Teknic SDSK HLFB brake control issue (Resolved)

[bleiler60]

Hi Arthur,
I had a similar issue with my z-axis sliding down after powering down. The original motors were stepper motors and never had a problem with the z-
axis moving after powering everything down. If you watch Marty's latest conversion using Clearpath servo's, he uses a brake for the z-axis to hold it in position after powering everything down. That's what I ended up doing and it works great.

[Richards]

Let's verify that the brake is ON (locked) when no power is applied to the brake and that it is OFF (unlocked) when 24VDC is applied to the brake. If that is the case, then the brake should stop the Z-axis from moving when the Acorn is turned OFF. If the Z-axis still slips, then check the weight of the Z-axis. Is it possible that the weight is too much for the brake? If so, you can add a gas strut, an air cylinder, or counter weights to the Z-axis to reduce the load on the brake.

[Arthur]

Hi Arthur,
I had a similar issue with my z-axis sliding down after powering down. The original motors were stepper motors and never had a problem with the z-
axis moving after powering everything down. If you watch Marty's latest conversion using Clearpath servo's, he uses a brake for the z-axis to hold it in position after powering everything down. That's what I ended up doing and it works great.

Hi bleiler60, (sorry don't know your name)

In my case, from the get go, when I was originally discussing the servo options with Teknic tech, I was suggested to use a brake on my Z axis, but I was sort off mislead to control the brake from servo's HLFB output. It did work, with a lot of click-clocking but didn't solve the main problem for me. After some experimenting with this servos (which are awesome btw) I found that they have no problem holding their position when energized. My problem was in power cycling. I did come up with temporary brutal solution to engage and desingage the Z brake manually on startups and shutdown, just for sake of getting through the rest of the build. So after cutting few different materials and tipping my toes into feeds and speeds I decided to revisit the issue and solve it as I should. Gary, pointed out to me and Marty confirmed, that its better solution to utilize one of Axis1,2,3,4 brake release outputs. So I did and it saved my ears from click-clocking of my Z-brake. When I turn the machine ON, my Z-brake is holding the Z Axis ball-screw since its not energized and after clicking on MDI or requesting any kind of movement on any of the Axis idles all my servos and energizes the Z-brake (releases), but at this point my Z servo is holding position with no sweat. The only sliding of Z axis I am getting now, is when I exit CNC12. There is a tinny delay/inertia between servo shutting down and brake gripping the ball-screw, but I can live with that. I am talking microns here.

[Arthur]

Let's verify that the brake is ON (locked) when no power is applied to the brake and that it is OFF (unlocked) when 24VDC is applied to the brake. If that is the case, then the brake should stop the Z-axis from moving when the Acorn is turned OFF. If the Z-axis still slips, then check the weight of the Z-axis. Is it possible that the weight is too much for the brake? If so, you can add a gas strut, an air cylinder, or counter weights to the Z-axis to reduce the load on the brake.

Hi Mike,

Thanks for your input. My Z tower is heavy, but the brake or servo have no problem holding it in place. Rewiring the brake control from servos HLFB (High Level Feed Back) output to Axis3brake release output of Acorn fixed my problem. The only sliding I encounter on my Z axis now is like literally 1-2 degree on servo itself, which translates into microns with my 5mm pitch ball-screw. I can live with that.

Best,
Arthur