rod-mill project - "mains" electric motor advice

A lot of the snowblowers and less expensive lawnmowers over here use a variable friction drive as the transmission. Similar to this:

You might find something similar on the cheap in your area🤷️

Going single-phase, thinking that one motor should be able to serve various projects...

If 2-pole 3000RPM motor were cheaper, maybe can get one with eg. a

I am not overly hopeful of coming-by single-phase motors second-hand...

Advice on brands and sources of motors - what is best value-for-money if price alone is not what dictates that?

Category of motor? There are various "capacitor-start" / "capacitor-run" specs.

What size of motor, given 1/2HP looks like about the minimum for this particular project but not necessarily future projects?

This is very wide-open as a question, for sure...

I think of mounting the motor on a plate of some simple rectangular dimension, which can be moved between projects and bolted into place. Being free to drill new holes in the plate for unique features to that project.

Thanks in advance, Rich S

--------------------------------------- Capacitor-start motors are for loads like air compressors that require high starting torque, unless they have an unloader. You could probably use any available motor and adjust the required power to match it by changing the reduction ratio or drum loading.

My 1/2 HP air compressor won't start on a 3KW generator unless I manually unload it by opening the pressure relief, for which I made a cam lever to raise and hold the plunger. My sawmill needs the heavy wheels declutched for starting, then gradually engaged over several seconds. There are many work-arounds.

A simple multi-use motor mount is a plywood square with loose pin hinges on the edge and a tension adjusting screw or wedge, push or pull depending on which way the belt goes, or maybe both.

The hinge pin is gas welding rod. A loose pin fit is OK because the belt tension removes slack. The hinges need to straddle the pulley position to hold belt alignment. Tight pin hinges can be converted by grinding off one pin end and punching it out. I learned this trick in theatre scenery construction where they are a standard way to join flats (panels), with nails dropped in as pins.

If the motor can run but not start the load add an over-center cam or toggle detensioner to either the hinged motor plate or a belt idler pulley. The clutch on my sawmill is a long rod from the operator position bent into a crank that pulls or releases a spring-loaded idler pulley, with an over-center stop for the crank. The spring was a longer one with the right stretch rate, shortened and rebent to hook over the rod. I can do either expensive first or cheap third world engineering as needed for the salvaged gear I've found.

The best type of motor for a dusty job is Totally Enclosed Fan Cooled, TEFC. WEG (Brazil) is a decent lower priced brand, but I take what's available as long as the bearings aren't loose, which may indicate erosion from electrical leakage. My small lathe has an ex washing machine motor with its large cooling slots protected from flying metal chips by a beercan metal shield. My father's bench grinder was even worse, the motor had burned out its start winding and needed to be pull-started by hand.

I suspect that one driven and one free support roller won't drive the drum as well as two driven rollers widely spaced to increase the wedging force between them. The pulleys or bicycle chain sprockets between them can be any size as long as identical. If their bearings are nylon sleeves that drop into frame slots the chain or belt will be easy to install.

You could drive both roller shafts separately with belts that support the weight of the motor, and then be able to adjust the roller spacing as needed for sufficient drum friction. A drive tensioned by motor weight or springs may jump and relieve the load's torque when started. A clamp-on ammeter on one motor lead may help tuning for efficiency or avoiding overload but power factor is more useful. jsw

The groove angle varies with diameter, since a large bend radius widens the inner rubber less.

I carved the crown on the unworn front motorcycle tire with an angle grinder, by hand and eye. The rear had been worn to the cords and was fine as-is for the bandsaw.

A millwrights guide, preferably older to cover vintage and replica tech, explains how to design and set up belt and other drives.

Hi again

Prices came in on 0.75kW motors = 1HP.

This is all "clean new start" - don't have to fit in with anything before.

"Inherently" single-phase motor:

Convert 1ph to 3ph and get 2nd-hand 3ph electric motors:

"Digital" converter - GBP250 for 1HP - then tax. Is 240V only (GBP420 if can do 440V - "star and delta") So needs "dual voltage" motor - assured most in last 30 years are (??) Says - typically fine for one-person user - only one machine at a time

- but can start ancilliaries like pumps etc. after big machine running. Not "DOL" - has to be simple switch. That's about 1HP converter can drive 1HP motor IF the digital converter does a "soft-start" - and if one motor already running, cannot "soft-start" the "new" motor (stating the obvious).

