Re: [CAD_CAM_EDM_DRO] Thk slides

Well Dave, you're scaring me. These Slides were represented as never used. When I got them, they looked to be in original package. It took me a while to clean what looks to be amber colored sticky substance. The package has been open (maybe to photograph for selling. I'm thinking either the bearing came off the rail and maybe some ball bearing escape or what ever the substance that I had to clean may ended up in side the bearings. Maybe I should do what you suggested in the first paragraph first. Do you know if the THK SR15 bearing have a way holding the ball bearing in place whenever I remove them from the rail?
thanks
bill

----- Original Message -----
From: David Speck
To: CAD_CAM_EDM_DRO@yahoogroups.com
Sent: Thursday, August 24, 2006 4:47 PM
Subject: Re: [CAD_CAM_EDM_DRO] Thk slides


Bill,

Rough running may indicate corrosion or debris in the bearings. If you
look at the travelers from the bottom up, you should be able to see if
there are gaps between the balls. If there are no major gaps, then the
roughness is probably not due to missing balls. You may have to remove
the travelers and clean them in kerosene before repacking them with
clean grease.

You will have to measure one of the bearing balls that you already have
with a micrometer to get the size. Bearings are easily available from
eBay or McMaster-Carr, and many other suppliers. They come out a whole
lot easier than they go in!

Reloading the bearings it lotsa fun. I scrapped some assembly machinery
over the past 2 years and found to my chagrin that many of the linear
bearings were not captive, so I've had more practice than I care to
admit. Turns out that it was only the caked on grease and grime that
held the bearing balls in the travelers. I have seen some new bearings
that come with a blue plastic loading fixture, but have never had one to
work with.

Before you start, put a tie-wrap or piece of wire through one of the
mounting holes at the far end of the rail so your "other" bearing
doesn't slide off while you work on your end. (You can probably figure
out why I suggest this!)

I use a magnetized Allen key a bit smaller than the diameter of the
bearings to pick up and manipulate the balls. I slide the partially
loaded traveler to the open end of the rail, with the rail on top, and
the traveler on the bottom, and pick up a bearing at a time with the
Allen key, and push it into the ball channel between the end of the
traveler and the rail. I use a wood dowel to push the bearing balls off
the Allen key. When the race gets nearly full, bearings will start to
push out of the recirculating channel as you push new ones in. Then you
should run the traveler back and forth to take up slack space between
the balls, until there is no more room to insert more balls, and your
done. Checking from underneath the traveler will indicate whether there
are still gaps in the stack of balls. It can be surprisingly difficult
to get the empty spaces out from between the balls in the circuit.

HTH,
Dave

wdavis364 wrote:
> I bought a pair of THK SR15 slides off a Ebay and one of the blocks is
> slides is moving rough as though it is missing some of the ball
> bearings.
> Can I reload the bearings here? I've seen ball bearing on sale for
> reloading. Is there info on how to do this? If this is doable, where
> can I look for this information and where to buy these ball bearing?
> thanks
> bill




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