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Unisaw Disassembly

Modified on 2011/12/18 21:36 by krucker Categorized as Restoration Topics
Keith Bohn posted

Starting of course means taking off the top unless you're really into pain. OK, it's mandatory onna 'count of you can't undo the trunnion brackets without the top off.

Next up you'll want to brush/blow/suck every spec of dust from the cabinet interior. This is because when you drop a part or screw you won't be having to fish around in the pile of crap in the bottom of the saw cabinet, unless of course you are into pain in which case I'll not discourage you.

Next up you'll probably find that the blade raising/tilt shafts are pretty skanky from years of pitch and gum building up. Get your favorite razor handle (I prefer the Titan (tm) brand).

After you have razored off the heavy gunk you can go at it with the Scotch-Brite (I prefer the No. 8541 Doodlebug Brown Scrub 'N Strip Pads/the closest thing you'll find to an abrasive griddle brick).\htm

Go across the shafts holding the Scotch-Brite two-handed like you were shining shoes.

(stops to wait while everyone Googles "Shoe Shining")

Now you want to inspect the shafts for dings or where some idjit took a vice grips to them because he was too brain dead to know better. File these down.

Once the shafts are brought back to smooth and shiney you can go about sliding them out. On the older machines the stop collars and worm gears were held in place with tapered pins. I like these better than the later roll pins. With both you'll need a proper pin punch but since these are the tools people should own (I have a single Starrett that makes my nipples hard but my more complete set are Enders and they are fine) you won't mind getting a set. With the tapered pins you can use a smaller than recommended pin punch but with the roll pins you really need to size the punch to match the pin otherwise you'll just curl over the ends and it makes for a skanky looking job. Take great care with the tapered pins to drive them out from the narrow end. The reverse will not free the pin and only lead to frustration and pain but again, you might like the pain so have at it.

I should note here that with the blade tilting shaft the shaft will have to be spun until the worm gear pin is horizontal (parallel to the floor). You'll notice a round hole beyond. It's there so you can drive the pin out.

So, as we said, be sure to mark everything as it's being taken off and pay attention to which way the pins went in if they are tapered and with the roll pins be extra careful to note the orientation of the collars and worm gears to the shaft. For some reason over the years there wasn't much in the way precision when these parts were machined and what you'll find is the drill holes won't be dead center and actually must mate back up with the collar put there at the time of first assembly.

One tiplette is to re-assemble some assemblies as you go along. For instance, with the shafts you can slide the collars, fiber washers and worm gears back on and set them aside. If you have tapered pins it's a good idea to drop them in their holes but there's no need to seat them. Just enough friction that they don't fall out on their own.

Also at this time you'll discover the fiber (fibre David) washers. Be careful that you keep them in the same order as they were found. Installing a too thick washer where it's not supposed to be will later cause you to exert too much force to raise/lower and tilt the blade.

Don't be afraid to flood the shaft with lubricant (I prefer Marvel oil but there are others) because this will make the job of removing the collars and worm gears easier. Also, you might find that some of the pitch and gum are close up to the collars and worm gears and this will temporarily slow you down. Once you clear that everything pretty much slides off with little resistance.

Something else you can try with parts that assemble to a shaft is to use zip ties (cable straps/ties/the uncomfortable style handcuffs that some police departments use).

With the shafts removed you can go about removing the rest of the guts. There are three major components. The rear trunnion bracket that screws down to the rear right and left hand corners, the front trunnion bracket that screws down to the front right and left corner and the trunnion/blade raising bracket/yoke assembly. Once the trunnion brackets are loosened it all comes out. Be mindful that you don't allow the trunnion brackets to fall into the cabinet. Once free of the cabinet they are a free agent and are no longer fixed to anything.

Lay the trunnion brackets aside and take a look at the trunnion/blade raising bracket/yoke assembly. The yoke is screwed to the trunnions and aligned with steel dowel pins. Once the screws are removed you can tap it apart with a rubber mallet.

The blade raising arbor bracket is assembled to the yoke via a heavy shaft that slides through the yoke and into the motor bracket. There is also a pin (tapered on older models) that will need to be driven out. Once the pin is removed and the screws are loosened it pretty much spilling on some lubricant and using a rubber mallet to drive everything apart. It does not hurt to have a fat wood dowel as a drive pin for this.

