4th axis problems

[Cezary]

Hi ,
I have home made 4 axis CNC.
I have calibrated all the axis and each one individually works well. The problem starts with 3D projects. Some times, for no apparent reason Z plunges all the way dawn. The other day the same project, the same code, no change at all …works perfect.
Now I am trying to get the 4^th axis going and I am getting real headache ….Trying to round a piece of 4x4 to 3” round .
I tried three different techniques and all three failed causing the same problem.
Machine starts all correct, but when is done with one cycle, the indexer moves to new position and Y axis gets stuck.
The Mach3 sends impulses and it shows that Y moves while in reality it doesn’t. This way I am loosing all Y reference to Zero position. I can hear humming as if the stepper were receiving impulses but it does not move.
When I stop program execution, set all to zero again , start from the line where problem occurred, it goes forward again with no problem until next cycle and Y stops again.

N3030 G1 A-124.5872 Y10.0000 Z1.7372
N3040 G1 A-124.5872 Y-10.0000 Z1.7372
N3050 G1 A-117.6453 Y-10.0000 Z1.7372
N3060 G1 A-117.6453 Y10.0000 Z1.7372
N3070 G1 A-110.7035 Y10.0000 Z1.7372
N3080 G1 A-110.7035 Y-10.0000 Z1.7372
N3090 G1 A-180.0000 Y-10.0000 Z1.7372
N3100 G1 A-180.0000 Y-10.0000 Z1.6250 F30.0
N3110 G1 A-180.0000 Y10.0000 Z1.6250 F100.0
N3120 G1 A-173.0769 Y10.0000 Z1.6250
N3130 G1 A-173.0769 Y-10.0000 Z1.6250 ( it happens in all location similar to this one).


Wrap G-code generated by vectric.

( tornoRounding Toolpath )
( File created: Friday December 30 2016 - 01:04 PM)
( for Mach2/3 from Vectric )
( Material Size)
( X= 9.425, Z= 1.500)
( Diameter = 3.0000 Inches)
( X Values are wrapped around the Y axis )
( X Values are output as A )
()
(Toolpaths used in this file
(tornoRounding Toolpath)
(Tools used in this file: )
(1 = End Mill {0.5 inch})
N130 G00G20G17G90G40G49G80
N140 G70G91.1
N150 T1M06
N160 (Tool: End Mill {0.5 inch})
N170 G00G43Z2.5481H1
N180 S12000M03
N190(Toolpath:- tornoRounding Toolpath)
N200()
N210 G94
N220 Y0.0000 A0.0000 Z2.5481 F100.0
N230 G00 A131.9785 Y-10.0000 Z2.5481
N240 G1 A131.9785 Y-10.0000 Z2.1859 F30.0
N250 G1 A131.9785 Y10.0000 Z2.1859 F100.0
N260 G1 A138.0215 Y10.0000 Z2.1859
N270 G1 A138.0215 Y-10.0000 Z2.1859

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• 4th Axis Problems

[Cezary]

I think I have solved this problem, but I run into another. This one is ( I suppose) on the software or post processor level.
When I create things for my 4th axis, I use Vectric gadget Wrapped Job Setup and Vector Unwrapped. When I machine it, everything goes well except one nasty groove made by machine in the place where the wrapped job joints.
I made the same design in SolidWorks and imported it to Vectric as STL file……The same thing is happening ( see attachment photo)
When I simulate run on Vectric I don’t see this groove.
This only happens when I run roughing toolpath. Finish toolpath does not follow the groove and it looks like it functions well but can not correct the problem , since the roughing takes too much material making that groove.
(vectric project is clean , but the real piece not)
Any idea what is going on?
Thanx.

[Cezary]

I am just wonder , why nobody knows the solution to this issue. I placed my question all over the internet and so far no answer. Even the people from Vectric. They gave me couple ideas but they were not sure if it will work .....and it did not solve the problem. To me, it looks like vectric software is not able to close correctly 360 deg wrap with complex faces.

[Cezary]

I am just wonder , why nobody knows the solution to this issue. I placed my question all over the internet and so far no answer. Even the people from Vectric. They gave me couple ideas but they were not sure if will work .....and it did not solve the problem. To me, it looks like vectric software is not able to close correctly 360 deg wrap with complex faces.

[awerby]

Forget about Vectric for 4th axis work. That whole "wrapping" technique is a terrible way of making 3D things, and often fails, as you've seen. Download a copy of DeskProto, which you can use free for a month. It supports 3D geometry with 4th-axis routines so you don't have to "wrap" anything. If you're a hobbyist, I can sell it to you for $250, once you've seen how much better it works.

[Cezary]

Great......is it compatible with Mach3?

[Cezary]

I already installed Deskproto....looks very nice , but have no clue how to use it, completely different setup than Aspire....It looks like it will take me more than 30 days to learn basics.

[awerby]

Deskproto is pretty straightforward; it shouldn't really take a month to figure out. It's just a CAM program; unlike Vectric, there's no way to build 3D models within the program. So you build the model in another application and save it as STL, open it in DeskProto using the "Load Geometry" function, define the machine you're using (in your case, a Mach3-based machine) check the box that tells it you want to use the 4th axis, size and orient it correctly so the center of the part (the A axis) is parallel to the X axis, tell it what tool you want to use, how finely you want to cut, how fast you want to go, etc. then it produces a G-code file for you that you send to the computer controlling the mill or router you're using. Let me know if you get stuck.

