CNC Taig Lathe

[N4NV]

I have been working on this project on and off for over a year. Over a year ago I converted my Taig lathe to CNC with steppers, a HobbyCNC driver board, and Mach 3. I was getting tired of working in the cold garage and had taken a notice to the fact that my wife had several aquariums around the house. The aquarium stands looks just about right for mounting the Taig lathe so I went ahead and purchased an aquarium stand.

After getting the stand I told my wife that my lathe was coming in the house and it was going to be just as attractive as an aquarium (more so to me). The pictures below pretty much explain what I did.

I got rid of the motor that came with the Taig and purchased a 3 phase 240V motor. Then I purchased a single phase 120V to 3 phase 240V VFD. This would give me the speed control and torque I wanted. I could also easily control the VFD with a 0 to 10V speed control card from CNC4PC.

In order to mount the motor, I purchased the longest belt that I could find that matched the original belt from Taig. The length of this belt would determine where the shelf would mount that would hold the motor. I mounted the motor on a piece of polycarbonate and hinges so the motor weight would hold tension on the belt.

The motor shaft of the new 3 phase motor was bigger than the existing motor so I had to bore out the motor pulley. To read the RPM of the spindle I mounted a aluminum disk between the pulley and the headstock. The thickness of this disk kept the pulley set screw from locking on the headstock shaft so I had to turn the pulley a little shorter to allow for the thickness of the disk.

I cut a 6mm wide slot in the disk and mounted a C3 index pulse card from CNC4PC to read the RPM. A very important note for setting this up in Mach: Make sure you set the index pulse bounce to 0 or at least a very low number or Mach can not read RPM at higher speeds (above about 300 RPM). It took me a couple of weeks trying various set ups and slot widths before someone at the Mach support forum suggested it.

To test the RPM sensor and threading I made a little project. It is a brass adapter that screws into a faucet (in place of the aerator) and then into a hose adapter my wife purchased from an fish store. The hose adapter came with a plastic adapter for the faucet, but the plastic threads would bind in the faucet and make it difficult to remove.

As you can see, I had to mount my tool holder to the rear of the headstock to get the travel I needed in the X direction. I did not think much about this until it came time to thread my adapter. I used the threading wizard in Mach and it worked great, except for one minor detail. I was turning the spindle backwards and had my cutting tool facing up. This caused me to make a left handed thread. I realized it as soon as I looked at the threads. My solution was to turn the cutting tool upside down and reverse the spindle direction (very easy to do with a 3 phase motor).

My only problem was not my cutting tools are 1/4" too low. For now, I added a 1/4" shim which brought up the tool to the center of the spindle. Maybe tomorrow I will make a new riser block that is 1/4" taller so I will not need the shims (I was not able shim my parting tool).

The last picture shows the completed adapter as well as the incomplete left handed thread model.

Vince

You may have read my CHNC conversion in this section. I am waiting on a new computer so I can proceed there as well. I should be able to thread with the CHNC soon.

[WilliamD]

Very nice! Love the fact that you convinced the wife to let you bring it inside. Wish I could do that! How many HP was the 3 phase motor you bought? Do you like the VFD?

[N4NV]

Originally Posted by WilliamD Very nice! Love the fact that you convinced the wife to let you bring it inside. Wish I could do that! How many HP was the 3 phase motor you bought? Do you like the VFD?

The motor is 1/2 HP, more than enough for this little lathe. The belt will slip before the motor stalls. I am really impressed with the GS1 VFD from Automation Direct. It's only $110 and has a lot of functionality found in very expensive drive, much more than I will ever use. When using a 1 to 1 pulley setup, the VFD's rpm readout is withing a couple of RPM of the index sensor. Of course you can have it display, frequency, amps, volts, %RPM etc. Once function I am using is the ability to output more than 60HZ. I have it set for a max of 120HZ which gives me a speed range of 0 to over 3600 RPM with this motor. With the pulleys I can reach the max rated RPM of the Taig at 7,000 RPM, and still have a lot of low end torque.

Vince

[Bob Adams]

Originally Posted by N4NV The motor is 1/2 HP, more than enough for this little lathe. The belt will slip before the motor stalls. I am really impressed with the GS1 VFD from Automation Direct. It's only $110 and has a lot of functionality found in very expensive drive, much more than I will ever use. When using a 1 to 1 pulley setup, the VFD's rpm readout is withing a couple of RPM of the index sensor. Of course you can have it display, frequency, amps, volts, %RPM etc. Once function I am using is the ability to output more than 60HZ. I have it set for a max of 120HZ which gives me a speed range of 0 to over 3600 RPM with this motor. With the pulleys I can reach the max rated RPM of the Taig at 7,000 RPM, and still have a lot of low end torque. Vince

I LIKE Your setup. How did you wire the C6 and C3 from cnc4pc in into the GS1?

[N4NV]

The GS1 is not tied to the break out board. I am controlling it manually. I will use a speed control board from Homann Designs when I am ready to control it from Mach. To thread, Mach does not need to control the speed of the spindle, only to know it speed.

Vince

[Bob Adams]

Originally Posted by N4NV The GS1 is not tied to the break out board. I am controlling it manually. I will use a speed control board from Homann Designs when I am ready to control it from Mach. To thread, Mach does not need to control the speed of the spindle, only to know it speed. Vince

Hi, thanks to you. I just bought the 1/2 hp Motor and the 1/2 hp GS1 drive.
Have a few questions:
How do you Reverse the direction on the spindle?
What settings did you change on the drive?
Thanks
Bob

[N4NV]

I set the motor paramaters, i.e. amps and volts. Forward and reverse is controlled by the DI1, DI2 and CM inputs, it's on page 4-20 of the manual. You need an external switch or you could program some relays to be controlled by Mach.

Vince