Considering G0720R Build

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11-29-2012, 06:26 AM
enyaw

Considering G0720R Build
Hello

ME (consider skipping to next bold face header): I am new to CNC and I'm a 50+ yr old that after 30+ yrs in IT has decided to change careers and become a Machinist. I am currently getting the third degree (literally) in Machining Technology at the local Community College.

My Mission: In order to get more practice I want to have a CNC Mill at home. I am currently considering getting and converting a Grizzly G0720R. I think I have what I'm going to do with the mechanicals (X,Y, and Z axes) figured out and I'm now working on the electronics. The Z axis ball screw will be driven by a NEMA 34 motor (w/gas spring to help support head) and NEMA 23 motors for X and Y ball screws. I'm looking at 5mm ball screws (5.08tpi).

My initial questions:
1. Are there any Must Have books on CNC I should be looking at?
2. Is there a White Paper out there somewhere on selecting stepper motors?
3. Which stepper motors to put on the X & Y axes?
4. Which stepper motor to put on the Z axis?
5. Are parallel ports (archaic technology) adequate w/modern operating systems to run CNC real-time operations?
6. Recommendations on drivers
7. I suspect this one is a religious question, but here goes, Mach3 or LinuxCNC and why?
That's probably as much as I can absorb to begin with, though as soon as I get the mill I'll also have to deal w/initial tooling.... Thank you in advance for you suggestions and insights.
11-29-2012, 06:59 AM
Connor

Any reason why going with G0720R vs a G0704 ?
11-29-2012, 07:11 AM
jalessi

Wayne,

There are quite a few RF45 conversion threads that you may want to read. The electronics (steppers, drives and breakout board) would be a shoe in for the overpriced G0720R mill. Many thousands of bench top CNC machines are still using the "archaic" parallel port successfully. If you are proficient with Unix then you will be right at home with LinuxCNC if not Mach3 works fine with Windoz.

Welcome to the Zone,

Jeff...
11-29-2012, 09:01 AM
enyaw

Quote:

Originally Posted by jalessi

There are quite a few RF45 conversion threads that you may want to read. The electronics (steppers, drives and breakout board) would be a shoe in for the overpriced G0720R mill.

I'll check out the RF45 threads. Are there mills for less money w/at least the same level of support Grizzly provides, and at least the same features (spindle power, X,Y,Z travel, size of table, rigidity, etc.)?

I couldn't find a US distributor for the XS4, and while I looked at Syil and Tormach mills they aren't in my budget.

Quote:

Many thousands of bench top CNC machines are still using the "archaic" parallel port successfully. If you are proficient with Unix then you will be right at home with LinuxCNC if not Mach3 works fine with Windoz.

Welcome to the Zone,

Jeff...

I knew that the parallel port was widely used, I was just wondering if there were issues and if there was something better, that wasn't on the bleeding edge or super expensive.

So as a control LinuxCNC is better? (the $175 for Mach3 isn't a budget breaker and I have no problems w/Linux, Microsoft, or Mac operating systems) The computer that runs this will be a dedicated machine and other than a calculator(s) and a text editor it won't be running anything else.

Quote:

Originally Posted by Connor9220

Any reason why going with G0720R vs a G0704 ?

The 704 is certainly attractive because there are "bolt on" (almost) conversions available for it and it would have cost just under 1/2 the cost of the 720 (after conversion).

I considered the 704 (along w/the 619 and the 463) and decided that since the 720 weighs almost twice as much (implied more rigid), has greater travel along all axes, has twice the hp, and it would last longer before I had to replace it.

What I really wanted was an old Mori Seiki Jr or a Haas TM1, but both were out of my budget, and the Mori wouldn't fit into my shop and required 3 phase power. (*sigh*)

Thank you for the direction and input.
11-29-2012, 07:17 PM
TiagoSantos

That is pretty much an RF45, isn't it? The only thing I'd say is you could save over a grand by buying an RF-45 from somewhere else.. Some of the improvements that add cost, won't be all that useful after the CNC conversion is done. That said, even though you could do a nicer belt drive conversion including VFD and 2hp motor for less than the difference between a stock RF45 and the grizzly, it would sure take quite a bit of work!

