# Z Axis power feed BF20 mill (Grizzly G0704)



## deeferdog (Sep 25, 2017)

Some time ago I posted about  the Z axis power feed modification I made for my Optimum BF20 mill, (I believe these machines are marketed as Grizzly G0704 in the US). The motor and the speed control and the electrics were  obtained from a cheap scroll saw and are ideal for this modification. The power feed has been operating for over a year and has not given any trouble. It is of great assistance as the head of the mill is quite heavy and manually winding it up and down soon lost its appeal. One irritation still remained and that was adjusting the cutting depth of the tool, this was still done manually with the feed wheel located at the top rear of the machine. This was not too much of a problem when standing, however on long jobs I find that I have to sit, (keeps my brains warm), otherwise my back will give me buggery the next day. When sitting, the feed wheel is difficult to reach so I decided to relocate it to the front. The bevel gears came from an old hand drill (remember those!) and it wasn't a lot of trouble to mount them as per the pictures. I spring loaded the shaft so the pinion is permanently disengaged, This prevents the feed wheel from spinning when the power travel is engaged. To increase the cutting depth is now very easy and comfortable for the operator. A gas lift has been incorporated to ease the load on the power feed motor and whilst I was at it I added a cooling fan for the motor, 12v computer fan. The power feed electrical box has been moved to the left of the machine. All in all I was pleased with the results. I have been very happy with this mill and would recommend it without reservation, these modifications make it even more enjoyable. Cheers, Peter.


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## petertha (Sep 26, 2017)

Nice job. 
Re the gas lift strut size & mounting location, do you set the mill head to its lowest possible operating position & that represents the max fully contracted strut. Then you need to have enough strut length to accommodate max head position? I'm just wondering on my mill how to go about sizing since there will be a bit of 3D effect of where it will mount.


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## deeferdog (Sep 27, 2017)

Hi Petertha, thanks for the compliment. I sized it pretty much as you describe, then I went to the Autobarn and ratted through the gas struts they had on display and got lucky. I have no idea what the compressive force is. I couldn't close it by pushing against it. After fitting it made a big difference to the winding up of the head, at a guess I'd say the motor is now only required to lift 10% of the total head weight, winding down is smooth and the motor has a bit more work to do. I took the easy way out when I fitted it as I wasn't convinced that it would be effective as a consequence it slants across the gibb adjusters and that has been a bit of a pain at times. One day I will make a plate at the top to move the mounting point directly above the lower one. I have included a pic of the total installation, sorry about it being sideways, I still can't rotate the damn things. Cheers, Peter


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