Motor Setup Advice Please?

[weepete]

Hi all,

I'm looking to start a wee home project and need some advice on...well everything really. The project is to build a small benchtop lathe for building fishing rods, so I need to put together a motor that's capable of turning a small chuck at variable speeds. Ideally I'd like to set it up so that the motor could be operated with a pedal at speeds of 0-100 rpm for wrapping the rods, a set speed of somewhere between 5-10 rpm to turn them while the varnish dries (for 8 hours or so!) and be mains powered (I'm in the UK so that's 240v AC). The chuck will be belt driven off the motor well, and as it's just for fishing rods it shouldn't require masses of torque, enough to turn 1-2kgs should be more than ample.

I'm sure there must be a relatively simple solution to this but it's been a few years since I did any electronics so am struggling to even start! If anyone could point me in the right direction or give any hints tips or advice I'd really appreciate it!

 

[cowboybob]

Find an old, working ceiling fan, (nice slow and fast speed range with fairly good torque).

Control the slower (rod drying) speeds with a wall dimmer switch/controller and maybe use a sewing machine foot speed control for the faster speeds.

I used a similar controller system for my Dremel tool.

You'd need some manner of switching arrangement to go between powering the wall dimmer or sewing machine controller.

It'll be a bit of a problem mounting the motor and attaching a pulley, but not that bad.

 

[weepete]

That's a brilliant idea mate, thanks. I won't need a variable speed control on the lowest setting so a simple switch may well do the job nicely. Mounting won't be too much of an issue, mechanical stuff I can do, just electrical that's a bit like black magic to me

 

[cowboybob]

Let us know how it goes.

 

[weepete]

Ok, will do. The latest is I've got myself a cheap ceiling fan, and now have another few daft questions!

The manual says not to use a dimmer switch, but doesn't say why. After a bit of research online I found a few pages that suggest it's because standard dimmer switches vary the voltage and for an induction motor you need to regulate the frequency to change the motor speed. So first question is will I get away with a regular dimmer switch without burning out the motor or do I need to get a hold of one that alters the frequency?

Secondly the manual also says not to wire it to a plug as I'm planning to do. Now I can't really understand why, as it would be run off the mains from a switch on the circuit breaker anyway if hard wired. So is this just the manufacturers covering their backs or have I ended up with totally the wrong thing?

Sorry for the daft questions, but gotta start somewhere...!

 

[Joe G]

better yet, how bout an old sewing machine. has a foot pedal already,

 

[weepete]

I'll have a scout about the second hand shops for one, if I can get one at the right price I may well have a go at building that one too! Seeing as I've got the fan though I'll stick with that for the meantime!

 

[Joe G]

yea, years ago i did the same thing.(fly rod rewrapping) the sewing mach. motor worked great, even for cresting my arrows.

 

[weepete]

Cool, its fun too but wrapping rods by hand gets a bit sore and turning the rod while it dries is very time consuming! I used to do a bit of fly fishing as well, I mainly now fish in the sea so it's big 14-16ft beachcasters now!

 

[Joe G]

the first times i did the wrapping thing, if i remember correctly, i used a toy car motor/gearbox, used a rubber band for the drive to the rod. and the four wheels pinned with needles in two
pairs (2 rolling v blocks) . I had a rubber washer to keep the rod from "walking".

 

[cowboybob]

I've got 3 ceiling fans running, at this moment, from wall dimmers.

Most regular, get'em at the hardware store dimmers vary the pulse width to raise or lower the speed of the fan.

Varying the frequency is an other issue.

Does your fan motor have the usual 3 speeds? If so, perhaps between them and a simple variable pulley system you can achieve your speed goals.

Just a thought.

 

[weepete]

Yeah mate, the fan has 3 speeds so it will be a possibility. I'll wire it up to the dimmer switch and see what happens then.

I'm thinking first things first though, my aim will be to take it apart and make up a prototype mount and just see if I can get it to turn once reassembled, so it'll be a wee while for me to get my head around the wiring, also having a bit of hassle getting the nut of the shaft that holds the switchgear and wiring. I don't generally like to take things apart that I can't put back together but may well need to make some room so it may turn out to be a hacksaw job so I can get in with a spanner!

