DRO now ($300) vs CNC Later ($700+)?

[hcanders]

I need help !
I have purchased an x3 from grizzly, and can't decide on the seq. of upgrade. As I don't have lot's of spare dough and I would hate to waste money on something I can use later.

Thanks Hans

[Bubba]

Hans,
I was faced with the same proposition when I got my mill/drill. As I thought "I will never cnc", I went ahead and put DRO on it, but within 6 mo. I decided I wanted to cnc it. I had also put power feed on two axis!
In other words, I was half way their, but had to go back and change everything out:{(
If you are going to cnc in say 2 or 3 years, then it might be nice to put DRO on as this will be helpful making the cnc parts. However if you plan on doing it in a short period of time, I would put my money to cnc parts!
My machine has NO handles so everything is done via keyboard for any manual things that I do now and the screen gives me any position information that I need.

[eaglej]

I got my X3 about a month ago and have just been noodling around with it and tooling up. I am pretty much cashtrated (money has been surgically removed) right now, but am making plans for the spring- lathe buy, DRO and cnc conversion...

I think I am going to go the DRO route first, for a few reasons. For one, it will help me make the parts for the conversion more easily, and once the conversion is in "test mode" it will allow me to set up the software and check accuracy/repeatability. I think the DRO will be useful to make sure steps aren't lost etc, as well as setting up a quick 1-off job. Since what you are seeing in Mach 3 is really just derived from motor steps, I think the DRO will be good as a sanity check to verify what is happening. Does this make sense to you?

For me, I think I would like to have some ability to manually operate- I am thinking about two shaft motors and keeping the handwheels. Has anyone done this- are their drawbacks? I know that freewheeling the motors will add some drag, but hopefully the ballscrews will move much more freely than the acme, so it might be a wash? Any input would be appreciated.

Good luck.
J

[hcanders]

I have been looking at Shumatech DRO but think if I can use Mach3 as my DRO display I'd be saving $. I deffenitly want to keep manual operation capabilities so eventually I'd either drive with pullies that could be disingauged or double shaft steppers.

I need to find out if Mach3 can use digital scale inputs now for DRO and later for feed back w/ steppers.I think that would be the most upgradable.
1st digital scales w/ mach3 as DRO
2nd steppers w/ scale feedback and Man. scale DRO

I hope thats possible?
Hans

[Bubba]

j,
Ballscrews ARE much more free to move. So much so in fact, they can and will be "back driven" by the forces on them. In other words you will have to hold the axis in position instead of just moving it there! And I don't think you want to leave the steppers/servos powered while you move manually? Therefore, the back driven problem is very real.
Any handles on the steppers/servos can become weapons of distruction (to you) if any body parts are in the way.
I was convinced by several people when doing my conversion not to have handles on my machine. I don't and haven't really found a situation where I needed them.

As for the worry about lost steps, this could (but shouldn't) be of concern IF you get your machine setup properly. As for one offs, this is mostly what I do on my machine and it lots of times involves curves (G02 and G03) which I would not even attempt doing manually! For simple moves, MDI is my friend and it will postion the table more accurately and quickly than if I had moved it by hand. My rapids have been limited by choice to 80 IPM in the X and Y axis and on a mill/drill, that is plenty fast. Try hand cranking it that fast to get to a point. Also, if I want to mill say a 10" slot, MDI will make the cut at a consistent rate (= better finish) and I can hardly do that by hand. A 10" cut at .1" per turn of the handle is 100 turns!
In both cases, you are going to have to pay attention to your setup and do it with care and many checks to make sure it is right.
We all have been there with the cash problem and having done it the way you suggest is the reason for my post. IF I was to do it over again and knew I was going to cnc in a relatively short period of time, I would not spend the $$$ or time installing DRO UNLESS we have available a different control program that will allow additional input (say from the DRO) to cross check the position.

Hope this helps.

[Rodm1954]

I have converted an X2 and just recently an X3 to CNC. Bubba is offering good advice here. We all start with an element of doubt about the accuracy of CNC and our skills to convert a machine. We all wanted manual backup because it is a safety net and allows us to go to familiar territory. I use a double ended stepper motor and just attach a knurled knob but on the X3 you can't do this for the Z axis. See photo of X and Y motors on the X3.
Truth is CNC is far better than manual operation so forget the handwheels and DRO's and save your money and effort.
As Bubba says if it is going to be some time before you do the conversion then DRO's are handy for manual operations.

