Z-Axis Home Not Where It Should Be?

Hi. Our HandiBot arrived today, and I had a lot of trouble with the Z-axis. When homing, either with Quick Launch or Fire Up, the Z axis ends up homed about 2" above where the material would be (In this case, the board that shipped with HandiBot). Therefore, it cut in the air. After trying this a bunch of times, I checked for this problem on the forum, and found some similar issues. Using that info, I zeroed to the top of the board. This cut the board, but far too deep. Once the machine was cycled on and off, the manual Z setting was lost.

So, I guess the real question is, where should HOME zero be? At the top of the material, or the top of the pivot-out alligator clip plate, or set at factory, or somewhere else?

Also, since this is the first cut and is designed to run with the tool set already prepped at the factory, does the program account for some negative Z offset automatically?

Finally, how can I get the tool to home to the right place automatically.

Thank you for your help.

Jim

Ok - so if I recall - when you use the XYZ home tool, it will home the Z-axis to the top of it's travel.

It makes sense to home to tool to the top so that you aren't dragging the bit across any material when x and y get zeroed. From the homing - your X and Y are zeroed automatically.

Once you finish homing your tool, you then have several choices to zero your "Z". Personally, I use the allen wrench to loosen the clamps on the router, let it 'free fall' until the tip touches the top of the material, and tighten the clamps. Then, press the little 'zero' next to the Z-axis, and poof! You are zeroed.

You could also use the routine for the z-plate to zero your Z.

The biggest hold up on zeroing the Z axis is making sure you have enough movement in both directions so you don't hit a hard stop while running your tool. Try and see how much Z travel your job needs, and make sure you have extra room from where you are zeroed.

It's confusing at first, but you'll pick up on it in a while!

When setting up tools at the factory, we do the following:
1. Run the z-zeroing routine using the little plate on the side of the cut area.
2. Check to be sure that this results in an accurate z-zero--and if not, we adjust the recorded thickness that the tool uses to calculate the distance between the metal z zero plat and the material that the tool is sitting on.
3. Re-run the zeroing routine with the plate to double check that any changes we made were accurate.

The Z zeroing process first bumps the z axis into the hard stop at the top of its travel--this way the tool can reference the bit length that it measure (something that can change frequently) to the absolute top of the axis's travel (something that never changes).
So when customers receive the tool and run the XYZ homing routine in quick lauch--the tool bumps into the top limit of the Z axis and then recalls the distance that it measured when we ran the routine in the factory. This will always work as long as the bit has not moved in the collet (shouldn't happen if the collet is tight) and as long at the z axis motion is not being obstructed by an obstacle.

As I've mentioned in past threads--I have a really sure-fire way of zeroing my tool (which we should perhaps give as an in-app option).
1. I drive the Z axis down until it hits the bottom of it's travel.
2. I hit the orange "0" button next to the Z position read-out on the tool.
3. I send the Z axis to the height of my material by typing the desired position into the Z position readout and hitting "Go"
4. I then hit the orange "0" button again--this is all to make sure I have enough downward travel to reach full depth on my cut while keeping the Z as low as possible.
5. I loosen the router bracket and allow the router to slip down until the bit touches the material.
6. Tighten the router bracket to fix the router in place--at the correct zero location.

So I guess that's 6 steps--but really it just takes a moment.

Thank you for your reply. I have run the zeroing many many times, both off the zeroing plate (last time bent the plate), and off of the part itself (with zeroing the Z). The behavior of the tool is as if the Z=0 is somewhere way below bottom plane of the tool, regardless of what I do.

Hi Brian, please see my comments below.

Brian Owen, ShopBot Wrote:
-------------------------------------------------------
> When setting up tools at the factory, we do the fo
> llowing:
> 1. Run the z-zeroing routine using the little plat
> e on the side of the cut area. Yes, I have done this many times.
> 2. Check to be sure that this results in an accura
> te z-zero--and if not, we adjust the recorded thic
> kness that the tool uses to calculate the distance
> between the metal z zero plat and the material tha
> t the tool is sitting on. Yes, it does.
> 3. Re-run the zeroing routine with the plate to do
> uble check that any changes we made were accurate. I have done this as well.
>
> The Z zeroing process first bumps the z axis into
> the hard stop at the top of its travel--this way t
> he tool can reference the bit length that it measu
> re (something that can change frequently) to the a
> bsolute top of the axis's travel (something that n
> ever changes). In one case, it MISSED the fold out zeroing plate completely, and dug into the material below the tool. In another case, it BENT the zeroing plate and kept trying to move downward. And YES, I did have the alligator clip attached.
> So when customers receive the tool and run the XYZ
> homing routine in quick lauch--the tool bumps into
> the top limit of the Z axis and then recalls the d
> istance that it measured when we ran the routine i
> n the factory. Understood. This will always work as long as th
> e bit has not moved in the collet (shouldn't happe
> n if the collet is tight) and as long at the z axi
> s motion is not being obstructed by an obstacle. Understood.
>
> As I've mentioned in past threads--I have a really
> sure-fire way of zeroing my tool (which we should
> perhaps give as an in-app option).
> 1. I drive the Z axis down until it hits the botto
> m of it's travel.
> 2. I hit the orange "0" button next to the Z posit
> ion read-out on the tool.
> 3. I send the Z axis to the height of my material
> by typing the desired position into the Z position
> readout and hitting "Go"
> 4. I then hit the orange "0" button again--this is
> all to make sure I have enough downward travel to
> reach full depth on my cut while keeping the Z as
> low as possible.
> 5. I loosen the router bracket and allow the route
> r to slip down until the bit touches the material.
> 6. Tighten the router bracket to fix the router in
> place--at the correct zero location.
>
> So I guess that's 6 steps--but really it just take
> s a moment.

