Thread: speed controller

I got one from jaycar about $45 including box & cords use it on my scroll saw just check what wattage you router is and ask them if it will work for you
Regards Michael

Is this what you are talking about?

http://www.jaycar.com.au/productView...eMax=&SUBCATID=

Have you had any problems with it? It looks like a nifty way of getting a variable speed router.

yes thats it & no not yet but only had it a month or so on the scroll saw do have to have it at full speed to start then adjust it back
Regards Michael

Originally Posted by johnny_v

Is this what you are talking about?

http://www.jaycar.com.au/productView...eMax=&SUBCATID=

Have you had any problems with it? It looks like a nifty way of getting a variable speed router.

That unit is only rated at 600 watt, and will only run a very small router.....maybe a laminate trimmer.

Originally Posted by hoopy

My router is a single speed makita, no soft start, old but mostly good.

I want to put on a speed controller, any tips where to get a good one, how to go about it or perhaps adapting something else, Dick Smith etc etc?

Cheers, Heath

Heath, take those ratings from the hobby shops with a grain of salt. I once used a Dick Smith 5amp rated controller on a 2amp draw motor. Controller burnt out first day. The 10amp controller works okay but I certainly would not attempt to use it on the Makita router with its big starting surge.
You could buy a new variable speed router cheaper than a suitable external speed control.

hoopy
I bought the 10 amp. kit from dick smith (assembled it myself) got the s.i.l to check my work (licensed electrician).
I have been using it for everything for two years and still going well.
Just plug it in, plug your power tool into the box and you have a wide range speed variation, full powered pedestal drill, table saw, router, have even used it effectively on an electric hand drill to slow it down for use with a fly cutter,
I think it was about $140 which might not look like a good buy, but when you consider the alternatives, i'm glad i took the plunge.
The assembly was the difficult part because my eyes were not working too well at the time but with the aid of a magnifying lens and patience it turned out O. K.
I think timbecon had some on order from an O/S manufacturer at about the same time as i originally started looking for one, i did order one from them but they never eventuated, they are usually pretty good but you cant always rely on O/S promises.
regards joe

Hoopy

I have to ask, why would you bother?

You can get a new Triton router (on special at Bunnies) with all the modern features for the same or less than the 10amp gizmo?

Occasionally 'variac's or continuously variable output transformers get listed on ebay under Business and Industrial, Electrical. These generally provide an adjustable 0-250V out for 230V in and a 10 A one should be beast enough for any Mak router that I have seen.

These units provide a a complete sinewave variable amplitude waveform for the motor which is better than using a dimmer style unit, which provides an constant amplitude variable duty cycle waveform.

The dimmer style units with their sharp transistions in the waveform cause high peak currents in the motor with inherent heat buldup at a time when the motor is running slower and hence not moving as much cooling air, resulting in overheating if the unit is heavily loaded. With a variac style unit, the motor current reduces with speed, and the nasty peak currents aren't generated, so overheating is less likely to occur.

Any addon speed controller is going to be devoid of feedback from the motor and hence cannot maintain a constant speed with variation in load. The better integrated units can provide speed regulation. Tools designed as variable speed from the outset will be designed to cope with the extra heating that the variable speed control system can create.

If you were to go the variac path, I would include an RCD plug on the device as a general safety measure, and you need to set the variac up in a low dust area. I might pay to blow out any dust on a regular basis as well

Malb's advice concerning the variac is excellent, it is still the best way of ac voltage regulation, regardless of what sort of electronics they think up. But they are indeed sensitive to dust and expensive.

But whatever you use for speed control (Malb also pointed to that), bear in mind that loss of motor cooling airflow is indeed an issue. The fan yield behaves "exponential" in accordance to rpm change. That means that at double speed, the yield is 4 times as much instead of 2. And it also means that the yield at half rpm is only a quarter of the amount it would be at full rpm! Many regulated routers contain a sort of coil temperature check, kicking in when overheating threatens, but a single speed router with an external control attached, will of course lack that.

I don't know if you ever built your own sound amplifiers and such, and are handy with soldering irons and making printed circuit boards. If so, i could give you a schematic of a 2000 Watts AC triac control. I also have an original French Thomson design, which they made especially for arc welding transformers, so this design is up to high peak currents and nasty voltage spikes. Alas it contains some exotic parts, but the other 2000 Watts design is reasonably "off the rack".

regards

gerhard

Thanks to Malb and my mate Gerhard across the border for once again sheding some light on a topic of great interest to me. I have no idea what they are talking about but understood the following:

• There are various types of external speed controls
• Some are better than others
• Ventilation and cooling factors should be considered when running electric motors slower than the RPMs for which they were designed.

