Sinumerik 840d Post Processor

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Adam Makin

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Aug 3, 2024, 4:40:23 PM8/3/24

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We have a CNC(DMG M1 with rotary axis) with the same control unit. I looked at the posts in the community and made a processor. I did a few tries on the machine and it worked fine. But there are some problems on the post output. I want to post first X-Y position then Z position line but some times processor doesn't work properly. I attached the processor files and the picture that shows the problem. İf someone help me to improve this post processor I'd be appreciated.

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I chose to write this article because of a repeated problem I see with CAM software vendors. They charge quite handsomely for Post-Processors, especially 5-Axis or Multi-Axis Post-Processors. However, more often than not, the VAR for a specific CAM software will task the actual work to someone who is completely incompetent for the task. The Post-processor is the most important part of the CAM system. It takes all the work done in the CAM software and formats the output for a given CNC Machine tool and CNC Control.

I repeatedly come across vendors who task post-processor development to someone who has never even run a CNC! I recently had one where the person in question had never touched a CNC and his last position was a security guard.
This is not to knock security guards but this person was clearly out of their element.

I recently dealt with this from a CAM VAR who believes someone with an Associates Degree in Computer Science from a local Community College and no CNC background is qualified to write a 5-Axis Post-Processor for a CNC Control he has ZERO experience with. Talk about delusional!

This is beyond unethical. It is borderline fraud.
The history of the CAM software is replete with stories of customers who were sold a bill of goods by their VAR and left with essentially useless software.
Whenever anyone is purchasing a Post-Processor there are several questions one should ask of your VAR to make sure that your aren't being ripped off.

1) Will someone within your organization actually be doing the work or are you farming out the job to a sub-contractor to get the job done?
If your vendor is farming the job out, demand to know who that sub-contractor is. You will become quite close to them as there will ultimately be multiple iterations of a post before it can be blessed and accepted. This use of sub-contractors is actually quite common and should not be considered as something unethical. However, disclosure and transparency is critical. Many smaller CAM VARs will take this route because it's quicker to get the work done and satisfy the customer.

2) Does the person developing the post-processor have any experience with the control system to be supported?
If the answer is 'No', stop right here.
Without the experience of actually knowing a CNC Control System, it is impossible to properly develop a post-processor.
The idea that someone with no experience with a SIEMENS 840D can write a usable 5-Axis post-processor for that control is intellectually offensive.
If they can't explain to you what a CUT2DF statement is or a CUT3DC statement is then they are in over their head.

3) Does the person developing the post-processor have any CNC Programming and CNC Machining experience?
Again, if the answer is 'No', stop right here.
Without the experience of actually knowing how a machine reacts in the real world to a given CNC Control System, it is impossible to properly develop a
post-processor. If the post developer doesn't understand FANUC AICC High Speed Mode or NANO Smoothing, it is foolish to believe they can implement the functionality. If the post developer has never operated a machine running a program that properly uses RTCP or G68.2 Tilted Work Plane functionality, it is foolish to believe they can write a post that properly implements that functionality. I had a situation where the CAM vendor in question actually caused a crash while trying to operate the machine to test his post-processor.
FYI to Post-Processor Developers regarding SIEMENS and G17, G18 & G19

4) How long will it take to develop the post-processor?
This is a bit of a loaded question but an important one.
An ethical VAR will immediately tell the customer that question is impossible to answer without knowing the specific Machine Tool, the specific CNC Control, the options the customer will want supported and what functions must be supported by the post-processor.

5) What do you need from me to assist you in developing the post-processor for our requirements?
This is a very important question and one that anyone in charge of procuring a post-processor should have on their list. You should be ready to give the CAM vendor as much data as possible. However, you, as the customer, should NOT be responsible for getting any reference data regarding the CNC Control System. CAM software companies are in the business of developing software to support CNC controls. That should ALWAYS be the responsibility of the CAM software VAR and vendor. The Applications Department of the Machine Tool Company or Distributor should be the first resource for the CAM software vendor.

There are some very good CAM VARs out there with excellent post-processor developers. If you use Mastercam, consider Dave Thomson at Postability , James Wakeford at Barefoot CNC or Colin Gilchrist at eApprentice.
Colin recently published an article on post-processors that every CAM system vendor and CNC Programmer should pay attention to.

If you use other CAM systems, reach out to other customers to find one that you will be comfortable with. Don't assume that because you use a well known CAM system, you will not get scammed. Conversely, don't discount CAM systems that are newer to the US market. Bill Genc and his crew at TopSolid are top notch.
(AlphaCAM users can feel free to contact me directly through Stiles Machinery.)

You may also want to consider 3rd-Party companies like IMS Software, ICAM Technologies or Spring Technologies. All three offer custom post-processors as well as machine simulation that run directly from your NC code.

Below is a list of our post processors from the legacy versions of software. These posts were originally created for the BobCAD-CAM standalone software V25-V28 and the BobCAM Plug-in for SolidWorks V2-V5.

These posts can be installed in the current versions of the software, however they have not been optimized for the newest version of the posting engine. They are using old post variables and do not have the newest post questions and blocks. Because of this some of the newer features of the software may not work, and some of the code output may be incorrect.

If you plan on installing and using these posts in the current versions of software, please do so at your own risk. Ensure proper testing is done prior to cutting anything on your machine. There will likely need to be some corrections made to the code before it can be used.

CNC Software Inc., producers of Mastercam CAD/CAM software, announced a 4-axis milling post processor that will unleash the productivity on SINUMERIK-controlled machine tools. The new post processor was developed utilizing the technical expertise of Siemens CNC engineers.

It is cooperation like this that provides Mastercam users the opportunity to truly complement their CAM investment and give their shops the best chance at a more efficient manufacturing solution, from design to part.

Mastercam recently announced the release of a new post processor developed with the technical expertise of Siemens CNC engineers. Introducing a 3- and 4-axis post processor for Mastercam Mill that supports the SINUMERIK 808D Control.