- Joined
- Mar 5, 2022
- Messages
- 36
So I made the first couple of upgrades/fixes for my new PM-728-VT and figured I'd document them here.
The first addresses what I consider to be excessive axial play in the quill fine feed shaft. The shaft has a groove into which a dog point set screw is inserted to keep it in place and react against the force the worm gear exerts on the quill gear when turned. Problem is, the width of the factory dog point was much smaller than the width of the groove so the fine feed wheel had nearly a quarter turn of backlash when reversing feed direction. I also wasn't happy with how the set screw is secured, which is with the addition of a backing set screw.
The solution was pretty trivial. I got a 35mm long M8 set screw and lathe turned a dog point that was about 0.001" narrower than the groove in the feed shaft. The length of the set screw causes it to project from the headstock casting, where it's secured with a jam nut and washer. The backlash is much less now.
The second upgrade was to add an LED strip to the lower edge of headstock casting, projecting downwards towards the table. This was inspired by Joe Higgins' 728 lighting upgrade but rather than use a separate power supply, I wanted mine to be a bit more integrated. As it turns out, the 728's motor driver board has an unused connector that suppIies a nominal 12V (~14.5V measured open circuit) for use by a fan in other applications. This is shown in the photo below, circled in red. Since I already had some 12V LED strip on hand, I decided to tap into that connector so the lights would come on and go off with the mill's main power switch.
The jack on the board is a male JST 2.54mm (0.1") pitch socket so I just picked up these pre-wired connectors to connect to it. I used a couple of WAGO connectors to extend the leads and ran the extension cable through the same gland that carries the tach and safety switch wires and into the headstock cavity. I terminated the extension cable with another JST connector and soldered a mating JST connector to the LED strip's pads. Finally, I ran the LED strip around the underside of the headstock. Rather than using connectors at the corners as Joe did, I just accordion folded the strip back over itself twice, the first to turn 90 degrees and the second to re-orient the LEDs downwards as shown in the photos. You can also see from these photos that my quill DRO upgrade is underway but I'll report on that in the thread I started back when I was soliciting ideas. The new LEDs turn on and off with the mill and I'm pretty pleased with the tidiness of the install.
The first addresses what I consider to be excessive axial play in the quill fine feed shaft. The shaft has a groove into which a dog point set screw is inserted to keep it in place and react against the force the worm gear exerts on the quill gear when turned. Problem is, the width of the factory dog point was much smaller than the width of the groove so the fine feed wheel had nearly a quarter turn of backlash when reversing feed direction. I also wasn't happy with how the set screw is secured, which is with the addition of a backing set screw.
The solution was pretty trivial. I got a 35mm long M8 set screw and lathe turned a dog point that was about 0.001" narrower than the groove in the feed shaft. The length of the set screw causes it to project from the headstock casting, where it's secured with a jam nut and washer. The backlash is much less now.
The second upgrade was to add an LED strip to the lower edge of headstock casting, projecting downwards towards the table. This was inspired by Joe Higgins' 728 lighting upgrade but rather than use a separate power supply, I wanted mine to be a bit more integrated. As it turns out, the 728's motor driver board has an unused connector that suppIies a nominal 12V (~14.5V measured open circuit) for use by a fan in other applications. This is shown in the photo below, circled in red. Since I already had some 12V LED strip on hand, I decided to tap into that connector so the lights would come on and go off with the mill's main power switch.
The jack on the board is a male JST 2.54mm (0.1") pitch socket so I just picked up these pre-wired connectors to connect to it. I used a couple of WAGO connectors to extend the leads and ran the extension cable through the same gland that carries the tach and safety switch wires and into the headstock cavity. I terminated the extension cable with another JST connector and soldered a mating JST connector to the LED strip's pads. Finally, I ran the LED strip around the underside of the headstock. Rather than using connectors at the corners as Joe did, I just accordion folded the strip back over itself twice, the first to turn 90 degrees and the second to re-orient the LEDs downwards as shown in the photos. You can also see from these photos that my quill DRO upgrade is underway but I'll report on that in the thread I started back when I was soliciting ideas. The new LEDs turn on and off with the mill and I'm pretty pleased with the tidiness of the install.
