Test part repeatedly 0,3mm out of spec. < resolved >

[the_Swede]

My money would be on incorrect calibration as you have all 3 axis set to exactly 5.00mm/rev which is highly unlikely. Carefully recalibrate each axis, resetting lash to zero before you start as that will need recalculating once fine calibration is completed

Hi.
Great point you´re making for sure, and it will be my next thing to try out.

What does confuse my a bit is that the machine moves really well, as I wrote in my initial post, when just moving with a G00 command och checking it with the DRO. (X axis only so far.) It´s hitting the numbers just fine.

But sure, it could be a compound error.

Is there a post or a link to a Youtube clip that describes the calibration procedure in detail that you can give me?
Got a pretty good idea on how to do it, but really just want to get past this hurdle and would like to do it "correctly" this time.

Thanks for your support.

[the_Swede]

I forgot to mention, your report says you are running 4.64 which is VERY OLD and no longer supported. You should think about updating your software before you continue. Please follow the instructions for installing the latest version of CNC12 and do not "restore report".

Yeah, I know....

The whole project has kinda been dorment for about a year or so.... picked up fishing again

[suntravel]

The reason I asked if a second finish pass will cut again, is that will detect flex in the machine under cutting load...

Uwe

[ShawnM]

Here are links to download the Centroid coarse and fine DRO adjustment procedures. You only need to do the FINE version as you are close.

Coarse DRO adjustment procedure - download/file.php?id=15355
FIne DRO adjustment procedure - download/file.php?id=15356

I recommend doing the procedure a few times to check the repeatability. Remember to set your backlash comp to zero before starting this. Once you are dialed in then you can check and re-measure backlash and re-enter those values as well.

[the_Swede]

Here are links to download the Centroid coarse and fine DRO adjustment procedures. You only need to do the FINE version as you are close.

Coarse DRO adjustment procedure - download/file.php?id=15355
FIne DRO adjustment procedure - download/file.php?id=15356

I recommend doing the procedure a few times to check the repeatability. Remember to set your backlash comp to zero before starting this. Once you are dialed in then you can check and re-measure backlash and re-enter those values as well.

Thank you so much, it´s gonna be a couple a weeks before I can find the time to get this done, but I´ll write an update as soon I´ve gotten some work done on the machine.

Once again, thanks for the support. Truly appreciate it.

[the_Swede]

Hi Y´all.

First of all, I would like to thank everybody for their great input/suggestions and the support from the forum.

Like I said, it would take a couple of "weeks" before I would got arround working on my CNC project again. But it finally happened .

Order of measures conducted, tried and applied, to sort the issue out is as follows:

1. Finished installing the linear glass scales on all three axis. (Amazon Chinese specials.)
2. FIne DRO adjustment procedure - as recommended and linked PDF by ShawnM
3. Lead screw compensation table via the installed linear glass scales.

Running the same test piece, as described in my initial post, I was constantly producing a part out spec by 0,1mm instead of 0,3mm. So not the perfect result I was looking for but at least it was consistent and better.
So what I did was to use tool compensation for that measly 0,1, and the results really supprised me. The part ended up within 0,01mm to 0,04mm. And I´m happy as can be. Not bad for a hunk of welded steel plate for a machine .

I´m pretty sure 0,1mm over/under size while using a professional machine like a DMG or Mazak would be an utter catastrophe, if you needed to use tool comp at such a "coarse" level.
But considering my machine consists of all the cheapest linear parts from Ebay/Amazon and is made out of steel, this is a great start. I can now use the machine to manufacture parts for its own upgrades.

Once again, thank you for your support. Any more advice is greatly appreciated.

Best regards:
P-J Johansson

[cnckeith]

thanks for reporting back and posting the photos always great to see!