[Bearhawk LSA]

Hello All,

I purchased a converted mill and when tearing it down to clean the ways and such I noticed a few issues that seem odd. The person who converted the mill did not directly couple the ballscrews to the carriage plates. The carriage plates have tapped holes that he used to pinch the plate attached to the lead nut to the carriage. Problem is the surface he is using as his datum is not perpendicular to the travel of the carriage. Is this a common way of coupling the stage plates. I have over 20 years in linear motion design and would never do this, but perhaps for these simple low accuracy machines its OK and a common practice. I have included a few pics and one shows the block that is forced against the leadnut to force it against the pocket.

Attachment 333484 Attachment 333486 Attachment 333488 Attachment 333488

I am considering buying another kit to redo all the connections and curious if there is a kit that will work with what I have as well as will work around any pockets the previous owner may have added to the carriages. I would design my own, but i dont have access to a machine and its likely easier and cheaper for me to buy than have a shop make one or two of something. Any suggestions.

I also found that the Y axis leadscrew has lost some balls. the plastic cap that helps with the ball return came off and balls likely fell out. Since the cap is loose and it looks like there is no retention clip I intend to replace the ballscrew. Anyone have a good link on a replacement ballscrew?

Luckily I got this for a cheap enough price that even with a few replacements I will still come out ahead.

Im open to any advice and or suggestions.

Marc

[chuckorlando]

Not much help. But I do know grizzly has kits as well as ebay for that machine.

[109jb]

What you describe is normal for a G0704 and has not posed a problem on my G0704. The lead screw nuts fit into the slots in the carriage and then set screws from the side clamp them to the back side of the slot. This is actually the way the stock G0704 is as well. As far as the slots not being perpendicular to the travel of the carriage, that is not what I experienced, but it looks like your conversion has had the slot for the X-axis nut opened up. It is possible not enough care was taken to align the carriage during the milling operation to open the slot.

[Bearhawk LSA]

Hello 109JB,

Thanks for the info and confirming it is a common method of coupling the stage plates. I will be buying a few new screws and also machine a flat piece to take up the slack in the oversized slot. I am sure if needed I can shim it straight.

Marc

[lcvette]

Think you are on the right track.. having them as they are allows you to align the ballnut much easier with the support bearings. Otherwise it would be a pretty difficult task.

Sent from my QTAIR7 using Tapatalk

[arizonavideo]

I don't think anyone loves the way the 704 holds the ball nut holders on the X and Y but is is what they did.

On the X nut, I square up the slot most the time when I cut the pocket for the ball nut. Often the slot is just a little short of letting the ball nut sit flat.

I bet if the ball screws are stock you will have .003" or so of lash out of them too.

I have my son doing repacking for folks that need it.

[Bearhawk LSA]

I don't think anyone loves the way the 704 holds the ball nut holders on the X and Y but is is what they did.

On the X nut, I square up the slot most the time when I cut the pocket for the ball nut. Often the slot is just a little short of letting the ball nut sit flat.

I bet if the ball screws are stock you will have .003" or so of lash out of them too.

I have my son doing repacking for folks that need it.

For my needs I can deal with .003" of lash. Nothing too precision on my parts since they are made from extrusions and I am just adding supplemental machining.

I tore down the entire machine and inspected everything. I had to buy a new ballnut to replace one that had issues. I plan to install everything this weekend and hopefully get the mill back together. One question, can I lube the screws with Vactra Way oil? I will not have remote oiling so figured something sticky like way oil might do the trick. Also it looks like it might be a bit tricky to get the axis installed and coupled. I was thinking to assemble the X axis first then slide on the X axis onto the Y and then couple the Y. Is this the best way. Since the carriage couplings are attached blind curious if there is a trick I am unaware of.

Marc

[KriegKuts]

I use vactra #2 on the ballscrews ( although through the lube port) and that oil works well. It would be best to use the fill port if possible so that the oil pushes out any chips and debris that might have gotten trapped but slathering the screw with oil is better then not.

[109jb]

I've just used grease lubrication on my ballscrews with no problem.