I find the idea of a reliable external control very interesting because it can be moved around to different tools. For example, an angle grinder can be slowed up to be used as a polisher, etc.

Will get round to it one day... Or Gerhard will drive down to me in Bavaria and build one

Originally Posted by gerhard

I don't know if you ever built your own sound amplifiers and such, and are handy with soldering irons and making printed circuit boards. If so, i could give you a schematic of a 2000 Watts AC triac control. I also have an original French Thomson design, which they made especially for arc welding transformers, so this design is up to high peak currents and nasty voltage spikes. Alas it contains some exotic parts, but the other 2000 Watts design is reasonably "off the rack".

regards

gerhard

I for one would love to have a lookee see at the circuits Gerhard.

Originally Posted by damienhazo

I find the idea of a reliable external control very interesting because it can be moved around to different tools. For example, an angle grinder can be slowed up to be used as a polisher, etc.

My variac is a 15A pre WW2 model that I got for AU$20 about 30 years ago (surplus, literally about to be scrapped for the copper winding wire, steel core, and heavy cast iron frame). By twiddling the 8inch bakelite knob on top, I can get a reliable output from 20VRMS to 260VRMS, and can go below this with less reliability. It is about 15 inches high, 14inches diameter, and about 45kg, but a fabulous piece of kit. I believe that it was originally used as a stage lighting dimmer in a theatre.

It has been used for a range of things over the years, including electronic product development and testing, part of a fast charge/starter sytem for the car when it lived outside and was expected to start at 5.30am midwinter in a frost, and five years 'tempering' 3 angle grinders at once for metal polishing in a furniture factory.

These grinders ran fairly solidly for 8 to 10 hour shifts without overheating, something that the very posh varispeed units could not do for long.

Hi Malb,

that's a prize possession you have, never throw it away! A variac this size is hugely expensive nowadays, since it contains a lot of copper. Most variacs on sale now do not go much beyond 500 Watts. The unit you own is obviously in the kiloWatts-range and was indeed used for stage lighting or general ceiling lighting in movie theaters. When used within nominal limits and kept dust free, these gadgets are almost indestructable. Their only disadvantage is a certain amount of power consumption even at no-load, which goes for of any type of transformer.

Hi Damian,

indeed a separate control -fitting many machines- is very handy. I use my homebuilt control for the testing of used machines that i just bought or to test rebuilt machines that i just overhauled and put together again. Used machines from unknown users hav an equally unknown service life and have all sorts of bearing or gear troubles. By running them on reduced power at low rpm a lot, a machine's behaviour and the origins of strange sounds can be studied much better.

I could give you clues on how to build such a control. I could also build you one, but a readymade one (sold by e.g. Conrad) may be a lot cheaper. I will watch out for you and mail you as soon as i see reliable and worthwhile options.

Perhaps it is useful if i also post a thread about electric conrols. A bit about their history, the sorts available and how they work. It's amazing how virtually the same technology can be found in dc battery drills and ac full sine wave regulated tools as well as in lifesize elecric locomotives, electric cars and plant process machinery.

greetings

gerhard

Hi Damian,

i believe i've found an example. You will probably know mail order electronics firm Conrad from Germany. They carry an item for € 26,- that might suit the bill. Even if it weren't ideal, it may be worth tinkering with, for this modest amount of money. The parts alone would cost me more, and than i have yet to design and etch and drill a printed circuit board first and solder all components. For such low cost i won't even heat up the soldering iron and buy it ready-made.

Just go to website www1.conrad.de and under "Schnellsuche" type 191343 in the left box of "Art.Nr" and 62 in the smaller right box. The article depicted beneath will then pop up. According to a quick study i made from the pic, my second attachment gives an idea how it should be connected. Fairly simple. Not depicted though is the aluminium cooling fin that should be attached to the flange on the module's top side. This fin will absorb the heat generated by the silicon switching device inside. Without such a cooling fin, the unit will fail quite quickly with powers beyond 600 watts. Only if the cooling is adequate, 2000 Watts of power can be controlled for prolonged periods of time. This unit is not fit for use with induction motors, but will work fine with series/brush motors. For heavy use with a fair amount of reliability, do not go beyond 1000 to 1200 Watts of tool power intake (something like a medium size Flex). Because for this price, 2760 Watts under heavy duty circumstances would be asked too much for such a simple device. You know how it is with these bold manufacturer's claims... they seldomly stand up to real life situations.

success & regards

gerhard