Motor Couplings?

[kolias]

The attached photos indicate a motor coupling arrangement I got from the web and I just like to educate myself with all these parts. Can someone tell me what items 1 to 4 are and why they are needed?

In comparison the other photo indicates my present arrangement which is the motor connected to the ACME screw with a Lovejoy coupling followed by a bearing and at the other end of my ACME screw there is another similar bearing and that’s all I have. Obviously with this arrangement I have noticed no problems in the way my machine works.

[lonnieh]

I'll bite. Both item 1 and 2 are a single shaft coupler. See: dumpstercnc.com Item 3 is either a thrust bearing sticking out of a recess or it may be just a washer. Item 4 is a collar to prevent the shaft from sliding.

I think by using thrust bearings on a leadscrew is just another way to minimize backlash. I could be wrong though!

Edit: Just another thought, I'm guessing that there is probably another collar between the shaft coupler and the aluminum block before 'Item 3'.

[brtech]

Take a look at this:
CNCRouterParts

The shaft coupler is there so that a hunk of smooth drill rod is between the motor shaft and the acme screw. The thrust bearings are to constrain the thrust loads axially. The collar holds the thrust bearing against the top bearing support.

[kolias]

Originally Posted by brtech Take a look at this: CNCRouterParts The shaft coupler is there so that a hunk of smooth drill rod is between the motor shaft and the acme screw. The thrust bearings are to constrain the thrust loads axially. The collar holds the thrust bearing against the top bearing support.

Much appreciated

[kolias]

Forgot to ask another silly question:

As per the link, Item 6 is a 1/2" drill rod (optional but helpful to maximize useable screw length) and it says “you cut to length”

I understand the meaning of all above but how do I determine the “you cut to length” the drill rod”?

[brtech]

Well, you have the motor mount, the shaft of the motor and the anti-backlash coupler. That defines the start of the rod. Then you go from the bottom shaft bearing, to the shaft coupler. That defines the length of the screw. The space between the bottom side of the antibacklash coupler to the top side of the shaft coupler is the length of the rod.

Mostly what the rod is doing is allowing you to get the maximum actual usable travel out of a given length of screw. So your screw length is just the travel you are looking for plus an allowance for the bottom bearing and the shaft coupler depths plus the height of the nut the Z axis rides on. Then the shaft is the remaining distance from the helical coupler to the shaft coupler.

[kolias]

Thanks brtech

[kolias]

Originally Posted by brtech Take a look at this: CNCRouterParts The shaft coupler is there so that a hunk of smooth drill rod is between the motor shaft and the acme screw. The thrust bearings are to constrain the thrust loads axially. The collar holds the thrust bearing against the top bearing support.

ok one more question because it’s not clear to me

On the CNCRouter Parts image, do we transition from the 1/2" drill rod (item 6) to 1/2" ACME (item 2) at the bearing (item 5)?

In other words is it correct to say that in the bearing (item 5) on the right side we have the 1/2" rod and on the left side we have the 1/2" ACME?