100 in/min X, Y, Z with IH CNC Kit. Any Trouble??

[haysys]

Hi All,

I've had my IH CNC conversion kit in place for about 6 months now, and have noticed a problem. I'm wondering if anyone else has had this issue.

I originally had all three axes set to 100 in/min and an Acceleration setting of 10 in^2/min. I use Mach 3 as the controlling software. After homing and then GoTo Z (say G55 with X=10, Y=4, Z=10) if I hit a GotoZ a second time, the machine would start to go to machine Zed in the Z direction (Safe Z moves set to Machine Zero) before it's return to G55 zero, but would halt in the midst of the Z-Axis move after an inch or so and then do this "clicking". The seever would sort of stutter. It worked fine in every other fashion but not here) At this point, all reference was gone, and the only recourse was to Home again.

After messing with this for some time (changing many things along the way), I finally discovered that if I turned down the the speed to 75"/min, the machine seemed to operate as desired. I have left the Z Accelleration derated to 7.5 as well. X & Y seem to be just fine at 100 and 10.

Has anyone else experienced a similar problem. What settings for Speed and Accel are you folks using???

Thanks for your replies.

David

[BobWarfield]

My tendency would be to want to carefully check all the connections here. If it used to work at 100 ipm, and now only works at 75 ipm, one wonders. Another possibility would be to readjust the gibs and relube, especially on Z-axis.

Best,

BW

[dnelso]

I had similar problems when i was first setting up my machine. The problem was i was running
the gibs to tight on the Z .I found the best way to adjust is to use a dial indicator and keep moving up and down .5 and keep tightening until it starts to hang on the way down and then loosen just a tick. Also on my machine the limit on the gecko needs to be turned all the way up to operate at full speed.Bob could be correct and maybe just needs clean and lube.
Later DN

[wildcat]

I ultimately set the Z to 75ipm and the X&Y to 100ipm and 10ips^2 on all axies. 100ipm on the Z worked most of the time but occasionally faulted (in only certain places). I found this to be a very dangerous situation because, as suggested, the IH conversion kit relays no information about the fault back to Mach3. If the head goes up and faults Mach is unaware of this... it continues sending pauses and believes it reached its designation. Now, the head starts going back down and crashes. I still worry about this situation and am waiting on a Err/Res board for protection. Breakout boards really should already have this functionality.

http://www.aree.com/gecko/gerc_rly_rev2_manual.pdf

[Cruiser]

Hello there, I would have to describe that as "sticktion" and a little oil and then travel slow through it and it should dissapate. it will be prevelent when cold ! I put a dab of molly lube on all slides and worked it in, then give it a wash of oil. my sticktion is not as pronounced now and goes away quickly with a few strokes of travel. then i'll referance and do my stuff.

[BobWarfield]

Originally Posted by Cruiser Hello there, I would have to describe that as "sticktion" and a little oil and then travel slow through it and it should dissapate. it will be prevelent when cold ! I put a dab of molly lube on all slides and worked it in, then give it a wash of oil. my sticktion is not as pronounced now and goes away quickly with a few strokes of travel. then i'll referance and do my stuff.

Some commercial machines run a warm up cycle that exercises the axes at startup. You want the system to be up to temps anyway if you expect any accuracy.

I've found good lube improves performance considerably. I'm planning to create a one shot lube system for my mill someday soon. It isn't that hard to do, and I've been collecting notes for one already. You can pick up the one shot pumps on eBay for $15-20 for a real Bijur pump. After that, its just a matter of fittings from the hardware store. It helps tremendously to have the machine apart, so I'll be plumbing mine during the CNC conversion.

Here is one such system done on an IH by Thomas Powell:



My notes on doing this are on this page (among many other things!):

http://www.thewarfields.com/cnccookb...istFutures.htm

Wildcat, I like the GERC board. I suspect you are right and this would make an excellent feature for a breakout board. However, I think they're almost universally predicated on Stepper use, so they see no need, only extra expense. The board you've shown makes it easy to roll your own. The other issue is most breakout boards are very I/O constrained anyway. I suspect if you can bring the output pin from GERC back, you can make Mach see it and act pretty easily. If nothing else, you can put the contacts in series with the limit switch circuit and Mach would just treat it as hitting a limit.

Best,

BW

[wildcat]

The GERC uses a relay to trigger the emergency stop on the breakout board so there is no additional parallel port pins used. The GERC_RLY version also disabled the power to the servos in the event of a fault. I guess there is a failure condition of the Geckos that could send the servos at full speed. The relays are also used to disable the servos in case you need to do some manual positioning. Just seems like there is a lot duplication between the breakout board and the GERC. It would be really simple to OR the fault lines and trip a relay to disable the stop. Startup would be a little more complicated because one would need to manually reset the Geckos or the breakout board would need to have logic to do it (like the GERC). After adjusting the gibbs faults are really uncommon... this is just protection for that one time when the shop is too cold/hot or the ways didn't get lubed.

Seems like steppers are becoming more and more standard. The Smithys that used to have servos now seem to have steppers. Don't know if this is a good thing... Their ad use to brag they used servos and not steppers.

[Runner4404spd]

the Gerc standard board also uses relays to trigger a stop on all the axis, but the relays are mounted externally. i used this setup for my cnc conversion,.

[Cruiser]

Ok Bob, I run some pretty big machines too, such as a vertical lathe with a 48" chuck in an unheated shop...... cycle the machine to warm the axis ! forget it ! won't happen in any way shape or form ! what we do try to do is warm the spindle a little, but again it is a lesson in futility, but i'm still expected to hold tollerances of +- .0005 no matter how cold it is. I wish the slides would warm up a little but they just don't. What machine is it you run again, i forget.

[wildcat]

48" chuck?!?! 48" in diameter? What do you turn on it?

Originally Posted by Cruiser Ok Bob, I run some pretty big machines too, such as a vertical lathe with a 48" chuck in an unheated shop......

[Cruiser]

Wildcat, I can't get specific but i run some jet engine diffuser casings, & a variety of turbine impellers as well some various other pieces oh like some ring and race parts for large ball bearings like using 1" to 1.5" balls, its no big deal really but it does make my paycheck !