Frage Losing zero-position during operation

Hi,

I finally managed to get the Stepcraft 2 / 300 to CNC something. There is still one problem though and I need some advice how to solve it.

I am CNC'ing a text. And at some point in the process, sometimes after 3%, but it also happens later in the process, I hear a high pitched sound from what I think is the y-axis and from the moment on the zero-position is shifted. Sounds like it is slipping or something.

I have setup the job in a way that it carves just a fraction of a mm to prevent strain caused by the bit. It still happens.

What can I do to troubleshoot the cause?

Thanks.

A suddenly upcoming noise is always a terrifying experience.

But you ask a question without giving us some information about the job you executing.
for instance how high is your feed over the X- and Y axis, how deep is your pass setting, what mill bit you use?

General check if you y-, x- and Z- axis move without heavy resistance, jog and listen if you hear a smooth traveling noise if not start over and mechanical adjust your machine.

I was able to complete the job at 70% feed rate in WinPC-NC. Clearly, that was the problem.

But I am confused about who is controlling the feed rate.

The job I ran was:

In VCarve Desktop Trail I did setup a tutorial job named 'Avalon nameplate'. I simplified it a bit to 1 path. Basically, it prints the text, Avalon.
I use a V-Bit, 90 degrees, 6.4 mm in a Proxxon IBS/E at approximately 15.000 rpm.
The material is MDF.

In VCarve I entered a feed rate of 25mm/sec for the bit. I read somewhere that this is a good starting point for the Stepcraft.

Next, I exported the path and opened it in WinPC-NC and inverted the z-axis, did the reference and zero-point setup and started the job.

Now I had to turn down the feed rate with the slider to about 70%.

It gives me the feeling WinPC-NC takes control over the feed rate? Is this true?

Also, the job took 2,5 hours to complete. I think that is a bit too long. But that is the next question.
First goal achieved. 100% finished job

Ok
Maybe I can help you.
Where you from?

Who is controlling your CNC depends on the settings you made or not made in WinPC.
Normally VCarve will set the feed, plunge rate and pass depth.

Netherlands, just like you according to your profile.

Alphen aan den Rijn om precies te zijn

Hi Tonp,

It sounds highly likely that your machine is loosing steps - probably on the Y-axis.

It is notoriously difficult to get this axis "tuned" correctly on the larger machines, made more difficult if not impossible if the machine is at all twisted due to not resting on a truly flat surface. Even a twist of a few millimeters will make "tuning" for free movement over the whole range of travel difficult if not impossible.

You could demonstrate this by temporarily removing the guide bearings from the non driven end of the Y-axis leadscrews. With the side rails set for proper free movement at the driven end, move the gantry to the other end and check if the ends of the two leadscrews remain centred in the bearing housings. If that isn't the case, then with the bearings in position there would be very high side loads on the leadscrew and precision nut.

You would need to find and remedy the cause of the lack of concentricity to get proper movement over the full range of the Y-axis.

As a matter of interest, on my SC420/2 I had to relieve the bearing housings by about 0.25mm to meet the above condition. These remote end bearings really only serve to prevent the end of the leadscrew flailing about at high speed, and are not critical to the accuracy of the machine.

Hope this helps.

Peter.