From here it time to buff bright the machined surfaces, cleaning the painted surfaces and just getting everything clean. Paint is optional.

Once all this is done it's time to re-assemble which for the most part is a reverse order of dis-assembly.

Prior to this though you would be smart to bench assemble the entire thing to be sure that you have everything where it should be. Dis-assembling a freshly re-assembled saw from inside the cabinet isn't the funnest way to spend an afternoon, right David?

With everything bench assembled attach the blade rasing hand wheel and see how it operates. It should be smooth. If not and you find something sticky take a look at the fiber washers where the mate up against the collars. They might be too tight in which case you could have the wrong washers in the wrong spots. Try switching them around and maybe even thinning them with a piece of sandpaper taped flat against your bench.

Something to keep in mind when bench testing the assembly is the works aren't as they were designed, i.e., hanging from the cabinet so try to be sure that something isn't proper because it's sitting on it's back.

When you are ready to drop the whole thing back in remove the shafts while keeping all the collars, washers and worm gears in proper order.

Give all the machined surfaces that run in a machined surface a good lubricating. You can use paraffin (Gulf wax), chain lube, graphite spray or any of the fanci-schmancy products on the market for this. Try to avoid greases that attract dirt because this will just become a gob of crap later and could cause binding and your'e back here doing it all again.

Next take the front and rear trunnion brackets and seat them against the front and rear trunnions. Using both hands and being careful not to allow either bracket to drop away (and crash onto the floor thus breaking) lower the whole assembly into the cabinet. It will stay in place at this time but drop the cap screws through the holes in the four corners and run the nut up just this side of finger tight.

Start threading in the shafts adding the collars, washers and worm gears as you go.

Drop, or drive the pins into the collars but don't seat them yet.

Again, with the blade tilting shaft the shaft will have to be spun until the pin is near horizontal (parallel to the floor) to get it in. This pin will have to be fully set before testing as anything sticking too far proud of this gear will rub against the casting and you will either have a hard time tilting the blade or you won't be able to tilt the blade at all. File it down if necessary.

So eventually you'll get all of this to where you're pretty much all back together but everything is somewhat loose. At this point you can grab the front and rear trunnion brackets and squeeze them towards each other. Hard finger tighten the screws going through the trunnion brackets at the four cabinet corners and then give them all just enough wrench tightening that they won't go moving about. Now test everything to see how it operates. Locate and loosen anything that seems to be binding.

You might notice some back lash in the hand wheel(s). Back lash is a term to define how far you have to go in one direction with a gear engaged to the other direction and have the gear re-engage. In other words, you're raising the blade, you stop, reverse direction but for the first 1/8 turn it isn't engaged. That 1/8 turn is your back lash. This is caused by there being a space between the mating surfaces each side of the worm spiral and the rack teeth. There is always some back lash, just degrees of how much. My saw is 65ish years old and I'm not bugged by it's back lash. You might be. I guess you could take a chance and buy a new trunnion(s) and worm gear(s). Me? I live with it.

And in case you were wondering, anything with "zero back lash" is otherwise defined as "froze up", i.e., you have to have some back lash, otherwise the resistance of both sides touching would be too great to over come. In other words, zero back lash is a myth.

So where were we? Oh yeah, rinse and repeat with the lubricating, tweak things here and there and when you're satisfied it's the way that God, Al Gore and Herbert Tautz intended it to be. You can tighten down all the screws, tap in all the pins and pretty much get it buttoned up like it was race day. I've left out a lot about the itty-bitty parts but with an exploded drawing you'll figure that out.

Further discussions, and another post by Keith Bohn here:

I removed the tilt trunnion bracket and the entire guts came free just like I knew something.

This is the piece.

In the same post, Bill Nance related his experience.

I just took the guts out of mine a couple days ago. I thought I had to remove the pins and pull the rods, but was able to get everything out without disassembling the rods from the brackets. Pretty much like what JohnnyApollo described... remove all the exterior parts, take off that tilting bracket in Keith's pic, make sure nothing remains connected. Then remove the trunnion bracket bolts, shimmy the various brackets around a little until you can slide the rear bracket off and lift it out. Then twist the yoke (?) a little to lift it out with the elevation rod, and finally pull the front bracket with the tilt rod.

In the same post, jblenzi suggested:

It's been a few years since I've done one, but it helps if you tilt the arbor some.

