Ratio of servo to ball screw questions.

[Brian L]

I have a Partner 4 with a Centurion 5 control, have been messing about with Centroid controls with a friend who does conversions and I've done some beta testing on the control/software. I've decided to do a retrofit on my mill using the Centroid all in one and to speed things up during the retrofit process, I wondered if anybody knew the pulley ratios on the X, Y, and Z axis. Also, lead screw pitches would be nice. I can get the covers off the X and Y fairly easily, Z would be a project for me from my wheelchair. Just wondered if anybody (maybe Sporty Bob) knew the tooth count of the pulleys and the ball screw pitches off hand.

Thanks,

Brian

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[dkirby]

Brian, I have a vm16 Partner 1. Do you think they are a similar set up? With a Centurion 6 control.
The reason I ask is because I just recently had to change the ratio on my Z axis, because it was setup for 10,000 rpm.
I bought the kit from Sporty Bob and I have all the tooth counts for Z written down somewhere.

If you think it would help I can look tomorrow morning for the info. It's 10:00 pm here now and I am in the house.
Dave

[Brian L]

Hi Dave,

I kind of doubt they were the same... and I'm not sure, but it sounds like you are talking spindle pulleys, I'm talking the servos to the lead screws for the X, Y and Z axis.

[dkirby]

Brian, I guess I may have confused the issue by mentioning the spindle pulleys but I had to remove the Z axis covers to do the job and I have the pulley info for the lead screw on that axis and for sure the X axis also, from a previous problem.

I don't know how much of a diff. these machines are and that was why I made the offer.
Maybe Sporty Bob will be along to set us both straight.

[Brian L]

Well, I'll take what you have for sure, and thank you. As for how consistent the machines are, I can't say, my machine is a knee mill and yours is a VMC style mill, so kind of completely different animals.

This isn't the clearest pic of the machine, but you get the idea....

[dkirby]

Hey Brian,
I found my notes and here is some info. for what it may be worth.

X axis screw... 1.250 dia. and looks to be 6 tpi. 18t sprocket and same on the servo mtr.

Z axis screw... 1.250 dia. and 6 tpi. 18t sprocket and the same on the servo mtr.

I don't have anything on the Y axis yet but with my luck I may be into it next.!!
Dave

[Brian L]

Interesting, I managed to get at my Y axis today, 5 pitch ball screw (near as I can tell, got 10 turns to 2") and the pulleys are 14T on the servo, 28T on the ball screw for a 2:1 ratio. I'll try in the cooler part of the morning to check the X, not sure I can get to the Z without my wife's help. I vaguely remember the X and Y being the same just with a different length belt because of the way the motors mounted.

[sportybob]

Hi Brian, early machines used a 13in lb motor and were belted 2:1 later machines used a 26"lb motor and were belted 1:1, most Z axis used a larger 40"lb motor with a brake and should be 1:1 ratio.

the ball screws used by Milltronics have been 5 pitch (.200) , 4 pitch (.25), 10mm and 16mm pitch. 6 pitch (.1666666) would make for some awkward math.

I know a guy in WI that does a lot of the centroid conversions.


Sportybob

[Brian L]

Thanks for that info, looks like my X and Y are 2:1 and 5 pitch, not sure on the Z, think it's 1:1 but I don't know the pitch. I have helped a friend do quite a few conversions now using the Centroid stuff, he does most of the conversion work and I do some programming and test running to get the machines dialed in.

I've been having issues with the Y axis servo jumping around a bit, and a spindle speed problem since I got the machine, so it's all starting to get a little long in the tooth and figured it would be a good time to upgrade.

[sportybob]

Hi Brian, I would say Z also has a 5 pitch screw.

Not sure of what " Y axis servo jumping around a bit" means.

Give me a call and we'll get it sorted out

952-288-6340

Bob