I have tried this, as well as combinations thereof, but without success. As noted before, it seems to think that Z=0 is below the bottom plane of the tool no matter what I do. And, I now have a broken bit, a bent zeroing plate, and one of our parts damage. Really at a loss, and don't trust the machine.

Thank you.

Jim,

Let's try a few things to see if we can diagnose what's gone wrong. Like I'd said above, the process you're using is the same that we use at the factory--so I'm concerned about whether something was damaged in shipping.

Try manually stepping the Z axis down to the material--like you did before your cut. Press the orange "0" button to set the zero. Then in the Z position field, type in a new position above the current position--try typing in 1"--and then hit the "Go" button to send the Z axis the 1". Once the tool completes the move--type 0" into the Z position and hit go again. This should send the Z axis right back down to where it was before.

What I'm wondering is if there is something preventing movement of the Z axis...this will at least tell us that the tool is able to jog up and down without stalling in the Z motor. If the tool does stall in the z motor then I've got a few quick maintenance steps that will fix that. Gotta dig up the document I wrote for it.

Brian

Hi Brian:

Will do, and I will report back. I just discovered when it tried to zero to the swing out plate and hit bottom, that it has twisted the clamps which hold the router. Another issue.

Thanks.

Jim

I'll be checking in all night--if you have time to try it today.

The router bracket is removable and can be switched higher or lower depending on the type of cut you're doing. There are two screws that hold it in place directly behind the router. If you pop the router out, you can get at those screws with the red 4mm T-handle that came with the tool. Give them a crank and your router bracket should stay put.

Hi Brian:

OK, I found the router mounting screws, so I can re-true that, no problem.

As far as the Z goes, I zeroed as you suggested, and moved up 1" and down 1" back to the material with no problem. This was repeatable, and accurate. That is good news.

SO, it seems like the problems I was having are probably in the Vcarve program itself, and I will review all of that, to make sure that is zeroed and moving correctly.

I will report back some time tomorrow.

Thank you very much for your help.

Jim

Also, if you wouldn't mind--could you email me the file that you're running on the tool? both the .sbp (cut file) and the .crv (vCarve design file). I might be able to notice something that could be causing the issue.

brian.owen@shopbottools.com

Also--I'll get a new bit and z-zero plate on the way to you tomorrow.

Brian Owen, ShopBot Wrote:
-------------------------------------------------------
> Jim,
>
> Let's try a few things to see if we can diagnos
> e what's gone wrong. Like I'd said above, the proc
> ess you're using is the same that we use at the fa
> ctory--so I'm concerned about whether something wa
> s damaged in shipping.
>
> Try manually stepping the Z axis down to the ma
> terial--like you did before your cut. Press the or
> ange "0" button to set the zero. Then in the Z pos
> ition field, type in a new position above the curr
> ent position--try typing in 1"--and then hit the "
> Go" button to send the Z axis the 1". Once the too
> l completes the move--type 0" into the Z position
> and hit go again. This should send the Z axis righ
> t back down to where it was before.
>
> What I'm wondering is if there is something pre
> venting movement of the Z axis...this will at leas
> t tell us that the tool is able to jog up and down
> without stalling in the Z motor. If the tool do
> es stall in the z motor then I've got a few qu
> ick maintenance steps that will fix that. Gotta di
> g up the document I wrote for it.

Brian,

I am having the same problem mentioned in this thread. I zero the tool using the 6 step method you describe. However, when I type in a 1 to move the tool up 1 inch, an ugly sound happens in the z-axis motor, the router moves up less than 1 inch, and my zero is thrown off. Can you share the maintenance steps with me?

Thanks,

Karl


>
> Brian

Karl,

Check out this doc (from the docs page): [docs.handibot.com]

A few quick steps should do it.

Let me know how it goes!