Falling Z ?

[myxpykalix]

I have only noticed this since i upgraded to the latest control software. What happens is after I get thru with a file for the nite I just run the carriage back to remove work in a random spot. Turn off computer, turn the control box off, come in the next day and the Z is dropped to the table surface.
There is absolutely no way that any part is wore out as I would estimate the whole thing has less than 200 hours cutting time. Nothing felt loose or gave me a lot of play to suggest looseness.

Is there any issues with the control software/board losing memeory or anything like that?

[jerry_stanek]

It's called gravity when you turn off the power your springs and motor are not strong enough to over come the force of gravity. The motor will free wheel without power to it.

[Gary Campbell]

Jack..
The software will assume that the Z is where it was when it was turned off. If it actually 4" lower, then it may cause operator anxiety or bit/table problems.

Think about it.... you may think that nothing has changed, but it seems obvious, something has... a spring is weaker, roller pressure is lighter, Z is heavier....etc. something had to change. You are getting different results in the same circumstances. Something, even tho not easily noticable, has changed.

If its a spring, we upgraded ours at ShopBot. They seemed to know what combinations took which spring.
Gary

[bill_lumley]

I had this start to happen when I added the air-drill to my spindle with the extra weight . I was told there not heavier spring that would fit yet ...... I was told to place a block of wood under the bit before turning the power off .

[wberminio]

I had the same problem.They are working on the new springs.It is a pain having to remember to put a block under the Z so it doesn't smash into ,the just finished, piece. Maybe if we all called tomorrow....

[Gary Campbell]

Jack, Bill...
Some time back I posted the spring specs from the OEM version and the one that SB sold me when I added my drill. I am sure that using the diameter of the coil and wire along with the length you can find some at McMaster Carr or another online hardware source. Here is the post:
http://www.talkshopbot.com/forum/messages/23372/23934.html
Gary

[myxpykalix]

I had never had this problem before and the only thing that had changed was the upgrade in software so naturally i figured it might be something in that. My bot though 2 yrs old is virtually new in that its not used every day and has low usage so my thought was not that anything was wore out. I still don't think that but who knows. It makes sense that springs wear out and go limp even from nonuse.

As a rule of thumb whenever i go to move the carriage I always raise the Z before i move it anyway. Before if i wasn't finished with all toolpaths but had to shutdown for the night I would JH and leave it there, turn off computer, turn off bot. Come back next day power up and all settings were the same.
Now I come back and because it loses its Z all settings are lost. That was why i thought it might be software related and not hardware.

[gene]

I'm the same as Jack, At the end of the day i JH and shut it down . The next morn it is in the same place and i resume from there . What is the life expectancy of the springs ?

[Gary Campbell]

Jack..
When the control box is shut down there is no power to the motors. This means any axis can be moved with a little resistance due to friction and the rotary resistance of the stepper motors. In the case of the Z axis, springs are added to offset the weight of the Z extrusion and router/spindle. The side benefit is that it will hold that position when unpowered. In most cases, SB has done a great job in matching these springs so that the Z will not drop when unpowered. The tension of the Z rollers, spring tension or weight of items attached to the Z are most likely the cause of your Z dropping. I dont think that anything in the software can be the cause.
Gary