Dual Zero Planes on a double sided job?

[Christopher Leech]

I have often tested the limits by shear accident.
Still getting the hang of managing the modelling tab in VCP.
I found the need for two zero planes on this 3D model in the 2 sided approach.
Once the STL was been brought in and sized/centered, we find a total height of 54.6mm and diameter of 290mm. This is arbitrary of course as I am working with some pine off-cuts that have been laminated together and the slug is 60mm Z, 300 Y by 300 X . As we set up, we are required to determine the zero plane for the piece.
In order to deal with the shape of this model, which is a bevelled gear, the total depth of cut required for one side is 40mm and the other is 52mm. So the fixed and single Zero Plane won't cut it. Pun intended.

Am I forced to make this in two separate projects? VCP won't allow 2 sheets with the same STL file brought in obverse aspects

Hope you are all well.

[ohiolyons]

I have never seen a vectric video that required dual zero planes.

There is a guy in the Milwaukee CNC user's group who cut a 3 or 4 foot similar gear on a Shark Piranha and he didn't use dual zero planes. For those of you who don't know it is a 12"x18" bed machine.

I know he didn't because I'm the one who showed him how to do it.
BTW he is a better man than me, I wouldn't of tried it on that small of a machine.

Hopefully Bob Hartig will see and post some photos.

[garylmast]

Not often, but every once in a while, I need to adjust the Limit (zero) plane on one side but not the other. Under the Modeling Tab, in the Components on each side there will be a different layer showing the Limit plane. In the Component Properties (crescent wrench icon), you can make adjustments there.

Gary

[ohiolyons]

You can have the same STL on 2 different sheets in VCP.

If it is 2 separate STL's then you can do that too.


Why aren't you doing this as double sided?

[Bob Jr]

I have never seen a vectric video that required dual zero planes.

There is a guy in the Milwaukee CNC user's group who cut a 3 or 4 foot similar gear on a Shark Piranha and he didn't use dual zero planes. For those of you who don't know it is a 12"x18" bed machine.

I know he didn't because I'm the one who showed him how to do it.
BTW he is a better man than me, I wouldn't of tried it on that small of a machine.

Hopefully Bob Hartig will see and post some photos.

John,
I think you're referring to Jerry A. and his hand drill project. (I'm the one who made the bubble machine and kite trolley.)
Bob

[ohiolyons]

Bob I was hoping you had photos from Jerry from the user's group minutes

[gregk]

I have often tested the limits by shear accident.
Still getting the hang of managing the modelling tab in VCP.
I found the need for two zero planes on this 3D model in the 2 sided approach.
Once the STL was been brought in and sized/centered, we find a total height of 54.6mm and diameter of 290mm. This is arbitrary of course as I am working with some pine off-cuts that have been laminated together and the slug is 60mm Z, 300 Y by 300 X . As we set up, we are required to determine the zero plane for the piece.
In order to deal with the shape of this model, which is a bevelled gear, the total depth of cut required for one side is 40mm and the other is 52mm. So the fixed and single Zero Plane won't cut it. Pun intended.

Hello Christopher,
It sounds like you could achieve what you want by using the overcut distance during STL import. Have a look at the Two Sided Marlin tutorial please as it explains how to use that feature.

Am I forced to make this in two separate projects? VCP won't allow 2 sheets with the same STL file brought in obverse aspects

Hope you are all well.

You cannot import the same STL twice, but you can duplicate or copy it to another sheet once you import it for the first time.

I hope that helps,
Greg K

[Christopher Leech]

To all who have chimed in, thank you for taking the time to help.
However....I have ended up pretty much exactly where I was before posting.
Caution, this could bore you to death. In light of that I have tried to be brief

I went for a blank of 300 by 300 by 60 to start.
I may not have mentioned that this STL arrived at a size that reflects real world dimensions and was scaled up to practice larger depth of cuts, more challenging 3D workflow along with my growing tool library. The file I will share has been altered to be lower profile than the original which is free to download from well known repository online. If you want the original, look for 24 tooth bevel gear. The file also comes with a 16 tooth mating gear that probably pairs nicely ie matching pitch etc.

As for managing the job in a single sided approach,
I could not make use of copying the STL to another sheet because
A: you get the same aspect, no flipping possible and
B: the modelling or zero plane is fixed as per the first dialogue during the initial STL import dialogue
in the modelling tab. Let me know if I am wrong by all means.

In a 2 sided approach, changing properties of the zero plane for the second side that made any sense to me went awry and I abandoned it. I can't begin to explain what I was seeing.

