Changed lead screw, no change!

[grahamshere]

Hey every one. I just changed my lead screws from 5/16 18 tpi to 1/2 10 tpi single start acme screws, ok now with the 18 tpi's I was getting 20" per min and with the 10 tpi's im getting the same, How can that be? my steps per are 16000, velccity 20 and accel is 10, im running micro steps and motors are 425s using mach3. After changing screws, bearings, drill new holes and making a new z axis and whine whine and whineing some more youd think id get some better speeds right? Graham

[debogus]

Heck I went from 30 max rapid to 100 IPM by changing from (single stack 23's that came with my xylotec 100 something ?) 1/4-20 to 276oz motors 1/2-13 allthread

velocity 20 ? DANG Ive got .75 which limits me to a nice no missed steps of 45 ipm.
I do know that my y axis ran ok at the slow setup but fought me for 3 days after the speed increase (alignment issues)

I'm running mach 2 for control (havent figured out all the settings for 3 yet)
Had that problem too, thought I would set up mach 3 for the new setup ,way slow , found its jog settings in a different place , and they were wrong.

Dave

[joecnc2006]

Velocity is how fast it is running increase it to 60 then 80, when you loose steps back off 20%


Joe

[joecnc2006]

Also what stepping are you using on the controllor? 16,000 steps per is 1/8 microstepping with the 2/1-10 acme screw.

[thkoutsidthebox]

Originally Posted by grahamshere .....I was getting 20" per min and with the 10 tpi's im getting the same, How can that be?.....velccity 20.... Graham

Velocity is your speed.
Velocity 20 = Speed 20ipm. Velocity 100 = Speed 100ipm. Velocity 47 = Speed 47ipm etc etc.
If you have a slaved axis (You probably don't but just in case) make sure you set both at the same settings before jogging.

[grahamshere]

Thanks for the reply guys. Ok Im using micro stepping, thats what is set on the controls when shiped right? No slave axis. When I up the speed and steps per I lose steps, or the machionr does not cut too the right size,(too short) thats losing steps right? Im sure I can get the y and z axis a little faster but x no. Oh I built the solsyvia, I know I wont get big speeds but should get atleast 40 in per.Hey debogus how do you get 45" per with velocity at .75? Oh my comp is 667 mghz pent 2 that shouldnt slow it down could it?Oh welcome back thkoutsidthebox, missed our silo chatslol, Hope the holiday was good? Thanks guys. Graham

[ger21]

16000 steps is correct. Try increasing the velocity to 50. Where does it miss steps, while accelerating or at constant speed?

[ger21]

Well, the slow PC could be the culprit. Also, those motors may not like to spin too fast with the Xylotes either. 1/2-8 2 start may have been a better choice. Also, you may have resonance issues. This thread may be helpful.
http://www.cnczone.com/forums/showth...639#post256639

[grahamshere]

HI ger, was waiting too see if youd pop up. It seem to miss steps at a constant speed, So if i change the steps per to say 8000 and and veloc to 40 then ask it to travel 2" it only travels 1", Im also wondering if my belt on the x axis might be to tight, would that affect any thing.I know I can get
100" per on the z axis but whats the good of that.And yes I should have got the 2 start but i got these a while ago and dont want to spend any more bucks on this one, Im going to build another, probably joes 2006 or if he is going to sell plans for his his new wicked looking machine. but this wont be for a while.Graham

[ger21]

You can't change the steps per unit, it's a fixed number based on your screw, so leave it at 16,000.

Try this:

Set the velocity to say 100.
Go to MDI screen.
Type in F20 for 20 ipm
Then do a G1 X10
Then G1 X0

If it sound good, then type in F30 and repeat. Keep increasing the Feedrate 'til it misses steps. Once it does, set the velocity to about 20% less then where it missed.

[grahamshere]

Hey ger, ok I tryed what you suggested. I did f20 and every thing went good, did f30 and it traveled 1" stoped and starrted to buzz really loud.Graham

[debogus]

grahamshere ,
in mach 2 it's .75, in mach 3 it's 60
Like I said I use mach 2, they put just enough changes in mach 3 to confuse the he(( outta me.
Getting real close though.


Dave