Got my X2 CNC running!

[BrassBuilder]

Hey All,
I got my X2 running under CNC! It was quite an interesting process. I'll tell you some of the things that I dealt with in a moment, but first I have a couple of questions:

1. How do I measure the backlash on the machine to compensate for it in Mach3? What exactly am I measuring???

2. Can you change the feedrate right from the main Mach3 screen? There is a feedrate setting, but no matter what I input, the rate of the table movement stays the same. I finally went into the motor tuning and upped the velocity (I think that is what it was called), to get the table to move faster.

Random thoughts on the build:

I used the cncfusion kit and a keling motor kit for the build. I converted the mill to belt drive from LMS. I am running Mach3 on an IBM NetVista P-IV 1.8ghz computer with 1gb RAM.

The wiring *almost* turned into a nightmare. It took quite a bit of google searching and looking at Hoss's site for motor settings to figure it out. I am electronically challenged.

I mounted all the control stuff in an extra Emachine computer tower case. The on/off switch for the computer was exactly the right size hole for the emergency stop switch. It fit perfectly. I have another case and I am thinking about taking the guts out of the IBM desktop computer (appears that the motherboard will fit) that I am using for Mach3 and install it all in the spare Emachine case. Then all my cases will match. I used D-sub connectors on the back to hook up the wiring for the X, Y, and Z axis. That way, all the wiring can disconnect should I ever need to move the mill.

I need to figure out a place to put some of this stuff. I pretty much lost my whole workbench to the computers and monitor for the CNC portion. I also want to tidy up the wiring going from the motors to the controls. I left the wires a little long and they are just laying all over the bench.

I took the mill completely apart and cleaned everything before I put it back together with the CNC components and the LMS belt drive kit. I have a lot of the manual pieces left over from the mill that I probably will never use again.

Wiring in limit switches is going to be the next to-do project.

I have a ShuttlePro controller coming. If I don't like it, I'll give it to my son in Los Angeles. He is an editor out there and he can use it with Final Cut Pro and whatever else he uses.

I finally got the chance to run something through the mill tonight. I used the "Write Wizard" in Mach3 to engrave my wife's name on a piece of aluminum. It took me a couple of hours to figure out how to "home" the mill to start where I needed it. Re-watching the coordinates video on the Mach3 site helped alot there. I also found that I had to tweak the automatically generated g-code to get it to run properly. But, once I got that figured out, it was pretty cool watching the machine do its thing. My wife thought it was pretty cool too. Especially since it was her name being engraved.

All in all, I know that I will be happier with the CNC instead of the powerfeed and DRO that I originally planned on. I still have a lot to learn though.

Mike

[LongRat]

With regard to movement speed, it depends on how you are commanding the motion. If you are using the jog buttons in Mach (press TAB to bring up the jog screen) then the speed will be whatever percentage of your maximum is displayed on the jog screen. The maximum (rapid, G0) speed is what you select in motor tuning. You should set this up first to be the fastest your machine can move, at all positions in the working volume, without stalling or losing any steps. Then take a bit off that for safety. You might find this is a little too fast for you to feel comfortable, so you can set it lower. As long as it doesn't lose steps when performing G0 moves, you are good. The acceleration is used in the same way - the highest you can have without missing steps.
If you are running G-code, through either an imported file or in the MDI screen, the feed speed is set in the code. But it still CAN NOT exceed the max velocity you've set up in motor tuning. For example if you have set 1500mm/min as the max x axis speed in motor tuning, and your code commands g1x100f2000, you will still only get f1500 movement speed.
Also, remember to check the feedrate override on the main Mach screen. This can be set to a percentage of the code-set speed.

Good luck with it, you will not be sorry you went for CNC. It's great!

[bilinghm]

This is exactly the conversion/components I am planning. Which steppers did you select? Did you buy the preloaded ball nuts? Is tramming of the head a problem?
Please post some pictures of your finished mill.

Thanks!

[ataxy]

you backlash is the amount of play the scew will have when you reverse your movement so lets say you go x-1 then x1 the screw will turn slightly before it engage in the opposite direction as an example you will get maybe on a brand new acme screw about 0.005 of backlash this would mean you would go x-1 and actually x0.995 and not x1 to check backlash on an a x2 i would check it at three point on the table with and indicator so both edges and themiddle and do and average but remember contrarly to ballscrew acme will wear faster because of the friction and in the case of circular interpolation like for round pocket backlash compensation does not a good job but on linear motion its not that bad but still not as good as ballscrew so if you use it recheck often to compensate for the wear of the screw

ps.: also remember that you wont be able to drive your motor as fast with acme as stepper tend to loose there torque at high speed wich raise the risk of loosing step wich is not a problem with servo where the encoder will make the servo compensate for the lost step

[BrassBuilder]

Originally Posted by bilinghm This is exactly the conversion/components I am planning. Which steppers did you select? Did you buy the preloaded ball nuts? Is tramming of the head a problem? Please post some pictures of your finished mill. Thanks!

I'll try to get some pics up this weekend. I still need to clean the workbench off. I have all my tools and spare parts laying all about. Sort of messy right now.

I used the "C" package with the 425oz steppers on this page:

http://www.kelinginc.net/CNCNEMA23Package.html

Both Keling and cncfusion recommended those for my X2. Plus they were only $30 more than the 282 oz.

I have not trammed the head yet. In fact, I have never trammed it since I bought the mill. I really need to get that done. But like checking the machine for backlash, I don't really understand the procedure. But...after figuring out how to CNC the mill, I should be able to figure everything else out now.

I bought the preloaded ball nuts from CNCfusion too. After I tossed around all the numbers and looking at buying part of it now and part later, it was just more cost effective to buy the whole works and be done with it. Plus, cncfusion needs to preload the ballnuts "in house" or so I understand. I didn't want to mess with it anyway...

Be prepared to spend some money if you buy everything premade. I think I spent around $1300 to CNC this. But that also included the cost of the IBM computer from ebay.

Mike

[dang]

Photos? Video?

[ataxy]

here check this
http://its.fvtc.edu/machshop3/BasicMill/backlashIS.htm

here is an example on my mill (ok its on now)
http://www.youtube.com/v/v2Sp-Z2AbnY

[BrassBuilder]

OK....I finally have the concept of backlash down.

Now...How do I measure it? I don't have a clue. I sort of see the setup in the second video, but I am not sure how it is measuring backlash.

I'll get some pics posted this weekend.

Thanks for all the comments!

Mike

[ataxy]

move your indicator on the face of a flat block
set it to zero
set the dial on your mill to zero or you dro
now start moving the opposite way
as soon as your indicator start to move check how much your dro or the dial on the handle had to move befor the indicator started moving this is your backlash