[tmarks11]

Originally Posted by hcanders I have been looking at Shumatech DRO but think if I can use Mach3 as my DRO display I'd be saving $.

Straight from the mach3 manual:

Section 4.12. Linear (glass scale) encoders. Mach3 has 4 pairs of inputs to each of which an encoder with quadrature outputs can be connected... Mach3 will display the position of each of these encoders on a dedicated DRO...

Of course, you are still looking at a hardware issue... getting the signal from the encoder into your computer. Sound logic makes a breakout board to connect the encoders to your computer, which will allow you to use the displays in MACH3 for your DRO:

http://www.rogersmachine.net/encoderinterface.html

Common wisdom would suggest that you not bother. Once you establish zero reference after power up, mach3 will effectively know your axis position based upon what it has told the stepper motors to do. Unless you have horrible backlash problems, you will only get a small improvement in accuracy with the separate linear scales over what Mach is already telling you for free (yeah right) with the existing cnc setup. Read some good stuff here:

http://www.cnczone.com/forums/showthread.php?t=24817

Like everyone lese here, you gotta figure out how long you will be running manual operations to see whether or not you are throwing money down the drain. Plus, you don't HAVE to use a DRO during manual operations to get a great product; it just takes longer.

[eaglej]

Bubba-

great info- I really appreciate it. Hadn't considered that the forces from the cutter could move the table. No, I wouldn't expect to have the motors energized- wouldn't be able to turn them a bit by hand if they are locked up. My buddy has a homegrown 2axis plasma table, and when it is powered off, you can move the tram, but the motor itself offers up some resistance- that is what I was referring to..

Overall though, I think I am seeing things your way. My mind just jumps straight from the macro to the micro, ie. How do you do simple stuff like walk the table up to edgefind? Do you write a 1 axis code to step in 0.001increments, and just repeat until your finder moves? Or do you have some sort of jog-wheel?

I am pretty sure I read an article about how to make a rotary jog wheel, but it looked pretty complicated. If I remember correctly, it had a switch so you could toggle between rapid/fine movements. Honestly, I have read some of the mach3 manuals to understand the functionality, but what I don't know could fill volumes.

Sort of long winded! Sorry. I appreciate the info though, as I am filing away what I can glean from here. I would prefer to learn what I can from people who have been there, so when I do my conversion, I don't immediately wish I had done it differently...

J

[skmetal7]

Originally Posted by eaglej Bubba- Overall though, I think I am seeing things your way. My mind just jumps straight from the macro to the micro, ie. How do you do simple stuff like walk the table up to edgefind? Do you write a 1 axis code to step in 0.001increments, and just repeat until your finder moves? Or do you have some sort of jog-wheel? I am pretty sure I read an article about how to make a rotary jog wheel, but it looked pretty complicated. If I remember correctly, it had a switch so you could toggle between rapid/fine movements. Honestly, I have read some of the mach3 manuals to understand the functionality, but what I don't know could fill volumes. J

use one of these http://www.cnc4pc.com/Store/osc/inde...98d23e17b0be4c

[tmarks11]

I would recommend you take a quick look at the Mach3 manual. All of this is very well explained; it is a very good tutorial on using mach.

http://www.artsoftcontrols.com/docum...Using3Mill.pdf

Jogging setup is described in section 3.3. You can use any keyboard buttons (default setup to cursor arrows) or even a joystick.

[Bubba]

j,
First off, I use Turbocnc instead of Mach so my comments are based on what I do with it as I am not familiar with Mach commands.
Having said that, I have never even set up the incremental jog function. All jogging in the jog window is done in continuous mode. In other words, if I want to gently move the spindle to the right using an edge finder, I simply push the right arrow key and hold it. I have my slow jog set to 1IPM just so I can creep up on an edge like that.
For discreet movements, I use the MDI mode and input a G code to make it move where I want to.
Yes, I use key movements not a mouse or track ball which even though connected hasn't seen use in a couple of years! I could setup an MPG (Manual Pulse Generator), but for MY setup, it would be just another piece of gear that I would have to find a place to put. The keyboard is in a convienient place and works very well for me.

[hcanders]

Thanks for the info, i believe I can use mach as a DRO until I am Able to CNC the machine. The links and disscucions really are enlitining. Thank again
Hans