Thread: Speed Reducer

Yes there is a kit to control induction motors up to 2hp.

jaycar kit KC5509

Speed Control Kit for Induction Motors - Jaycar Electronics

You may be worrying about something that is not that significant as turning tools are usually made from high speed steel that can handle high temperatures.

You could also spend $229 for this controller and find you will still be burning the steel because you might not have the right grinding wheel.

Using the right grinding wheel and being careful when grinding means you may not need the controller to grind HSS and it will be a lot cheaper than buying the controller.

Simplest way to go would be to use a smaller wheel of possible. From the specs provided I am guessing that you have a 6in/150mm unit. A full 150 wheel would give a surface speed of around 1,345m/s. Half the diameter, (75mm) would halve the surface speed, but you may be running into the sides of the guards with your tools.

Induction motors as used in these grinders have a speed dependant on the supply frequency, but also need a 'start' winding to kickstart them in the right direction. The start winding is controlled with a speed sensing switch which disconnects it once the motor gets to about 80% of rated speed, and reconnects it if speed falls below that. Therefore variable frequency drive systems (such as the Jaycar kit above) frequently won't work on these motors unless you are seeking a very modest reduction or an increase.

Three phase motors get their direction information from the phase offsets between the three phases and don't need the start winding and switch. They therefore respond fairly well to variable speed drives.

To help prevent your tools from burning, don't press so hard on the grinder. A light touch is all that is required.
Kryn

I would suggest that you come to my demonstration weekend at the Hunter Valley club on June 1st and 2nd.

A lot of your questions will be answered.

Originally Posted by

I would suggest that you come to my demonstration weekend at the Hunter Valley club on June 1st and 2nd.

A lot of your questions will be answered.

Absolutely the best idea. Do go if you can, you will learn so much. A tip, take your chisels with you.

I would shop around for a new grinding wheel as the factory fitted wheels are not suited to the grinding you want to do, and also get some garage sale chisels to pratice your technique there is a fine line! some days I should not go near my grinder!
I bought my current wheel for $70 and it has made an improvement. do you dress your wheel regulary? as they become clogged with metal

Robo has given you good advice go to the demo if you can join a club you will not only get advice on sharpening but allso on how to use the tools correctly , by a cold cutting wheel your supplier should be able to give you the right type just make sure you take the shaft size in case you have an oddball ,if your tools are not Hss but carbon steel you need to cool them in water to stop them over heating

Originally Posted by

I would suggest that you come to my demonstration weekend at the Hunter Valley club on June 1st and 2nd.

A lot of your questions will be answered.

As the organiser of 's 2 day demo at the Woodturners of the Hunter I must agree with his comment. You really don't need a new grinder OR an expensive speed control, assuming you have a motor suitable for one.

My advice would be to join a club, dress the wheel and learn to sharpen with a very light touch and also where to start and finish on the tool and you won't be burning them.

Can't tell you the price yet until after the Board meeting on Thursday night, but the price will be worth it - great food, great company and - what more could you ask for and it's only just up the road! As an indication, I organised a demo by Rolly Munro (NZ) just recently and the fee was $35 and we had to pay his airfare as well. On the Sunday will be doing a workshop for beginners and less experienced turners as well.

I haven't started advertising fully yet until the price is set but there is already much interest from outside the club.

If you pm me I can send you info about the day.

Cheers
Paul

Literally overwhelmed by the quantity and quality of advice regarding my Speed Reducer inquiry. Really appreciate the effort you have all made to put me on the right path.
Sounds like the Robo demo is the way to go, would appreciate further details when available.
My burning the turning tools is not a frequent problem but there is a fine line between it happening and not happening and I thought slowing the speed would extend that line for me.
I see that Carbatec have a Slow Speed Wide Stone Grinder for $105. Sounds like this would be a better buy than an expensive speed controller and my old Abbott & Ashley could be then used as a general grinder. Anybody have any experience with the Carbatec model?
Currently I have a white 150mm Aluminum Oxide wheel that is dressed every so often.

Good to know that there is a tremendous amount of experience on tap out there with so many willing to share. My thanks to you all.

Go to 's if possible. If not join a men's shed with turners.

If you can't do either of the above, get a softer wheel, be sure to dress it so that it is sharp. A too hard wheel or one full of ground off metal makes heat. A sharp soft wheel looses grit as it takes off metal, and along with it the heat.

Always a light touch of short duration, especially with carbon steel. If you do heat it to where the shiny part turns blue, just use it a bit, then resharpen.

Especially with a thin section or thin edges, a quick light swipe will do the sharpening without heating the tool. I like to sharpen my skews by hand on a flat stone or a diamond pad. I do a few swipes on the stone on each side, do a pass or two on the spindle, repeat.

Some say dipping a hot tool in water can cause some tiny cracking. Others say not so.

I bought a used name brand 120 grit stone dirt cheap. The first time I used it the small gouge tip turned red hot. I have learned to do the above and it does fine.

Originally Posted by Storm5

Literally overwhelmed by the quantity and quality of advice regarding my Speed Reducer inquiry. Really appreciate the effort you have all made to put me on the right path.
Sounds like the Robo demo is the way to go, would appreciate further details when available.
My burning the turning tools is not a frequent problem but there is a fine line between it happening and not happening and I thought slowing the speed would extend that line for me.
I see that Carbatec have a Slow Speed Wide Stone Grinder for $105. Sounds like this would be a better buy than an expensive speed controller and my old Abbott & Ashley could be then used as a general grinder. Anybody have any experience with the Carbatec model?
Currently I have a white 150mm Aluminum Oxide wheel that is dressed every so often.

Good to know that there is a tremendous amount of experience on tap out there with so many willing to share. My thanks to you all.

You don't need it.

For the rest of the month (until 's demo), you can cheat to achieve a "light touch of short duration" by executing it while the grinder is coasting to a stop, typically about a full minute unloaded.

Cheers,
Joe

Originally Posted by joe greiner

For the rest of the month (until 's demo), you can cheat to achieve a "light touch of short duration" by executing it while the grinder is coasting to a stop, typically about a full minute unloaded.

That's cheating?


Oh, my god! I don't know how to sharpen!