Thread: BF20LV Vertical (Z) axis info

The last part of my Optimum BF20LV ball screw conversion has finally been completed.

Biggest job was to work out what's inside the Z-axis tower and how the ACME screw is connected to the vertical carriage.
While it was all disassembled I decided to take a short video so other BF20LV owners know what to expect before disassembly.

Here is the video:
https://youtu.be/j62E6lhtysM
I'm not a seasoned YouTuber, so I apologise now for my video mistakes.

A Fusion360 3D model of the Z assembly is also available if anyone is interested, just send me a PM.

Hope this is useful for someone.

Cheers

The Apprentice

Hello Aprentice,

Thanks for the video ! It seems that you have overlooked one very important point.

There are two grub screws that adjust the angle of the pin socket, these are there to ensure that the pin doesn't bind when the pin socket is tightened up. I found that on my BF20LB that the socket would bind the pin at a couple of positions down the length of the column. I oiled the pin and socket on mine and spent some time adjusting it. I also found that the drilled hole is not truly square in the block. Its only a fraction out but if you pull the pin block flat up against the back of the recess and use a piece of straight bar in the hole for the pin block, using a square you will see that it leans slightly. Using the grub screws you can get the pin dead square.

I also found that the bevel gears on mine didn't mesh properly and they started to skip teeth !

Originally Posted by BaronJ

.... It seems that you have overlooked one very important point. There are two grub screws that ......

Thanks BaronJ,
you are correct, the grub screws are indeed very important. I will add them into the video.

Interestingly, on my machine they appeared to be doing nothing and the pin block shows no signs of ever having been in contact with the grub screws.
Maybe I'm lucky and recess and pin hole are square?
I made my own pin and block to suit the Ball screw which is now installed.

How did you find out that your socket was binding up? I wound mine up and down manually and couldn't pickup any tight spots.

Originally Posted by TheApprentice

Thanks BaronJ,
you are correct, the grub screws are indeed very important. I will add them into the video.

Interestingly, on my machine they appeared to be doing nothing and the pin block shows no signs of ever having been in contact with the grub screws.
Maybe I'm lucky and recess and pin hole are square?
I made my own pin and block to suit the Ball screw which is now installed.

How did you find out that your socket was binding up? I wound mine up and down manually and couldn't pickup any tight spots.

Hi Apprentice,

Initially I had found over time that when raising the head the bevel gears started to skip teeth, so having bought a DRO and needed to fit it, decided to do any repairs and modifications I wanted to do at the same time.

When stripping the head and column I found that the bronze bevel gear was slightly damaged and only catching on the very edge of the teeth and the screw was slightly bent. Turning about 10 thou off the brass washer raised the steel bevel gear enough to give full engagement. Having sorted out the gears, I found that without the head fitted to the sledge and the pin socket secured to it winding the sledge up and down caused two tight spots, the one nearest the top being worst.

At this point I had sorted out the gib strip, which was slightly bent and the adjusting screws which had brass plugs underneath were not working properly and binding against the brass plugs. You could tighten the locking levers without actually locking the head. It turned out that whoever put my machine together just used short lengths of brass screws in there. Replacing them with proper, turned to size plugs cured that problem.

Once I had the sledge moving smoothly and refitted the column screw was when I discovered the binding and adjusting the two grub screws altered the behaviour. Taking it all apart again and checking the pin hole for square was when I found that the hole was not true to the block and that the grub screws allowed some adjustment.

There are pictures and some explanations of the work in this thread,

https://metalworkforums.com/f65/t206308-dro-instalation

Thanks to the input from from BaronJ and one of his photos.
Here is the updated video on the Z-Axis:

https://youtu.be/s13ytwzfMrw