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Rebuilding a Deere 33 Tiller - part 2
September 22, 2012

46" / 48" Mower Deck
Just a quick side note about my 46" mowing deck that I couldn't find online and thought that it might help someone in the same situation.

Problem: The belt from the PTO to the mower deck was jumping off the deck pulley.

Background: Both the deck (blade) belt and PTO belt were on the tractor when I bought it and I've been mowing with it for a couple years. When the PTO belt jumped off the sheave, I reinstalled it and it promptly jumped off again.

I replaced the belt with a Deere M82718 belt, but also found that others had used both 4L-90 and A900 belts. The Deere belt was a bit more expensive, but I was going to be up at the Deere store anyway.

I didn't think to check the blade belt and as soon as I engaged the deck, the sound of mower deck engaging wasn't what I was used to, so I shut the 317 down and pulled the deck off. Once I had the deck belt covers off, I saw that in the two years since I had serviced the deck a lot of dirt and grass clippings had piled up beside the belt. I also found that the belt had jumped off the right side pulley and was hung up below the sheave.

I cleaned all of the dirt and grass, then since I had the deck down, sharpened the blades. I checked, lubed and readjusted the idler pulley, then re-threaded the belt; which didn't appear to be in bad shape.

I got it all back together and within a half hour it threw the blade belt again.

The fix was to replace the blade belt. Apparently the blade belt had broken a cord or three which was causing the belt to flip off of the blade sheaves. I learned my lesson. If I should have the problem again, it will be worth my time to just replace both belts.

Tiller
Removing the tiller tines from the carriers took a while. To get started, I torched off the ends of the tines so I could chuck the carrier up in my lathe. I used a carbide tool and faced down the welds to a bit below the blade surface with the lathe. Not precision work by any stretch of the imagination, but it was good to get a little lathe time after not using it for a few months.

Once I'd faced off the welds, I moved each carrier over to the vise and cut through the thinnest part of the blade with a hack saw. I did this on both sides so that the tine was split in two on the carrier. I then used a cold chisel to wedge open each of the cuts. A few whacks on either side split the blade in two and allowed me to remove it from the tube.

Not the quickest or easiest thing to do, but it worked and I ended up with two tine carrier tubes sans tines.

cut_extensions
cut_extensions2
The blade tips were cut off, then the remaining metal was torched off so that the extensions would fit in the lathe.
Close up shot.  Thankfully I have a torch and lathe. Doing this with a hacksaw, file and grinder would have taken a while.


The next day I did the same for the two extensions. One worked perfectly and the next didn't. It seems that I didn't cut deep enough into the weld on the lathe. Since I had already used the hack saw to cut the remainder of the tine in two places, I wasn't happy about putting the piece back on the lathe. Interrupted cuts and uneven surfaces don't do well in a light lathe. I could have used a grinder and spent half the day grinding the tine and welds off, but I decided on another approach.

cut_welds2
cut_welds1
Using the lathe to cut through the welds that hold the tines to the tine carrier.
Switching to a 4-jaw chuck and cutting the tines off of the tine extensions.

I mounted the extension in my mill and cut the welds off using a 5/8" roughing cutter. This took eight set-ups, but since this wasn't precision work, the set-ups were quick. Once I had cut the welds around the tube in an octagon, I moved to the grinder to finish removing the welds around the circumference of the tube. A couple hours work, but better than doing it all by grinder or breaking a bit on the lathe.

I honed the inside of the carrier tubes with a 2-stone caliper hone and mounted the 1 1/4" shafts on the lathe and filed off the rust. They now fit together well. When I reassemble them, I will use some marine grade anti-seize to see if I can prevent them from rusting together again.

Getting the tines ready for welding was the next job. Unfortunately, I am not real impressed with the holes that were stamped in the center of the new tines. They weren't really round and this meant that I needed to re-size each of the holes in the 14 tines to fit over the 1.375" carrier shaft. I used a small drum sander mounted in my drill press. Pretty quick work if you only had one to do, but I had 14. Pretty shoddy quality control on the part of the manufacturer.

Welding the tines on to the carriers and extensions was the next job. With the tine holes re-sized to fit over the carriers, I lined each tine up with the punch marks I had made before I cut each one off. Each welded tine appeared to be offset by 45° on the carrier and then the square plates offset the tines by 90° on both the inner and outer welded tine. You use a left and right tine on each carrier so that the sharpened portion faces the same direction. Both carriers are identical and are just mounted from opposite ends so that the sharpened area faces the front of the tractor.

The actual welding was done with my new-to-me Lincoln 225. It's an old beast of an AC only arc welder, but in remarkably good condition. I laid a couple practice beads down on the old tines and changed the amp settings until I got good penetration. I used E6013-1/8" rods and a setting of 100 amps. I must confess that I am not the most experienced arc welder, but by the second tine, I was laying pretty good beads. Not the prettiest of welds, but strong. I did have to grind down a few welds and re-do them, but I am pretty confident that the welds will hold.


hone_tines
tine_weld
Upper tine has been reamed to 1 3/8".
Lower tine as received. Not a very round hole.
I'm starting to get some nicer looking welds after a bit of practice.

