Re: [CAD_CAM_EDM_DRO] Re: Ball screws and bearings

Re-assembly of a ballnut? Oh you are in for some fun. Its not that bad really. With the lathe machine a sleeve with its outer diameter arrived at in this manner: with calipers measure from one side of the screw to the other inside the lowest point of the radius that being the screws smallest diameter. This will be the outside diameter of the sleeve you are making. The Inside diameter of the sleeve should slide over the end of the leadscrew where a pulley/handwheel would mount. Any portion that stops at the beginning of the ballraces of the screw.

I'll outline for a single ballrow nut. If you have two ballrows you would just slide the sleeve up and start the process all over for the second.

Slide the sleeve into the ballnut past the first return scoop and almost up to the second scoop being the end of the ballnut toward you. hold the sleeve in that position by hand on the farside of the ballnut away from you. Start feeding the balls with an awl or small screwdriver in past the return scoop. As you do you'll notice it gets easier when the balls support the full diameter of the sleeve. Continue feeding the balls in this manner until they emerge from the return tube. As I said before if it is double row just slide the sleeve up to the next series of balls and repeat the process.

With the sleeve completely through the ballnut and balls loaded, slide the sleeve and ballnut over the end of the leadscrew. The sleeve will stop when it hits the shoulder where the ballraces begin. Slide the ballscrew with balls loaded down the sleeve up to where the ballraces begin. While making sure that the sleeve stays up tight against the shoulder on the ballscrew, start threading the ballnut on. As you do the sleeve will be ejected out the back and eventually fall away.

I hope I explained this well. Its quite easy actually. Go about .005" less on the outside diameter of the sleeve to make it easier. And .005" over on the inside diameter as well.

Note: Some ballscrew assemblies have their races completely filled with ball bearings and others dont. I dont have an explanation for this. I just fill them completely. The more the merrier.

Ron




Gregory Kamysz <smsupply@...> wrote:

Thanks for the leads on bearings. I ended up
finding a place around the corner from work. I'll
be tackling the ballnuts tonight, I didn't find
any good info on how to get everything back
together though.

Greg Kamysz



metlmunchr wrote:

>
> This site has 7201's in both standard and class 7 grades.
> http://www.bearingsdirect.com/product.htm
> Standards are about 12 bucks each, and the class 7's are $134 per pair.
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, Gregory Kamysz
> wrote:
>
>>Anyone have a link for cleaning and reassembling
>>ball nuts? I took one apart thinking it was
>>dirty, turns out it was the bearings.
>>
>>I need to find some 7201K angular contact
>>bearings. 12x32x10mm Is this that uncommon of a
>>size? I haven't seen any online. I'll check with
>>the local supplier during the week.
>>
>>Also does anyone have a link for crossed roller
>>rail sets cheap? I need a 6350 size.
>>
>>Greg Kamysz

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