About 10 months ago I started this project with a semi-busted rambo (or so I thought), a Rostock V2 printer, and a whole lot of excitement.
My first mistake was printing out all my parts with Carbon Fibre PETG. They looked absolutely sexy, felt stiff, but as soon as any stress was applied the layer lamination strength immediately caused part failures. Didn’t get far with that at all.
My next few part runs I tried with Hatchbox PLA. It worked ok, was wayy stronger than the CF-PETG, but I was finding that it was giving me poor print quality and finish, and parts would quite easily break along the layer lines during failure, made them far too touchy when I was tightening bolts. As soon as a layer started to separate it split apart with almost no extra effort. Oh well.
Finally I started using Ecotough PLA from Filaments.ca and that has appeared to be fairly strong, it’s stiff and when I break test pieces it splits across the layers, not through them. I’ve found the trick is to used kapton down with acetone, then subsequently misted with acetone again will keep your part stuck well, first layer is very slow (2500-3500mm/min) at high temps (230 nozzle, 70 bed). With subsequent layers at 205-215 nozzle and 45 bed.
Anyways once I got that figured out I was able to make a push last weekend and get my 24"x 24" system up and running!
Hopefully soon (once I get a vacuum mounted with an enclosure) I can try out aluminum and other fun materials. The Fusion 360 PP makes using the MPCNC an absolute dream.
3500mm/m is just about twice as I print at the fastest and the first layer is 50% speed for me. an I print at about 218 for all PLA, kinda sounds like you are too fast and too cold to get proper layer adhesion.
After 8 months of silence I’m back! The machine is out of commission at the moment so I have time to show off what I’ve accomplished.
Sample Bracket
This was the first project I did, just a simple bracket I cut out of a pine board with a 1/4" 2 flute cutter. Didn’t really have a purpose in mind when I designed it, but I may use it as a mount for an enclosure. Tolerances were pretty sloppy on it, I soon realized my belts were wayy too loose.
Garden Gussets
With the winter retreating, I decided to build a vegetable garden on the back deck of the house. I made the whole thing from scrap materials, and used the MPCNC to make these rounded gussets. Tool was a 1/8th endmill.
At this point I should make clear that I have a tendency to bite off more than I can chew, and combined with a very busy work/school schedule, my projects often end up being realized in a rushed and usually ham-fisted manner
Anyways, having two wooden projects under my belt I decided to try metal.
Aluminum
This was a tough one. I designed a simple little widget to test out, and in fusion used a facing, adaptive clearing, and finally a contour operation with a 1/8th single flute cutter. The facing went ok, but the endmill broke very soon into the adaptive pass during the first pocket. I dropped my feed and DOC and managed to get pretty good results with the next attempt, until the endmill got gummed up on the deep contour. Definitely should have added some roughing passes. At that point I was all out of endmills, so I cleaned the part up and freed it from the stock by facing the other side using my shaper. All in all it turned out rough, but I don’t think it was too bad for a bumbled first-attempt.
Not bad! Those are some very promising results for a first run through aluminum! That gives me more confidence to give it a try.
It is really gooey to machine though, depending on the alloy. Did you spritz it with WD-40? That’s actually a decent lubricant for aluminum. Also if I were planning on cutting aluminum I would order some specific bits. I can’t remember the kind off the top of my head, but I know there are some flute types and coatings that work, and some that just don’t.
Also, what kind of shape have you got?! Those are cool!
Yeah I was beside it the whole time spritzing it with Wd-40 every few seconds. From what I know single flute is the one to choose for aluminum. I haven’t tried aluminum since, I wanna add rigidity to the machine, and maybe a compressed air blower to help clear the chips before I try it again.
The shaper’s a '65 south bend 7" precision model. I was lucky enough to find it being sold for cheap. The owner said he would’ve scrapped it if I hadn’t of got it, so I’m happy I was able to save it.
Those are great results. Your machine is somewhat tall, and you may have more success if you prop up the workpiece so you are working near the maximum Z.
You should be able to feel/see a difference in stiffness with the tool near the top vs. near the bottom of Z travel.
Yup, Frame stiffeners and a platform to bring the workpiece closer are definitely on my to-do list. Even with the height I’m impressed with the rigidity.
