Someone has tried threaded rod, but backlash must suck. Maybe I can try to covert to ballscrews. Pricey but man that would be sweet. You would have to mount the steppers somewhere on the outer rail
So not normal to have that much play?
You should not be able to wiggle it that much by the tip of the cutting bit, that is not normal. If both of you are having this issue we should work it out, you both want to make major upgrades to the design (and Dui has already). There are tons of these out there, I know it can be a lot better without any modifications.
Kevin, I just want a picture of your whole machine in a single frame. Preferably a few from different angles.
Took some sexy shots with a dslr. Theyâre actually so sexy that theyâre about 6mb each, all over the upload limit 
imgur to the rescue
Much improved from the beach sand level graininess of the other pictures. My zipties barely move, to be honest I donât know if I can really get it much better. It may actually be my conduit since that one axis flexes more than the other. Shame though cause even with .5mm stepover 4mm doc adaptive clearing, my cuts are pretty undersized. I tried a 20mm pocket and got like 19.5mm. That is a little too far off for my liking. I really want to be able to cut at a higher doc though, cause beating up the poor tip of the endmill with low doc slots ruins the cutters so fast. Not to mention when the tip is gone you canât plunge the material anymore, might as well throw the bit out.
Let me explore a finishing pass though. All this deflection is gonna happen no matter what, so maybe a conventional finish pass is what I need 
I will upload a vid later on youtube of some of my sketchy cuts. I think I basically just reached the limit of the machine. I mean for something that weighs like 20lbs and costs $400 canadian pesos, I am pretty happy. I am curious to see how duiâs 3040 goes, that was actually what I was going to get originally last summer.
On the more conservative settings that many others seem to use my cuts are coming out great. Maybe I should stop complainingâŚ
You absolutely must use a finishing pass, even on wood. I thought those numbers were with a finishing pass? Every cut other than HD foam needs a finishing pass, always. rough out all the material and then a finishing pass. If you are within .5mm in aluminum with a 3âaxis on a roughing adaptive pass you will be spot on with a finishing pass, adaptive takes bites out of the path walls a finishing pass makes a cut along the path.
So after watching the shaking video you put up, again, and again, you do not have the steppers energized, there is no flex, your rollers are moving correct? I have been so focused on the center gantry when I looked out at the steppers they are moving. so either you have about 1/4-1/2"
of belt movement or the steppers are powered off and not holding. How exactly did you make that video, what steps did you take to energize the steppers?
They were energized for sure. I use repetier host for loading my gcode I make from f360. I just rapid it like 1mm x and y, so that way they engage and they hold their place. They make the buzzing sound we all are not fans of. In that video I was really moving the bit. Like I said, I doubt my material will ever lash out on me that harshly without everything chattering like crazy. Didnât know a finishing pass was so importantâŚoops. Well my new endmills are going to be delivered in an hour or less so let me make the videos and see what kind of numbers I come up with. What radial stock do you go with? The fact I am undersizing with remaining stock turns off in f360 makes me think, do I even need the offset? I suppose I can just make it do a contour around the pocket.
An idea of where you are at, and keep in mind still with only a roughing pass, there is nothing that says you canât do two finishing passes as well. you are in the ballpark of ârough-standardâ machining, The price is ever increasing on that scale.
http://blog.cnccookbook.com/2017/04/29/the-high-cost-of-tight-tolerances/
You are cutting a full 4mm deep and .5mm wide in aluminum, that was unheard of for this machine 6 months ago before we all learned the benefits of adaptive/trochoidal milling. My video was made a year ago and my business exploded when people saw this, .3mm DOC at 5mm/s. You are doing at least ten time the material removal with your cut.
I am not sure what you are expecting but I just wanted to kind of show you where your at and I still think it will be much much better with proper CAM.
OhhâŚmy god. The finish pass. This is a game changer lol.
