Okay my Xylotex 4-axis system has proven to be a good investment.
It’s still going strong. There is excellent support as well.
One thing I get a bit confused with still is Mach 3 (nothing to do with Xylotex). I seem to loose my settings once in a while.
The motor is 200 steps per revolution.
The drive multiplies this by 8 for 1600 steps per revolution.
You then multiply this number by your lead screw pitch to get steps per inch.
For some reason I have 320 steps per inch in there. I’ll have to go look at my other documentation to see how that got there.
30m later: I just figured it out. The lead screw is a 1605 which has 5mm of linear travel per revolution. So I guess that’s 3200 steps per cm. or 320/mm. I’ll have another look at the mill later and see if I can get the settings right and to get them saved.
With the help of my friends I was able to make my first part. This part is a mounting bracket for a generator for a human powered project.
Took a while but there is a learning curve.
It turns out the most appropriate endmill I had on-hand was a 1/8th, 3 flute carbide. I was using a 4 flute of a different brand that I bought bulk. They don’t like aluminum. The flutes are close together and the viscosity and surface tension of aluminum get’s busy with it.
With the speed override of Mach 3 I was able to get some control over cutting speed. Below 10ipm it was easy to adjust it finely. But the next step over 10ipm was 20ipm which was a bit much.
The other thing I did was to use the vacuum to keep the area clean. It’s easy to blow the aluminum away as as well but I think I’d eventually get dizzy. 🙂
There were lots of delays. At one point (as you can see at the right), I noticed that the endmill was not aligned with the spindle. 🙂 Actually, I broke about 5 or more endmills during this. I broke about 3 cutting acrylic yesterday as well. So I’m getting a little bit of endmill anxiety.
My vacuum assembly worked well but because I kept breaking endmills I had to keep removing it so I operated without it. Next time I make the vacuum holder I’ll keep that in mind.
The file was exported from Sketchup to STL format using an STL Exporter plugin in Sketchup.
The STL was processed into g-code using FreeMill.
The g-code was then run in the CNC machine to produce the part.
If you get this error in FreeMill, it's because you have to run the program as admin. Cannot find the c:Program FilesMecSoft CorporationFreeMILL emp.acl file. Do you want to create a new file?
I got stuck on Freemill for a while. You have to run it as administrator (right click then “run as admin”). If you don’t it will fail when you get to the end because it tries to write the g-code into it’s own program directory where there isn’t sufficient privilege for the program process.
I used pretty well all of the defaults of FreeMill except I put in the specific dimensions of my endmill (1/8 diameter, ball radius 0, length 1).
Part dimensions: The measurements of the part do not match the measurements of the drawing from Sketchup. I suspect I have to calibrate the machine (Mach3) or there is something wrong with how I made the g-code.
The 4 1/2″ measure in Sketchup is 4 1/16th” on the part. The 12 1/2″ measure in Sketchup is about 12 1/8″ (measured with ruler). So those two came out a little shy.
I find this puzzling because the 1×1″ square in Sketchup is 1 3/8 x 1 7/16″ (1 3/8″ side is in the direction of the 12 1/2″ measure).
Something is fishy that the 12 1/2″ came out shy but the 1″ along the same line came out long.
Feed Rate: It took really long. Next time I will us a feed rate that is much faster. I’m supposing next time I’ll try a feed rate that is about 5 or 10 times faster. I was running on full override and it was still crawling.
Holes: It seemed to miss the holes. I think I made them right in Sketchup but they didn’t come out on the part.
Multi-pass: The g-code is quite simple. It removes all material in one pass. When it made the edges it plunged about .6″ and cut across the board at that depth. I will look in FreeMill to see if there is a feature to have it remove material in layers.
Clamping: I had to move a clamp and the workpiece shifted a bit. The piece has to really be clamped well. I’m going to get more hardware for clamping.
Dust: This is still an issue. I don’t like lording over the piece with a vacuum. I went out and got some hose so I vacuum near the spindle automatically. I wound up with some 1 1/4″ ID pool hose. It’s pretty light and flexible. I got enough to mount it on the machine. I now need to make a mount for the spindle and a mount for the base so I can just plug the vacuum in when I want.
If you get this error in FreeMill, it’s because you have to run the program as admin.
I learned more about the operation of Sketchup and Phlatboyz plugin. I was able to design and cut out the second laser mounting bracket in one sitting.
I ran the first parts on a faster speed to see if cutting would be quieter. I also changed the multipass depth to .05″ from .10″. I noticed it was just as loud, maybe worse at the faster feed rate despite the smaller depth.
I noticed that on one pass when it was taking less than .05″ it was quite quiet. Perhaps next time I cut cast acrylic I will try .03″ per pass. It might take longer but it will be easier on the ears.
I did have an incident where one of the parts came unclamped. It took me a moment to figure out I had to go for the emergency stop button. No damage done to the machine or the work piece. It’s amazing the punishment a carbide endmill can take.
So I now have two mounts. One that is adjustable and one that isn’t. The non-adjustable mount has three little tabs that will contact the laser tube. The adjustable one will be drilled and threaded to 1/4-20 so that three nylon bolts will contact the laser. This will provide a fine adjustment of the direction of the laser.
I have it on video when the work came unbolted but I didn’t show it in my video below since I’m to embarrassed to show what a klutz looks like in real time. I guess if somebody asks I’ll put it up.
I think I’ll be making a lot of parts in the next while. I won’t post stuff except when I make new discoveries.