nightmare begins?

That might be considered an advanced DYI project I have a mill sitting out here with a 24 station tool changer on it. I wrote the software to run it.

I wonder if it would be possible to attach a 3D printer head to an R8 taper some how- and use a CNC mill as a monster 3D printer.

Yes, absolutely! You need a 4th axis available to do it. I'm going to do this with both my router and mill.
.
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[HEAVYMETAL87]

Jim, sorry about that. I was kinda going on a tangent.

A few folks I know including myself really like shadowed tool boxes. The idea was to set up a small business where people could design and order custom inserts for their boxes made out of plastic that would be made on a CNC router. The plan was to figure out a way to make the website and the CNC software work together.

That still sounds totally badass though- having a tool changer like that. Then again though, it would also imply a powered draw bar.
What's the forth axis if you will forgive me being dense?

If I have plans for something as a PDF, can that be imported over to the software and used as a start point- or would I have to basically reproduce it all?

 

[JimDawson]

A few folks I know including myself really like shadowed tool boxes. The idea was to set up a small business where people could design and order custom inserts for their boxes made out of plastic that would be made on a CNC router. The plan was to figure out a way to make the website and the CNC software work together. If I have plans for something as a PDF, can that be imported over to the software and used as a start point- or would I have to basically reproduce it all?

There are PDF to DXF converters, so yes that is possible. To get the scaling correct you would need a couple of accurate dimensions. I do this all the time. There are also methods to import a picture and scale that. It requires a bit of work, but once you get the hang of it, it's pretty easy.

That still sounds totally badass though- having a tool changer like that. Then again though, it would also imply a powered draw bar.

What's the forth axis if you will forgive me being dense?

Not a problem, we are here to help educate. X, Y, and Z add up to 3 axis. The stepper drive on the feeder of the print head requires an axis also. So you need a 4th axis to operate it. Mach3 will handle this.

 

[HEAVYMETAL87]

Wow.

Well that is convenient. That tool changer you built is too awesome for words. I was just thinking of something like the Tormach ones.

A lot of the plans have literally got dimensions everywhere on them- so that would work in my favor as well.

 

[JimDawson]

I didn't build that tool changer. I just put a new motor on it, built a new gearbox, designed the controls, and wrote the software.