I agree that the 0704 is a nice for the size and price, but not quite the same as an RF45.

Tormach as a white paper on how they selected their stepper motors. It's a nice piece and it taught me a few concepts that I hadn't considered.. But their stepper motors, as nice as they are, aren't easy to find! And Tormach certainly wants a whole lot of money for them.

Parallel port is fine, cheap and easy to work with, lots of support and people who have done it before..

Mach3 vs LinuxCNC - well, I'm very comfortable with Linux, use it exclusively at work and have a linux install at home as well, shared with Windows. I picked Mach3 purely for the incredible amount of support. It's well documented, there is pretty much nothing that hasn't been done or tried already :) I'm sure LinuxCNC is great, I might even play with it at some point, but I didn't feel like reinventing the wheel..
11-29-2012, 07:25 PM
Connor

I think the travel on the G0704 is more on the X Axis. The G0704 can do 18-7/8" According to the Grizzly page, the X on the G0720R can do 16-1/8". Now the G0720R Does have more Y travel. I can do 9-5/8" while the G0704 can do 6-7/8".. However, Hoss has extended that by another 2" in his conversion. The Z travel isn't really that big of a deal, 13" on the G0704, 16-5/8" on the G0720R, but, you can flip the saddle during the conversion on the G0704 and pick up another few inches. I don't recall what it is after. Also Weight doesn't always translate to more rigidity. You've not told us what your planning on using the mill for. So with all that being said. *IF* you really want a larger mill than the G0704, then go with the above mentioned RF45's, otherwise, consider the G0704. I've not seen ANY threads on anyone doing a G0720R conversion, so, you would be a "pioneer" in that front. LinuxCNC is a really good choice. That's what I use personally. If you combine it with a MESA card and breakout board, you can do allot of things. I run my Mill using a Intel Atom B525 board without issue (using parallel part, not even with MESA). Something about using windows for a controller just makes me nervous.

Thanks, Connor
11-30-2012, 12:03 AM
691175002

You pay a lot for the power feed, DROs and other bits and pieces that will be thrown out for a CNC conversion.

The g0720 costs twice as much as some RF45 clones and is inferior in pretty much every aspect that matters for CNC.
11-30-2012, 12:27 AM
wizard
Quote:

Originally Posted by enyaw

Hello

ME (consider skipping to next bold face header): I am new to CNC and I'm a 50+ yr old that after 30+ yrs in IT has decided to change careers and become a Machinist. I am currently getting the third degree (literally) in Machining Technology at the local Community College.

That is a major switch. Will you be going into business for yourself or working for somebody else? I ask because it impacts how the questions should be answered.

Quote:

My Mission: In order to get more practice I want to have a CNC Mill at home. I am currently considering getting and converting a Grizzly G0720R. I think I have what I'm going to do with the mechanicals (X,Y, and Z axes) figured out and I'm now working on the electronics. The Z axis ball screw will be driven by a NEMA 34 motor (w/gas spring to help support head) and NEMA 23 motors for X and Y ball screws. I'm looking at 5mm ball screws (5.08tpi).

Grizzlys mill is very nice and frankly I've been looking at that model myself. do realize that if you CNC the machine much of the value you are paying for will be stripped off the machine or at least not used much after the conversion.
Quote:
My initial questions:

Are there any Must Have books on CNC I should be looking at?
1. Smid? Honestly though if you are enrolled in a machining technology program the school should have that covered. Don't dismiss the online offerings, there is a lot to learn at LinuxCNC for example.
  
  Quote:
2. Is there a White Paper out there somewhere on selecting stepper motors?

Try the Gecko web site. Honestly though Google is your friend here, a bit of searching should have a half dozen sites at your disposal.

Quote:

Which stepper motors to put on the X & Y axes?

Which stepper motor to put on the Z axis?

