Roto Electric Blower

BLACKSMITH REOSTAT + FORGE BLOWER - tools - by owner - sale

I like the old rheostat-controlled set up.

It is a great oldtime blower. It would look good on my forge, but distance is against going after it. I have been using my Champion forge this past few weeks, with the Number 400 geared hand blower. It blows a good blast, but it's either crank the blower to heat the steel, or step away to the anvil or vise. With multiple pieces of work, a power blower would be a good thing. Thinking along those lines, I got hold of a vintage Kirby vacuum cleaner and am "repurposing" the blower. With a "Variac" to control blower speed and a new mounting for the blower, it will make a fine forge blower- just not as classic looking as the one in this thread. I am having pangs at going over to a vacuum cleaner blower on a vintage forge, but I know that to get the work done, I need a power blower. It will be my first time owning a forge with a power driven blower, and I will miss the gentle sounds of gear noise and the low rustle of the air from the hand blower. The sounds of a Kirby blower, even at low speed just do not sit well with me. Wish this blower had been posted a couple of weeks earlier and was closer geographically. Most old forge blowers of this type have a 4 position selector switch to cut in different resistances. By the time they make it to this point in time, the speed selector switches usually looks like an invitation to a short circuit, electric shock or worse. This one with the rheostat looks like a good deal.

Not continuously-variable

I wish I could read the rating plate on that funky old motor! It has brushes; I surmise that it is an AC-DC commutator motor as used inold drill motors.

My read on the rheostat is that it is a tapped resistor rather than a continuously-variable one. Twenty-five taps on the resistance stack, which seems to consist of five concentric rings. The taps, like the resistance coils, are embedded in a ceramic body.

Carefully cleaning, polishing, and painting that thing would probably need 40 hours of work, but, by golly, it would look very attractive if it was restored like that! It was built in an era of honest copper, brass, and cast iron.

John Ruth

John:

Most of the old electric forge blowers had what are termed "Universal" motors, a type which you, as an electrical engineer are likely well familiar with. It is the same type motor as is used on some power tools such as drills and saws. The nameplates on the old forge blower motors often read for "current": AC/DC; or; DC-60 cycles (covers all the bases including the old 25 hz AC or districts where the only power available was DC).

I got a Variac made in Bristol, Connecticut, off ebay in excellent overall condition for 50 bucks. It does the job and is what a lot of our local blacksmiths use for forge blower speed control. A Variac is a variable output transformer, so the speed control is stepless. An idea I had, if I did not score a Variac, was to use a heavy-duty lighting dimmer. These are a silicon controlled rectifier and potentiometer, and put out what is likely half-wave DC at variable voltages. I've seen some blacksmith forges with the old blowers wired to lighting dimmers. Looks kind of out of place, but it obviously works.

The Variac, while not a classic old forge blower speed control or the big rheostat as in this thread, at least has a molded Bakelite knob and pointer and looks a bit more appropriate at the forge. The Kirby vacuum cleaner blower is at least as old as I am (66), and I've built a mounting for it that utilizes attachment points on the blower and motor casings. I'm going to cheat a bit and use a "Fernco" molded rubber drainage pipe coupling to tie the blower discharge to the blast pipe of the forge.

Finding anything with a genuine universal type motor is getting a bit harder these days. Universal motors used to be a lot more common on small appliances, power tools, and on smaller machines. I've got a heater out of the cab of an ALCO diesel locomotive that was being scrapped. The heater is basically a hot water/forced air heater. It has a 32 volt DC motor. I plan to hang the heater in part of my shop, but I do not want to get rid of the original motor. Plenty of rectifier bridges are available on ebay for small money, but finding a transformer with a 32 volt output is elusive. The name of the locomotive cab heater is wishful thinking (knowing how cold an old locomotive cab can be in winter): it is called the "Hades Heater". I think it will be kind of classy to heat an area of my shop with an old locomotive cab heater, so will be building a dedicated DC power supply. Up on the locomotive, there was a box with a simple rheostat to vary the fan speed, but like a dummy, I did not grab it.

I like the old universal motors. A brush type motor with a commutator and the faint smell of ozone is one of those things that can take a man of my age back in time.

Looks like a series wound DC motor with what was referred to as a 2 point starter box to me. It will run on AC but it will run a lot smoother on DC.