Repair of damaged Mbox M1a Caterpillar Scraper (completed)

[Tinman]

This Major Pack M1a Caterpillar scraper was gifted to me some time back. It one of my favorite Majors, so I wanted to do it justice. I've pointed out all the problems in the photos but I'll list them here so I can go through my choices for restoration.

Scraper body:

1. The pin which allows the scraper body to hook onto the tractor was broken off flush. I cut a short piece of steel rod and placed it into my drill (to make a mini lathe). While turning the rod, I used a small file to make the round over on one end. Next, I used a pin vice to drill out a small hole (the same size as the now shaped rod) where the connecting pin used to be. Test fit the pin, cut to right length and secure in hole with epoxy.

2. I fashioned a new upper half of the bed raise/lower lever using a scrap of plastic laminate. I shape the plastic, while leaving the part I'm making, connected to the bulk of plastic at what will be the base of the leaver. This allows me to work with a small shaped part while holding on to a much larger amount of material. When I'm happy with the shape of the part, I cut it free at the base. A trial fit or two determines how tall it needs to be (shortened by removing excess from the base while holding the part with needle nose pliers). The remains of the old lever are filled off leaving a nice flat spot for the new part. Secure the new part in place with epoxy.

3. The push point was fashioned out of a small piece of aluminum. I shape it as much as possible while the part is still joined to the bulk of the stock, then cut it free. The broken end of the scraper is filled flush for a good fit and the new tip is secured with epoxy.

Tractor:

1. The missing exhaust stack is easy. I drill a hole (size determined by the diameter of replacement part) where the old stack was on the hood. The old stack was 1/16 (.375) of an inch in diameter and I used some aluminum tubing of the same size. Place a dab of epoxy in the hole and insert tubing in hole. I placed some putty on the under side to hold the stack at the right height and to keep it straight. Once the epoxy set, I removed the putty (from the underside) and placed a drop of epoxy on the top of the stack to make the round over.

3. The driver was the hardest part. Maybe I'm just confusing hardest with most time consuming part of the project. The driver that closest matched the one on the cat (in scale and appearance) was one from a #43 Aveling Barford Tractor Shovel. The main issue with this driver is that it is cast as part of the base on that model and is quite "involved" with the seat and driver cockpit of the tractor. I used a busted up #43 and cut the driver free from most of the base. Then began a slow laborious process of carving away all the excess metal and saving only the driver and seat. I had to be careful how I held the driver as attempting to place a clamp of any kind (on the driver) either damaged the driver or blocked too much of the areas needing to be carved away.

I ended up holding the driver part using a 10 mil rubber glove (to give extra grip) and carving away using small diamond de-burring bits (with my Dremel). Since the tiny driver would heat up quickly, I had to keep dipping into a cup of water to quickly cool it down. The first time I did this, the moisture made a lubricant that kept me from holding the driver tightly. This is the point where I spent twenty minutes searching for the driver that was flung from the grasp of my wet gloved fingers. Once i found the driver, I sprayed the fingers of my gloves with some spray contact adhesive. This gave my gloves the needed extra grip to hang onto the driver after cooling it. The remainder of the carving went along without further incldent. The finished driver was joined using epoxy.

It's rainy here now and is forecast to last at least another day. So I am getting every thing ready for painting as soon as the weather clears. I'll show more photos as soon as it's painted. As always, if others have done this or similar tasks in a different way, I'm always eager to hear about your methods. Click on thumb nails to enlarge images.

[tractorboy]

Always amazed at the quality of your restoration/repairs. Look forward to seeing finished article.

[MatchboxFreak]

Nicely done!
Your attention to detail and fine execution are amazing!
Looking forward to seeing the completed project.

[Tinman]

Weather finally came around and I've finished several projects that were waiting for final paint work. Here's the completed Cat Scraper.

[tractorboy]

Beautiful job, amazing restoration when you look back at what you had to begin with.

[charliep]

Nicely done. Besides skills, one needs good eye sight & a steady hand. By any chance, do you have a picture of the right side of the model?
I am interested to see how you ended the axles. Thank you.

[Tinman]

Nicely done. Besides skills, one needs good eye sight & a steady hand. By any chance, do you have a picture of the right side of the model?
I am interested to see how you ended the axles. Thank you.

Thanks for the kind words. My hand is not as steady as it used to be. I have a couple of "rests" I use to stabilize my wrist while doing fine work. I wear a magnifying visor that gives me several power of magnification for a better look at what I'm doing.

I have yet to finish photographing the model (so just this one pic for now). The tractor had crimped axle ends. I had to cut the axles to get them off the model (too rusty) and the replacement axles for the tractor are now crimped as well. The scraper axle was also crimped (it too had to be cut off) and the replacement axle (which was formerly rounded over) is left without any round over (left with a ground off round over) and fixed in place with a drop of water soluble glue. I didn't want a crimped end rubbing up against the fresh paint.

One interesting thing I discovered is that it would seem the wheel hubs for these are chrome plated. The hubs on this particular model were some of the worse I've dealt with.  I tried to buff them up with a fine wire wheel but they were too far gone. When the crud was buffing off, copper plating steadily began to show.  Copper plating is always laid down first, before chrome.  Both the hubs and tires on this model were exceptional in their quality.  To this day, the tires always remain supple and don't crack and the hubs always keep a bright finish (unless badly abused like this one) which is indicative of chrome plating. 

I recall seeing a prototype or prepo of another Lesney model and it used the hubs and tires from the M1a.  It was a 1-75 and it's a no brainer to figure out why the production model didn't use them. The cost of the M1 hubs and tires would have made the model profitless (I think it was a #24 Weatherill, but not positive about that).

[Idris]

I recall seeing a prototype or prepo of another Lesney model and it used the hubs and tires from the M1a.  It was a 1-75 and it's a no brainer to figure out why the production model didn't use them. The cost of the M1 hubs and tires would have made the model profitless (I think it was a #24 Weatherill, but not positive about that).

The box art on the first release boxes shows these hubs fitted to the rrear axle of the everse colour 2c Muir Hill Dumper

[Tinman]

I recall seeing a prototype or prepo of another Lesney model and it used the hubs and tires from the M1a.  It was a 1-75 and it's a no brainer to figure out why the production model didn't use them. The cost of the M1 hubs and tires would have made the model profitless (I think it was a #24 Weatherill, but not positive about that).

The box art on the first release boxes shows these hubs fitted to the rrear axle of the everse colour 2c Muir Hill Dumper

The Muir Hill was my first thought, then I made the mistake of second guessing myself and went with the Weatherill. At least my memory isn't totally fried (yet).

[Diecastmolester]

What's next then?
Having the wheels and making the entire model for them?

You are not that far away from that.