Ultimately it depends upon what you want to achieve.

Quote:

Are parallel ports (archaic technology) adequate w/modern operating systems to run CNC real-time operations?

It depends pon what you mean. Parallel ports are not archaic at all, eventually you need to get bits in and out of the computer, it is the Operating System that causes issues. In this regards Windows is less than excellent thus the proliferation of interface cards handling pulse generation.

Quote:

Recommendations on drivers

Gecko and Compumotor come to mind at first but honestly there are dozens of manufactures to choose from, it is a matter of how deep your pockets are and your willingness to craft the support electronics.

Quote:

I suspect this one is a religious question, but here goes, Mach3 or LinuxCNC and why?

I'm not to sure most people see it that way. Both solutions are really good but neither is the last word. By that I mean there are a number of competing software or hardware/software solutions out there. Flashcut is one example. These people have a really interesting take: Dynomotion | Motion Control Boards, which is the home of KFlop and the associated software. Look long enough and you will find many CNC controller projects on the net. The gentleman running the CNC Machinist Cookbook: Software and Information site has an interesting article here: CNC Control Market Shares: What Are the Most Popular Controls? « CNCCookbook CNC Blog CNCCookbook CNC Blog

Personally I'd keep an open mind as to which software (software and hardware) you go with. Some of this stuff crosses over from hobby to pro usage very well.

Quote:

That's probably as much as I can absorb to begin with, though as soon as I get the mill I'll also have to deal w/initial tooling.... Thank you in advance for you suggestions and insights.

Yeah tooling is a good way to blow a budget.

Honestly I'd look around a bit for a cheaper bit of cast-iron. Depending upon you usage an "45" class mill may make sense. However for a learning platform it may be a bit expensive even if you find a cheaper version. I'm with you on the additional clearances though which may come in handy if you are to go into business with the mill.

You guys always skip the Weiss 30LV also called the PM30.

PM-MV Milling Machines

It cost less than the 720 and has had a few convertions done on the Zone. I have one and it is a fine machine. 480 pounds big table and great finish.

The G0704 is way smaller.

I have not seen the 720 CNC'ed but it should be just fine and the motor should be more powerfull than the others, but we change all the stuff later anyhow.

I have three of the benchtop mills. A IH/RF-45, Weiss-30LV and a G0704 so I can compair the performance somewhat but mainly it is just how big they are. 300 pounds, 480 pounds and 1000 pounds.

You might want to look up a few of the Weiss 30 builds and perhaps ask them how they like them.

It's been a few weeks and along w/research, life happened (*sigh*).

The G0720R, RF45, and PM30 while in the same class are very different designs. I spent a fair bit of time looking at the RF45 and the PM30 (actually kinda' like the PM30 design) but in spite of the delta in the cost, I've ordered the Grizzly and the stand they offer for it. I decided on the G0720R for several reasons; easier to speed up the spindle (2hp DC spindle vs gear head), Grizzly's customer service, and engineering/design.

For the mechanical bits, I'm working w/Michael at CNC Fusion. I have also decided to go w/Mach3 initially due to the support available for it, both software support and the availability of supported accessories. After I'm making metal shavings I may re-examine LinuxCNC, but it looked like it would take longer to get up and running and using the CNC machine is more important to me ATM than the journey (the build itself).

I am now working on the electrical and electronic pieces. It looks like the computer is going to be a re-purposed HP all-in-one w/ Windows 7, Core 2 Duo, 4GB RAM, and a 21" touch screen (my wife sees my CNC Mill as an opportunity to upgrade her desktop). The only downside I see to this solution is the lack of a parallel port. I guess I'll either be using an USB or Ethernet based solution.

Checks have been written, I'm committed (or should be) now. :eek:
More to come.

I'm looking forward to seeing the G0720R build. I dont think it has been done here before.

Your paying a little extra for the A/C motor but that also means youu won't have to mess with that to get good milling speeds.

If you need any help let us know.

