good afternoon hello all newbie here with a problem.. i have a 480 watt sander which i need to use a speed controller for a project im doing. i have wired a speed controller to it and it works but i need the sander to stop on the controller. as soon as i plug it in it starts running any guides please thank you

 

turn off the speed controller unless you want the sander to run.

 

If this is the typical Triac Universal motor controller there is usually a switch fitted integral to the speed Pot?
If it does not have you could fit your own, or just an ordinary SP switch ahead of the controller?
Max.

 

thank you very much for both your speedy replys electrics is a bit over my head is there a unit i could buy to solve this? i might not of explained it very good but i need the sander to start from 0 rpm if this is possible thank you

 

There are the dimmer type power versions for the Universal motors that come with a switch, but when the switch is turned on it usually switches the motor to very low rpm, do you want actual zero rpm when the switch is turned on?
It almost sounds like you want the same set up they have on treadmills where if you switch power on, the pot has to be returned to zero before the motor starts, but this would entail a slightly more sophisticated controller.
Max.

 

max thank you yes thats just what i need zero when i switch on could you let me know which items i need if you dont mind thanks dave

 

The T.M. controllers are a bit more sophisticated that the average simple Triac controller, I am not sure it would be worth incorporating the pot circuit into one of those.
Do you have much experience building simple circuits?
Not quite the same outcome, but one thing you could look at will the pot set zero speed when the turned to the off position and the switch jumpered out to see if it is a case of the pot causing the motor to run as it comes off the switch, if this works for you you could jumper the pot switch and fit a switch ahead of the unit, if you get my drift?
Max.

 

thanks max im not an expert at ciruits far from it but il look into what you said and see if i can make it out.. appreciate your time cheers... dave

 

Sorry if I'm too far off topic here, but what are you using this variable speed sander for? I do a lot of sanding myself.

 

hi floomdoggle im doing a project where i need to make a shaker system and needed it to start from zero rpm.....so not a sanding project but i welcome everybody ... thanks

 

Just know that as you slow a tool/motor like this down, the heat in the motor will be higher. The motor also drives the cooling fan and the fan won't move as much air at low speed.

 

hi shortbus and thanks for your input are u thinking id need to add a cooling fan for the motor ? cheers

 

Maybe we should back-up and start from the beginning Just reread the post where you are making a 'shaker'. Is this sander a rotary or vibrating sander? If a rotary/motor driven sander an extra fan probably will be needed if running very slow. Try it and see. Not sure if a vibrating type sander can be slowed down. They work on the 60Hz cycle of the power line.

 

Depends on the motor technology, induction or Universal, the OP mentions running with possibly a Triac controller, induction do not normally like Triac controllers if Cap start/run motor.
Universal are OK.
Also if 1ph induction, you cannot go down to zero rpm
Max.

 

hi shortbus and max and thanks for your replys im starting to understand it more now so cheers

 

hello all again trying to get my head around this electrics but having no luck and struggling to understand ..im trying to get this sander to start from zero rpm and these are what im trying with could somebody be kind enough to tell me how i need to wire it and what i need .......if its possible to do it....

 

That is a Universal motor according to the RPM.
It looks like one of the Hong Kong speed controllers off ebay?
Have you tried it yet and this is the one that does not go down to zero?
I would be interested in knowing the number of the large IC on the heat sink.
It could be Triac, or PWM control, although the PWM usually have a 555 IC on the board.
Max.

 

hello again max and appreciate your reply it is just a cheap one from ebay and yes it wont slow it down but speeds up no problem ..the number on the heatsink is BTA76 600B if that looks rite to you .. cheers dave

 

Appears to be a Triac, what does the pot do? did you try adjusting it, I imagine if it one of the ebay cheapies there were no instructions?
I see one of the ebay ads mention voltage control from 50 to 250, also mentions SCR, but I think they mistakenly mentioned bi-directional SCR instead of triac.
Max.

 

cheers max .. no instructions i was going to ask you about the little screw does that do adjustments to slow down? would you have any ideas how i could do this with another device? im quite happy to buy anything that would work ok.. cheers