# more cnc Q.



## MCRIPPPer (Jan 25, 2015)

ok. i want to start collecting parts for a cnc conversion of minimill. i want to start with the computer. looking on best buy i can get refurbished computers for $150 or so, running windows 7. thinking i will go for mach3 software and a usb control device. is it ok to run CAD on the same computer that controls the machine? i have been playing around with freecad and like it so far. what is a usable free or cheap CAM software?

i cant seem to find any computers with a parallel port, so i guess im stuck with usb.


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## JimDawson (Jan 25, 2015)

There are still some computers out there with a parallel port, I just bought a used laptop ($139) the other day that has one for that very purpose.  I just called my computer guy and told him what I needed, and said go find it.  You just have to look at the mom & pop computer shops.  Failing that, there are add on parallel port cards available for cheap.   Goodwill and Craigslist are another resource.  My preference is a laptop because you have everything in a small package.

There is no reason that you can't run Mach3, CAD, and a CAM program on the same machine, just not at the same time.  Mach3 does not like to be disturbed when running.  

For a CAM program my preference is CamBam http://www.cambam.info/  Free to download, with 40 free full featured runs, then reverts to 500 lines until you buy a license. $149, they also have an older completely free version.  It plays well with Mach3.

There is also open source software available, but I have no experience with it.  Linux CNC is one open source software that comes to mind, and there is free CAD and CAM software out there.

When you get ready to buy the motors and drives, Amazon and Ebay both have a number of CNC kits available at reasonable prices.

I hope this helps.


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## MCRIPPPer (Jan 25, 2015)

thanks. 

im wondering if it is worth it to just pay the 150 or so for a usb type driver board and avoid weird issues with mach3 getting interrupted? (thats what i hear at least, that usb does not have that issue) anyone have experience with mach4?


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## MCRIPPPer (Jan 25, 2015)

is it possible to run both a mill and lathe (at different times) on a single computer with mach3? im guessing i would need two breakout board setups.


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## JimDawson (Jan 25, 2015)

Absolutely possible.  The breakout boards normally come with the motor kits.


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## MarkStephen (Jan 25, 2015)

MCRIPPPer said:


> ok. i want to start collecting parts for a cnc conversion of minimill. i want to start with the computer. looking on best buy i can get refurbished computers for $150 or so, running windows 7. thinking i will go for mach3 software and a usb control device. is it ok to run CAD on the same computer that controls the machine? i have been playing around with freecad and like it so far. what is a usable free or cheap CAM software?
> 
> i cant seem to find any computers with a parallel port, so i guess im stuck with usb.



Shouldn't be too hard to find a decent computer with a parallel port for around that price that will run LinuxCNC / Mach3-4. If your thinking of LinuxCNC I would shy away from laptops. 

If your going to use a 2D CAD program, most any computer will do. However, if your thinking of a 3D solid or polymesh CAD, you will almost need a computer with OpenGL capabilities, (3D video card/chip). 

As for usable free or cheap CAM? In the free arena, there are a number of 2D CAM programs and plugins, like the CAM plugin for Inkscape, and even browser based CAM like MakerCAM. For 3D maybe the best you'll find today would be PyCAM, though you will be looking for your 64 node Beowulf cluster to run the thing on once you start trying to do 3D follow contour paths. It is not known for it's speed. 

I say today, as some of the developers of the mentioned FreeCAD are working on a Path module that should be very fast in it's computations and work from true solids (instead of meshes), but like most everything FreeCAD, it is being developed by very talented volunteers in their spare time and it will be done when it's done, and not a moment sooner.  

In the "cheap" or inexpensive, category there is CamBam, (already mentioned), that is very popular and capable as well as the slightly more expensive MeshCAM (which I like). There is also Estlcam which also falls well into the cheap category. 

Machine control - of course there is Mach3/Mach4 and LinuxCNC, but there is also grbl which runs on an Arduino and uses a USB input and takes the Gcode streamed to it from programs like Grbl Controler if you want to go the bare bones / dirt cheap route. The up side of Grbl Controler is that it will run on a Raspberry Pi or Beaglebone just as well as it will on a high powered desktop. 

Anyway, some things to think about and there are plenty of options out there. 

Mark


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## rdean (Jan 25, 2015)

Instead of USB take a look at Ethernet.  Very fast and stable.

Ray


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## MCRIPPPer (Jan 25, 2015)

thanks guys. thinking of cambam with mach 3 would work well for me and still cheap enough. 

is it a bad idea to leave the stock leadscrews in my machine for now? i would just have to make sure to conventional mill right?


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## JimDawson (Jan 25, 2015)

MCRIPPPer said:


> thanks guys. thinking of cambam with mach 3 would work well for me and still cheap enough.
> 
> is it a bad idea to leave the stock leadscrews in my machine for now? i would just have to make sure to conventional mill right?




Conventional mill, yes  You can use the stock leadscrews, it just won't be quite as accurate as ball screws, also you will need to program in the backlash compensation in Mach3.  I would also go with higher end of the torque range motors in the NEMA 34 size because the acme screws have much more friction than ballscrews.


