# Thread: best way to get very low precision 1000ipm linear motion

1. ## best way to get very low precision 1000ipm linear motion

I have been reading a while planning my cnc machine, but another project has come up first. This project is so far from the norm that I thought I would offer it up just for a change of pace I'm considering a belt drive, but I thought I would see what you think.

I need 20" - 24" of linear motion at at least 1000ipm moving 15 lbs, precision is not important, just cost. If I can know within 1/4" of where I am at that works great

Thanks for any help or suggestions!
If I should stick to more cnc related post just let me know and I will be more than happy to do so, I hope to start that project soon!

2. X,Y Z straight line motion without accurate angles? Contouring like circles etc.?

24" of acceleration probably will never get to 1,000 IPM. Then there's deceleration to avoid smacking into the end of travel.

What's the product, real or fake substitute?

Dick Z

3. Air powered cylinder with adjustable shocks for positive stops.

4. Call it a standard trapezoidal movement pattern with a 15# load and a 1000ipm top speed? Let's say that you have 24" of travel and want 6" of acceleration, 12" of run and 6" of deceleration to make the math doable:

1000ipm = 16.67 ips
Velocity (ending) = d / t = 16.67ips
Velocity (beginning) = 0 ips
Velocity (average) = 16.67 / 2 = 8.33 ips
Time = 6 / 8.33 = 0.72s
Acceleration (linear) = Ve / t = 16.67 / 0.72 = 23.15ips^2

Now let's bounce over to metric to convert this into a multiple of G:

15# = 6.8kg
23.15ips^2 = 0.588 m/s^2 = 0.06G
Force = m * a = 0.588 * 6.8 = 4 Newtons

In other words, you will want some good-sized servos to hit that kind of force/acceleration.

5. You could use a method I outlined here of Hydraulic cylinder, air over oil.
http://www.cnczone.com/forums/linear...sitioning.html
To control it you could use a Siemens Logo controller.
http://www.automation.siemens.com/mc...s/Default.aspx
Al.

6. Sorry guys, I made a typo, 5 lbs not 15

It will be just one axis, horizontal, but at a slant, say 30 degrees.

I have never seen an air over oil system before, it looks interesting. I can make the controller if it can interface to a micro-controller in some form.

It's not my personal project< I'm just a helper, let me find out what their published use case is..

Thanks for all the awesome tips.

7. It's hard to give exact advice unless one knows the exact nature of the project and what you are trying to do, and the resolution you need.
Al.

8. I don't see why I shouldn't be able to detail the project, but I will check just in case and come back. Thanks!

9. Originally Posted by anotherchance
I don't see why I shouldn't be able to detail the project, but I will check just in case and come back. Thanks!
Remember also to distinguish payload from total moving mass. With a pneumatic or hydraulic ram, there will be some incremental mass associated with the total moving mass above and beyond the payload. With an R&P or some belt drive systems, there could be a lot more mass attached than just the payload.

10. What about one of those big garage door rack & pinion fitted with a big motor? They sell the racks separately, so I'd be a matter of machining or getting a matching pinion.

Belt drive seems like a very nice option, and probably more elegant.

11. A linear actuator maybe another option, Ebay 250839450923.
There are many makes out there.
Al.

12. I can do this with one of our Kollmorgen servo ballscrew linear cylinders easy. cost would be about \$ 3000 plus \$ 1000 for control/drive.

If interested, email me at Mike@KilroyWasHere.com and I will quote exact part nos.

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