[David Da Costa]

Okay so I give up with the new PC having tried everything myself and everyone else has suggested to no avail.

So before I cut my wrists I went back to using my original 1.4Ghz P4 PC that use to have the controller built into it.

I now have the controller in a separate box with the power supply and the CNC4PC card. I have bypassed the CNC4PC card to simplify my tests and although I think the machine movements may be a bit better, I cannot get anything reliable out of the machine.

So moving backwards, I took 3 135oz/in steppers back of my Sherline Mill and along with the sherline controller I connected them to my 1.4Ghz PC (the same one the Xylotex board was connected to. The last time I tried the sherline setup I used the PC that the sherline controller was connected to as well.

The results a very good, I can run all axis at 60 velocity and 8 accel totally reliably and the sound good. So this means I can rule out the PC as a problem area, so that leaves me with the Xylotex controller and cabling. To reduce any cabling issues I had already removed my extended cabling from the loop and was just using the cables made up by Xylotex.

I have attached a small quicktime movie of the y and the z in motion with the sherline and I think you will agree it sounds good.

The only other thing to be tried on the Xylotex is the power supply which I will test in a minute with my two PC PSU.

Beyond that I am getting to a point of looking for a different controller, possible the HobbyCNC one which I think I can use with the 425oz/in steppers I recently bought from Xylotex which are 8 wired unlike the 269 which are 4 (Joe can you confirm?)

[gtschance]

David,

Just got back from my business trip. Sorry you are having such issues.

Have you thought about driving the small motors from the Sherline with the Xylotex setup as a test case?

George

[David Da Costa]

Okay, so I wired the 2 PC PSU in series to get 24v 13a and powered the xylotex controller up. Put the 425oz/in stepper back on the z and as you can see from the attached movie it is **#*#.

So it does not appear to be power and I am having a difficult time believing it is cables as the only cable hocked up is the z-axis, so that leaves the xylotex card.

[David Da Costa]

I would have to rewire them but I could do that. Also remember that I have run the xylotex with the original 269oz/in motors with the same problem.

It would be interesting and I guess the same test to hook to 425 up to the Sherline controller

[gtschance]

David,

I definitely have heard that sound before. In fact, I can reproduce it at will with my setup by setting the max speed too high or binding the movement of any of the axes.

That sounds just like mine did with axis alignment issues. The sound starts with the motor actually attempting to spin up to fast which starts it missing steps. I could almost always get the axis to move in the 30 to 50 range but before fixing alignment, I got exactly that sound.

I will suggest that it is not necessarily the driver board.

G

[joecnc2006]

Okay, so I wired the 2 PC PSU in series to get 24v 13a and powered the xylotex controller up. Put the 425oz/in stepper back on the z and as you can see from the attached movie it is **#*#.

So it does not appear to be power and I am having a difficult time believing it is cables as the only cable hocked up is the z-axis, so that leaves the xylotex card.

Start off with motor tunning at 40 and accel. at 15, then increase the vel. 10 each time. there should be no reason you can not jog atleast 80ipm.

we have a few machines that run that all the time.

I would think also not the controllor.

(Make sure leadscrews are lubed also again)

[David Da Costa]

Well I will try that again, but I have tried pretty much all combo of accel and vel. Also remember that the machine is working at 60 and 8 with the sherline

[gtschance]

David,

Shooting in the dark here but when I was having alignment issues, I could generally count on good results when my axes were at mid travel (mid 1/3 for each). I could almost always get fast movement and good acceleration until I was in either of the outer thirds of movement range.

One of the tests I did was to back off tightness in all bearings (lead screws, anti-backlash and slides - so that each was "sloppy/loose." When results improved, I deduced it had to be alignment issues. All the while, without the lead screws in all axes would glide easily by hand AND with the lead screws in, I could turn all of them by hand (fingers actually).

As I thought about it, I tried to "feel" if any of the lead screws varied in how hard they were to turn through 360 degrees. While I could not testify they were not all even around the 360, my belief was that in each case of a trouble axis (the exact sound you are getting), there was distinct variation in ease of turning.

If you refer back to one of my previous posts, you will read how I remedied the situation [bearing seats for the lead screw] and now have movement for all, clean and 80 IPM/10 accel or better for all.

George

[David Da Costa]

Just tried 40 and 15 still locking up.

I dont think it is an alignment issue as I checked all that and besides the 135 oz steppers and sherline controller are driving it nicely at 60 and 8 (see video)

[gtschance]

David,

Not to dispute....the smaller motors may not be as capable of acceleration as the larger ones are. You may recall I stated the driver board purposely limits current. It is within the realm of possibility the motors are trying to overcome resistance (binding in table movement) and stalling because alignment will not let them accelerate properly (forcing them to demand more current than the board will supply).

Do you have access to an o-scope? I could explain how you could measure and tell fairly quickly if you are hitting current limits. You may in fact be able to measure directly if you have a volt/amp meter that responds fast enough. Let me know if you want to discuss same. I would be happy to chat with you via telephone if you want.

George

[David Da Costa]

But if both the sherline motors/controller and the the Xylotex motors/controller are both set to the same accel and velocity and the Sherline provides a good result does that make sense, or are you saying that the sherline is not really achieving the same accel and velocity.