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## compsurge (Jan 25, 2015)

You can check out Autodesk Fusion 360. It's what I use for CAD and CAM. Well, I've at least played with setting up the CAM. I haven't used it quite yet on my CNC that is not complete:shush:. You should be able to register it as a hobbyist and use it for free.


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## bladehunter (Jan 25, 2015)

Go for ballscrews straightup, from memory mine were $180 AUD delivered for my BF20L (G0704 equiv). You'll get frustrated with the stock screws soon enough.

CamBam is easy enough to use, once I get the $$$ together I'll purchase it a full version, but for now I just break each machining task into separate files.......also gets around the 500 line limit on Mach 3........which I will purchase once the $$$ come in.

As for CAD eMachineshop's program can be used, for simple things, draw your part up and export each view as a dxf and import it into CamBam. It's not perfect but you can get a 3D view of your part.

Try a few trial versions of various CAM products, don't commit to one particular product too soon, get a feel for what you feel most comfortable with.

I'm a virgin CAM\CNC user so I may not be speaking with any sense.


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## MCRIPPPer (Jan 26, 2015)

thanks for all the comments. 

thinking of this motor setup.


http://www.automationtechnologiesin...a23-cnc-kit-36v9-7a270-oz-inkl-4030-duplicate

and the ethernet smoothsteper

http://www.automationtechnologiesin...pper-ethernet-motion-control-board-for-mach-3

running on windows7 desktop machine, with mach3, cambam, and freecad. other than wire, screws, aluminum and other(REAL) hardware, what do i need?


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## bladehunter (Jan 26, 2015)

What machine are you thinking of converting ?


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## MCRIPPPer (Jan 26, 2015)

SX2 mini mill. 




where is a good source for ballscrew parts? i have a lathe also so i want to make my own conversion parts as well.


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## bladehunter (Jan 26, 2015)

Chai is your man. Send a message via ebay.

http://www.ebay.com.au/usr/linearmotionbearings2008

Unfortunately he hasn't got anything listed, but by all accounts he is the man to deal with. Even tho being China based his English communication is top notch. If you do have any issues with parts, Chai is quick to rectify the situation most promptly. Have Chai do all the end machining for you, just send him a drawing of what you require. He will even grind\machine down a flange on a ballnut if you require that done. From memory I think he does sell 12mm ball screws.

I used his ballscrews on my BF-20. 

All though an X3 conversion you may want to have a look at this:
http://www.arceurotrade.co.uk/projects/X3-CNC/X3cncIndex.html

And don't forget to checkout cnczone, a wealth of information available.


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## JimDawson (Jan 26, 2015)

You might want to consider a bit more torque since you are planning on running the acme leadscrews  Maybe this kit http://www.automationtechnologiesin...-2x570ozin-3-stepper-drivers-etc-120vac230vac  or better this one http://www.automationtechnologiesin...is-kits/nema-34-stepper-motors-3-4-axis-kit-7

I'm not sure just how big your mill is, but NEMA 23 motors are OK for small tabletop routers, but not for mills.  NEMA 34 motors would be better.  You can always cut the power back on a bigger motor, but you can't add more to a small motor.  You could grab hold of the leadscrew with your hand and stall the 381 oz-in NEMA 23 motor. Also consider how much torque it takes to raise and lower your Z axis.

It looks like the Ethernet card would work fine, but I have never used one with Mach3 so I can't really comment on it.

Besides the normal hardware, you will need some way of coupling the motors to the leadscrews and mounts for the motors.  Belt drive or direct couple?  Either way works. but hardware will be required.


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## JimDawson (Jan 26, 2015)

Here is everything you need to know about converting the SX2.  http://www.hobby-machinist.com/show...l-CNC-Conversion?p=57918&viewfull=1#post57918

I had forgotten about this one.  Makes for a good read, but is going to take a bit of time, 381 posts in that thread.


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## bladehunter (Jan 26, 2015)

570oz/in work great with a G0704 class mill with ballscrews, even for the Z axis.

The articles I linked to included some of the math required to determine stepper sizes. 

As for my own conversion I just ran with what a lot of others have had a lot of success with. ATM I running quite conservative speeds & accels

I know that ACME screws do require more power than ballscrews but what you can get "chinese ballscrews" for I don't see the economics in sticking with the ACME screws.......cos eventually you will get sick of them.

Yes yes I know the difference in quality between a THK screw & nut and the chinese gear, but that does come at a great cost.

As I said before I'm no expert and if I'm wrong please please point me in the right direction.

One thing of note if you do find a PC with a parallel port you can go that route and "upgrade" to a smooth stepper at a later date.

For breakout boards cnc4pc and Homann Designs are highly rated by those in the community.

But most importantly have fun.


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## MCRIPPPer (Jan 26, 2015)

looking at the hossmachine website, i see he is running a bit over 200 oz in (on the same mill as i have). the kit im looking at has 380 oz in all three axis, so i think i have enough juice for my size mill. im thinking i will just look into ballscrew conversion as well.


