Just call Marvin Hedberg 'The fine jeweler of model farm engines.' That's because the Rush City, Minn., craftsman constructs model farm engines with great precision.
'Some people have compared me to a jeweler,' the 59-year-old says, 'because some of the work I do is so small and so fine. I use the lost wax process, which allows me - like jewelers - to create very fine detail. I can put small lettering and details in a mold, and it will show up just as clear as can be.'
Farm engines first intrigued Marv as a child living on a farm near Moose Lake, Minn. 'One neighbor had a 6-horse International Harvester M engine on a saw rig to cut wood for the stove,' he says. 'On a real cold winter day, you could hear it sawing wood a mile away.'
His foray into the vintage engine hobby started with his family's involvement in agriculture. 'I grew up in the 1950s on a farm that had a threshing circle of 7 to 8 families who went from farm to farm following the threshing machines,' he says. Twenty years after his threshing days were over, Marv attended a threshing show and became reacquainted with old engines and iron. As fate would have it, he bought the very same 6-hp Model M engine at an estate sale he'd heard cutting wood during his youth. As much as he liked that old engine, Marv realized his true passion for miniatures when he first saw model engines at shows. 'I figured they'd be a lot easier to carry around and handle,' Marv says. As a trained toolmaker with his own machining equipment, he was confident he could put his skills to work crafting model engines.
Big engines, small engines
Marv's first model engine was an English Wyvern model constructed from a kit. 'I wanted to build an engine based on how the English made them -a sideshaft, throttle-governed engine where the sideshaft operates both the intake and exhaust valves,' he says.
The Wyvern kit maker asked Marv how many engines he'd built. 'I told him none, and he said I'd better start on something simpler,' he says. The kit maker wasn't aware of Marv's machining experience, and he definitely proved him wrong. After he completed the kit, Marv got creative and added his own touch. 'That engine didn't come with a governor,' he says. 'But I made a flyball governor for it that works just fine.'
Still enamored with the saw engine from his youth, the second model engine Marv built was a 1 1/2-hp IH Model M, also a kit.
Unfortunately, the kit he wanted had yet to be completed, and Marv waited for more than a year while the final designs and patterns were finished. When Marv finally received the kit, he discovered there was no crankcase breather on the model. Always one for intricate detail, Marv made a pattern for the breather and crank guard and sent the design to Moyer, who returned the favor by giving Marv a cart kit to carry the engine.
During the year-long wait for the completed Model M plans, Marv didn't just sit on his hands. The tireless craftsman restored a full-sized, 1 1/2-hp IH Model M and adapted it to a 1/2-scale Farmall Model F tractor body. The clever creation was definitely homespun. Marv used a manure spreader's rear wheels, a garden tractor's trans axle, the front wheels from a grain binder, a steering wheel from a threshing machine and even adapted part of a cattle stanchion for the frame. Understandably, Marv gets lots of attention driving that contraption at shows.
The full-sized M also served as a reference model when he made parts for his half-scale engine. 'I measured the breather, rear cover and thumb screw off the real one,' he says, 'and made scaled-down versions for the model.' The muffler details on the kit weren't correct, so Marv remachined the mold to ensure the muffler matched the original. He also made water fittings that attached to the pump jack and added details to the governor system.
Some components from large engines are better suited for models, Marv says. For example, a hand crank on a full-scale engine can be dangerous. 'One time, when I was cranking an engine, the crank flew off and broke my nose, he declares. 'Another time a crank took out a friend's front teeth!' On model engines, cranks are more useful and add to the overall attractiveness. As a result, Marv designed a pattern for a miniature hand crank and crank guard. The company that makes the 1/2-scale M engine liked Marv's detailed design so well that engineers added the details to its model kits.
Marv's efforts and meticulous attention to detail paid off. The Model M took first place at the Pacific Rim International Model Engineering Show in Oregon in 1998.
Built From Scratch
Marv's third engine is the first one he built entirely from scratch. It's an intricate replica of a 4-hp, hopper-cooled sideshaft IHC Mogul engine. 'I had the full-sized Mogul engine on skids, and I liked the way it ran,' he says. 'Making a model engine that nobody else has ever done is a challenge.'
