Electric Motor speed control question

[jack404]

I know its not directly a model
but i'm making a filing machine for model work and general filing needs

besides changing pully sizes how would be a good way to vary speed on a electric motor

( i have a few uses for this motor, filing machine, wire wheel drive motor etc)

or should a get a electric motor that is capable of speed control ?

i am a know NUTHIN when it comes to electrical stuff

any help very much appreciated

cheers

jack

 

[RonGinger]

The best way to get variable speed is with a 3 phase motor and a VFD (Variable Frequency Drive). Problem is small 3 phase motors are hard o find.

Next best is a PM DC motor, best choice here is one out of a treadmill. There are a couple surplus places that sell them, with the speed controls. If you have a friendly dump (or Transfer Station) you can get them free.

Common sliplt phase AC motors cannot be made to vary speed. Any brush type motor- as in a shop vac, can be made variable speed with a simple light dimmer control, but they are limited to fairly small power.

 

[tel]

I have a 3/4hp 3 phase motor doing nothing here if it's any good to you Jack.

 

[jack404]

Thanks gents

guess i'll be sticking with the 1/4 HP washing machine motor and a range of pulleys

Tel, no good to me mate but thanks i've 3 phase at the workshop but not at the flat

guess i'll do a proper job now and make a quick change clutch for it

cheers and thanks again

jack

 

[Tin Falcon]

Jack: I do not know what things are like down under But I have been able to score a couple of used tread mills. one for sale along the road and another at a yard sale (aka tag sale , estate sale, garage sale) IIRC I paid US $40-50 each) then removed the motor and controller board to use on machines. These have variable speed DC motors. The first one was a full 1hp and that was put on a buddies lathe. The other one is waiting to be mounted. Just a thought. The platforms can be recycled into bench tops.
Tin

 

[jack404]

Tin,
never seen a tread mill outside a gym here,
they gotta exist, theres a catalougue with some in it from some store

but here we generally walk outside ( one of my evil pleasures is watching the girls club go by every evening in spring/summer, they walk past my place then along the beach and back , 35 year up girls to clarify) and i walk the 5 kilometers (2.9 miles) to my workshop and back each day

kf2qd i have never seen a lawn mower that has that rig ( i guess i dont get out that much) my lawn mower was made in 1954 ( 2 stroke victa) and i have not looked at the new ones other than to repair friends ones

i guess a lotta common things in the US aint that common here but thanks anyway gents!

i do have these though

cheers

jack

 

[gunboatbay]

Jack. You should take Tel up on his offer of the 3-phase motor. Contrary to many people's assumption, you don't need 3-phase power in your shop for this purpose. A VFD, as mentioned earlier, usually has a single phase input and a 3-phase output. One the size you'd want for the 3/4 hp motor is housed in a box about 3"x4"x6". Using this on a 3-phase motor gives you the ability to vary the rpm from practically zero to well beyond the normal rpm of the motor without appreciable loss of torque and is the perfect solution to eliminating belt changes for most any application. Also, you don't need to be an electrical "guru" to set this up. If you want more information, just ask.

 

[bentprop]

Sorry,Jack,but there's no easy(read cheap) way to get variable speed with a mains voltage motor.Dimmers,fan speed controls and the like are cheap in the USA,but not this side of the pond.Besides,I think they might be a bit too light for your 1/4 horse motor.
I think the pulleys you have are probably your best option,with some sort of quick-release to make changing the belt easy.Perhaps an over-center handle on an idler wheel.
VFD's,3phase etc. are all very nice,but expensive,and hardly worth the bother for a homemade filing machine.my 2 bob's worth.

 

[jack404]

gunboatbay

this looks like what i was after but theres a few issues

1 i dont have a decent DC power supply

2 ease of use, i know its easy to those that know but i am one that does not know, straight 240V stuff i can get my head around (JUST) anything more i dont trust

3 cost $335 plus GST ( tax) is not cheap ( the price for the cheapest VFD i can find) also this will pull a heap of electricity, way more than a 1/3 HP motor, about triple from what i can figure ( but i am probably wrong )

4 getting the bits here, i've sold my car and bike to finance my business so have only feet for transport for now

i know its probably all sounding like excuses but to me they add up

i have this rigged today and i'll make up a frame and box to house it from a old crate box

its a 1/3 HP motor from a old GMC drill press and a switch block from old mitre saw

i've fitted the motor on the large lathe bed and turned it on to size the shaft from 16mm down to 14mm and milled a flat on the shaft to fit the smaller multi size pully in the previous pic its rough but it should be fine

with this and a 4:1 Ratio on the spindle shaft i should be able to get 300-750-1250-1550-1900-2650-2900-3100-3600-4500 SPM ( stroke per minute) for the filing machine and all these speeeds will allow me to use the same motor for other things wire wheels etc

i appreciate the help but its just a bit too expencive and beyond my skill level for now and i really want to get the critter working within the next week with no more costs.

i've blown my budget until about march 2009 ( unless i get more sales) and this i can make, a VFD i cant

cheers

jack

bentprop you posted while i was replying

I think the pulleys you have are probably your best option,with some sort of quick-release to make changing the belt easy.Perhaps an over-center handle on an idler wheel.

exactly i'll make a tensioner cam based for a quick change that i know how to do on the cheap

cheers eh

jack

 

[Hilmar]

Jack,
Electronic speed controll, 240 V single ph in, out 3ph.

fm50
230V, 1/4 to 3HP

from $99.00
Hilmar

 

[Metal Mickey]

I don't have an answer but this is a valid thread and I for one am interested in seeing it develop as it is something I will follow up myself at a future date....

 

[jack404]

Jack,
Electronic speed controll, 240 V single ph in, out 3ph.

fm50
230V, 1/4 to 3HP

from $99.00
Hilmar

and people wonder why i spend so much buying stuff in the USA

thanks Hilmar here one up to 2HP is $335 ( forget the model and type )
( plus 10% tax plus delivery which is double what Travers.com charge for delivery of my tool order last month)

i found the exact same one on ebay (USA) for $56.95 USD, buy now!!!

i bought a t cutter (US standard 204) from travers for $13.95 USD ( $16 AUD) here the same thing is $69 plus tax

delivery from the US for 5 cutters is $14.50 USPS ( $18 AUD) delivery for 1 only here from 15 kilometeres away was $33 AUD

dont get me started on ER 25 spring collets!!! rant rant rant i paid for them 5 weeks ago and still waiting but they have advised me i'll have to pay extra when they do arrive,( was told they where in stock back then) i'd have been better off buying those from LMS or MCS direct it would be cheaper AND faster and i'd have the things by now

i really do try to buy Australian but in most cases I CANT AFFORD TOO and the costs just impose on your creativity too much for these type of things ( stuff you cant make yourself) end of rant

cheers folks

jack ( the broke)

PS i am making a multi tool table to fit this on, with interchangable plates

i'll mount the filer to another smaller section of 7 ply that will slot onto the main table

the motor will stay fixed to the table but i'll be able to swap out the filer with the wire wheel or polishing wheel and whatever else i come up with with a few bolts or maybe wing nuts we'll see what i have in the junk pile later today

cheers