Do you have any dust collection going? That really helps too.
When you take off the bottom lock for the dw660, the internal fan’s air flows down and near the collet. It blows the chips out of my cuts, but I plan on getting an actual air blast.
I am sorry Ryan, I can not let go of my zip tie issue. D: The issue is that my zipties are creating almost a form of backlash. More like just play but you get the idea.
It is a shame because it is probably not an issue for anyone but me and dui. I just redid all my belts as short as you pretty much can. I used zip ties that are so thick they barely even fit in the slot on the corner mounts. In my opinion, something about the design should change, or at least some sort of upgrade if there is a v2 or pro version. It may even be more important than new feet, just one persons point of view.
Maybe some thicker belt like htd3m would help a little. It is not the slippage or torque capability, it is just the sheer stiffness and ability to be fastened I need.
May make a short video to show what I am talking about here. Even at maximum zip tie stiffness, when putting lateral force on my end mill, almost all of the deflection linear to the gantry, not flex in any way. The actual gantry pushes with the end mill, and the steppers move with it as well.
On big machines this becomes less and less important, because conduit flex actually becomes a thing. Tall z axis also overpowers my point here. But for short and relatively small work areas, it is becoming an issue.
I think this is why when I tried 4mm DOC .5mm stepover 10mm/s, I got an undersized pocket. I wasen’t chattering as much as I thought, maybe a tiny bit. Surface finish was great but the lateral force on the cutter is causing the overall cut to shrink. Solved a little with a really light finish pass, but still, I feel like this zip tie thing is giving up a lot of rigidity. Shame for me to have almost unflexable everything, then see my gantry can move due to the belt fixture.
Don’t want to come off as too negative, don’t get me wrong I am really enjoying my mpcnc. I am practically nit picking at this point but I really want to see where I can push this design for science!
I appreciate constructive criticism, don’t feel bad about it.
I would love to see what is going on. I have been testing belt stretch, but from what I can tell the belt moves much more than the zipties, and that’s only on the 9.5’ of lowrider belt and it is very very little over the entire distance with the load of the giant gantry on it.
In the morning I will show you a picture of how I use zip ties on mine.
I am guessing your large zipties are actually the problem. They are so large they are acting like springs. The zipties I recommend, 40lb ones, actually get hard square corners and are pulled taught. On top of that if you have a longer one there is another way to constrain them from bounce. They have to be weak enough to have some plastic deformation occur, if they are too strong they will only elastically deform and will forever be a spring.
Bigger isn’t always better.
So you’re saying I have to like…strain harden my zip ties. Never knew the zip ties were so in depth lol. Yeah probably true they are a little springy. I used the el cheapo clear zip ties. The female end of them is too big to sit flush with lock corners. I’ll get some of the ones you originally shipped me. I have probably wasted a pound of zip ties by now…oh well. When I get this solved though I feel my machine will be a lot more stiff. I will upload a vid tomorrow of what I am experiencing.
I’ve been playing with mine. Have a piece of 1/8th inch thick 2" aluminum flat stock attached to my bed. Started out with a 1/8th inch 2 flute end mill. Full depth of cut, 15mm/s 10% trochoidal. Started okay, but eventually started chattering and then pulling the bit around. Changed to 5mm/s, got a little farther, but eventually started doing the same thing. Then I had to go to dinner. This is with the chinese spindle, which I really think with the collet holder, the bit sticks way too far down. My eventual goal is to make some property tags for our work ladders, then rivet them in place.
Barry, how far can you get an endmill in the collet? I never even thought about that part I just didn’t like the collet on a shaft setup those things have, never stopped to think about the shaft stopping you from properly choking up on the bit. That is a pretty big deal breaker, I have just received some “stubby bits” but it turns out they are the same overall length just the flutes are shorter for what I assume is a slightly more rigid bit. I think I am going to put an experimental bit pack up for sale to get me eyes on these things to see which ones are worth buying more of.
Kevin, I am not totally against doing the zip tie method a different way. The main reason I didn’t start that way is if it has a screw, most people will overtighten it. The zip tie in my opinion is the most efficient, where anything else means more print time and more hardware, and more tech support for over tightened belts stalling out machines. The first versions of the machine the motor mounts were easily bent by the tension of the belt, the new version can take enough tension to stall the motor. I will keep an eye on this for sure, but I have really been beating up the Lowrider and I have those belts super tight with zip ties. I will to engage the motors and use a dial indicator to get some real numbers on this issue.
As close as possible, you are right best would be a hard mount on one side. No argument there.
As short as possible on this side would be best but I found that adding this little gem takes out all flex I can see with my eye instead of rebelting.