Unfortunately, I do not have a o-scope.

[David Da Costa]

I am going to see if I can wire a 425oz/in stepper up to use the sherline controller and test that

[joecnc2006]

Beyond that I am getting to a point of looking for a different controller, possible the HobbyCNC one which I think I can use with the 425oz/in steppers I recently bought from Xylotex which are 8 wired unlike the 269 which are 4 (Joe can you confirm?)

Sorry did not see the post, the 425 are bi-polar, and yes you can wire them to uni-polar they will run at 305oz, i have run my X axis with one using the HobbyCNC board.

Joe

[joecnc2006]

I am going to see if I can wire a 425oz/in stepper up to use the sherline controller and test that

do you have specs on the sherline controllor? We will get this resolved sooner or later, we have a few people here for resources.

[David Da Costa]

Thanks Joe, I should take a picture of the router at the moment, there is electronics and cables and tools all over it .

The specs are here http://www.sherline.com/8540pg.htm, what do you think?

[gtschance]

David,

I dug into the specs and cannot tell based on the links I visited (a dozen or so) that list info about the Sherline supplied motors if my theory has any validity. I most definitely did not see anything that would invalidate the theory though.

Fact: The acceleration rate available on two different designs of motors will almost always be different.

The acceleration rate you specify in Mach3 is the rate at which it increases the pulse rate sent to the driver. The response of the driver and motor are whatever they are. They can indeed be snappy and "obey" the Mach3 pulse acceleration rate or they may not. Even if they are "slow" to get going, they will not necessarily stall. It is a function of the driver motor combination. Unfortunately I do not have enough engineering specification data to look at to make a conclusion.

The starting torque available for a stepper motor will always be different than the torque available when it is in motion already. In other words, some may be hard to get moving from stop but have loads of torque available just after they start any movement. I have my suspicions about the 425's in combination with the Xylotex driver. Steppers of course are more powerful (more torque) at lower speeds than higher speeds.

Again, shooting in the dark. The fact you can get a lower powered setup to work well when the more powerful (supposedly) system will not is very curious. I remain extremely puzzled about what I see and hear in your video clips. I fought with what looks and sounds identical to me for many many hours. As I have stated before, adjustments and bearing surface truing got mine to behave.

Just for giggles, please describe exactly how you have the wiring done from the driver board to the motors. Please include motor wire colors and describe your cable run (8 singles going to 4 pairs near the motor or near the driver board).


George

[David Da Costa]

It is very baffling, I currently have the sheline setup on the y and the xylotex on the z and by swapping the printer cable between them I can quickly compare settings. I have just been running the sherline at 70 velocity and 8 accel and can see on mach 3 that it is reaching 70 and it runs perfect. If my xylotex was running with those settings I would be perfectly happy.

Okay so the cables, from the motors there is the usual 10" or so long pigtails, which I put in loose plastic sleves to hold them together (same as Xylotex did on the 269 motors).

These are connected to 4 pin molex connectors and as I did not have any spares, I cut them of the 269 motors leaving a couple of inches of cable, which I then soldered and covered each one in cable wrap. From there a male molex connector plugs in and uses 18AWG 4 core none shielded cable to the controller where it has crimped on pins to go into the controller. This cable was made by Xylotex not me. I have extended the cables with more molex and 22AWG 4 core non shields cable but for the sake of testing I have these out of the loop. All other limit switch cables are disconnected.

Each motor has its own 4 core 18AWG cable

So in summary the only part of the cable that I effectively touched was grafting the molex connectors onto the motors. I am pretty sure the solder joints I did are good not that I am an expert, but I applied solder to both sides of the cable first then melted the two together making sure the solder flowed.

[David Da Costa]

I need to work out if I can, but I would like to wire one of the 425 motors to the sherline controller and see how that behave.

[David Da Costa]

By the way, I dont seem to be the only one having such problems check out this thread http://www.cnczone.com/forums/showth...5&goto=newpost

[gtschance]

David,

I too noticed the other thread. Does make the Xylotex suspect doesn't?

I put the loose 425 motor wires into short sections of left-over tubing from the z axis bearing slide build. I hard wired (mechanically stable twist connection, solder, then heat shrink tubing over the joint) the connection at the end of the pigtails with my longer cable. My 8 wires to four pairs is at the motor end. The cable I used is 18AWG 4 wire shielded (foil with a drain wire). The shield is connected to the chassis on the driver end and NOT at the motor end.

By the way, 22AWG is generally NOT appropriate to deliver power at up to 2.5 AMPS. It will in fact be possible to get significant voltage drop depending on the length of the cable. When you do get to the point where things are working with the shorter setup (you will!), do yourself a favor and get larger guage cable for the longer setup.

Over the next couple of days in between my regular job activities, I will try a different Xylotex setup (the 3 axis version with the 269's - my future mini-lathe CNC setup). I will also try the servo setup (3 Gecko 340's w/400 oz/in peak servo's) I have for my mini-mill. I will purposely stall the motors (by binding the axes) as I can now with the present Xylotex setup.

That will give me some comparitive data that may reveal something. I have wanted to get to that anyway just to see the differences.

At the moment, I have no other suggestions.

George