Didn't ask if offers speed-control - ability to control over +-30% range would be a blessing - not have to vary speed with different pulleys.

The "digital" 1ph-to-3ph is a good brand.

Folk - any guidance?

It would do me a lot of good to get this project done, so I am not going to sweat this too much - in the absence of being shown the way, I will likely get the single-phase 0.75kW motor, do the belts and see this thing running a.s.a.p. In a lifetime, sometimes it's better to get that next step done and know all about what you'd do next when it comes around again.

Regards, Rich S

It would do me a lot of good to get this project done, so I am not going to sweat this too much - in the absence of being shown the way, I will likely get the single-phase 0.75kW motor, do the belts and see this thing running a.s.a.p. In a lifetime, sometimes it's better to get that next step done and know all about what you'd do next when it comes around again.

Regards, Rich S

---------------------------

I built and ran a 1/2 HP electric sawmill before building the 6.5 HP gas one. Bandsaws that make a wide cut have a problem not seen as much with narrower cuts, the teeth need a minimum pressure to cut into the wood and it adds up with length until reaching the point where the pressure to make a dulling blade cut forces its center back until the front edge loses tension and deflects (buckles) up or down. I tried coarser, wider, thicker blades and discovered that they cracked bending around the wheels. More blade tension might have helped but the blade tensioner wasn't adequate for this misuse.

I didn't expect those problems and spent a lot of effort understanding and adjusting for them. It's a good example of the need for debugging a small (less expensive) prototype before moving to the full sized machine. The 1/2 HP bandsaw is back in its original upright configuration.

My windmill rock tumbler needed tweaking too.

Single to three phase converters were once a lively topic here.

An oscilloscope and clamp-on AC ammeter are very helpful if not essential. Standard practice with high voltage is to work with only one hand. I like to see the power plug lying on the bench rather than depending on a switch.

There's a crude and simple way to use a three phase motor that I decided not to post. Just hinting that it exists.

I looked at the second-hand bulletin boards. Some "possibles". The cost of travel to look would absorb a lot of the second-hand saving. I will go to see family up in "the North" imminently - will look at "doubling-up". See if can get to see and maybe collect on a journey I am already doing.

Best wishes, Rich S

I looked at the second-hand bulletin boards. Some "possibles". The cost of travel to look would absorb a lot of the second-hand saving. I will go to see family up in "the North" imminently - will look at "doubling-up". See if can get to see and maybe collect on a journey I am already doing.

Best wishes, Rich S

----------------------------------------------- Building custom stuff consumes either money or time and gasoline. When a customer was paying everything was designed first and then components ordered new or built in-house, my home projects are mostly scrounged. I watch for likely local sources; thrift shops, flea markets, small fab and repair shops with scrap bins, and do enough preliminary design to be able to judge on the spot if a find is suitable, for example knowing the needed HP and available electrical service. If I didn't have machine tools I'd need to match the shaft and keyway size. I designed the sawmill track and gantry hoists -after- finding a source of used 3" and 4" channel iron.

This is what I bought (locally) to replace the 3-phase motors on my lathe and surface grinder.

I looked at the second-hand bulletin boards. Some "possibles". The cost of travel to look would absorb a lot of the second-hand saving. I will go to see family up in "the North" imminently - will look at "doubling-up". See if can get to see and maybe collect on a journey I am already doing.

Best wishes, Rich S

------------------------------------------

I think of New England as small compared to the rest of the USA; MA or CT to the ski slopes of northern NH is a day trip. Mercator projection distorts sizes, this compares the UK and New England at equal scales.

I looked at the second-hand bulletin boards. Some "possibles". The cost of travel to look would absorb a lot of the second-hand saving. I will go to see family up in "the North" imminently - will look at "doubling-up". See if can get to see and maybe collect on a journey I am already doing.

Best wishes, Rich S

----------------------------- When people ask me for free help with some project I detail the difficulties that I've faced on similar jobs before and suggest they could help with the leg work, like finding a source of your motor. Often the request fades away when they realize how much they have asked for. I've mentioned the machine tools and electronic test equipment I found I needed to recover from stumbling blindly.

At Mitre the engineers would roughly specify the project and order critical components before asking me to complete the design details and handle construction. That worked out well, they knew the theory and I knew the practice.

They consulted you first to find-out if your instinct aligned with their analysis and intention to progress?