Marv measured the original engine and used a computer drafting program to design the pattern. In the process, he learned the hard way what many builders went through at the turn of the 20th century when internal combustion engines were initially designed. Yet, through trial and error - and a little modern technology - Marv made it work. 'With the computer,' he explains, 'I scaled the engine down to 1/4 size, learned how to allow for shrinkage of iron, made my own patterns and had castings made from them.' The castings were then machined and assembled.
Marv drew the smaller parts and scaled them on the computer, then used a Computer Numerical Control milling machine to craft the metal parts. 'Basically,' Marv laughs, 'the way I build a model, it takes a half million dollars worth of equipment to do it. Other people do it in their home shop, but I like to use the computer where I can generate programs to cut the parts. That way I can control it down to the finite detail.'
The most critical elements of model engine fabrication are making sure intake and exhaust valves don't leak and adjusting the timing components. 'When you make a model,' Marv says, 'you're also scaling down the tolerance area on timing, fits (of parts), and the way things work together. It is much more critical on a model than on the big ones.'
Marv's patterns for the 1/4-scale Mogul will be used to generate casting kits and finished engines by M & E Products, a South Carolina company owned by Mike Burns. 'You can't make big bucks in model engines,' he says, 'because it takes too much input to get anything out of it. Plus, there's a very limited market. The general public isn't interested in them.'
The fourth model engine Marv built is a 1/4-scale version Kansas City Hay Press Co. Lightning balanced engine. 'Balanced' refers to the fact that it's designed so the opposite-moving pistons reduce vibrations as the machine works.
Marv heard that the very unique flywheel engine was located only 30 miles from home. 'When I looked at it, I said, 'Oh my gosh, I want to model that engine,'' Marv remembers. 'I knew I couldn't afford to buy it, and he wasn't selling it anyway, so I measured some parts, drew them in the computer in the shop, and went back and forth until I was finished.' Then Marv made the individual pieces with the CNC equipment.
The Lightning engine doesn't have a camshaft, but it's a four-stroke engine.
'It uses a very complex timing ratchet mechanism on the side of the engine,' Marv explains. Engine timing components were made with heat-treated steel and cut with a computer-guided technique to make them precise enough to function properly. Marv's friend, Roland Morrison of Benton City, Wa., spent months perfecting the timing and other parts on the model engine.
Marv machined all the pieces for the first Lightning model from solid brass and steel bar stock, and only the flywheels were cast. He and Roland are currently building molds to cast components for 12 more Lightning engines the pair were contracted to construct. Roland also assists with the castings, which are made using the lost wax technique - also known as investment casting.
Lost wax casting
First, wax is injected into the engine design's aluminum molds, which Marv builds with the high-tech CNC machine. The molded wax is then taken to a foundry where a plaster-like product is poured around the wax. Next, it's baked in an oven, and the wax vaporizes, leaving a hollow cavity in the hardened shell. Thus, a mold is born.
Next, liquid iron, brass or bronze is poured into the mold, hardens, and the desired component is complete. Finally, the cast components are machined to fit and function.
Roland is also a real stickler for detail. 'He keeps me on my toes,' Marv laughs. 'He has a machine shop with a screw machine, so he can produce very fine parts. The wheels on the Lightning engine cart each have 38 pieces in it, exactly like the original. That's how detailed we're getting.'
As far as Marv knows, it's the first time the portable Lightning balanced engine was ever modeled. Marv's other engines include a 1/10-scale, 8-inch (bore) Ericsson hot-air pumping engine.
'The Ericcsons were used to pump water,' he says. 'A fellow in Duluth (Minn.) made three castings for it - the base, outside cylinder and flywheel -but I had to make all the rest, including the displacer, link arms, burner, firebox and all that. Then, I had to get the timing right.'
