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Bearing removal on lapidary saw


#1

Hi everybody

I’m renovating a 6" Beacon Star Super lapidary combo
(saw/grinder/lap) unit - which has seen better days.

The grinding stones need to be replaced (they’re about 3" diameter
rather than 6") - and, while I’m at it I’m going to try and replace
the bearings, which are currently a bit sloppy.

The strip-down of the main shaft has been OK so far - all the screws
and Allen setscrews have come undone - but I can’t see what’s
holding the bearings in place. Are they ‘fixed’ in some way - or are
they held on by rust ? I’ve not yet tried WD40 - I guess that’s
the first thing ?

This machine seems to be based in ‘inches’ - I managed to find some
metric bearings that are the correct outside diameter, but I think
I’ll need to ‘invent’ some thing metal shims to make the new
bearings snug on the old shaft - think this should work ??

I’d appreciate any comments from anybody who has been here and done
this - before I get the big hammer out !

Many thanks
Adrian
Suffolk UK


#2

Hi Adrian,

Chances are the bearings would be pressed on, with the rust
contributing its own holding power. Try heating the shaft with a
blowtorch, let it cool, put on lots of WD40 and hammer, holding a
piece of hardwood against the base of the bearing and hammering the
hardwood. Most times they will come off. If that still fails borrow
a bearing puller from a mechanical friend, one of these three claw
grippers with a screw in the middle which you tighten down onto the
center of the shaft while the claws are hooked over the bearing.

Cheers,
Hans Durstling


#3

(I hope this helps…) In automotive applications, they use special
gear pullers. It looks kind of like a three legged claw with a screw
on top. Tightening the screw makes the claws grip and pull on the
bearing while the center bolt pushes on the shaft.

Also, bearings are pretty tight tolerances. I kind of doubt you’ll
be able to rig it up and have your saw work right. There may be
markings on the bearing when you pull it. I shimmed the bearings in
my old rolling mill. It still chewed up thin wire. Look for the
right bearing…

-Stanley


#4

First, if it is rust, try something more potent than WD40. KROIL is
available in the USA through mail order only, is one of the best
penetrants I have ever found, works where nothing else will. If you
cannot see any set screws or such, I would think they are pressed
on. Might suggest taking the shaft to a good machine shop and see
what they think and maybe they could remove them with heat and or a
press or cut them off. I personally would not try to shim the
bearings to get them to “fit”. Try to get the correct bearing,
especially if this is a high RPM shaft.

I have to say that I have not worked on this particular type of
equipment, but if I were, the above would be my directions taken.

Best of luck,
John Dach


#5

Adrian,

I have repaired many old lapidary machines and each one seems to be
different. It’s been awhile since I worked on the old Star machines
so I can’t say with certainty that the bearings are held in place
with set screws. If they are…it will be evident…the screws will
be on a collar on the outside of the bearing. If there are none
there then they probably are rusted in place. This is very common on
old machines. One way to remove old bearings is the first clean the
shaft outside of the bearings so they won’t have to pass over further
rust and dings in the shaft. Use medium to fine sandpaper the clean
everything nice and smooth. Then…don 't use WD40…it is not meant
to loosen things…rather it drives out moisture. Get some really
good penetrating oil such as Kroil soak everything very well and
give it several days to penetrate. Then use the end of a 2x4 against
the bearing block and gently tap it off. You should try to get the
same size and type of bearing for replacement. Shims are alright for
temporary use but tend to loosen and shift over time. This is
especially so on heavy duty lapidary machinery. Otherwise, good
luck…Cheers from Don at The Charles Belle Studio in SOFL where
simple elegance IS fine jewelry! @coralnut2


#6

Hi Again Folks… KROIL also goes by the name of AEROKROIL.(in the
aerosol form)… If you’re lucky, an Industrial Distributor in your
area may stock it…(My outfit does)… Absolutely amazing stuff…
Another one is PB Blaster And another is TriFlow(this one has teflon
suspended in it, too)…

In the day job…I sell to the Industial MRO market. A maintenance
professional is a true craftsman in his/her own righthe/she is what
keeps the wheels of industry turning…

Sometimes one can make up for slight bearing discrepancies with
Loctite bearing retaining compoundsthere are several types, and they
can bridge various gap discrepancies…

Mind you, not a substitute for the exactly correct bearing when ya
mount it But if you have to Mickey (Mouse) itsometimes it can do the
trick…

Gary W. Bourbonais
AJP (GIA)


#7

Hi Adrian, Maybe can help. I’ve removed & replaced lots of lapidary
saw bearings. The method used depends somewhat on the style of
bearing used. Without seeing it I can’t be sure.

Generally, lapidary saws use a stock bearing mounted in a pillow
block. Most of the time these bearings have a collar that’s turned
forward or back to secure the inner race of the bearing to the shaft
to prevent the shaft from turning in the race. The collars are
usually held in place with a set screw.

To remove the bearing, loosen the set screw & then turn the collar
to free up the shaft. This may require the shaft to be held by
someone/something & a wrench/spanner be used to turn the collar.
Generally the collar doesn’t need to be turned much, 1/4 turn or so.
Which way is another matter. it depends on how it was installed.
Turn it one way & if that doesn’t work try the other.

Dave


#8

All. Here is the best tip for bearing removal I have ever been given.
First soak the bearing in penetrating oil and remove all the set
screws. Second use a pipe that will slide over the shaft and rest
against the bearing. Place the end of the shaft on a large wooden
block. Use another large wooden block on the pipe end of the shaft.
Wack the block against the pipe with a large hammer. I use a 5 pound
sledge. Sharp blows will lossen the bearing quickly. After bearing
removal go over the shaft with fine metal sand paper to remove most
rust and burs. Lubricate the shaft with bearing grease and install
the new bearing. I have never seen a lapidary shaft that did not use
a stock bearing. Check with a bearing supplier and I would bet they
have a replacement that will fit your shaft.

Gerry Galarneau