Hey everyone

Earlier in the "fwiw - rod-mill project start" (concentrating then on "metallurgical" part of rod-mill) someone mentioned continuously variable transmission speed ratio using two disks, with one impinging on the other at right-angles.

The drive from then-on being by belts.

The position of the second disk could be fixed and you could slide the entire motor along to change speed-ratio.

Would be brilliant for a tumbling-mill - rod-mill or ball-mill. Could adjust until get the ideal "cateracting" (the grinding medium and ore detaches from the wall of the shell at about 2/3rds height of shell and crashes-down on the opposite wall at about the "7 o'clock" position) or "cascading" (the grinding medium and ore tumbles back over itself after being climbed some way up the side of the shell).

Thanks. It's a positive thought...

Best wishes,

This is what the bottom tranny area looks like on my old Snapper Snowblower. The silver colored disk is belt coupled to the 5hp engines power-takeoff shaft. It spins all the time the engine is running. The rubber disk contacts it when a hand grip is squeezed. The lever in front slides it left to right changing speed and reverse by contacting the other side of the disk. Everything you want is already here. This is a common drive mechanism in the snowblowers here and some lawnmowers...

They consulted you first to find-out if your instinct aligned with their analysis and intention to progress?

------------------------------------- They gave me increasingly challengingly design tasks and found I could handle them. They were deeply but narrowly focused radar and radio communications engineers, I have a wide and strong background in computer and measurement hardware, both design and construction, so when they asked for a high precision data acquisition board for the Mac, atomic clock to computer interface and digital radio front end I was the right person. Additionally I had learned how to package a project to look like a professional product instead of the usual technicians' Bud Box chassis from Radio Shack. A retiree taught me and several others the amateur radio course to update us in that field. Digital radio takes over at the mixer output and replaces complex demodulation hardware.

I see Mitre just lost a project.

I think a key difference is that being less secure, private industry attracts the more self-confident risk takers. Mitre et al. attempt to straddle the border, though the intrusion of politics and conflict of interest is unavoidable. Clinton cut off my work in order to fund Midnight Basketball. In his second term he realized how much power aerospace electronics gave him and boosted funding.

Britain did similarly with the R100 / R101 airship project. Despite socialist hopes and expectations the "Capitalist" version won, so the whole idea was cancelled in disgust and embarrassment.

This is what the bottom tranny area looks like on my old Snapper Snowblower. The silver colored disk is belt coupled to the 5hp engines power-takeoff shaft. It spins all the time the engine is running. The rubber disk contacts it when a hand grip is squeezed. The lever in front slides it left to right changing speed and reverse by contacting the other side of the disk. Everything you want is already here. This is a common drive mechanism in the snowblowers here and some lawnmowers...

The friction drive operates only the ground wheels, a separate pulley on the engine shaft drives the auger and impeller on mine, with considerable reduction to both the auger and wheel drive pulleys. The old friction disk on my Toro slipped rather easily though the rubber rim was mostly intact. It might be enough for a 1/2 HP motor, I'd rig a test setup before committing it into a machine.

Round splined shafting could replace the hexagonal shaft and sliding hub in the photo as you wouldn't be changing speed and direction nearly as often.

The auger drive is a right angle worm reduction from the impeller shaft that might be useful.

Yeah, just the ground wheels on mine too. Almost all the blowers use something like this for the wheel drive. I looked at a lot of parts manuals last fall when thinking of buying one...

The old Snapper 8hp riding mowers use the same mechanism for the wheel drive. That was my first encounter with one. It's held up well, a lot of miles on that machine cutting grass and hauling my butt around on it. Control is just the opposite, you push in the pedal to release the drive wheel.

Close up image of the drive here:

Yeah, just the ground wheels on mine too. Almost all the blowers use something like this for the wheel drive. I looked at a lot of parts manuals last fall when thinking of buying one...

Leon Fisk

------------------------------- I'm very familiar with the Toro because it was worn out when I bought it. As it's old enough to be all steel it wasn't difficult to restore after complete disassembly. The engine needed only carb cleaning and adjusting, the drive needed belts, the friction wheel and some new bearings. It's possible that lawn and garden equipment replacement bearings might be less expensive and easier to mount than industrial grade ones.

Today I spent the latter, flea market season has begun again. Specialized technical stuff sometimes appears on tables of vendors who have no idea what it is and let it go cheap. This was $5 IIRC.

Newer models may clip onto DIN rail instead of mounting with screws.