Another Z axis dropping conundrum

I know this has been asked many times but I am still struggling despite searching for a solution in the previous posts about the problem. I wish there was an article or sticky post explaining how to use the machine when one end falls down no matter what you do.

I have just completed a Lowrider 2 with a Rambo 1.4 and everything is working as it should outside of being able to work with it with one end of the Z axis falling.

I am trying to use Repetier Host and have managed to draw out the crown. However I can’t get my head wrapped around a start position for the Z axis when Repetier has no way to zero Z besides the position it’s in when the board is powered on.

That means (for me) that the plate is all the way down on one end so zero is too low to get a bit in after I turn it on. It’s a balancing act to get the end that falls to stay in a raised position to even get the board powered up. I was able to get it to stay up the one time long enough to draw the crown but not since. I have tightened up the brackets on that end as far as I dare to but it still falls.

Ok so assuming it’s ok to start with both ends all the way down I still need to raise it to get a bit in and then postion it at a x-y-z start position, right? Repetier Host thinks Z zero is where I powered it on and it goes back to that spot when I start the print. If I had a bit in it and the router powered on the bit would be driven into the material until the z axis was where it was on power up.

Here’s a couple workflows I’ve tried:

Start with Rambo unplugged and RH not loaded.
Lower both ends so Z axis is even on both sides
Power Rambo on
With LCD raise Z to about 1" above table
Start RH
Z far side drops on it’s own to bottom :frowning_face:

Try again
Everything unplugged
Lower both ends so Z axis is even on both sides
Power Rambo on
Start and connect RH
Raise 1" using RH
Load G code
Start print
Z drives slowly to the bottom with plate dragging on table
Print starts moving but plate is all the way down. :frowning_face:

I just don’t get it.

I am also experimenting with CNCJS just because it seems to have a way to zero out the axis’ but so far my board isn’t responding to it even tho it appears to be connected.

Sorry for asking this same question again but I don’t know what to do from here and it’s frustrating me to see so many others having success and I can’t figure this out.

When you have your bit in the start position for cutting (usually the tip of the bit just touching the top of the stock), you need to set that as the origin point for your cut. You can send a G92 X0 Y0 Z0 from Repetier-Host from the manual tab, or if using Marlin, the top item on the V1 Custom menu sets send this g-code. Or it can be added automatically by adding to the start text in Repeteri-Host. Once this has been sent, Repetier-Host and your LowRider will be synchronized.

If you are saying one side of Z falls while powered then likely that stepper is not getting enough energy and the driver needs to be adjusted.

That sounds like it might be the missing piece. I’ll try that tomorrow when I get back in the shop.

How do I do that on a Rambo?

The typical reason for dropping Z is due to using both Z plugs on the control board. But since you have already had a topic that addressed your dropping, I expect this is something you’ve already checked out. As for adjusting the driver current, it is done in the firmware…at least in the firmware that V1 maintains. It is set at 0.8A, and it works as set for LowRider users, so this is unlikely the root of your problem.

Thanks for your help Robert. Sending that G code was the answer I needed. It all makes sense now.