Another little tip is using some needle nosed pliers to square off the corners of your zipties if they are round, force them to comply. A straight line can’t flex.
Not a Hollywood director as you can see. Couldn’t get a shot of my belts because filming with 1 hand while pushing something came out terrible. As you can see, the whole gantry actually moves. You can see the bearings actually rotating. Little of it is gantry flex, a tiny portion is the x aligned rail because it is about 32" long. May switch to screws, or hell maybe I can try to tie them with another loop of belt itself, it is rather stiff lol
Can you get a shot of the zipties as you do that? That is pretty bad. Legs, rail flex, zip ties, a complete shot of the whole thing might help but that can’t be just zipties.
Check the pulleys if one, do not come loose.
At the brach today, have to get a shot of it all tomorrow. Tried doing the same test at a corner to minimize conduit flex. Results were barely any better.
That’s what we are getting at, it shouldn’t be flex. lets see the whole thing, what you are seeing there is far from normal. something is wrong. If it was a ziptie issue your zip ties would have to be flexing a ton. I am chasing issue that are so small they are hard to measure, yours is like a 1/4".
42-ish mm to the end mill. I have it pretty much as far in as it will go, might get a couple mm more, but it will start hitting the flutes. I also need enough hanging out for the dust collection. With it how it is right now, about half the end mill will stick out the bottom.
If you push it at one of the x or y motors, then you’ll eliminate a lot of culprits. If you do it where the belt is 4x longer on one side, then if it’s the belt, then it will stretch 4x longer in direction and not the other. Be sure to test the 4:1 and 1:4 to eliminate differences in zip ties.
Ryan, those ties are much tidier than I’ve seen before. I want to go check my low rider out now.
Looking at those pictures I can see the Y axis on mine has a loose belt, the just out of focus ziptie is too round. I don’t want to touch it though it is printing so perfectly right now.
The video is soo bad…helping me is going to be a challenge. Phone camera is broken so I have to use one of those 2012 digital cameras, super grainy. I will make a cutting aluminum shot tomorrow when the lighting is good.
You can’t really make out anything in that video. Unfortunately I think I am suffering from one of my classic, “sum of everything” problems where there isn’t one cause. It can move linearly more across the Y than the X. This is likely from the x conduit being a lot longer so the gantry can actually bend it more. It still bugs me though that my steppers can actually move with the belt though. Just checked, none of the pulleys are slipping off the stepper shafts.
I may just put this to rest a little and wait until I make whatever the mpcnc 2 ends up being. Brushless spindle rpm controlled, stainless steel, hex hardware, better belt system, more perpendicular, and whatever new designs there might be.
Just my opinion, if there is an mpcnc 2, one of my requests would be to do some sort of upgrade to the belt system. That or include it if there is a pro version. This is really only an issue found on smaller machines that have such little conduit flex.
The lowrider is 9’long and uses the exact same setup.
Take some pictures it doesn’t have to be video. I just need to see it all.
What in particular do you need pictures of? Tried the best I can…sun is setting. I don’t think it is even my zipties anymore. This is so hard to explain. Hey if you drive down 7 hours, maybe you can take a look :D. Jk, but if you saw this irl you would probably know whats up in like 5 minutes.
In those videos I am pushing pretty hard, harder than the material I cut will ever push back with. Honestly if you need to work on more important stuff that is fine by me. Though if you really do think what I have here is really abnormal then be my guest All my corner legs are JB welded so they are really stiff. The workbench they sit on is also quite stiff.
I think what you describe is normal, I have the very same problem, though I have quite a bit less play compared to your first video. I think this is a limitation due to the belt system, not much can be done here. I tried tightening my belts like crazy, at which point the gantry becomes quite hard to move, entirely removed the zip ties, but it still has some flex.
The only thing I have not tried yet it to swap those tiny belts to some wider ones, but I don’t think I will, because it’s a lot of work for an uncertain result.
In my opinion, the only sure way around this is to change the belt system for a threaded ball bearing system or at least a threaded rod, but it it quite a lot of work and the Z axis itself will probably never be rigid enough anyway.
I’ve just purchased a 3040 CNC frame, should receive it tomorrow. I’ll use it for aluminum milling and keep the MPCNC for softer materials.
Maybe you could try to tigthten a bit more your bearings, it will reduce a bit the natural movement freedom of your machine and can help to lower the backlash a little
I have been planning to try using PU belt instead of the usual rubber ones. I have both types in 6mm and 10mm width and everything required to mount it. Only thing missing is time.
Upgrading to 25mm stainless hydraulic tubing (found some at a local scrapyard) seems to have reduced the flex a lot.
I have only made a couple cuts in alu with partial success, broke a bit the first time