Unisaw arbor bearing replacement

[Spalted Walt]

Has anyone replaced arbor bearings on a Unisaw? If so, did you do it without removing the table top, or did you remove it first?

This article makes it sound fairly simple without removing the top OR the arbor bracket, only the arbor shaft:

The procedure on sawcenter.com has the top removed AND he removes the whole arbor assembly as well.

My Unisaw is a model 36-844, circa 2001. I changed the belts yesterday, and while the belts were off, I could hear the sound of dry clicking bearings when I spun the blade by hand. There is no slop and they still spin freely but I figured it would be best to go ahead and change them out.

I'll be replacing the originals with 2 quality Nachi bearings:

Any input?

[Markem]

Well you do need to remove the top.

That might help.

Mark

[jo4hn]

I have noticed over the years that most repairs of this sort are more easily accomplished as a bench top job rather than trying to get at nuts, washers, springs, clips, etc. inside the casing. Or maybe I just don't have enough joints in my fingers. mahalo, jo4hn

[Leon]

I have never ever done this but here is something to think about.

I highly suspect that after removing the arbor and replacing the bearings that the blade is not going to end up exactly where it was before the bearing replacement. If you are worried about upsetting blade alignment by removing the top you may not be making things easier by not removing the top if the alignment still has to be reset.

[Leon]

Hummmm my virus protection prevented me from going there and identified a Trojan threat.

[Spalted Walt]

My anitivirus (Symantec Endpoint) did the same thing - which is why I didn't post the the complete link. I don't know if the site has recently been hijacked or if it's just a false-alarm but I've been to it many times in the past few years without any problems.

Also, while Googling "unisaw bearings" the woodworker forums (lumberjocks, sawmillcreek, etc) recommended that same link numerous times.

The link below IS safe. It's an archive of the original sawcenter instructional:

[Spalted Walt]

What I'm actually more worried about is the weight of the top (I'll be doing this solo). With the wing removed I believe I can manage it. Any idea what the weight of the top is?

[Leon]

It will be heavy, but that is relative. I would imagine in the 100lbs range.

But if you do pull that top off there will probably be shims at each or some of the corners between the top and the cabinet. You will want to make sure that they go back in the right place.

[dpb]

On 4/6/2013 12:02 PM, Spalted Walt wrote: ...

About 250 or less...I don't recall exact dimensions but they're roughly

27" deep by 40" including wing iirc. Presuming extension is 10" that's 27x30 and if assume 1" thick on average that's just a little over 200 lb. or so.

[Leon]

I think you are way over estimating, the motor and trunion will be a majority of the weight and the top is not solid, typically it is about

1/4" thick.

[dpb]

A) Intended.

B) Is solid, but webbed.

OP can guesstimate as wishes from starting point if wants to get better estimate by estimating webbing fraction. Starting w/ a 1" thickness makes the ratioing easier.

[Leon]

Yeah, what I meant to indicate was not solid 1" thick.

[Leon]

Actually to be anal about it, using an iron weight calculator, a 1/4" thick by 27 x 40 would weigh about 70lbs. Add 50% more for the webbing and you are at about 105 lbs.

[Lew Hodgett]

RE: Subject

Not to get the cart before the horse, but to properly install the new bearings, you are going to need an arbor press.

You are going to take the arbor and bearings to the arbor press, not the other way around.

Lew

[Morgans]

What he said. If you are too rough on the cast iron yolk that holds the bearings, you will break the casting.

DON'T ask me how I know that. Be Very careful with the amount of force you use.

[Spalted Walt]

With a bright flashlight and reading glasses I found 3 of the 4 large cap screws do indeed have shims, a couple have multiple shims. I was expecting thin metal shims but they appear to be some sort of amber phenolic material varying in thickness.

[Spalted Walt]

Actually I won't. I'll be using a bearing separator/puller to remove the bearing nearest the blade and I believe I can use it to slide the new bearing home as well. I've had a set of these for about 5 yrs, used the small one once, the neighbor has used them a couple of times. They work great.

Here's a photo of a Unisaw arbor shaft with the bearing in place:

Also, I WILL NOT be changing mine out in the manner this guy did either ;-)

always nice to learn from other's mistakes...

[Spalted Walt]

27 x 40 would be the dimension of the top w/both wings attached. I would've thought that would be closer to 200lbs or more.

I Checked the thickness of my top. Took a 6" C-clamp, screw side underneath, and snugged it up on a flat area (not on webbing). Wrapped a piece of tape around where the clamp's male threads entered the female thread clamp portion. Removed clamp, screwed the thing until the the tape just hit the female portion and measured the distance between the swivel pad and the stationary thingy and got a distance of 3/8"!

The top by itself (no wings attached) measures 27 x 20, it's 3/8 thick, the edge is 1 5/8 wide, the edge and webbing are roughly 5/16 thick.

I'm curious to know what the weight is if you plugged those figures in your 'cast iron calculator' :)

[Spalted Walt]

???

Perhaps if you had researched this as much as I have you would realize just how silly your reply is. No idea how old your are but perhaps with a few more orbits around the sun you'll come to the realization that there's ALWAYS more than one way to skin a cat, (or push on a bearing).

[Lew Hodgett]

-------------------------------------------------------------------- It is very easy to brinnel a ball bearing if proper installation techniques are not followed.

If the installation load to seat the ball bearing gets applied from the outer race, across the balls to the inner race, or vice versa, brinnelling is almost guaranteed to happen.

The load rating of the ball bearing is for a bearing operating at rotating RPM and load, not the static load that happens when the bearing is improperly installed.

As far as tapered roller bearings are concerned, have been in a couple of Timken plants but never got involved in a design application so can't comment on tapered roller bearings from an engineering stand point; however, the installation methods are totally different and would not be subjected to the installation brinelling experienced by ball bearings.

Lew