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View Full Version : Upgrade to a 1 inch ball screw with a .5 lead...???



bgolash
01-24-2005, 01:20 PM
Hi Group
Hi All

I have my X axis running at about 220 ipms. I am thinking about
upgrading to a 1 inch ball screw. At the moment I am using a
5/8 diameter screw with a .2 lead. Also, I am contemplating changing
the lead to .5. I am concerned regarding two points. Will the new
lead .5 be able to push my 300 pound gantry. And second,
will this adversely affect my resolution.
Stepper is 1200 oz*in
Gecko 210
53 Volt power supply

Thanks for the help

My work so far:
http://www.cnczone.com/gallery/showphoto.php/photo/983

ger21
01-24-2005, 01:33 PM
I don't know if you've seen the Data-Cut plans http://www.data-cut.com but Chris that sells them recommends .5 lead screws for any router. I wouldn't think you'd have a problem, but have no experience with them.

Al_The_Man
01-24-2005, 02:57 PM
I have my X axis running at about 220 ipms. I am thinking about
upgrading to a 1 inch ball screw. At the moment I am using a
5/8 diameter screw with a .2 lead. Also, I am contemplating changing
the lead to .5. I am concerned regarding two points. Will the new
lead .5 be able to push my 300 pound gantry. And second,
will this adversely affect my resolution.
Stepper is 1200 oz*in

That increases the drive torque required by 2.5 times. You could always put a timing belt reduction of 2 to 2.5 later if it is a problem.
Al

Torsten
01-24-2005, 03:36 PM
Not a easy decision, may I ask why you want to do this?
Whipping of the current Screw?
Get faster rapids?
Are you using a Timming belt reduction on this.
If not your motor would be doing about 1100 rpm pretty good for a stepper.
Seams like the way you are setup leaves you with plenty of power for
cutting hard items Aluminum etc..
If you are setup for dirrect drive I don't think I would tempt faith with such a
drastic change in gear ratios.
If you are setup for Timming Belt reduction you will have the options of making
some ajustments if things don't pan out by simply and cheap change some pulleys.
A little exess Power is always a good insurance of peace of mind when cutting on
a system without feedback.
Good Luck

ger21
01-24-2005, 07:12 PM
Are you using a Timming belt reduction on this.
If not your motor would be doing about 1100 rpm pretty good for a stepper.


At 1100rpm, he'd be moving at 550ipm. Did you misread something?

ger21
01-24-2005, 07:19 PM
Here's a router that used .5 lead screws (1/2-10 5start)with 440oz-in motors. You might want to read through the thread. http://www.cnczone.com/forums/showthread.php?t=2249&page=1

eman5oh
01-24-2005, 07:27 PM
Something to consider is steppers make more torque when they are turning slowly. You should look at the torque curve of your motors and match up the your most used cutting speed with the .200 pitch and .500 pitch.

bgolash
01-24-2005, 07:41 PM
HI eman5oh
I wish I could. The suppliers of the motors have no torgue charts.
It makes this much more difficult with limited information.



Something to consider is steppers make more torque when they are turning slowly. You should look at the torque curve of your motors and match up the your most used cutting speed with the .200 pitch and .500 pitch.

3t3d
01-24-2005, 11:36 PM
HI eman5oh
I wish I could. The suppliers of the motors have no torgue charts.
It makes this much more difficult with limited information.

You can easily measure the torque at whatever rpm you want to.
Add a disk to the motor, and wind a string around it like a windlass. The string is supporting a weight, and you are holding the top of the string. The weights are supported on the table... Make sense so far?
The stepper is free to turn since you are not holding the string tight.
Program the stepper to run at the rpm you are interested in.
Pull up on the string to tighten it onto the drum and lift the weights.
Loosen the string to let the weight fall, and unload the motor.
If the stepper does not stall, add more weight.
The radius of the disk, times the weight gives you the torque value.
It's really that simple. Now you can plot the torque curve for the motor in it's _present_Condition_ with your current driver, at whatever rpm you are interested in.

Pete

Torsten
01-25-2005, 02:59 AM
At 1100rpm, he'd be moving at 550ipm. Did you misread something?

He stated 220 ipm * 5tpi = 1100 rpm on the stepper if driven direct.

I don't think I misread?

ger21
01-25-2005, 09:37 AM
I don't think I misread?

I thought you meant he'd be spinning at 1100 rpm with the new screw. I guess I misread. :)