I think Hennie would like that one too! :)

Wow!, where do you guys get all this nice stuff from?

Heath have that one already that is the link where I got my joint from

Look what I found the weekend. It's old, it's dirty and needs some TLC. All the slides feel SOLID.

Does anybody know what make it is. It is about 600mm long. It needs a motor. Somebody modified it to take a v-belt. What would be my best option, small motor with VFD was my thought.

Attachment 10166

Attachment 10167

Attachment 10168

I liked, Kobus.

VFD is my option.

looks like a chinese 7x12 minilathe stripped of the electronics and the motor gears, you plan to use it as a 4th axis?

http://www.mini-lathe.com/

I would not use a VFD, because it cannot increase torque as the speed goes lower.

Thanks Pablo for the link.. No I have my 4th axis. This will be stand alone. Maybe I will CNC it later.

So what other options do I have ...small motor with LIGHT's DIMMER ?

IMHO, before you start spending money on it you should check how much it costs one of these in your market, in USA they go for around $500 or less and here in Argentina double that. I had one of these years ago, it used a KBIC-125 speed controller (or similar I dont recall the exact model)
These mini lathes usually go from 100 to 2500 RPM with the electronic speed controller.

Or to make things simple you can make it single speed with a 1450 rpm single phase motor, later you can add pulleys to get more range.

Check the photo (crappy lighting conditions sorry) I just took of my small cnc lathe, with this setup you can go from 200 to 2000 with 100rpm increments

Just to show that old Big Blue Brakpan is not always PLAYING. Today had to cut some kiddies chairs for a paying customer. I don't often use the full 2.4m X-axis, but today I was cutting OVER THERE..

Attachment 10190

In between cutting I also stripped the mini lathe and washed all the parts. Will put some new Hammertone paint on it tomorrow. Managed to get a new motor for R 750.00.

Then I started with my Rocking Chair. It is such a great succsess that my son don't want to get off it.....that is MY beer :p

I still need to attatch the arm rails and the bottom rail, but could not wait to show it. This thing is very stable and he could not flip it over. Thank's Fabrice....now we have to design an Adult version. but I did sit on it...it is SUPER strong.....and no glue.;)

Attachment 10191

Attachment 10192

I am still very happy with my UIM Stepper drivers, my MotionKing motors without Gearbox...super smooth contours all the way.

Baie mooi Kobus.
I see you are working with ply mainly.
I will have to move away from the MDF as well. It looks like I am allergic to the dust or the wood. Not sure. I am full of little blisters for months now.

Johan, you should move back into the house now that your MM is up an running...stop sleeping on the machine. :D

I hate MDF as well, lots of dust,,,,,bad dust,,, and this stuff is really not that strong.

The SHUTTERPLY I am using is also a lot cheaper than the MDF for the same thickness. I pay R 220.00 for a sheet of shutterply.

It also seems to lay FLAT on the table..much better than MDF

Where are you sourcing that shutterply? I am paying about R175 per sheet here in CT but the quality is not anywhere near as good as the ones you have used so far. Lots of knots and open cracks in the face plys.

Kobus the only thing with ply is that we don`t get a good quality ply, and shutter ply can be very rough sometimes.

I bought some from Builders W/house...very nice quality overall...must be imported, because the local Sabie stuff is rubbish.

Just got a number from a chap in Primrose (close to my work) that has a LAMINATING shop. He made up 18mm ply for a friend...this stuff is magic.

Kobus,
Don't you find that the shutter ply pulls after you cut the job?

I miss that luxury of having those suppliers around me.

I have not noticed anything yet Marius.

My little lathe is commin back to life. Assembled it tonight.. I need a favour from the electronic guys on the forum... I need a circuit for an electronic speed control: Spec...DC 25 - 220 volt and no more than 2 Amp. Thanks

Attachment 10208

R1 100K ohm
R2 10K Ohm
R3 100 Ohm
P1 pot 1M Ohm
C1 capacitor, poliester 39-56 nF, 400V
C2 capacitor, ceramic, 10nF (mark 103)
C3 capacitor, 100nF, 630V (marked with 150nF on shematic)
Q1 triac, TIC216M, 6A, 600V, 5/10mA
D1 diac, BR100/3, 32V

I used this to speed control my little trim router, be very careful with mains voltage!

http://www.md-tim.com/mechmate/speedcontrol.jpg

Good circuit, but the motor in question is DC, not AC. You could add a bridge rectifier to the output, perhaps?

My mistake, I have not seen that the motor is DC

No problem as long as we get there in the end. That little late must run by Saturday ;)

DC motors are not controlled by that kind of circuit. You need a PWM (pulse width modulated) controller. I have been out of the electronics world for to long to help you with a circuit and PWM stuff is a little more tricky. Try http://electronics123.co.za/ for PWM kit. Dont use a regulated power supply as this will not give you linear torque over the range. A PWM motor controller is best.

Actually, Marius, that looks like it is a PWM circuit. Specifically, it uses 2 X the line frequency. The Triac turns off every 1/2 cycle as the AC voltage crosses zero. It doesn't turn on again until the resistor / capacitance network charges to a sufficient level, effectively giving you pulse-width control.

However, the output is AC. If you rectified the output, and perhaps added a capacitor to smooth it (slightly, not too much or it won't respond to the control), it looks like it would drive a DC motor.

I've been musing on how to solve Kobus' problem. The mains voltage is 220 there, right? The simplest circuit would involve just rectifying to DC, then adding a motor controller. Unfortunately, most motor controllers don't like voltages higher than 30 or 50V or so. So now we're talking about building a power supply first, then applying a motor controller, which could be H-bridge based like an LM18200 or LM18245.

Another (unidirectional) approach could be as simple as a single MOSFET and a timer circuit (NE556 comes to mind). The MOSFET could be chosen to run at 200+V, although you'll still need to come up with a power supply for the 556, perhaps using a simple voltage divider circuit.

Kobus asked for a schematic, so presumably he wants to build his own as opposed to buying a kit.

Kobus, what do you want? uni-directional? bi-directional? Do you care if it's a kit over a schematic? Do you have a large electronic parts drawer?

Thanks Brad, Yes I would put it all together if somebody does the design. I can get a Mosfet IRF 840 B that can handle the high voltage. Bi-directional I will do with a SPDT toggle switch with a Centre OFF position after the speed control. So basically all I need is a circuit schematic to take the 220 volt AC and give me a 25 volt - 200 volt DC output by means of a control pot. The logic supply can be done with a simple circuit or a small mains adaptor.

Here's a design (I haven't tested it, obviously!)

You'll need a motor power supply up front of it to produce 200V DC for the motor, and then a logic power supply.

The motor power supply up front could be just a bridge and capacitor ( 220v * sqrt(2) *2 / Pi is 220v * 1.41421 * 2 / 3.1415926 = 198 V). Don't forget to fuse it well, and I would prefer to have a transformer in there, even if 1:1 to limit current.

For the amount of current the 555 and the mosfet gate need, you can likely just use a pair of 1/2 watt resistors as a voltage divider. With a 10k resistor from the 200VDC and a 470ohm resistor from GND, you should end up around 9V to drive the oscillator.

As always, someone check my logic and math, please!

I see that N-Channel Mosfet is only 55 Volt. Suppose I can replace it with the IRF840B that I can get over here.

Kobus,

How about one of these:

http://www.varispeed.co.za/modules/D...show&id=MTI%3D

I used one on a ring roller, slow, fast, forward and reverse. You do need a 3-phase motor, which is cheaper than a single phase in any case and a pot to regulate the speed.