[ncdeftones]

I have a question for any of you using stock screws with the G0704. What should I set my Kernel speed to in Mach3? I left it on the default (25 kHz I think), but I did notice I'm awfully close to over running the Kernel with my motor setup. My steps per are around 16000...yes 16K not 1600. When I was first calculating my steps I misfigured and entered 18000 and I got a message stating something like my motors were running faster than the Kernel would allow.

I gotta get me a lathe and order me some ball screws, but that's not going to be anytime soon.

[mrcodewiz]

I have a question for any of you using stock screws with the G0704. What should I set my Kernel speed to in Mach3? I left it on the default (25 kHz I think), but I did notice I'm awfully close to over running the Kernel with my motor setup. My steps per are around 16000...yes 16K not 1600. When I was first calculating my steps I misfigured and entered 18000 and I got a message stating something like my motors were running faster than the Kernel would allow.

I gotta get me a lathe and order me some ball screws, but that's not going to be anytime soon.

What values are you using to calculate your steps per?

[ncdeftones]

What values are you using to calculate your steps per?

I used the tuning feature under the settings menu. When I was first tuning using the numbers on the table I entered an incorrect value and it calculated the steps per as 18000 something. I existed out of Mach3 and when I went back in it gave me the warning message. I re-tuned using my dial and test indicators and got the actual value or right around 16000 steps per and I no longer get the warning, but I'm not sure exactly where the Kernel starts having problems so I don't want to cause an issue. The machine is moving the distance it should so he steps per are correct. I'm running my drivers in 1/2 step, the highest setting on my driver. My speeds are set relatively low at 50 ipm. I can lower it more if it will help. I'm not really worried about quick rapids. As long as it cuts my part I could care less.


NEVERMIND! SORRY! I think it was a glitch. Now when I play around with insane high numbers now it automatically drops my max IPM slider to compensate for the change in steps per. I guess something somehow got entered incorrectly.

[mrcodewiz]

That seems high. The lead screw is 10 TPI right? How many steps per rev are your motors?

I believe the calculation (for imperial) is

steps per X micro steps X TPI

or in your case (if the motors are 200 steps per rev)
200 X 2 X 10 = 4000

Do you have the units in mach set to inches or mm?

[photomankc]

Motors are 200 steps per rev.

Screws are 10 revs per inch:
Full step should be 2,000
1/2 step should be 4,000
1/4 step should be 8,000
1/8 step should be 16,000


Ball Screws would be 5 TPI so:
Full step should be 1,000
1/2 step should be 2,000
1/4 step should be 4,000
1/8 step should be 8,000

Ball Screws would help you keep the pulserate to something manageable on a slower system. On EMC2 my maximum rate is around 20KHz and that's with little margin for error so I backed away from using 1/8 microstepping and stuck with 1/2, that and I was stalling much easier on 1/8.

[ncdeftones]

That seems high. The lead screw is 10 TPI right? How many steps per rev are your motors?

I believe the calculation (for imperial) is

steps per X micro steps X TPI

or in your case (if the motors are 200 steps per rev)
200 X 2 X 10 = 4000

Do you have the units in mach set to inches or mm?

I'm pretty sure I set it to inches...but that is a very good possibility. I'll have to check on my machine when I get home. I just have Mach3 installed in demo mode on this PC I'm on right now.

You know what you mentioning the formula that it should be around 4000 steps per got me to thinking...I better triple check to make sure it's in 1/2 step mode and not 1/8th. Because 200 x 8 x 10 = 16000 steps. Thanks for your help!

Sorry I'm new at all this. I did cut a really pretty pocket last night. Needed 1.82 in and it cut it dang near perfect with backlash comp on.

[mrcodewiz]

Could anyone be so kind as to post up a closeup of the front gib adjusting screw on the G0704? I already had to fix the rear screw because the gib could slide past the screw head - now I think I have to do something to fix the front one. When I tighten down the screw a little it forces the gib upward (maybe thats OK?) and it tends to make the screw go cockeyed (perhaps because of too little thread engagement?)

thanks

[hoss2006]

Could anyone be so kind as to post up a closeup of the front gib adjusting screw on the G0704? I already had to fix the rear screw because the gib could slide past the screw head - now I think I have to do something to fix the front one. When I tighten down the screw a little it forces the gib upward (maybe thats OK?) and it tends to make the screw go cockeyed (perhaps because of too little thread engagement?)

thanks

Hows this.
Hoss

[mrcodewiz]

Perfect, thank you. I think my problem is actually the 'fix' I put in for the problem with the Y gib sliding past the rear screw. It tends to push the washer at an angle and jam it into the channel. I am just going to have to make a replacement screw for the backside of the Y.

[ncdeftones]

Perfect, thank you. I think my problem is actually the 'fix' I put in for the problem with the Y gib sliding past the rear screw. It tends to push the washer at an angle and jam it into the channel. I am just going to have to make a replacement screw for the backside of the Y.

