WoodNet Forums: Re: Anybody want to build a UniSaw?

Mike,

I'll answer some of your questions as I continue here. Plus I've got an extra photo or two for you at the end.

Continuing with that Front Trunnion Bracket

I've hauled a lot of saws, repaired a fair number of saws, tore down a lot of saws and even broken a few. By far for me, the part that kicks my tail is the front trunnion bracket.

This is a fairly large, semi-complex casting with a fair number of inherent weaknesses.

The front trunnion bracket (hereafter referred to as FTB) mounts to the cabinet in three places. It bolts to the top lip at the two ears. It also is secured to the side of the cabinet where the tilt shaft exits through the cabinet. The escutcheon or cover plate for the tilt shaft performs this function. We will see this closer to final assembly.

As described earlier, the FTB provides the rotation point for the front trunnion. It also provides a second function by securing the tilt shaft in two places.

Inside the casting on the right, two plug perform the shaft locking function, keeping the shaft from rotating when the locking knob is tightened. We will go over the shafts soon.

Also as indicated, the stops for 90 and 45 degrees are incorporated into the front trunnion bracket. The bolts on the front trunnion are adjustable to zero in the 45 degree and 90 degree stop feature.

You can break these tabs off. In my small opinion, a person could use a saw with working locking knobs despite a 45 degree stop being broken off. However, the stop most likely to be broken - every one I've ever seen - is the 90 degree stop.

Again it's just my small opinion, but the lack of a 90 degree stop renders the saw unuseable in the long term.

These brackets are prone to breakage in other areas.

This crack wasn't visible from even the inside of the saw. I had to physically remove the bracket before I found it.

This saw was a customers and still was in use. With the top off the crack was still too subtle to notice immediately.

It wasn't until I went to unbolt the FTB from the cabinet that I discovered . . .

. . . the ear was broken off.

This seems to be the most common fracture on any part in a UniSaw, at least in my experience. Unfortunately, this part runs about $250 from Delta dealers new and even used can run $125 on a bad eBay day (good day for me

)

The ears aren't the only potential fracture site. Here is one that is right in the middle of the casting.

This crack is very fine, I had to wet it to make it visible. In this case, because of the crack location, the bracket was repairable. This involved drilling a relief hole and employing a welder who was capable of welding cast iron. That's probably a subject for some other day.

While the ears seem to be the weakest area of the bracket, that doesn't seem to have always been the case.

Or at least Delta made it much worse at some point.

At some point in time, around 1976 I believe, but I'm still working on nailing that down, the 'notch' in the FTB was squared up. The curved shape is the original design and dates back to the original. The squared notch was done in conjunction with a redesign of the top. A cast iron support rib on a newer top conflicts with the older FTB.

While I have seen some of the older FTB broken at the ear, I have seen many more of the newer, square style broken. As I mentioned, if you discover that the newer style bracket is broken you cannot substitute an older style FTB, without also changing the top. If you can avoid shipping charges this can be cheaper, but bear in mind a number of the older table tops do not have the 'T' shaped mitre gauge slots. We can talk about that down the road as well.

Does the reverse work? Can I put an older top on a newer FTB? I don't know. I should pull a top and try it tomorrow, but I've got a bunch of things I should do tomorrow.

Don't hold your breath on me.

Finally, there is a hole on the bottom of the FTB that receives a bolt that secures a retaining clip. This clip holds the front trunnion to the front trunnion bracket, not that they can completely separate. But it does keep them close, thus keeping the front trunnion on the worm gear.

The Yoke

You've seen that big old yoke right down the middle. This the part that everybody oohs over when they say Look how massive that saw is .

This casting is pretty bulletproof as well. I've seen them broken, but not very often.

As mentioned the two purposes of the yoke are to tie the front and rear trunnions together and to provide a mounting point for the motor and arbor brackets.

This pictures shows the two mounting surfaces at each end in a split photo.

The previous poster asked about indexing pins. You can see one of them in the left image.

Each trunnion is held to the yoke with two bolts and two substantial roll pins. I usually try to keep the roll pins with the yoke, but seems like I managed to get trunnions and a yoke with only one roll pin in the eight holes (4 joints)!

Not much else to say - if you break the yoke, start tearing it down.

Tear it ALL down.

The Front Trunnion

Here's a nice bright shiny front trunnion that I grabbed to use or sell one day.

You can see that is has some features we saw on the rear runnion. It has a half moon 'dado' to mate to the FTB. It has a brass bushing to support the elevation shaft. Just like before, leave that bushing alone, unless it's damaged.

Here are some other features of this part.

The two bolts, one on each side, function as the tilt stops. By loosening the nut and adjusting the bolt in and out, you can position the blade 'stop' positions.

Two holes allow the mounting of a dust deflector that wraps around the front of the saw blade. This is done with two longer bolts and a pair of standoffs. Here is the dust deflector mounted.

Here is the other side of the bracket.

This trunnion got me in trouble. Surrounding the elevation shaft is a cylinder or sleeve with a pointer on it. It serves to lock the elevation shaft and to indicate degrees of tilts. Almost every year of them mount with an indexing pin and two screws.

Here it is -

Unfortunately this is what my bracket looked like.

Yeah that's what I thought as well. What a pain that would have been trying to tap that in place or pulling the whole assembly apart.

Anyway, I think I covered all the internal castings. I'll get some pictures of different vintages of shafts to show you next.

Then we will have a few tips on cleaning up the internals, but for the most part that will go quickly (in terms of posts, can't promise how fast I will move

)

Sound out with any questions, so I feel like there are still folks reading this. With all the other threads going on the same subject, this might be getting redundant.

Regards,

Chris

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I may be wierd now, but I'm saving to be eccentric.

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