the Walnut Diary

My 1995 TAFE 35DI came with a very good loader and a cab fabricated in the dealer’s shop. Clearly the tractor had been used primarily for winter snow removal, as it had only 340 hours on it when I bought it in 2004.

The door is a little narrow for my girth, so that spring I decided to remove the entire cab  as I had a lot of mowing to do around my trees. Peter Myers made a replica of the top part of the roll bar and we lifted the cab right off the tractor and stored it. Peter’s replica bolted neatly into place and the roll bar was again intact.

Next I ordered a vinyl roof. $700 later it arrived with a sticker “For the prevention of skin cancer.”

Fall involves switching the cap and the cab by lifting each in turn into place by a chain block attached to the top beam of the car hoist and maneuvering the tractor into position beneath.

But the limitation of this cab, or “half a cab” as Lloyd calls it, is that it consists of laminated glass sheets fastened with caulking to the outside of a 1 1/4″ square tube frame. Vibration and sudden wrenches on the cab frame tend to stress the glass panels. One particularly energetic session this spring had broken one small pane outright and stressed a couple of others.

We removed the broken pane and I took it to Kingston Plate and Window glass. No problem, they would make a copy of the broken part at $18 per square foot, rounded corners included. When I picked it up I asked for a tube of caulking to fasten the glass to the frame. That’s when the trouble began.

Basically, silicone caulking won’t do the job. They suggested I talk to an auto glass expert, so today in Smiths Falls I stopped in at Dave’s Independent Auto Glass to inquire. The two guys about my age were very helpful.

The key part of the process is the sanding of the frame down to bare metal and the application of a special primer to both the frame and the area of the glass to contact the frame. One guy exhorted me to mask the area of the window I didn’t want painted black, as everyone gets wobbly with the little brush which comes with the primer — a small furry ball on a metal stick like a shoe polish brush back when they had such things.

Finding a warm room came first, as this is not a cold-weather job. I parked the TAFE in Ruby’s garage and lit a fire in the box stove. Then I had at the offended frame with an angle grinder, finishing up with my random orbital sander and 40 grit.

An hour and a half later the shop was warm, so I gingerly brushed the primer onto both frame and glass. Heady fumes there, almost recreational, but nothing exploded.

Then came the polyurethane caulk which holds modern windshields in place. They had warned me that it takes 72 hours to cure fully. I vowed to give up the shop for that interval, though I noticed on the tube that it claims a 2-hour drive-away rating. The nozzle with the caulking tube had an unusual slit in one side. Dave explained that the nozzle leaves a triangular bead on the frame which the glass then squashes into place.

I broke open the seal on the caulking and tried a couple of squirts with the caulking gun. The stuff had the viscosity of frozen tar.

Not to be defeated by arthritic hands, I went to the wood shop and collected my pneumatic caulking gun and hooked it to Charlie’s big-ass air compressor. Bet turned it on and I signalled her to shut the motor off as soon as the black goo began to flow. Too much pressure would empty the expensive tube in a couple of seconds. The large air supply meant that I could caulk the entire window with only a moderate reduction in pressure. With my smaller compressor for a subsequent job I set the pressure to around 30 lb. to produce the same effect.

This tool cost a bit over $60. at Princess Auto. Its advantage is that it releases pressure instantly when the trigger is released. Cheaper models do not.

The bead went on nicely and held very well to the steel. At the last moment Bet placed a metal C-clamp on the bottom rail in what we hoped was the correct position to hold the weight of the window in case the caulk did not.

I set the glass on the clamp, tried to line it up, and pushed it up against the frame. It held. Bet placed a restraining hand upon it while I scampered up the step ladder to attach three strips of wide masking tape which I had previously set on the roof. They tightened up nicely and removed the risk of a crash. More bands of masking tape went everywhere, just to be sure.

The following morning everything had firmed up nicely, so I backed the TAFE out. If this window holds, I’ll replace two others.