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## compsurge (Jan 26, 2015)

You might also want to check out CNC Fusion kits.


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## bladehunter (Jan 26, 2015)

I'd stick with what Hoss recommends or uses, I've followed his recommendations and had no trouble what so ever, so have a lot of others. It is possible to have a stepper that is too powerful and have power that never gets used. There is a few guys using 425 oz/in steppers on a G0704 type mill and seem to be quite happy.

What you may want to look into is the various power curves for each stepper, work out or maybe ask around what cutting speeds WOC & DOC an X2 is happy with and go from there.

If memory serves me correct one or two of the docs on the gecko drive site touches on this subject.

I've seen "self styled experts" suggest stepper motors for the Z axis on a mini lathe in far excess of what I use on the Z or X axis on my mill.


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## MCRIPPPer (Jan 27, 2015)

my mini mill seems happy with light cutting. it does not do well with any sort of heavy milling due to low rigidity of the design. 

i dont really want to go with a premade screw kit because machining and building one off stuff is what i like to do, even if it is not the quickest easiest way. 


for some reason the mini lathe guys seem to think that the head weights several tons and needs a serious power plant to lift. 



i do plenty of manual milling at work so i want a nice little cnc for my home projects.


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## JimDawson (Jan 27, 2015)

Here is the stepper you need to drive your mill.:rofl:  Just unpacked this one, I bought it for a project that I'll post later.  4200 in-oz NEMA 42.  About the same locked rotor torque of a 3HP induction motor.

That's a NEMA 23 stepper sitting on top of it.


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## MCRIPPPer (Jan 27, 2015)

you should save that one and build a winch for a truck.


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## MCRIPPPer (Jan 27, 2015)

looking on ebay, ballscrews for all three axis is only about $100.


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## Karl_T (Jan 27, 2015)

JimDawson said:


> Here is the stepper you need to drive your mill.:rofl:  Just unpacked this one, I bought it for a project that I'll post later.  4200 in-oz NEMA 42.  About the same locked rotor torque of a 3HP induction motor.
> 
> That's a NEMA 23 stepper sitting on top of it.
> 
> View attachment 93513



This reminds me, I have three nema 42 steppers the same diameter and half that long that do 2400 oz-in. I'd be willing to sell them to somebody CNCing a full size mill.

Make an offer.

Karl


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## compsurge (Jan 27, 2015)

Newegg sent out an email today and they have a lot of options for refurbished computers. Here's one that looks decent at $190 and another at $90. Both have parallel ports. Here's the link to all refurbished results that are $50-200.


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## Karl_T (Jan 27, 2015)

I'll mention I've had GREAT success with compac/HP D530 computers. Very cheap on fleabay.
http://www.ebay.com/sch/i.html?_odk....TR12.TRC2.A0.H0.Xd530+&_nkw=d530+&_sacat=179

I stick with one model for all my CNC machines. Then i can just clone the HD and put it on another computer. If i suspect ANY sort of problem, a complete brain swap takes just a couple minutes.

Karl

PS I'd buy this for $50 total if i needed one today
http://www.ebay.com/itm/HP-Compaq-d...204?pt=LH_DefaultDomain_0&hash=item2349c56f44


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## Eddyde (Jan 27, 2015)

Karl_T said:


> I'll mention I've had GREAT success with compac/HP D530 computers. Very cheap on fleabay.
> http://www.ebay.com/sch/i.html?_odk....TR12.TRC2.A0.H0.Xd530+&_nkw=d530+&_sacat=179
> 
> I stick with one model for all my CNC machines. Then i can just clone the HD and put it on another computer. If i suspect ANY sort of problem, a complete brain swap takes just a couple minutes.
> ...


Hi Karl,
I am also shopping for a pc to run my CNC mill project, this is one being considered:
http://www.ebay.com/itm/321497867225?_trksid=p2060778.m1438.l2649&ssPageName=STRK:MEBIDX:IT
I'm attracted to its very small size, It doesn't have a parallel port but I don't think I'll need one as I'm going to use a Galil 2240 motion controller that uses RS232 or ethernet. Am I on the right track or do you see any pitfalls I am not aware of?

Thanks

Ed


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## MarkStephen (Jan 27, 2015)

Eddyde said:


> Hi Karl,
> I am also shopping for a pc to run my CNC mill project, this is one being considered:
> http://www.ebay.com/itm/321497867225?_trksid=p2060778.m1438.l2649&ssPageName=STRK:MEBIDX:IT
> I'm attracted to its very small size, It doesn't have a parallel port but I don't think I'll need one as I'm going to use a Galil 2240 motion controller that uses RS232 or ethernet. Am I on the right track or do you see any pitfalls I am not aware of?
> ...



I'm not so sure of this one. These types on minis have a tendency to bottleneck, especially running windows. If your streaming to a caching controller, (do the Ethernet controllers cache?), this would probably not be a problem, though for modest increase in size, I would think this one mentioned before would be a better machine for the task and leave the option for parallel port intact.

Mark


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