Dave

Quote:

Originally Posted by enyaw

It's been a few weeks and along w/research, life happened (*sigh*).

The G0720R, RF45, and PM30 while in the same class are very different designs. I spent a fair bit of time looking at the RF45 and the PM30 (actually kinda' like the PM30 design) but in spite of the delta in the cost, I've ordered the Grizzly and the stand they offer for it. I decided on the G0720R for several reasons; easier to speed up the spindle (2hp DC spindle vs gear head), Grizzly's customer service, and engineering/design.

Nice! It will be good to see a fresh build on this forum. I just hope that being the guinea pig is up your alley.

Quote:

For the mechanical bits, I'm working w/Michael at CNC Fusion. I have also decided to go w/Mach3 initially due to the support available for it, both software support and the availability of supported accessories. After I'm making metal shavings I may re-examine LinuxCNC, but it looked like it would take longer to get up and running and using the CNC machine is more important to me ATM than the journey (the build itself).

Well that is the #2 solution depending upon who's numbers you believe. Generally you don't hear to many complaints about Mach 3

Quote:

I am now working on the electrical and electronic pieces. It looks like the computer is going to be a re-purposed HP all-in-one w/ Windows 7, Core 2 Duo, 4GB RAM, and a 21" touch screen (my wife sees my CNC Mill as an opportunity to upgrade her desktop). The only downside I see to this solution is the lack of a parallel port. I guess I'll either be using an USB or Ethernet based solution.

USB solutions are bad voodoo, go with Ethernet.

Quote:

Checks have been written, I'm committed (or should be) now. :eek:
More to come.

Better to write that check now then to wait till 2013 when none of us will have any money.

I found linuxcnc quicker and easier to set up than Mach3. I also find it simpler and more intuitive to use. Linuxcnc has advanced a lot in usability over time.
To do some fancy things can require some simple editing of text files, but i find it more reliable and with greater control of how i want it to work.
Setup for 3 axis with limit switches, home switch, spindle sensor and various other options is all handled by an easy gui wizard. The general install is a dead easy livecd then install.
I'd try it for a couple of hours before shelling out for Mach3.
Probably the biggest problem with linuxcnc is that there is less info available targets at the new user. A lot of what is around is hard to understand at first.

"USB solutions are bad voodoo, go with Ethernet." - That is absolutely not true. There have been some problems (a fairly small number) reported with the USB SmoothStepper, but many of us used ours for years with no problems that could be reasonably attributed to the USB interface. And there are certainly other USB motion controllers, like the KFlop that I now use, that are virtually bullet-proof.

Regards,
Ray L.

Heads Up, If your considering going with LinuxCNC later than I don't believe you have any USB or Ethernet options available. From only what I read, they will not support those items due to the latency. Things may have changed but you really need to research it before you back yourself in a corner.

Using the LPT port on a decent machine still leaves you with many options. A PCI card can always be added if your board doesn't have the LPT port.

I'm looking forward to watching your build.

Richard

Quote:

Originally Posted by HimyKabibble

"USB solutions are bad voodoo, go with Ethernet." - That is absolutely not true.

Wrong! It very much depends upon Windows and any system management features built into the computer. Windows can and does ignore USB for long enough to impact many USB interfaces for Mach3.

Quote:

There have been some problems (a fairly small number) reported with the USB SmoothStepper, but many of us used ours for years with no problems that could be reasonably attributed to the USB interface.

You may be a lucky one others have had problems. It is very difficult to predict ahead of time just how well any one board, BIOS and Windows version will work together in this sort of application.

Quote:

And there are certainly other USB motion controllers, like the KFlop that I now use, that are virtually bullet-proof.

That may be true but KFlop is a different implementation with exceptional intelligence in the hardware.

Quote:

Regards,
Ray L.

What you need to ask your self is why the SmoothStepper people went with Ethernet.

Though your repurposed computer is nice, it is overkill. Go to a garage sale and get one with a PP and be done with it.

Quote:

Originally Posted by wizard

That may be true but KFlop is a different implementation with exceptional intelligence in the hardware.