Why is this such a challenge? My guess is as follows:
The zero plane required for the bottom aspect, given the shape and undercut, is 34.8 mm from the Z -0
The top aspect requires a zero plane of 40.9mm from Z-0.


Try it for yourselves if you are so inspired. This would be much more efficient at arriving at a concord.
Or convincing me that I am talking rubbish
I went for the separate project approach but employed elements of the 2 sided job to attempt to keep registration.

After importing the file in either the top or bottom aspect, I scaled it's X and Y to 290 x 290 mm. I took note that the Z became 54.248mm. So began again using that number for the Z dimension for the blank. Now 300 x 300 x 54.248
In hind sight, leaving only 5mm spare X and Y was a bit tight. But I am currently doing the 3D finishing of the bottom aspect and seems good. The only thing that may unhinge this quest is the ongoing problem I am having with spurious triggering from a noisy VFD.

In two separate projects, the bottom must be done first as once finished, there is a flat surface to fix to the spoil board, we employ dowels that are 90 degrees to one another to register the piece rotational to the Z axis for the flip.
Tape and CA glue will be used for work holding for the top aspect machining as there is no means of clamping the tapered contour of the finished bottom aspect.

As mentioned, bottom side was first.
The center bore of the gear that would accommodate it's shaft in real life is roughly 49mm diameter after scaling up. To avoid machining vertical surfaces with a tapered ball nose I enlarged the center bore to 52mm dia and cut the full 54.248mm depth with a pocket cut to prevent the tapered ball nose from having to do a vertical surface, and solves that problem for both sides. The first hour or so of the finish pass is just cutting air and that's fine. I only have one R1.0 3.8 deg tapered ball mill and can't risk breaking it in the name of experimentation.

Top side will have to use the same corner for the WCS, ie. lower left origin becomes lower right after the flip.
But before this is done we will remove the part and make the opposing dowel holes in the spoil board using the WCS for the bottom.
Then we put the tape and dowel and CA glue and cross fingers.
Then the new origin will be set using a probe sequence and a three sided corner finder. ( Pssst,....I am actually going to use aluminum tape wrapped around the corner and an alligator clip, because the only good quality corner finder is made by Bill Griggs and he is MIA.
It will be the first time I have used the edge finder in the probe dialogue and looking forward to that.
You can figure out the rest. Model I used is below.
https://www.dropbox.com/s/kf13pn1b5cb9k ... e.stl?dl=0

Christopher

[adze_cnc]

No cutting air. All flats and shaft hole cut with pocket toolpaths. No zero planes beyond the one set at the centre of the model on import. Overcut distance specified so 3D finish of the gear teeth will go below centre plane. 3D finishing constrained by "Select Vector"
 

[Christopher Leech]

No zero planes beyond the one set at the centre of the model on import. Overcut distance specified so 3D finish of the gear teeth will go below centre plane. 3D finishing constrained by "Select Vector"

Surprised that one could specify an overcut as large as what would be required. The Wiki speaks of applying small values here, ie. the radius of the ball nose bit to avoid small cusps at the zero plane. There is no mention of using it to address matters such as these. I think it is un-intuitive, and I reflect on other 3D design and slicing software that I employ daily that assist the user as he hovers the mouse over any input or variable, detailed graphic and exhaustive descriptive text, illustrating the use of same said to assure you of the choices and ranges. Anyway,.......
Very cool indeed. Thanks for that.
And sure enough, using the selected vectors is obligatory. Hadn't the faith in them at first, but now it's a whole new ball game.
Pocket where ever it will save you time. In this case I will even do the corner sections on one side at lleast.
Keep an open mind! A good mantra for sure.

A bit of trial and error while you refine the over cut value for the first side. And then for the second side, the adjustment of the limit plane is the key. Sure helps to light a candle rather than rail at the dark.
I trust this approach will allow me to dispense with making the material exactly 54.25 mm thick as I did using two separate projects to complete the part. I will be able to zero my tools off the spoil board.


Apart from one spurious triggering event that inspired me to cut the input wire from my X++ limit switch (solving the issue temporarily) I was very pleased with my first kick at the can.
And it took hours more than the second version will.
Thanks to adze_cnc

[Christopher Leech]

I wanted to show you the results I got in spite of doing it the long way.

[adze_cnc]

The Wiki speaks of applying small values here, ie. the radius of the ball nose bit to avoid small cusps at the zero plane.

Where is this Wiki that you speak of?