Building Linear Actuator- Advice Needed

Thread Starter

Sp@ceR

Joined Mar 11, 2018
50
I am planning to build a X-Y axis linear actuator, it is somehow similar to CNC router, but in 2D. The actuator I want to build looks like this picture taken from the Internet:
s-l1601.jpg
I have bought a some parts and arrived yesterday, including:
- Nema 24 Stepper (VEXTA PK566HNAW-A1)
- slide rail and block (approx 3 kg per pair)
- Lead screw and nuts (Instead of ball screw, due to lack of cost)

The stepper motor specification:
index.jpg

I did research on the stepper motor and found nothing about the torque values. My concern is that, will this motor able to rotate smoothly at X axis given the load (Y axis) weights at approximately 7kg or lesser? I have attached another rough sketch of actuator. PS: The stepper comes with its own driver SD5128 which seems to be a full step driver (0.72 deg.).

I am not sure what to do now. Should I go for a higher torque motor (Sanyo Denki 103H7126-2542)?

Any advice is appreciated.
 

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Sensacell

Joined Jun 19, 2012
2,587
Nothing can be calculated from the numbers you provided.
You would need much more data to perform any meaningful calculations.

Since you have the stuff already, hook it up and try it.

If it doesn't work, you can find another motor and driver that might provide higher power output.
 

Thread Starter

Sp@ceR

Joined Mar 11, 2018
50
Nothing can be calculated from the numbers you provided.
You would need much more data to perform any meaningful calculations.

Since you have the stuff already, hook it up and try it.

If it doesn't work, you can find another motor and driver that might provide higher power output.
Hi Sensacell,

It seems to be the only way to find out, despite I only have another 2-3 months to finish the project. Fingers crossed.

I might get the Sanyo Denki (Nema 23) motor as well. Just in case VEXTA doesn't work I'll swap it immediately.
Did you read the Operating Manual? There are load ratings there in.
Hi djsfantasi,

Yes I read the manual. The ratings are for thrust load and overhung load. But from my understanding I should refer to torque as to know how much 'force' the stepper can exert to rotate along X axis to move the 7kg load. Am I right?
Go to the Gecko Drives site, they have a tach manual on sizing steppers etc.
https://www.geckodrive.com/
Max.
Thanks for the information. I will read through before getting another stepper.
 

Thread Starter

Sp@ceR

Joined Mar 11, 2018
50
Do you have the drives yet?
Or what versions are you considering?
Max.
Hi Max,
Yes, I already have the driver. It came together with the VEXTA motor as a set. Model is SD5128 CMOS type. You can refer to the spec sheet I attached at main post.
 

MaxHeadRoom

Joined Jul 18, 2013
21,267
Looks like a ground ball screw and nut to me?
Or could be cold rolled, still OK if pre-loaded.
Edit: I missed the bit about lead screw.
Max.
 

Thread Starter

Sp@ceR

Joined Mar 11, 2018
50
Yes I do.

The materials I bought already cost me an arm and a leg, and I want to keep both kidneys, seriously :D.

Unless i feel the need to upgrade in future, there's still chance to modify into ball screw. I just don't have enough spare cash right now.
You do know you won't get the accuracy from a threaded rod and nuts right ?

Brzrkr
 

Berzerker

Joined Jul 29, 2018
621
@MaxHeadRoom and @Sp@ceR
Was just trying to make the point of accuracy and I understand the wallet side of things.
I would use two lead screw nuts (One on each side) to place pressure on the rod in opposite directions to get the a lot of the play out of it.
It's depending on how accurate it needs to be is what I was getting at.

Brzrkr
 

BobTPH

Joined Jun 5, 2013
2,505
How dof you determine that there is a 7 kg load?

You do realize that the screw has a large mechanical advantage, right?

Also, is the Y axis horizontal ot vertical?

Bob
 

Berzerker

Joined Jul 29, 2018
621
MaxHeadRoom said:
Basically how a pre-loaded ballscrew works.
Max.
Yes
I worked with Hydraulic positioning systems in the past but they also had PLC's and built in position rods that read back to a readout telling you where your position was within .001.
Tried my hands at a few ball screws but the tolerances and repetition over time on a ball screw would degrade.
So it was a no brainer.

Brzrkr
 

MaxHeadRoom

Joined Jul 18, 2013
21,267
In the CNC world which I am familiar, retro fitting using such as Fanuc and Mitsubishi controls, the pre-loaded ground ball screw has pretty much been the standard and I found it stood up pretty good over time, the rolled screw has problems if you want really good resolution and positioning.
There are still many machines decades old now that are still holding acceptable tolerances with ground ball screws.
Max.
 

Berzerker

Joined Jul 29, 2018
621
@MaxHeadRoom
Yes They have their advantages cost being one. But I don't know about decades without replacing parts or adjustments. I'm a machinist by trade and I worked with lathes and milling machines. Even though we had DRO's the ball screws from use over time would need to be tightened/adjusted to keep the slack out of them.

Brzrkr
 

Thread Starter

Sp@ceR

Joined Mar 11, 2018
50
@MaxHeadRoom and @Sp@ceR
Was just trying to make the point of accuracy and I understand the wallet side of things.
I would use two lead screw nuts (One on each side) to place pressure on the rod in opposite directions to get the a lot of the play out of it.
It's depending on how accurate it needs to be is what I was getting at.

Brzrkr
Hi Berzerker, is this what you mean? Imagine there is a block in between both nuts welded to each side.
lead screw.jpg

How dof you determine that there is a 7 kg load?


You do realize that the screw has a large mechanical advantage, right?

Also, is the Y axis horizontal ot vertical?

Bob
Hi Bob, the 7kg load is just an assumption made based on the expected materials to be used on Y axis. Y- axis is to be laid vertically on the carrier block of X-axis.
 

Thread Starter

Sp@ceR

Joined Mar 11, 2018
50
I have a question that pops up out of curiosity while I was looking at other NEMA 23 steppers.

Does bigger size usually define higher torque? For example, 2 NEMA 23 steppers: one having length of 5cm and another having 7cm. Is it possible to say that the one with 7cm length will have higher torque than 5?
 
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