Hello,
I’m about to invest into a CNC for prototyping BC flute corrugated board.
I went through all the forum regarding corrugated board cutting and creasing using Lowrider, but I can’t find any proof that it is working.
The key point I noticed is:
Lot of work have to be done on the code for each angle as the blade need to get out and get down again.
No post about crease
No feedback about rigidity, creasing need probably a lot more down power than milling.
I will be very happy to get some testimony from owner of LR that use it for creating corrugated board packaging.
Thanks
I haven’t seen anyone doing creasing of cardboard. You would be blazing the trail yourself. I have seen a tangential cutter cutting cardboard, but it was very much a prototype.
Thanks for the link.
This drag knife seems to request 2 pass while this one need only one : sorry I can add a link:
youtube : CNC DRAG KNIFE and CREASE TOOL SET. CARDBOARD BOX from viewcreative
But no idea if it is a limitation of the MPCNC or if it is drag knife related.
If I can get a feedback from user, I can take a decision based on working proof.
I really think you should be careful hoping that this is some kind of proof that it will work for you. This will be a risk and how well it works in a video my not at all be how it works in day to day. I am not trying to discourage you, but you will not get any guarantee from anyone that this will work and if you go down this road, get frustrated, or just can’t get the results you want, You are going to lose your investment. This is just very far from the core function of a low rider. It is very much on the bleeding edge of the capabilities and there are a lot of road blocks to get there.
That said, if you do have a high tolerance for risk, and a good attitude, we have a strong community here and we will help when we can. We can’t put our hands on your machine, so you will have to be doing all the work, but there are a lot of smart people here who would be interested in a project like yours.
I used to work for a place that made purpose built cncs for corrugated. You need quite a bit of down force for the crease roller to squish the board. I’m not sure the lowrider can do that. It’s pretty easy to deform the stepper couplers.
Thanks, my plan was to make a 1m width working area, so the bend will be minimized to due the small dimension.
As for the stepper, won’t it be the same issues with small Nema motor or it as nothing do do with such parameters?
The video from viewcreative with their drag and crease tool run on a Workbee, but I have no idea about the repetability, and I don’t know what type of Nema is mounted on this CNC.
The lowrider design relies on gravity (for the most part) to keep the router down in the cut, with the expectation that the cutter is removing material, so the kerf can grow “horizontally” (I hope this is making sense). Even with a drag knife, most of the resistance to the cutting force is parallel to the surface that the material is resting on.
To get a fold by pressing a roller into the surface, I’d expect the tool is as likely to rise against gravity as to press into the corrugated material. You can probably overcome this with different couplers and appropriately beefy anti-backlash nuts, but as @jeffeb3 noted above, you’re back in to “prototyping changes to the machine” rather than “using the machine to make cardboard prototypes.” If your project or business plan can absorb the additional time to sort that out, go for it. If not, you should probably be targeting an already solidified solution.
Ryan has some video of his lowrider lifting weights in addition to the router. I wonder if it’s feasible to just make it heavier for the scoring? Add a bracket to pile on some discs or something. I’d worry about the brass nuts wearing out faster, but they are pretty cheap. Or maybe ballscrews would be better? It’s been a while since I looked at the y plates, so I can’t recall how creative you would have to be in the event that the screws don’t line up with the motor.
Practically every CNC router that I’ve seen is at least somewhat dependent on gravity to keep things in place.
I don’t see a problem with adding additional weight to the gantry to press the cardboard down, so long as you take that into account with motor power, and you aren’t bending the gantry rails.
It should be possible to get >5kg of downforce from Lowrider if you fill gantry tubes with sand. By default it may not be heavy enough, although it depends on what wall thickness the tubes are and what size the machine is.
Passive drag-knives that sit in a router collet are relatively common and easy to find. They are also fairly easy to make yourself and software solutions are almost out of the box. Plugins exist for most popular packages, including Fusion360. Here’s a looong video by the author of drag-knife support in FreeCAD which does a pretty good job of explaining how it works https://www.youtube.com/watch?v=40CRimcwAZo
I would recommend to start with a passive solution because motorized (4th axis) versions are a lot more complicated, especially because the software side of things is a lot less mature.
If you go motorized route, consider going a step further and trying an oscillating design. I’m not sure if an ability to simply turn the knife is worth the extra hassle and hardware.
Like it was said earlier: All of this is highly experimental in the context of a Lowrider CNC. I see no good reason why a weighted gantry would not work, but you’d be squarely in a pioneer territory. On the other hand, lot of people enjoy machine building and some expensive parts such as the router are transferrable to a Workbee or another hobby class machine if needed.
Thanks,for posting the link (I wonder why I can’t do it myself).
As per the gantry weight, I didn’t catch the point of the gantry weight, because from a theorical point of view, the flexibility is the problem not the weight.
With a lfexible gantry, then if you add more weight on the gantry, the Z probe will be void and uneven from center toward extremity. If no weight, then the same will happens (in a reverse direction, more pressure on extremity, less pressure in the middle).
In both case, the crease won’t be equal, the board can be cut where the pression is more, in the center in case of gantry load with sand, on the extremity if the gantry is not loaded.
But anyway, it sounds like I need to build one a make some test, then shift to more rigid CNC later on.
Thanks
The weight is only important because the machine is designed to hold itself down. If the upward force is enough to overcome the weight of the gantry, the couplers may stretch, or the roller wheels will just come off the table.
