Attachment of pulley to ball screw on EMCO F1

[tome9999]

My table (x-axis) moves inappropriately (0.1") and I have traced this movement to the connection between the x-axis ballscrew, the bearing that it rides on, and the fitting that attaches the ballscrew assembly to the table itself.

In the first picture the two parts I point to are loose and can be moved. We have quite a few of these machines in the shop and none of the others have this problem. This movement of the fitting translates to movement of the table.

Does anyone have a drawing or detailed description of this assembly? I have the manual and exploded view diagrams but they don't address this detail.

How is the ballscrew attached to the bearing (or is it)?

How is the bearing attached to the mount (or is it)? It doesn't seem to be as it is loose and can be rotated about the ballscrew, but also rotates in the mount.

The 2nd picture shows the end of the assembly. In the center of the pulley there a set screw (removed in the photo below).

What does this set screw do exactly?

How is the pulley attached to the ball screw?

[ipmmiller]

if im reading this right thats ALOT of play.Was going to suggest using ballscrew compensation .....until i realized the amount.I hav'nt experienced this condition but now im curious about how that fits together,been awhile since i had to clean trash out of my x screw and i cant recall that part.If you own a few others im guessing you know how dangerous it is to move that loose ballscrew to far the wrong way ....free bb gun ammo.If your near Ca. someone has an F1 listed right now on ebay that would be a good parts machine.Let us know what you find out

[tome9999]

It turns out that with various folks in the shop discussing it and some web surfing (an older discussion on the Yahoo Group - emcof1mill), we determined that the pulley is threaded onto the ball screw and that the set screw is there to lock it on.

In order to keep the ball screw from turning you have to grip it just inside of the bearing block (mount). There is a smooth, non-threaded, area there. I am surprised that emco didn't put a flat spot on the shaft to enable one to use a wrench. I used vise grips there which bit into the shaft a bit. I put a piece of scrap copper over the pulley itself so I didn't crush the teeth, and used vise grips there to grab and turn it. There are two holes in end of the pulley that can be used for a spanner but we didn't have one, hence the copper/vise grips.

Once we got that off we took the bearing block/bearings off to figure out how it was intended to go together and to figure out what the problem was.

To make a longer story short, we determined that all that was needed was to tighten the pulley further which pushes the bearing block up against a shoulder which is cut into the end of the screw. This causes the whole assembly to snug up.

A friend and I measured everything and did a drawing of the assembly. I will clean that up, scan it and post it here later.

-Tom

[tome9999]

Attached is a drawing of the EMCO F1 x-axis ballscrew and bearing block and pulley.

-Tom

[ipmmiller]

nice job Tom,glad you got it fixed, thanks for posting the results and the diagram.

[Bob La Londe]

Thank you for that break down and confirming for me that the pulley is the bearing nut as I suspected. Since I am using the F1 ballscrews to retrofit a totally different machine that lets me know that I'll need to fabricate one more part than I originally planned.

[tome9999]

Originally Posted by Bob La Londe Thank you for that break down and confirming for me that the pulley is the bearing nut as I suspected. Since I am using the F1 ballscrews to retrofit a totally different machine that lets me know that I'll need to fabricate one more part than I originally planned.

Glad it was useful to someone!
Tom