- Joined
- May 22, 2015
- Messages
- 89
Since I got my Bridgeport BOSS3 CNC retrofitted with MACH3, I use my manual mill very little. I recently noticed the noise and vibration in the vari-speed head (of the manual mill) was getting worse. I suspected that the lack of use had put a "set" in the shape of the belt. But it was now getting so bad it affected the surface finish of the part, and was unusable. Even though I use it less, when I do need it, I NEED IT!
Upon disassembly, I found that the belt was trashed. Yes, it had taken a "set", and this weakened the belt in the curved area and it was now breaking up.
I had been planning on getting rid of the mechanical vari-speed drive and replacing it with an electronic Variable Frequency Drive. So I figured this was a good time. This meant I needed to remove all the monkey motion pulleys and springs and replace that with a micro-v belt and pulleys.
I had some parts from an old job that only needed slight modification for the pulleys. I needed to cut the micro-v profile and machine a tapered hole in the center (I made a "taper-lock" hub to mount them to the shafts). Here is what the pulleys look like when finished:
A year or so ago, I wanted to learn to program AVR microprocessers, so I made a digital tachometer as an exercise to learn with. My plan is to replace the front cover of the vari-speed drive (where the RPM is displayed in the little window) with the tachometer and a slide pot for changing speed, like this:
The tapered hub has a flange for tightening with a series of screws around the perimeter. I put a piece of brass shim stock between the tapers to keep them from galling. I also used an indicator to make sure the pulley was not wobbling as it rotated. Tightening the screws the appropriate way would make the pulley tilt slightly, so I used that to make sure it ran true. The tachometer counts the windows in a disk and you can see that disk on the pulley here:
This is the head reassembled without the front cover:
Here you can see into the front where the cover will be. The belt is visible as well as the tachometer disk. An opto-interrupter will be mounted in here to count the windows:
The mill runs SOOO much smoother and quieter! I wish I did this years ago!
Next I will post the setup of the VFD and the remote on/off switch, etc.
Upon disassembly, I found that the belt was trashed. Yes, it had taken a "set", and this weakened the belt in the curved area and it was now breaking up.
I had been planning on getting rid of the mechanical vari-speed drive and replacing it with an electronic Variable Frequency Drive. So I figured this was a good time. This meant I needed to remove all the monkey motion pulleys and springs and replace that with a micro-v belt and pulleys.
I had some parts from an old job that only needed slight modification for the pulleys. I needed to cut the micro-v profile and machine a tapered hole in the center (I made a "taper-lock" hub to mount them to the shafts). Here is what the pulleys look like when finished:
A year or so ago, I wanted to learn to program AVR microprocessers, so I made a digital tachometer as an exercise to learn with. My plan is to replace the front cover of the vari-speed drive (where the RPM is displayed in the little window) with the tachometer and a slide pot for changing speed, like this:
The tapered hub has a flange for tightening with a series of screws around the perimeter. I put a piece of brass shim stock between the tapers to keep them from galling. I also used an indicator to make sure the pulley was not wobbling as it rotated. Tightening the screws the appropriate way would make the pulley tilt slightly, so I used that to make sure it ran true. The tachometer counts the windows in a disk and you can see that disk on the pulley here:
This is the head reassembled without the front cover:
Here you can see into the front where the cover will be. The belt is visible as well as the tachometer disk. An opto-interrupter will be mounted in here to count the windows:
The mill runs SOOO much smoother and quieter! I wish I did this years ago!
Next I will post the setup of the VFD and the remote on/off switch, etc.
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