Another machine - also a miniature -he dubbed the Swedish coffee engine. 'It runs on a cup of hot coffee, just like a good Swede,' Marv says with a big grin. 'It's a low temperature differential, Stirling-cycle engine that uses an external heat source to displace air inside it, from a hot end to a cool side.'
The air expansion creates a very low horsepower, and the machine will do light work, Marv says. Similar engines run only on heat provided by a human hand, he adds.
In One Word
People usually express amazement for Marv's engines in one word: 'Wow!'
'Most people can't believe it, and at first they don't understand,' Marv says. 'A lot of them say they've never seen engines like these before.'
Marv's engines run on propane or gasoline. 'We often use Coleman lantern fuel, a white gas that doesn't gum up small passages of model mixers,' he says. 'Old engines basically squirted fuel into place and hopefully the air mixed it up, so they're not very fuel-efficient.' Those old hit-and-miss engines make unmistakable sounds: Hit, choo, choo, choo, hit, choo, choo, choo. The hit-and-miss governor prevents the engine from excessive work by holding the exhaust valve open so there's no pressure. Then it slows down until the governor kicks out. Under a load, it will hit almost every time, though. Marv's fancy Lightning engine is also a hit-and-miss model.
Throttle-governed engines, on the other hand, hit every time, with the air and fuel controlled by the throttle to sound more like: thump, thump, thump, thump. The Wyvern, Mogul and M engines are all throttle-governed engines, thus they sound distinct from the hit-and-miss variety.
The Good Old Days
Most gas engines were built from 1905 into the 1930s, Marv says, until rural electrification came to the farm.
'Very few people had tractors with PTO or belt power,' he says. 'These engines were used during horse times to pump water, grind grain, run elevators, run washing machines or anything else people needed rotary power for.'
'Of course,' Marv says, 'I had to build water pump jacks to go with both the Wyvern and the half-scale M so the engines had something to do when I was displaying them. A lot of people don't understand what the old engines did, and the primary work for engines on a farm back then was to take care of the drudgery, like pumping water.'
Marv says he enjoys building model farm engines because he learns how they function. 'Every engine has a different way of doing things,' he says. 'I measure the engine and generate the part, so they'll do exactly the same thing and the style of motion as the original. The more unique and special an engine is, the more intriguing it is.'
There's a little bit of danger in building engines, but Marv is careful. 'If a model engine bites you, it's not quite as drastic as a full-size,' he says. 'You just have to make sure your fingers aren't in the wrong place at the right time.' As a result, he's cautious when he displays the engines. 'None of this stuff was OSHA approved,' he says. 'They didn't have OSHA (when early engines were made). If someone got hurt doing the job, they just got another guy.'
At model engine exhibitions, the owners often polish the brass and castings, and paint them to a very high luster, Marv says. 'That's called a museum-quality engine, and that's hopefully what I'm building. That's what I strive for. When they're finished, they'll shine just like a jewel.' Marv says he and Roland have more projects than they'll ever have time to finish. 'For me, the greatest enjoyment is the modeling process and the people I meet along the way,' he adds. Just look for Marv and his model engines at a show sometime this summer. He'll be the one driving the truck that sports this slogan: 'growing older is natural, growing up is optional!' E-mail Marv at firstname.lastname@example.org to learn more about his experience with model engines. FC
- Bill Vossler is a freelance writer and the author of several books on antique farm toys. Contact him at Box 372, 400 Caroline Lane, Rockville, MN 56369; (320) 253-5414; e-mail: email@example.com
Those who want to build model engines can obtain kits, some of which were inspired by Marv Hedberg's designs. The 1/2-scale International Harvester Model M engine is sold by Wismer Machine Co. Inc., 1006 Old Bethleham Pike, Sellersville, PA 18960. To obtain a kit for the 1 /4-scale hopper cooled, sideshaft Mogul engine, contact M & E Products, P.O. Box 37, Simpsonville, SC 29681. The 1/4-scaie Lightning balanced engine may be obtained from Morrison and Martin Engine Works, P.O. Box 555, Benton City, WA 99320 or online at www.morriso-nandmartin.com/kcl.htm.