During the process of getting the old tines off and the new tines welded on, I put another couple of coats of paint on all of the parts. Aside from painting the tines, carriers and extensions black, I am pretty much done with the painting.

After going through my boxes of plastic scrap, I finally found a piece of 3/16" thick Delrin that I could use to face the drive chain tensioner. I cut it to size and measured the area that the chain would ride on. There was just enough room to drill and counter-sink some holes so I could rivet the Delrin to the tensioner.  Hopefully the Delrin will wear well in this capacity. If not, I can always braze on a new steel face to the tensioner.
tiller_paint
tensioner6
Pretty much all of the parts now have a coat of Deere yellow.
The chain tensioner gets a facing of Delrin.

I did some more work on the tines today.  This time I worked on the tine extensions. I finished reaming all of the holes in the tines that weren't circular. Then after checking the pictures I had taken before disassembling the tine assembly and figuring out which way the tines should face, I welded up the extensions.  I used a small L square to make sure that the tines were square with the extension carrier.  The welds on the extensions came out even better than the best welds I had made before. I guess I am learning a bit more.  I did a mock assembly of the tines and main chain shaft to make sure that everything came out correctly.  Unfortunately it didn't.  I welded the left carrier outside tine 90° out of phase - 45° the wrong direction.  Darn. I checked that darn tine twice. I guess I should have checked it a third time.  In the great scheme of things it won't matter as the tines are all staggered so they'll balance and won't introduce a vibration, but I hate it when I mess up.  Yes, I could grind off the weld and re-do it, but I won't.  The fact that it would look right won't be worth the added work.  Cursing a bit, I then took the tines outside to give them a coat of black paint. 

align_tines
tines_assembled
Aligning the carrier to the tine. Yes, it's high on the left, but that was fixed before welding. Taking pictures while working isn't always easy.
Checking the alignment of the tines on the bench before they get painted and assembled. Yes, I use pictures any time I can.

Assembling the chain case is pretty straight forward. The top shaft has the long side facing right. Bottom shaft doesn't seem to matter. I attached the chain and put the tensioner in place with the bolt loose. I used a good quality sealant to seal the case halves.  Since I wasn't ready to attach the chain case to the tiller body, I put bolts and nuts in all positions around the case halves so they would cinch down evenly. After using an L square to make sure that the lower tine shaft was perpendicular with the chain case, I tightened the four carriage bolts on either side of the bearing housings. I then centered the tine and top shafts and installed the eccentric locking collars.  Once I had the tine shaft square and true with the case, removed one bearing housing at a time and installed the thick steel attachment plates and reinstalled the bearing assembly.  Hopefully this would allow me to keep the tine shaft square with the case. The last thing to do was to adjust the tensioner.

locking_collars
cut_washer
With the chain case sealed, I aligned the tine shaft, then centered the shaft and installed the eccentric locking collars. 
To fix the bearing guard, I opened the center hole of a large flat washer to 1.39" as there needs to be a little space around the 1.375" shaft.

Outboard of the tine shaft bearings, there are a couple stamped sheet metal covers that help keep crud out of the bearings. One side was in pretty good shape, but the other had seen better days. It appeared that roots had wound around the tine shaft an worn through the end of the cover. There was now a 2" hole where there was only a 1 3/8" hole on the good cover.  I found a large washer in my parts bin and chucked it up in my lathe to enlarge the center hole to 1.39".  I then brazed the washer on to the end of the cover.  It came out pretty nice and should keep the bearing a little cleaner.

braze_washer
test_fit
I aligned the washer on to the bearing guard and brazed it into place.
Before I gave it a coat of yellow paint, I test fit the bearing guard to check to make sure that the center hole was centered on the tine shaft.

Due to Deere using carriage bolts for holding the bearings on the chain case, it's a little tough to get sealant on both sides of the mounting plates and bearing holders and then get everything aligned before the sealant sets up or is rubbed off. It's hard to align bolts that move around.  I'm pretty sure that the case won't be totally oil tight. My original operating manual specifies 30 weight oil in the chain case, but if I get leaks, I will probably resort to using motorcycle chain lube. I assume that Deere expected leaks as the recommended time between oiling the chain is only 8 hours of use.  That sounds like a "total loss" oiling system to me.

chain_case_assem
chain_case_assem2
The chain case is assembled. The case got a bit greasy during the build.
The tine assemblies are added.

I added the tiller tine assemblies, making sure that the shafts and locating pins were liberally coated in marine anti-seize. Hopefully the next time this tiller needs to come apart it will be an easier job than I was treated to.  The sheet metal body was installed. The right side extension was a bit tweaked, but I got it pretty close to being the correct curvature before I put some paint on it.

Next on the list was to install the upper link arms and height adjustment screw.  The top of the link arms were greased and the adjustment screw got a coat of anti-seize.  The inside drive chain case half that I repaired the mounting tab on was installed.  Next project will be the slipper clutch.

chain_case_assem3
chain_case_assem4
The tiller body and extensions are added.
It's beginning to look like a tiller again.
The upper link arms and height adjusting screw is installed along with the drive chain case half.

More as I get to it.


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