It's still a USB device, and no more, or less, tolerant of USB issues than the SmoothStepper, or most other motion controllers. It does not do any exceptional buffering or anything, and it's control interface is quite similar to the SmoothStepper.

Quote:

Originally Posted by wizard

What you need to ask your self is why the SmoothStepper people went with Ethernet.

I don't have to ask myself. I was speaking to both Greg Cary (the SmoothStepper developer) and Brian Barker (the Mach3 developer) on a regular basis when it was being developed, and I was one of the first beta testers. I have used several SmoothSteppers, both USB and Ethernet over a period of many years. I was one of the first adopters of BOTH the USB and Ethernet SmoothSteppers. How much experience do you have with either SmoothStepper, or any other motion controller, for that matter? Were you at all involved in the development and testing of either one? Or are you just repeating things you've heard, or extrapolating a single negative personal experience into a far bigger problem than it really is?

The fact is, Greg developed the Ethernet version for reasons completely apart from what you seem to believe.

*Every* interface has problems on some machines, even the parallel port. But the fact remains, the number of users who had problems due to USB issues was, and is, quite small compared to the total installed base. That is a fact, based on conversations with those who actually *know* first-hand, and not just my opinion.

Regards,
Ray L.

1 Attachment(s)

WARNING: This post is mostly me processing my thoughts in a public forum, though the issues and reference materials may be of use to the next person doing their first build.
Still struggling with understanding the electrical pieces and the issues surrounding them. for those that follow me, these resources may be of help:

Stepper Motor Basics - I found this one easier to read and more practical than the one on the Gecko site.
Drive Circuit Basics - The word basic here is very relative.
Microstepping - Gets technical fairly quickly.

I've talked to Michael at CNC Fusion and it looks like there will be enough clearance on the X & Y axes to allow the use of NEMA 34 motors, so moving the 117 lb table (and whatever workpiece I decide to put on it) won't be an issue.

I've been playing with a spreadsheet (see attached) that a friend of mine developed and attempts to predict which will stall first the spindle or the stepper motor. It unfortunately doesn't take into account lost steps, but it's an interesting starting point. Currently I'm chasing down the torque curves on some NEMA 34 motors in the 800-900 in/oz range to put into the spreadsheet. I haven't decided what to use on the X &Y axes yet, but I'm planning on a 1200 in/oz motor for the Z.

Still reading on Drivers and Microstepping. And of course there is the issue of how to talk to the drivers. Initially (for political reasons, and she didn't hassle me on buying the mill) I am committed to using the HP IQ524 All-in-One. It has a 10/100/1000 Ethernet port, 5 x USB 2.0 ports and an IEEE 1394 (firewire) port.

In the end I'll probably use either an Ethernet or USB motion controller w/some smarts built into it. If there is a sufficient buffer, It seems like it should run fairly smoothly.

Neither the USB nor TCP (UDP is better suited have to check for support) is well suited for real-time operations. And I haven't found an affordable motion controller that supports IEEE1394 let alone that is supported by Mach3 (or LinuxCNC). I was hoping to find an affordable IEEE1394 to IEEE1284, but no luck so far.

For those that read this far, sorry for the rambling and online processing of my thoughts.

Glad to see another G0720 headed for CNC.

Hi,

Glad to hear that someone else decided on the G0720 series mill. There are only two other G0720 mills being converted to CNC on this site. One belongs to Jeff(Velocirex) and the other is mine.

Both of our builds builds have stalled for pretty much the same reason; life. I see that you are considering using NEMA 34 motors for your conversion in the 800-900 oz-in range for both X and Y and 1200 oz-in for the Z. Good choices to be sure but going 1200 for all three will simlpify your power supply requirements. Unless, of course, you were planning on powering each motor individually.

If you have yet to buy your ballscrews, do yourself a favor and get 1605 ballscrews for the X. Saves you the trouble of having to grind the ball nut flange of a 2005 for clearance.

Joe

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