66 replies to this topic

[ProfHawking]

When i have tried to connect the motor i have found 4 wires instead of the normal negative and positive?..the motor has seperate field and armature excitment?..

i had a 24v motor a while ago that had a brake built into it. it had 4 wires, 2 for motor power, and you put 24v across the other two to disengage the brake.

Are the wires different guage? Have you got a multimeter to check each wire against the other three for resistance? remember to turn the motor as you check, because the contacts might not be in the right place.

[Arthur Brown]

If the motor turns by hand there isnt a brake. I would expect a separate field and armature though. there may be a thermal trip also. Look at the wires do they pair off? the field may well be thinner wires. Check with a meter the armature should be lower resistance (than the field) and may flicker as you rotate the shaft.

As a guess the field will draw 2a max so be (24/2 = ) 12 min ohms and the arm. will me almost a dead short less than an ohm. The controller must allow a startup current of 40+ amps for say half a second.

[sasman]

The motor turns freely no brake... Assuming that i know the correct connections Do i need to apply 24 v to the top 2 connections then a another 24 v to the bottom 2 connections..??

I also tried connecting a electric drill chuck to the motor spindell, turned on the drill and tried to measure the output voltage hoping to be able to pinpoint the correct terminals... but the voltage was very eractic.. so stopped experimenting...

It appears im a bit thick when it comes to electrics...i thougfht i had got a good motor...i wish it had 2 wire's like all the other motors i have always used..

[ProfHawking]

voltage might be erratic. try sticking a chunky capacitor accross the multimeter terminals to smooth out the current. if its electrolytic with polarity try both ways. use a diode too caus putting the wrong polarity over them can make them pop.

[Arthur Brown]

First assume that the field and armature are separaate, then check. You will likely have a field of about 6 - 12 ohms and the arm should be MUCH less, may look like a short but be 0.1 - 0.3 onm

A basic controller for a DC motor energises the field with the rated volts and supplies a controlled voltage/current to the armature.

First find the firld winding, then power it 24v DC then power the arm. with 24v That's full power. Change the armature supply to change the speed, it will likely reverse if you reverse the applied volts.

You may not learn much about it's motor performance from attempts to make it generateas you will need a controller to keep it generating.

[JamesH]

I built a star roller recently, from bits and pieces i had lying about the workshop. It's based on Kyle's nascar star roller design on passfire using a car tire as a rolling chamber. I adopted a different method of spinning the tire, using a central hub rather than rolling it on 2 rollers like a ball mill. The hub was a rear hub/brake drum assembly from a citroen ax. On my lathe i machined a v groove into the circumferance of the drum to accept a v-belt. The belt was then connected to a 25:1 reduction gearbox which was in turn connected to a 1425rpm E-motor. The tire turns at a rate of 22rpm.

Heres a few photos: -
http://i11.photobuck...22/5180e6bc.jpg
http://i11.photobuck...22/9372467b.jpg

Has anyone else made or used a star roller of this type?

Regards,
James

Edited by JamesH, 05 September 2005 - 10:59 AM.

[maxman]

What is the speed of a 24" dia tyre meant to be for the nascar roller? Just working on one at the moment

[Strobe]

I don't much at about the various motors being discussed here so this is just a thought...

Could a record player/phonograph be converted to a small star roller?

[portfire]

I don't much at about the various motors being discussed here so this is just a thought...

Could a record player/phonograph be converted to a small star roller?

I doubt it,all though it may depend on what type.Alot of old turntables are belt driven in which case you've got no chance,your best bet would be direct drive and even then alot of them dont have the torque.A technics 1200/1210 may work but at around £350 per turntabel you may aswel build one from scratch



regards
dean

[dr thrust]

hi,ho hum iam getting to the star roller stage now! after lots of reading,trawling the net ive seen two rollers one with a wiper motor, one with a wheelchair motor,think ill go with the wiper,anyway which is the best drum type/ a plastic bucket or stainless mixing bowl ?

[TzaRocket]

Oh,guys don't you think you are exagerating?My star roller machine is a 18 V car window engine,whit like 80 rpm ,on whitch I have screwed a tin can,and mounted it in a angle.It works great and it is easy to clean and use.
Tought I have a question:I use little sugar bals(like the ones on the cake) to make my stars and they work great.Now I ask you if it is better to use sugar balls instead of lead bals(like the ones used by united nuclear)?

[seymour]

In my opinion, if they work, then yes! It is always a good idea to avoid scattering heavy metals. Fireworks give off enough unavoidable environmentally unhealthy products already.

[Arthur Brown]

For serious rolling the can should be inert (pyro wise) so an iron can may not last long but may survive hobby use.

Many mixes do not need cores if you get the compound and the moisture right.

Do please consider the electrics and switching. It is hard to completely clean all powder dust from the insides of motors where just one spark could wake the neighbours. - Similarly switches - they should be in the next room.

[TzaRocket]

OK.I thinck you are right.Thanks for the tips