Pronterface problem

I am a newbie. Have printed successfully from my Medel90 + Panelulo2 from files on the SD card prepared by the previous owner of the machine.
Downloaded some files into slic3r fine. Sliced and sent .G file to Pronterface. Pronterface appears to process OK with all the preprint reports giving the correct sizes and weight. when I print thro the USB cable the printer moves about 1/10th scale. - Must be doing something real dumb. But I have seemingly checked every parameter I can find without success. Pulled down three different files all process correctly.
Any ideas as to what trick I am missing here please.

Sounds a lot like the steps per mm are set incorrectly, but the fact that you can print other files without problem seems to indicate that the slicer settings are at fault. The only thing is that the slicer generally doesn't know anything about steps per mm of the printer. Could it be that the previous owner had the steps per mm wrong all along and was just compensating by scaling the models before slicing?

If you do a manual move does it move the indicated distance?

Is there a way to set cm vs mm as the units of the incoming STL files?

Hi - Thanks for reply. Will be trawling through the Gcode, on the good files, for clues today.

No clues in the Gcode.
How does Slic3r find the steps per minute for it`s configuration? I have not found a reference to it, or a call for it.
Here`s hoping that someone will know better.

Slicer doesn't your firmware does.

Would the steps in the firmware be incorrect if it is working from the the old print files. I guess I am asking if the step/min/sec are contained in Gcode/*.G files. If this is the case then I can see way forward.
Will be checking again in the firmware for my Step/min/sec printer settings.
Thanks for advise so far.

Quote
polisher44
Would the steps in the firmware be incorrect if it is working from the the old print files. I guess I am asking if the step/min/sec are contained in Gcode/*.G files. If this is the case then I can see way forward.
Will be checking again in the firmware for my Step/min/sec printer settings.
Thanks for advise so far.

No, steps/mm aren't contained in the g-code. The g-code works in mm and the firmware does the conversion to steps. However, if the steps/mm are wrong in the firmware it's possible that someone manually scaled the model to compensate. It's simple enough to check - use pronterface to command some simple movements (units in mm) and measure how far the head moves. E.g send G1 X10 Y100 Z1 F600 and mark where the nozzle is, then send G1 X110 and see if it moves 100mm to the right.

Thanks yes. Did this early on. All Pronterface manual commands are accurate. As are the prints I make off the SD card (on the Panelulo2) generated by the previous owner.
Just cannot print my designs, or any downloaded designs. Even though the pre-print report on Pronterface advises the the correct dimensions.
After three days of parameter changes and experimentation, I feel like my brain is stuck to the hotplate with Pritstick!!

Quote
polisher44
Thanks yes. Did this early on. All Pronterface manual commands are accurate. As are the prints I make off the SD card (on the Panelulo2) generated by the previous owner.
Just cannot print my designs, or any downloaded designs. Even though the pre-print report on Pronterface advises the the correct dimensions.
After three days of parameter changes and experimentation, I feel like my brain is stuck to the hotplate with Pritstick!!

I can't think of a reason why a G1 sent manually would have any different behaviour to one contained in your sliced model. (Umm, maybe excepting one g-code flipped the units to inches, but that would be a factor of 25 not 10). Could you post the simplest working g-code and the simplest one you have sliced for comparison? If you have test cubes that would be great - and tell us what size they are supposed to be.