Tuesday, March 29, 2011

Unisaw - Completing the Arbor and Tables

So a few days ago I got busy completing the arbor rebuild and starting the tables. The first thing I needed to do was address the big piece of the table edge that was missing (broken off - see the first post images and you'll see what I'm talking about). Ideally this would have a new piece braised back in, but frankly, I've yet to find anyone locally who I felt comfortable with doing the work. Cast iron is rather finicky - the technique requires heating the metal up to cherry red before welding so that the metals interlock, then allowing to cool slowly (like it sand) so you get a strong joint. When talking to any of the welders around here, the only process they know is to immediately start going at it with rod - after thinking about this a while I decided to just fill it as best I could with JB Weld. Since it's not a load bearing surface and wont be under any stresses, metal-filled resin just seemed easier to me (to work, particularly). I cut a few pieces of hard plastic and made a small form, mixing up the two parts and laying it into the void. The stuff was pretty much self leveling.

JB Weld within Form
Cardboard palette and Popsicle stick applicator
Allowed to dry and harden over-night

As you can see the color approximated the raw, cleaned cast iron. I continued to work down the resin using rasps, files and finally sandpaper





Ready for Paint!
While I starting taping off the tables and wings for paint, I also finished up the arbor rebuild. The first time I put the arbor together I wasn't happy with the result - the pulley could slide back-and-forth along the shaft about 3/32" - the threads on the bearing side were also a bit buggered so the retaining nut wanted to cross-thread. So before I torqued everything down and screwed something up, I took it all apart and made a few posts on OWWM to ask for some opinions. I knew I would need to chase the threads so with it apart it would be easier to get things to go together when assembled. One idea I got from the forum was to put everything together sans bracket so I could see how it would fit - that way I would know how much room I would have for the final nut and belvedere washer. While taking things apart the far bearing nearly fell out of the bearing - so I knew that was probably part of the problem. It was too loosely pressed in (the retaining nut wasn't applying enough force), so apparently what happened was that when I applied pressure on the arbor to press everything into final assembly, it loosened the far bearing - that was the slack I was seeing (understand there was so much slack that the spaces would slide - that's where I got my 3/32" of looseness). The second time was the charm - this time I applied a drop of blue LockTite to the far bearing, then made sure I got the retaining nut very snug. I did have one mishap - the punch slipped and hit the plastic bearing sleeve hard enough to scrape the coating, but not hard enough to puncture (luckily) so I went with the same bearing with the hope that it wasn't bad enough to warrant a replacement (only time will tell!).

Starting to press the bearing

Watch the spring washer so it doesn't get caught

You can see the small spot of coating where I slipped

TIP: Place small screwdriver blade under belvedere washer until nut is tightened

Slightly pry upward then go to a larger screwdriver (careful not to hit the bearing sleeve)

Final step to add the pulley lock (with a drop of blue LockTite)

Completed Arbor Rebuild!

I tried to group the photos together a bit, but in practice I actually went back-and-forth from inside to outside while I hit the wings with primer, then two coats of paint (if you look at the camera times you can see the order). I also got two coats on the underside of the table.

Table after Second Coat
Wings after Second Coat
In all I feel pretty good about where I am thus far. I still need to finish painting the cabinet, plus the motor cover, cranks, feet and pan, but those will need to wait for a clear day. I'm going to start the sub-assemblies and probably get the motor apart so it can be cleaned, potentially turn down the commutator and fit new bearings (may get new brushes as well).

-- John

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