January 11, 2019 at 9:59 pm #83463
So I have had trouble with finishing passes. On this particular cut I am cutting 6 round holes evenly spaced on long pieces of extruded aluminum (88 inches). The rough cuts seem to be fine, but when it travels back to the start, it has lost maybe 1/8 inch along the way, and then the plunge of the finishing cut is hitting next to the original hole, and at full depth, obviously its breaking the 1/8th bit. So I have a two part question: is there a way to have estlcam do the rough cut, immediately followed by the finish cut, then proceed to the next hole? I cant seem to be able to select the finish cut in the machining order and move it separately from rough cut. It wants to do all the rough cuts, then all the finish cuts. If I can do both at each hole before moving on, I wont have an issue with it losing some on the Y travel.
Second, has anyone had luck with 1/4 bits in aluminum? The aluminum cutting guide says not to use them, but I think it would help with breakage. At $35 a pop, I cant afford to keep breaking them.January 12, 2019 at 8:48 am #83475
Select each hole individually and when you are done with your CAM makes sure you like how it shows for the Machining order. You should be able to rough and finish in sequence.
You should not have moved an 1/8″ something else is wrong, I suspect the work actually moved.
What size is your build and what exactly did you use for your settings, all of them, bit type, aluminum type.January 12, 2019 at 2:46 pm #83529
I don’t think the piece moved, it’s an extruded box 88 inches long, 8 inches wide, 2 inches tall. It weighs prob 20 pounds. It was also clamped to the bed.
When try to edit machining order, it won’t let me click on the finish pass like it does the roughing pass. Maybe I am not zoomed in far enough?
The bed has a slight sag in the middle, so when I zeroed Z at the left edge, it was too low for the center and when the bit got to those holes, the bit plunged prob a mm or two at the start of those cuts. You can see where there is bit deflection at the start of each hole past the first two.
The bed is 24 inches in the X, 96 in the Y. I used a 1/8 single flute onsrud 63-612 bit, 1000 mm/min x and y speed, 0.30 mm z plunge. I’m not certain on the alum type, but I imagine it’s the harder variety since used in an outdoor structure for a louvered roof system.January 12, 2019 at 2:56 pm #83532
Here are pics of the work piece. First one is the entire piece. Second is where it plunged and broke on second hole’s finishing pass, and last is the hole after just the rough cut. You can see the bit defected at the plunge, (work was flat, table sags so work is high) and then walked back to straight.
Attachments:January 13, 2019 at 9:37 am #83578
In ESTLCam are you chosing Hole or Drill? I would try using Hole and choose the LeadIn option. This way you can have your bit plunge into the material inside of the hole you are creating and that should help with the deflection of the plunge. You can try this with the finishing pass as well.
As for it being off by 1/8″ – that sounds like a problem with the table or the steppers skipping steps as its running down the board and back. Have you tried just a simple “drawing” to have the gantry run all the way to the end and back and make sure it comes back to the exact same spot? That will help determine what is going on. During that test run, just use a marker on the table itself. Have it start at z0 with the pen touching the table to leave a mark (the finer the point the better), have it go to Z5 or something, then run down the length of the table (and maybe have it run in the X direction as well) and then have it go back to your Home. Set G92 X0 Y0 Z0 at your starting point – this sets this as you Home. At the end of you gcode put in G00 X0 Y0 Z0 – this will tell it to go back to your home. Basically the beginning and ending of the gcode should look something like this (first manually move your gantry to where you want it to start with the pen touching the surfave):
;Set to Absolute Positioning
;set the current position to home
G92 X0 Y0 Z0
;raise Z 5 mm
;then have your gcode to move the gantry to the end of Y and put is some X motion as well
;after the gantry has finished its movements the end of the code should be
;goto Home in the X and Y direction
G00 X0 Y0
;goto Home in the Z direction – drop Z back to zero
After it does this – your pen should be exactly back where it started. If it isn’t, then there is something wrong with the build somewhere causing it to be off.January 13, 2019 at 10:18 am #83593
Zip and link your Gcode so I can take a look.January 13, 2019 at 10:20 am #83595
Also a few pictures of your build will help.January 13, 2019 at 10:25 am #83600
I use the hole option. Honestly the bit deflection is not bad in and of itself as the hole is for a puck led light, so it’s covered by light when it’s installed. My main concern is if the higher load is causing belt stretch and of course bit breakage. I don’t think I heard the motor skip during the cut.
The lead in would be good for the finish pass for sure, except if the rough cut didn’t make it all the way through the material, which happened on the first hole. I may even just remove the finish pass altogether as it’s not even necessary for what I’m doing. I probably have about 1/4 or even 3/8 inch to play with on the hole diameter, so what’s the .20mm of the finish gonna help? Centering of the hole on the X axis, and distance between holes on the Y are far more important than hole size tolerance. Obviously I want to fix the issue with it losing track over the length of the bed for repeatable cuts. I built the LR2 with this specific job in mind. I will use it to cut these light bars repeatedly so I need it reliable. This particular light bar is one of four going into a $42,000 install. This is the first one I have done with all 6 holes on a single run. The first light bar I cut, I did it with just a single hole and I manually centered each one. It worked, but was a lot more effort. But even doing each hole separate is way better than using a hole saw and a drill. My boss spent 6.5 hours cutting 24 holes and almost broke a rib when the drill caught. This 6 hole cut took about 26 minutes.
Jeff I will try your suggestions and see how it does.January 13, 2019 at 10:28 am #83602
Ryan, I can take some pics. You want to see the gcode from the 6 hole cut?January 13, 2019 at 11:18 am #83616
The one that gave you the poor results.January 13, 2019 at 11:31 am #83623
Here is a few pics. 2×4 table frame, 1/2 inch ply top. 4×4 legs.
Attachments:January 13, 2019 at 11:33 am #83631January 13, 2019 at 11:45 am #83633
Hmmm, you are cutting as 16.6mm/s you might want to move slower and maybe cut a little deeper per pass instead.
As for the cutting order the finishing pass should be linked and should go in order. I just double checked, it looks like this and works as you want.
1 user thanked author for this post.January 13, 2019 at 6:14 pm #83690
Ok so I figured out what I did wrong: I didn’t populate the finishing pass parameters on the tool list, I made a second tool with different rough parameters which drives a toolchange. It automatically puts all the tool change moves behind the roughing to avoid extra tool changes.
What about the 1/4 or 3/16 bits for aluminum? Anyone used the larger sizes with any luck?January 13, 2019 at 7:29 pm #83703
Dui, ni shuo de duiParticipant
Very nice lowrider, that’s a great build!
You shouldn’t have such a huge backlash though, something is wrong and you should first solve it before being concerned of the finishing pass order, because it won’t be your only problem if you have these kind of gaps. You will likely end up with misaligned holes in whatever you’re cutting if this isn’t solved.
I’d check first for the following things:
-Make sure that your pulleys are super tight on their shafts
-Check the belts tension
-Check your motor drivers voltage
-Double check your cutting speed figures
-Check that the gantry moves freely all the way long
-Protect your cables from electromagnetic interferences, especially around the spindle. Also, some vacuum cleaners can induce some interferences, leading to missed steps.
This won’t be easy to troubleshoot but it is the priority here.
Good luck!January 13, 2019 at 11:35 pm #83750
So I decided to tighten the Y belts cuz it’s hard to know what is tight enough. Then I ran the 6 hole cut with a pointer attached, and under no load it came back about half a mm off or so. I would totally be fine with that if it did that under load.
First pic is before, second is after.
You must be logged in to reply to this topic.