In the same post, rjconleyy2003 offered the following tip.

I have disassembled a few Unisaws and those tappered pins are a #%@&! What found that works best is a large tappered punch. I have 12" long punch that is 5/8" dia and tappers down to just under the pin dia. Slicker than snail snot. Brakes the pin loose and the you drive the pin out with a round punch. The punch is long enough and stiff enough that you can give it a good whack with out assuming an awkward position inside the cabinet and worrying about hitting a casting. First time I tried it the pin went flying out of the hole. Hum, a little to much force and I had to tap the punch free from the other side. No real damage to the tappered hole but the next one was a better measured blow. After worrying on the pins for hours and getting nowhere a single wack was gratifying. The tappered punch made short work of the tappered pin holding the shaft that the arbor bracket is mounted to also.

Some discussion of when the Unisaw switched from tapered pins to roll pins, then rjconley2003 shared:

The roll pins are not tapered and are a lot easier to get out. You need a roll pin punch to drive them in or out correctly. The roll pin punch has a little ball on the end to keep the punch centered on the pin. I don't know when they changed to roll pins but you can tell the difference visually since the tapered pins are a solid cross section and the roll pins are hollow.

Paul C reminded us here

Note the alignment of the collars on the shafts. They only go together one way. Take a lot of pictures of those before you disassemble. If/when you do take them off of the other parts. Reassemble those collars on the shafts and set those aside until you are ready to clean-up / reassemble.

In the same post Chris J said:

The shafts don't have to be removed in the cabinet.

As mentioned remove the motor and the arbor bracket.

Use a gear puller to pull both the hand wheels off. Remove the trunnion retaining clip pictured above, remove the escutcheon from the tilt shaft.

With all the bolts from both trunnion brackets, separate the rear trunnion from the rear trunnion bracket. Use a small screw driver to start it, a larger one to pry them separate. Remove the rear trunnion bracket.

Pull back on the assembly until the front trunnion bracket and front trunnion separate. You may have to help them come apart.

Once they are separate, grab the elevation shaft and allow the whole assembly to rotate upside down. (The yoke is now below, you are hanging onto the longer shaft).

Drop the rear trunnion down towards the bottom of the cabinet until the elevation shaft clears the front trunnion bracket. Once clear remove the entire assembly.

Remove the front trunnion bracket with its shaft.

bhaydama tore his Unisaw down and shared the process and some pictures here

I have started the tear-down of the saw, and that is where the good story part comes in. Like an earlier poster, I was able to get the guts out without removing the tilting-shaft and raising shafts first. Here’s the process:

1) Remove all possible parts incl. guide block hand wheels, pointer bracket, arbor bracket, etc.

2) Unbolt the front and rear trunnion brackets and remove the bolts.

3) Lift the guts up tilting up the rear…this is the tricky part. It may not seem like it will work but lift the rear trunnion bracket up as far as it will go, then lightly knock the rear trunnion bracket up and away (towards the back of the machine) until the u-shaped lip disengages the matched groove in the rear trunnion. This won’t happen easily, and you may have to bump the rear trunnion bracket a few times with your fist to get it loose-no need for hammers here, your fist is enough.

4) Once the rear trunnion bracket comes loose from the rear trunnion, you are home free. It is a bit scary when the bracket lets loose. Holding the yoke assembly with one hand, remove the rear trunnion bracket with the other and set it aside (while still holding the yoke). It may be good to have a table or cart nearby. The yoke assembly will want to rotate down and upside down with the front trunnion gears pointed towards the roof – let this happen slowly. Once the yoke assembly is upside down, tilt the back of the assembly toward the floor and slide it back so the raising shaft slides through the cabinet. You can either set the yoke assembly on the floor of the saw or lift it out.

5) Lift out the front trunnion bracket. 6) You’re done. Have a beer and pat yourself on the back.

What good would a story be without pictures?

Serial number and modern inventory sticker - I will remove the sticker.

The inventory tag - this is a keeper!

The guts are out, the tilt raise shafts are still in place.

The guts - close up.

On the same thread, bobblack offered:

The arbor comes out on the side of the arbor flange. Remove the bearing nut and loosen the setscrews on the sheave. Be sure to check when it comes apart for spacers at the bearings. Early saws had wide inner race bearings and no spacers. Later units have normal bearings and spacers. Doesn't matter which, just keep up with the parts.

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