Are these kind of tapered gib strips common? All the other adjusters I've seen usually have 3 adjustment screws on the sides instead of these 2 on the end and the gib strips are not tapered like the ones on the G0704.

I'm hoping I don't develop problems with mine since I had to do a fix on the rear adjustment screw as well. I also noticed that the back side of the gib strip is fairly wavy and not machined smooth like the face that rides against the gibs. I'm not sure if that's something to worry about since it doesn't actually ride on that side, but I would have thought the surface would have been a little more flat on an important piece.

What exactly is your current problem anyway? Is your table seizing up?


BTW, I was on 1/8 stepping so that's why my steps per were so high. I set it to 1/2 step and I'm now down to around 4000 steps per with stock screws.

[mrcodewiz]

It's probably OK, really. The problem is that I had the rear screw in too far when I installed the gib and front screw. I tightened the front and then loosened the rear (and repeated) to get it tightened up but what that did was it pressed the spacer at an angle and jammed it into the channel. It didnt bind the gib but it made it so I couldn't push the gib deep enough into the dovetail to get rid of all the slop. It was so close it was barely noticeable.

I think if I had started with the rear screw out, pushed the gib all the way in with the front screw, then installed the rear that it would have been OK at least for a while.

[Starleper1]

Are these kind of tapered gib strips common? All the other adjusters I've seen usually have 3 adjustment screws on the sides instead of these 2 on the end and the gib strips are not tapered like the ones on the G0704.

Tapered gibs a lot more common then the non-tapered style. The straight style gibs are cheaper to manufacture, that's why you see them on the cheaper hobby machines. I think it is safe to say that any machine from the G0704 on up (Size&Price) you will see tapered gibs.

Everything I've ever worked on besides the X2/X3 has had tapered gibs.

~Scott

[ncdeftones]

Tapered gibs a lot more common then the non-tapered style. The straight style gibs are cheaper to manufacture, that's why you see them on the cheaper hobby machines. I think it is safe to say that any machine from the G0704 on up (Size&Price) you will see tapered gibs.

Everything I've ever worked on besides the X2/X3 has had tapered gibs.

~Scott

Ok, thanks. Yeah I've only been around little hobby machines and this is my first CNC venture of any kind.

[photomankc]

Yeah, and I can say I really don't miss trying to get those three screws all snugged down and locked without over doing it or under doing it just to have the machine vibrate them loose again.

The only down side is it's a lot harder to make your own if you happen to get bad ones.

[mrcodewiz]

Hoss-

What do you have your motor tuning set to? I am in 1/8 microstep and had the x and y set to 200 IPM, 100 verlocity. The Z was 150 IPM and 50 accel I think. I can run each axis individually just fine but if I try to run multiple axes at once, one or the other will stall. I have to crank them all down to about 100 IPM to prevent it. That seems like a lot considering how well they run individually. I know the power supply is sufficient.

[hoss2006]

Hoss-

What do you have your motor tuning set to? I am in 1/8 microstep and had the x and y set to 200 IPM, 100 verlocity. The Z was 150 IPM and 50 accel I think. I can run each axis individually just fine but if I try to run multiple axes at once, one or the other will stall. I have to crank them all down to about 100 IPM to prevent it. That seems like a lot considering how well they run individually. I know the power supply is sufficient.

I set the X and Y at 8000 steps per (1/8 microstepping), 300 Velocity (IPM), 60 Accel.
The Z was 8000, 290 and 60.
I lowered them all down to 275 Velocity (IPM) for these tests so they all were moving at the same rate.
That's at 45000 Hz kernel speed too.
Could the difference be your unregulated supply and my regulated one?
How fast is your PC, the one I'm on now for the mill is a 2.6 Ghz.
I could set the kernel speed higher with it but I saw no gain in speed.
Hoss

[mrcodewiz]

It could be the power supply although that seems odd. It is 20A split into two 2 AMP outputs - the Z doesn't share it's 10A output with either of the other Axes.

I am running a 3.1 Ghz dual core AMD, set to 45000 kernel speed - also tried 25000, 1.2 Sherline mode, I lowered the accel down to 50. It seems very strange to me that a single axis would run just fine at 200 to 250 and 100 accel but lock up just because I introduce motion on another axis. That would make me think it was power supply related but that seems inconceivable with this PS.

[mrcodewiz]

I was just looking at the specs for the drivers I got (8060s) and noticed this:

Full or Half Current Mode: Sw4: 0= Half Current

They are all currently set to 0 so I wonder if that is my problem? That is just how they were set when I received them - the pin descriptions on the driver itself doesn't mention anything about this pin 4. Should they be set to Full Current?

[Starleper1]

With that power supply you need to wire the two outputs in series to get the 20A out. You probably don't need 20A but just an FYI.

~Scott

[photomankc]

I think that refers to idle current reduction, but I would try it with full current since idle reduction has been known to cause problems.