Just tried 5mm doc .5mm stepover! Did a big slot in 5 minutes. The results are nothing but amazing. The finish pass is incredible! It left a beautiful finish and left my tolerances better than anything I had ever seen on my machine. Final width is within .05mm across the whole pocket. It really works! Nominal 20mm, the pocket is about 19.96mm. I got to video this, nothing but amazed. I got a slight bit of chatter but, seriously 5mm doc, .5mm stepover, single flute, 10mm/s. It was really going at it but it managed to get the job done
Edit: my calipers have the ability to rack a little, so I donât trust that tolerance. Still, no doubt I am in my .1mm goal.
There we go I knew something was not rightâŚ
I was literally scrolling down to say this, when I ran into those pics.
That looks awesome.
Iâm still in the process of printing parts, so I canât speak from experience, but I do have a question regarding the zip-ties. The ones in the photos above look like they are really tight around the posts, but I donât think that would necessarily mean they were pulling the belt tight enough. If I compare those to the ones in the build instructions, the instructional photos always show one end tight to the post and the other with a small gap between the end of the belt and the post where the zip-tie has been tightened to almost form a rectangle between the post and belt. Could this be causing slop in the belt on Lionkevâs machine? (Attached image from assembly instructions)
Wow, that is a pretty cut, very impressive.
Mike it turns out is was a CAM issue not a ziptie thing.
Need to do a little better with my shooting, but you get the idea. Once I square up my tool the slight chatter should go away. On my finishing pass when the bit is sliding across the walls, it chatters, so clearly a rubbing issue not a lack of rigidity per say.
2 Likes
That looks great. Much faster than I was imagining.
That video makes me want to try cutting alu again, my MPCNC might be a bit to big though. Better build another one 
Pretty nice video, I might need to tune up my machine a little bit. All that troubleshooting paid off!
Great success Kevin, congratulations!
I think I might try with a different bit, it might be the issue with my attempts. I thought the one I bought was for aluminum, but apparently it is for steel. And it turns out that milling aluminum with steel tooling is not good at allâŚ
The results you got are pretty impressive, and speed seems to be quite decent,
Keep up the great work, would love to see a few actual parts coming out from your machine!
Amazing results!
I never could imagine a machine like this could get almost mirror like surface finish in alu, guess the secret is in the cam software and applying your cuts wisely
WelpâŚlets just say the success was short lived. Just tried doing some real cuts in some very thick aluminum plate, 3/8 inch. That is practically the length of the entire flute of my end mill I use. It went about as bad as you could imagine. I lost 3 brave end mills today, 12 dollars just grew legs and walked out of my garage.
Okay, for real parts and not just pockets, the story changes. Just letting everyone know out there, if you plan to contour a shape, do NOT do it as a slot all the way around. You can get away with this if your part is rather thin, I would say 6mm or less in thickness. Otherwise you got what I just got, a mess. What happened was eventually the slot got so deep that the chips were pretty much stuck even with a vacuum. The bit started recutting and things got hot quick. Eventually it got so bad that the whole end mill got clogged with molten aluminum. Everything started chattering and I thought my the dw660 was gonna explode lol.
I also get this terrible chatter that actually broke 2 of my bits at VERY specific parts of my adaptive pockets like in the video I posted. It is so disappointing because everything sounds like its going really well with aggressive settings and then all of a sudden, this horrible chatter begins and the bit breaks. Itâs very important to note that this happens when the cutter is NOT removing much material (for example, a light and slow finish).
That really bugs me, I am not sure what to do here. Dui is right in saying that the mpcnc for aluminum is sensitive. At this point I feel I am back to square one Nothing seems to have gotten the results I wanted quite yet. The biggest problem for me is that chatter I said earlier. I will upload a video of it if I canât solve it.
What I am going to do now is
- move up my workpiece even further to the point where the bottom of the z conduit almost falls out.
- Try to get some air blast going. Seriously. The chips are so nice but they just get recut cause I canât get them out of the way.
- Slot using trochoidal which in my opinion doesnât make much sense but worth a shot MPCNC Trochoidal Milling First Test - Aluminum - YouTube
- Praise our lord Ryan Zellars