[Cezary]

Yes , I already notice that I cant build models....too bad....Vectric is a really nice tool to design, but I cant create 3d model for 4th axis that will be understood by Deskproto. Any wrapped project is really saved as flat.
I already set type and size of my machine, but still having hard time to set Zero anywhere I want. for turning I usually set zeros in very center of the part, but in Deski can only move the zero point all around the edge of the part.
Another thing I don really like is that there is no simulation for 4axis jobs. It would be very nice option.............still trying to understand it, with only couple free hours in the evening will take me some time.....Thank you very much for help.

[awerby]

There are plenty of 3D modeling programs which will let you construct a model that's not flat and doesn't need "wrapping". Some free ones are Blender, Hexagon, TinkerCAD, FreeCAD, etc.

In DeskProto, you can change the starting zero point to the center in Part Parameters/Translate. It gives you the option of setting the zeroes differently for each axis, so for instance you can zero X and Y to the center and Z to the top of the part.

[Cezary]

I am sorry my man , but I cant get it going.....the g.code generated by the software is absolutely incompatible with the setup of my machine...I tried to do something and it makes absolute mess. Since the program does not have capacity to simulate in 3D I cant check if the pats are correct.....and dont want to practice on the machine to avoid serious demage. .......Aspire is so clear and easy to learn...to bad the wrapping does not work well.
I have no idea what I am doing wrong with DeskProto...I have red Help file , I use Wizard to import stl file and create code....I made very simple 3d STL files on SolidWorks......and still my machine goes crazy with the code generated by the software.

[awerby]

When you say things like "absolute mess" and "goes crazy", it's hard to pinpoint what you might be doing wrong. Do you think you could be a little more specific about the problem? While it won't do simulation of a 4th axis part, looking at the toolpaths (those red lines it makes) should give you an idea of what it's going to do. Could you post a screen-shot showing the toolpaths it generated for your part?

[Cezary]

See I made my own machine...is a big unit 3m x 1.5m .....The 4 axis is also massive 1.5 m long by 25cm diameter, made for very dense and heavy local wood ( i live in Yucatan jungle , south east Mexico). My 4 axis runs along Y ..there fore X should not even be considered by code. .....and generating it in DeskPro it goes all around X and does not coordinate noting with A ( my 4th axis) ....Z gave me troubles too, it actually went so deep in to material that my axis coupling broke......I always worked with automated machines but in plastic industry and I know very well how to move around PLC programming and automated element......but all these CNC softwares are something absolutely new to me and Mach3 programing is still a mistery to me....that is why I cant figure out what is going on and how to set it all correctly....Cheers CZ

[RCaffin]

IF - IF, you are getting something strange with the 4th axis and wrapping, I wonder whether the 4th axis is correctly calibrated?
Can't really tell as the info is far too inadequate, but I wondered.

Cheers
Roger

[awerby]

See I made my own machine...is a big unit 3m x 1.5m .....The 4 axis is also massive 1.5 m long by 25cm diameter, made for very dense and heavy local wood ( i live in Yucatan jungle , south east Mexico). My 4 axis runs along Y ..there fore X should not even be considered by code. .....and generating it in DeskPro it goes all around X and does not coordinate noting with A ( my 4th axis) ....Z gave me troubles too, it actually went so deep in to material that my axis coupling broke......I always worked with automated machines but in plastic industry and I know very well how to move around PLC programming and automated element......but all these CNC softwares are something absolutely new to me and Mach3 programing is still a mistery to me....that is why I cant figure out what is going on and how to set it all correctly....Cheers CZ

[That would explain it. DeskProto is set up for an A axis that's parallel to X, not Y. But the solution is simple. In Mach3, just switch the ports and pins so that Y becomes X and vice-versa. Then everything should work fine. Set the operation subsegment so that Z doesn't go too deep; just a little below the center of the axis is as far as it should need to go.]

[Cezary]

yes ....my 4tx axis iz very well calibrated, and very exact. Tested with high quality angle sensor..The error is 0.001deg.. In fact it works perfect on any other projects and simple turning jobs....I only get problems when I try to turn little complicated shapes.....But even when I do simulation on Vectric it shows a strange behavior right on the line where the wrap joins.

[RCaffin]

But even when I do simulation on Vectric it shows a strange behavior right on the line where the wrap joins.
Ah, whoa up a few metres there. Are you sayng you can see this problem on the screen when running a simulation?
Does that mean that when you try to machine something the fault on the wood is the same as the fault on the simulation screen?

If true - OH. SW problem, not HW.

Cheers
Roger

[InMesh]

I have seen where it cuts too far in one direction and then in the other so it gives a confused finish maybe it's doing 365 deg both ways.

[Cezary]

If it does...how to correct it?

[RCaffin]

Yeah, well, that's the big Q, isn't it?
IF it is being generated in the CAM SW, them MAYBE there is a setting for the amount of overlap?
I wouldn't know as I don't use that SW, but I would expect it to be highly possible.

Cheers
Roger