Seems so strange to have to put a sacrificial aluminum sheet down to cut this. I see you doing this sort of cut daily Brandon so I’m just totally confused as to why this is something I’d have to do, and it’ll get might expensive having to do that for all the pieces I need to make.
Yeah buddy! Al is a challenge on any machine compared to wood. Let me run this thing.
Ben you don’t need an aluminum spoil board. Just get the cardboard from a soft drink case flatten it out then put the Aluminum down. Cheap and effective.
Don’t use calculator. It should be a feed rate that the machine feels good. Try 300 mm / min. And try 1/2 of your plunge feed. The problem with he plunge is if the end mill has too much resistance it too fast if feed rate. It will float on top of the last cut and the chops get under the cutter. And if the Z backlash is off at the end mill will never have the force to cut thru the last cut.
Confused. What size should the inside hole be?
Inside hole should be 28mm. Bolt holes should be 5mm, whole piece should be 63.5mm.
@Steve_Popmarkov I dread to think of the accuracy of my pocket depths if I use a sheet of cardboard under the workpiece…I have some pockets I need to cut to reasonably precise depth.
Hey bud looks like your cutting the outside of the 28mm hole. You want the ID open correct to install the bearing?
@Brandon_Satterfield don’t think I am, I’ve dropped the bearing into one of the bad cuts before and it was just about right, a little tight but good. Oh I just downloaded the file and I think I see what might have happened, I had a style reference for the cut, and it pops up a window when you load it if you’re not careful that reverts it to Outside cut… let me clean up that file.
Nothing will happen to your accurate icy zero the tool on the top of the work and work down form that. Instead of your spoil board. And it works. The soda cardboard is exactly 0.5 mm and two layers your 1mm. You can waste 2 more days with all the BS that Aluminum has to offer. As an example you have a sigh on a back wall and the sigh is 2mm thick. If you cut 2mm in to the sigh it won’t come of the wall. If you cut 3mm in to the sign the tool hits the brick and is wasted. If the cardboard is between the sign and the brick wall you cut 2.75mm deep the sign will be cut and the card board saves your tool
@Brandon_Satterfield just uploaded a new copy of that file to the drive. Fixed now, should load cleanly and show the inside cut.
@Steve_Popmarkov that is true, although you are assuming even thickness of the cardboard all across. Also, why the hell would cardboard work where MDF causes the issue? I don’t see the cutter having any trouble cutting up the MDF, so why would cardboard be better?
I’ll give it a shot as a last resort, but all this feels like hacks on something that should be dead simple and that I know others with this machine are achieving perfectly.
I’m not sure if I’m hoping for it to fail the same way, or to succeed… 
@Ben_Delarre video uploading now. Changed DoC to .6
Target depth -6.8, plunge was OK at 5. Tabs ok as well.
Posted a video. Part about done.
Ok, so its not the gcode, and its not the touching the MDF…its clearly something mechanically not right with my machine, or my controller?
This machine is old as dirt, loose everywhere. Same end mill. Factory collet.
Do make sure your material is held down firmly and is square to the spindle. Al has a horrible bow in it for the most part.
What bearing are you putting in it?
I have been doing the z zero at the bed, since I can’t probe, then assuming the material was 7mm tall and air cutting at the start down to 0. I don’t see how that’d change anything in the cut though. I think I may have tried an increased DOC, but I can give it another go I guess.