Custom scale model builder Ad Gevers has recently finished a special custom repair project:

• Caterpillar Holt 75 Track-Type Tractor

Last month I got the oppertunity from a very good friend, Butch Diggins from Keystone Construction Diecast, in America to become the very rare Caterpillar Holt 75 Track-Type Tractor. Without any doubt THE number ONE on my must have missing scale models in my Caterpillar collection. This handmade brass construction precision scale model is made in a limited edition of only 75 pieces in 2002 by Classic Construction Models (CCM) in scale 1:48 in the "Tractor Holt Mfg Co Byron P. Hunter" Edition. Besides that small number there have been released 300 pieces exclusively for the American Caterpillar dealer HOLT in the "Holt Manufacturing Company" Edition.

True to the original machine and its legacy, each model Holt 75 Track-Type Tractor scale model is hand-assembled from individually cast and etched brass pieces and hand painted. It features individually linked free rolling track shoes with working track tensioners, drive sprockets, track rollers and idlers. The exposed engine reveals the cooling system complete with radiator hoses and fan belt. Within sight of the operator’s seat is the steering wheel, throttle controls, clutch lever, shifting lever and friction levers. All models are individually serial numbered. A must have for every Caterpillar scale model collector.

Butch did have #113 from the Holt Dealer serie which unfortunately was not quite more whole and complete and which also lacked the luxurious gift box and the signed certificate. But still a unique opportunity .....

...... and so after (very) brief consultation with Ad we decided to take up the challenge to bring this Holt 75 Track-Type Tractor to The Netherlands and restore it and restore it back to its former glory. And I can already tell you: I have not regretted it !!!

Enjoy reading & watching!

Ad and Wouter

The History

The first commercially successful Track-Type Tractor was designed and built by Benjamin Holt in 1904. Supported by an endless track of wood and steel, Holt called his invention a “Caterpillar” and the name stuck.

The Holt 75 was equipped with a 4 cylinder gas engine that produced over 70 hp. That power, combined with its ability to negotiate difficult ground conditions, meant it quickly replaced the horse and ox as the primary sources of motive power. Easily out performing round-wheel tractors, it forever changed the face of farming, logging, construction and even warfare.

The Kickoff

Ad never thought when he did built a Holt 75 Track-Type Tractor for himself about 20 years ago from scratch (pictures to follow-)) that he would restore a rare Holt 75 Track-Type Tractor produced by CCM for me.

It is and remains uncertain if you decide to buy a scale model based on a few photos. Especially if this is a rare scale model and the seller indicates in advance that the model is not complete and needs some restoration. You can not go up and down to the US to take and watch the scale model yourself. So it was an anxious wait until the package arrived from the USA.

We do not know what exactly happens to it and it is no longer possible to find out. There is limited paint damage, some repair work on broken or loose parts and a lot of dust.

Ad started with the reassembly of the loose parts and because several screws broke off, some things had to be glued together.

The Tracks

One thing is certain: the original Classic Construction Models Holt 75 tracks are missing and the included tracks are intended for a modern Hydraulic Excavator, so they certainly won't be mounted!

Fortunately, Ad figured out that, like me, he had a kit of the Holt 75 that we had previously purchased from McKenzie Iron & Steel from the USA.

For enthusiasts among you, this white metal kit of the Holt 75 in 1:48th scale that was released by the now sadly deceased Bill Roy of McKenzie Iron & Steel is now sold by the American company Wiseman Model Services under number #H501 for US$ 219,95 and can be ordered online.

Ad had already started building the "Mackenzie" Holt 75 kit, but he had not yet progressed as partly of assembling a number of individual tracks.So we decided to use Ad's tracks now and then replenish them with my kit's tracks and have the missing tracks casted from metal for future project as well.

The "Mackenzie" tracks are just a fraction too long, but actually it is a sublime idea. Ad then custom-made a small metal filler plate, which once serves as a spacer so that the shaft with tension wheel remains in its front position. Perfectly solved!

The painting of the parts

The biggest challenge after customization the tracks is to spray the white metal tracks in exactly the same color as the original Holt 75 Caterpillar Track-Type Tractor from CCM. With this we can perfectly finish this mini "Making of ... Caterpillar Holt 75 Track-Type Tractor".

It is indeed a challenge, but if you know the right professionals, it is actually very simple again: The choice is to make a spray can with exactly the same color as the donor scale model.

For this Ad falls back on his trusted craftsman Toon, who works at De Beer Verf, the paint specialist since 1952 with branches in Venlo, Nijmegen and Helmond in The Netherlands.

Toon makes a customized spray canl based on a color sample from our donor model. Not cheap, but perfect quality paint with the exact matching color. The Beer Paint motto - "Paint is our profession". Highly recommended!

Our choice is to make a spray can with the same color as the donor scale model. For this we rely on skilled Toon, working at De Beer Paints into their facility in Helmond, The Netherlands. Toon makes, based on a color sample of our donor model, our spray can on demand. Not cheap, but perfect quality paint with the exact matching color. Higly recommended!

In exceptional cases, Ad was allowed to take a look from start to finish (and shot some photos) behind the scenes in the laboratory, where Toon worked on the preparation of the recipe based on a color scan, various color fans and his own craftsmanship to create the paint for this unique red brown color for the Holt 75 and finally filling the spray can.

The photos speak for themselves:

The end result and rightfully a proud craftsman: Thank you Toon!

The last step of the build-up phase is to test fit all the original and customized parts and after this finall test to clean up all the parts again with some lukewarm warm water provided with a little ammonia for degreasing.

After thoroughly cleaning with some lukewarm water with a little ammonia for degreasing let all parts, preferably at room temperature or even warmer dry. If necessary, place all parts briefly on a rack above the heating so the spray primer and paint adhere well directly on the resin or metal parts.

As a priming coat all parts are first put in the spray primer. Often this is a gray primer or a gray primer in which already has been added and mixed some drops of yellow paint to create the perfect ground layer to spray on your final color.

After spraying of the parts in the final paint layer, in this case, of course in our custom made Holt Red, take enough time in order to let all parts under ideal conditions dry and curing. So keep your freshly painted parts free from dust under a dome or a keep them in a fully enclosed space. Preferably not in a cold hobby barn, but at a slightly warm room temperature to achieve the best adhesion of the paint.

So how difficult it might be, Do not touch! Do not waste all your work if you start to quick with the final assembly. Please kind in mind that how great the temptation is: Hands off!

After keeping sufficiënt drying time Ad finally may start with the fitting of the painted tracks on the undercarriage of our Holt 75 Track-Type Tractor.

Done!

Now the model is "Ready for work" and it can be added to the collection in its (temporary) display cabinet. -)

Thanks Ad!