calibration

[luke11cnc]

step/mm is 85.46301769

James

[Jonathan]

step/mm is 85.46301769

That's very interesting...I just don't see how with 30T pulley on motor and 15T pulley on the 10mm pitch screw it could be anything other than 80 step/mm. Unless the pulleys got mixed up somehow. Sounds silly but could you count the teeth on the Y-motor pulley. I reckon bearingstation accidently sent me 28T pulleys and neither of us noticed as that gets 85.71429 step/mm which is very close. If that's the case you should check Z and put the 85.714 in for Z.

Jazz did you arrive at that number by scaling and measuring, or some calculation?

[JAZZCNC]

Jazz did you arrive at that number by scaling and measuring, or some calculation?

I could tell you but then I'd have to kill you.!!. . .:rofl:


I did nothing other than explain to James how to let Mach do all the hard work and use the Set steps Per unit feature on the settings screen. . . . Simplizzzzzz

[JAZZCNC]

So you've only got the metric collets.

Nope they are long nails. .

[Jonathan]

James did you check how many teeth are on the Y-axis motor pulley? The mach3 wizard has got you very close, but diagnosing the problem properly by counting the pulley teeth is better as that gets it spot on. Also this means the Z-axis is also out by 7% if you've not already changed it. If it's 28T on the Y and Z motors and 30T on the ballscrews put 85.71429 (i.e. 400/5*30/28=85.71429) in the motor tuning for both.

[luke11cnc]

well I've been in my cold garage this morning Jonathan and the pulley is a 30t so there is some think going wrong then,? it is not stalling and the only thing I have changed is the set up as described by Jazz on motor tuning(witch is working)

any idea's Jonathan on this problem

James

[JAZZCNC]

Yep I have.!!. . . . . . I think it's because the pulley diameters are not exactly to spec and therefore the ratio is different. Thats why I ALWAYS use the Mach wizzard because it works of the actual movement travelled and doesn't relay on calculated specs based on unknown specs of inacurate components like pulleys.!

So long as you measure the distance traveled accurately, preferably over the longist distance possibly then it works perfect.

Either that or the screws pitch are not exactly what they say they are.!!!. . . .(Very very unlikely)

[luke11cnc]

I was thinking the same Jazz


James

[Jonathan]

I ALWAYS use the Mach wizzard because it works of the actual movement travelled

No, you measure the distance travelled. But we can't ever measure it with zero tolerance, so it will always be slightly out. For most people that doesn't matter, but that doesn't make it all-right in my opinion.

I think it's because the pulley diameters are not exactly to spec and therefore the ratio is different.

Definitely not true. The only way the diameters could be different is if the number of teeth is different. If you look at the tolerances for the pulleys it's not possible for such a large error. Also having made several pulleys it's obvious that if you get the diameter out by the smallest amount the belt simply doesn't mesh with the pulley, so if the diameter was wrong the pulley wouldn't work.

James did you count both pulleys on Y and Z? It just seems too big a co-incidence that the number is so very close to making it 28T.

[JAZZCNC]

Ok "Boy wonder" your the "Man" for calc's All I know is how to make it work correct.! :dance: