Bartman's LR3 build thread - A New(bie) Adventure!

Wow, this is awesome! Thanks for the updates and info!

So a bit more incremental progress to report…

While I’ve been procrastinating (er, umm, I mean researching aluminum cutting feeds and speeds), I decided to do a bit of cleanup on a few items.

First of all I mounted a power bar with a kill switch, and a shutoff valve for the air supply to the mister assembly. I put it near the future Min X Min Y location (I’ll be converting from Portrait to Landscape shortly) so that it will be close by when starting cuts.

From there I ran some air hose and an extension cable to the midpoint of the rear of the table, and made it so that everything can be quickly disconnected.

Next up I installed a “drain wire” inside the section of vacuum hose that connects to the LR3 for static grounding.



Also I designed and printed a bottle holder for the Iso-Propyl Alcohol (IPA) for the mister system.


Coming up, I really have to get off my a$$ and start cutting the aluminum struts, followed by new aluminum XZ and YZ Plates.

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Progress!!

After a lot of procrastination (er, um…I mean research), I think I have sorted out the feeds and speeds for cutting my struts. I used G-Wizard (CNC Kitchen) to come up with the following suggested rates for 2.5mm DOC, Single Flute 1/8" mill, with 0.35mm finishing pass:

Any comments/sanity checks are more than welcome.

After a bit of a misadventure trying to figure out EstlCAM parameter sets, I managed to create and save the g-code for a variety of different speeds. Tomorrow (or at least this weekend) I hope to do some air-cuts to test for excessive vibration and shaking at different speeds, and then hopefully start making some aluminum chips!

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Even at 2250 mm/min, there really doesn’t seem to be any concerns about vibration or shaking, at least with the air cut. I’ll try actual cutting as soon as I get a couple of hours free to devote to the project.

1350 mm/min @ 0:00
1685 mm/min @ 1:12
1965 mm/min @ 2:12
2250 mm/min @ 3:15

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Great progress, then a great setback…

The day started out well, with the first cuts in aluminum. I went with the 20000 RPM settings, because it said that it would only take about 2.5 hours.

(turn down the volume for this video)

The chips looked really good, mostly smaller segments because of the Trochoidal milling, but some good spirals in there as well…


The AIr Mist system worked really well, and blew all of the chips out of the cutting path quite well.

I made it all the way through cutting all of the screw holes, as well as the first strut part, when disaster struck…

I put screws into several of the strut screw holes to secure the material to the spoil board during cutting. I had EstlCAM Clearance Plane set for 3mm.

When the first part was finished, the gcode called for a rapid move to the next part. Unfortunately that path was right over (through) one of the screw holes that had a screw in it, and there was contact. I had used a mix of 1/2" and 1" screws, and fortunately the screw in question was one of the shorter ones, so it pulled out rather than snapping the end mill. However the resulting loss of steps caused the router to start cutting into the just-finished strut part.

So the next step now is to re-run EstlCAM to produce a new gcode with a 5mm Clearance Plane, use Notepad to remove everything up intil the start of the second strut part, re-home X & Y, reset Z using the touch plate, and try again.

I did notice a couple of issues during the initial cut:

  • Every time my compressor kicked in (8-10 minute intervals), the ensuing voltage drop resulted in the router speed decreasing enough that I could hear a change in the cutting. The chips still seemed ok, but it sounded like it was struggling a bit.
  • EstlCAM estimated that the whole thing should take 2.5 hours, but cutting the holes and one of six struts took over an hour, so the actual time is more likely going to be closer to 5-6 hours

More updates once they happen

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If I’m not too late for a suggestion I would go higher with your clearance plane. Always better to have too much than not quite enough. I was using screws with 3D printed washers for the V5 parts and I believe I set mine at 10-15mm. Way more than I needed but never once did it get anywhere near a screw lol

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I was going to say the same as I was reading it. I keep mine at 10…for peace of mind

So I made the changes noted above (and increased the Clearance Plane a few more mm as recommended), and restarted the cut. Before doing that I checked the end mill and noticed a bit of aluminum welding to the cutting edge, so I changed out the end mill for a new one. Probably happened when the mill tore into the material and I had to hit the emergency stop.

It all went well for about 90 minutes, and then the mill snapped off. Kinda surprising, because the material was well secured (so no chatter), the air mist (IPA) was keeping the slot free of chip buildup, and the sound of the cutting was consistent with the previous 2.5 hours of cutting.

I may need to pick up a few more end mills before I start up again, and the program ran for a few minutes before I paused it, so I will probably have to figure out where in the gcode the mill broke, and edit to restart a few seconds before that point.

Only mildly annoying, and it is giving me a great opportunity to learn about editing gcode. Also gaining more experience with every hurdle. Pretty soon I might even have a clue about what I am doing! :upside_down_face:

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