So I’ve been tuning my (much delayed) LR3.
My test was to layout and cut a 100x100 millimeter square, then measure the result. That turned out to be 104.74 x 104.9
I’m hoping someone can validate my method to dial it in.
I looked at the steps per mm and it was set to the default of 100.0000
Since the error was 4.79mm in X the math seems pretty straightforward.
I just divided the total error - 4.74 for X - and divided it by the desired cut of 100 mm and got a correction of 0.0474. I subtracted that from 100 and set the steps per mm to 95.26.
I did the same for Y and this got me closer, but not quite there - I’m still coming up a bit short and seeing some variability in the cuts (between 99.22 and 98.77), but maybe I’m expecting too much?
If I did this wrong I hope someone can set me on the path.
Sage advice. Use a sharp V bit, and some painters tape. Use the bit to jog down and mark spots, then walk around within your build volume and then measure that. (Lower the bit just enough to make a tiny dot puncture in the tape)
Also command the moves around multiple times to see how repeatable your machine is.
I do this manually before trying any CAM just to charactarize the machine.
A few notes on my settings:
Using a 6mm spiral bit.
I did have a finishing pass.
The total depth of cut was 8mm, with a max depth per pass of 6mm, 20 degree plunge angle.
I’m currently getting finished dimensions of 100.19 x 99.96, with my steps per mm set to
96.0836 for X
95.6947 for Y
Two questions:
If 5% is “too much” how much would you consider acceptable?
What else might be wrong? Everything seems tight - no play in the carriage, belts are moderately tensioned, but I could possibly make them a bit tighter.
I tried the blue tape method as follows, using the terminal in the SKR software:
G0 X0Y0 ; position over start
G0 Z-.5 ;make a mark
G0 Z20 ; raise
G0 X100 ;move down X 100mm
G0 Z-.5 ;make a mark
G0 Z20 ;raise
similar for the Y axis…
My X and Y distances measured out at about 96mm even though I specified a 100mm move
I reset the steps per mm back to the default, (100 per mm) and repeated this and got very close to 100mm on both axis!
My previous testing was using G code generated in Estlcam - could something be amiss there?
I’ve got a SKR board, and using the Marlin profile.
Do the sinplest test possible of your settings and post the gcode here (rename it to .txt or zip it up or just paste it in). We should be able to see if therr is an issue.
Otherwise, take a look at estlcam basics and make sure the settings are right. The only thing I can think of is that instead of doing a “part”, which would keep the bit on the outside, you did “engrave” which makes the bit move exactly on the line. That would make it smaller by the size of the bit.
The simplest thing I could think of was to drill two holes, and measure the space between them.
I did this along Y for a start.
Using a 6mm bit, holes spaced 106mm on center - should be 100mm edge to edge.
When complete, the edges of the holes were measured at 105.71mm apart, with 100 steps per mm.
Notice the Y values in bold. The difference between them is 111.2834 - shouldn’t that be 106??
Code from Estlcam:
;Project 100mm_spaced_holes
;Created by Estlcam version 12 build 12.068
;Machining time about 00:00:09 hours
G90
M03 S24000
G28 X Y Z;home X Y Z
;set absolute position
G90
;set x=0, y=0
G92 X0 Y0
M0 ;pause for probe and then probe
G38.3 Z0
;set z to be 0 then set it to be 0.5 - the thickness of the probe
;this makes Z=0 be the bottom of the bit or top of the material.
G92 Z0
G92 Z.50
G1 Z10 F1500
M0 ;remove probe, powerup router
G00 Z5.0000
I selected a standard view (top) and exported as DXF. Imported that into Estlcam.
What I SHOULD have done was also select “parallel projection” before exporting. Doing that put the holes the correct distance apart, because, of course the standard perspective view doesn’t produce true dimensions! …argh!
I see Fusion or FreeCad, or something else - anything else - in my future…
Not familiar with onshape.com. I’ve stuck with SketchUp since I have many years with it, going back to when Google had it. But over time, as it’s matured, I still see some of the same problems I saw with it all those years ago. Don’t get me started on that…
I typically shy away from web based tools, because I live in a rural area and historically there are periodic issues with internet access. Slow speeds, loss of connectivity, etc. But I may need to give that a look as things are improving.
Appreciate your assist… I’m getting closer to actually making something with the LR!
Like Jeff, I use Onshape as my primary CAD. I also used SketchUp and DXF export (with the “parallel projection” gotcha…) back when Google had it… when my late golfing/fishing/flying buddy and I were needle-cutting/building/flying/crashing RC foamy aircraft in my pasture.
I also live in a rural area. I had horrible DSL internet service until I switched to Starlink a couple of years ago. I absolutely love it. It is especially nice during stormy weather when it automatically recovers from brief (usually) dropouts as soon as it can see satellites again; i.e. no lengthy, painful service provider calls to off-shore call-desk personnel. Starlink is a bit more expensive but far higher-performance, more reliable, and convenient.
As I said, things for me are looking up. Spectrum has a big initiative underway, pulling fiber to my neighborhood. Hoping for more reliable, consistent service with higher speeds. We’ll see
The nice thing about moving to onshape, fusion, freecad, solidworks, is that they all have a pretty similar workflow. So once you learn one, you can move to another without much trouble.
If you get fiber, you’ll have better options than I do in a suburb of denver.