Sometimes I long for a workshop (used to work in one!) so would just make tools to do the job...back in the day

 

[cowboybob]

Sometimes I long for a workshop (used to work in one!) so would just make tools to do the job...back in the day

I hear that.

I've got a pretty good deal here. My wife "overlooks" my having turned pretty much the entire domicile into a workshop.

In return I have to keep what isn't workshop "tidy".

I can do that...

I'll be looking for your return.

CBB

 

[weepete]

Here's a wee pic to show where I am ATM!

**broken link removed**

 

[weepete]

Ach mate, that sounds like a good arrangement! Must admit my missus is pretty tolerant too, I've allways got one wee project or another going though the land of spare oom has recently been turned into a resurrection for my old drum kit (my daughter has decided to give it a go) so there is now some spill over!! I recon it's just a matter of time now till I get consigned to the garage (and that is a project I'm putting off...!!) but hey, I get my own bait drawer in the freezer and she doesn't complain when I stick some live crabs or worms in the fridge so fair play!

 

[cowboybob]

Looks like a fun project to me!

 

[weepete]

Latest update is that it's taken me a while to get back to this project, but after some mucking about I've ditched the fan motor idea, and turned my initial project spec on it's head, after finding an old black and decker quattro that is now in bits I'm turning to the idea of DC power instead, largely as I can test it with batteries without too much of the fear of doing something wrong and toasting myself - I know us Brits are pale but 240vac is a bad way to get a tan!

So......currently I'm not a huge amount further on but have aqquired a few more toys now, an old A/C sewing machine with a supposedly working motor, an old cordless black and decker quattro (now in bits!) and my newest aquisition.... A como drills 919d1481 4.5-15vD/C variable speed geared motor (which I have most hope for ATM!)

New Aim: to build a D/C rod wrapper/turner. I'm rethinking the whole thing as this will give me a much smaller and portable unit that I can test initially off battery power, ultimately though the aim will be to have a wall plug but this will let me play about with it a bit more without the fear. I'm also now chopping and changing between a pulley and a direct drive system, but my immediate concern will be speed control (I've been advised against a PWM and the suggestion was to get something with short circiuit protection too!) I'm gonna try and wire it up before I start building a bed, chuck etc just so I can find if it works!!!

Again, if anyone has any more advice or guidance, please chip in as I'm still stumbing about a bit in the dark here!

 

[Diver300]

Most DC motor speed controllers are PWM, and there is nothing wrong with it. The inductance of the motor is so large that the current will hardly change at all during a cycle of the PWM. There are various controllers around.

Something like this **broken link removed**

is probably fine.

 

[weepete]

Thanks Diver, I'll bear that in mind and see what I can find

 

[Boncuk]

Hi weepete,

you have quite some options for your project:

1. AC ceiling fan (not recommended)

AC ceiling fans are three speed devices being driven by a single coil transformer (see image)

2. Sewing machine motors (highly recommended)

that kind of motor uses a "gas pedal" to increase/decrease rpm. The electronic control circuit is located within the gas pedal enclosure and contains the necessary snubber network to avoid interference with radio and TV receivers caused by switching a triac for phase control.

Those motors are brushed AC motors and are normally rated 100W.

They are very reliable and the entire set (motor and pedal controller) is wired by prefabricated plugs fitting only the correct way.

Many young women in Thailand earn their income by doing sewing work for customers and normally do their business in front of stores along the markets to pay their electric consumption costs directly to the shop owner. Their machines are old Singer, Pfaff and Victoria brands still working precisely.

They are pretty cheap to have. If you reflect on one of those I'll check out the price and ship the set to you in the UK. (My estimate is about ThaiBaht 3,000 (US$100)).

3. DC-motor and PWM control (not the ideal case for your application)

DC motor control is easy, but you'll have to make all connections from mains (DC power supply, plugs and receptacles etc. on your own)

Please PM me your decision.

I'll take care of the rest.

Regards

Boncuk