I just realized this part needs to be heat resistant. Then make a mold and cast the part with a stiff mixture of glass fiber and epoxy. Polish the inside with paste wax like you'd on on a car.
You can print a hollow mould or make the part then a plaster mold from the part. It is a lot of work for just one part. Why not mill it from a block of aluminum. I would still make all the part bigger and use huge fillets, less metal to mill away. On Sat, Oct 8, 2022 at 3:39 PM gene heskett <ghesk...@shentel.net> wrote: > On 10/8/22 13:25, Chris Albertson wrote: > > I am a big fan of "plain old PLA" The problem is not the plastic you > are > > using but the engineering design. The part looks like you are used to > > designing with metal or wood, where you start with flat stock and screw > > parts together. If you need good rigidity with 3D prints, then fill > all > > the air space around the part with plastic. Use thick skin and 30% or > more > > infill. > > > > PLA is not "tough" because it is rigid and will not bend. So it breaks > > like glass. But as long as you do not break it, PLA has the least flex > I would think that being in close proximity of thehot block, like 2mm away, > that PLA would soften and bend or stretch at that bar across the bottom of > the big vent hole. > > I've had the hot end mounting bosses break off clean at the surface despite > their being buried a mm into the surface, but there is room at the > bottom of > the boss to expand that, so since the boss is a cylinder that can be > tapered, > its now tapered up to 12mm at the bottom and the hole is expanded .1mm > to ease > the torque of self threading the screw. I'd already buried a 3mm hex nut > in the > back of it. The boss holding the prox switch is hell to clean out the > hole, so it got > expanded .1mm to ease inserting the prox switch, which IMO beats the pants > off a bltouch. > > Very poor access to the bottom eccentrics to adjust how tight the > POM wheels grip the X transport extrusion bar, but I did add a 10mm tall > fin to > both edges to stiffen that. So another is now making on the prusa mk3s. > And the > Ender checked, Z re-zeroed and restarted as the jerk was too high on the > Y and > it lost a few steps about 4 layers up on the last start, so jerk was > reduced about > 20%, as was accel, so maybe it might work at 350mm speeds this time. If > not, a > 42 volt psu for the Y motor is next, along with a higher voltage driver. > That motor > will be hard to source in a stronger version as its a double shaft. > Drives both ends > of the x crossbar from one motor. And that is the heavyweight piece in > this puzzle. > I'd love to find a carbon fiber sub for that extrusion. Even a square > with a linear > rail s/b lighter, but bring a little red wagon full of cash for that. > > Actually, I found the bug in cura that is a showstopper for a tronxy > 400mm cubed > printer I bought, and it would be far far easier to swap its puny xy > motors for 1NM > 3 phasers I already have. Then the precision will be limited by the > length of the belts > it uses as its a doofy arrangement where both motors drive both x and y. > So to move > in straight y, the motors run in sync but opposite directions, and move > the same > direction for a straight x motion. Both belts go over a slew of pulleys, > and are around > 9 or 10 feet long. > > But the tronxy doesn't use POM wheels, they are all steel, running on > round steel > rods set into off center grooves in the extrusion. > > So the potential for increased accuracy is there. I put small casters on > it so its on > the floor, but so is the tiny little controller display. There's enough > ribbon cable to > move it up some so I will, and I'll probably unload the bed from the psu > in favor of > an SSR with a line voltage feed. 80C takes it over 10 minutes from room > temp on > the tronxy. > > The head is quite similar to the enders so another Spider 300C hot end > will be here > Sunday, and I've 70 watt heater resistors for that. W/o the bed, the psu > should > handle that. The ender psu is handling both, but the bed is slow, 5 to 6 > minutes, the > plus model is 350mm square heated. So I heat its bed before hitting the > 70 watter > in the hot end. And I've found a better way to calibrate flows, look at > the infill. Thin > and puny looking, increase it 5%, thick and lots of sloppiness, reduce > it to suit, with clean > infill the target. 690 is recommended for the ldo, and its actually > about 100 too much. > I'm currently running at 670, and flow is still being turned down to 85% > to get nice, but > fat and clean infill. With jerk lowered to 45, and accel at 3000, accel > is still too slow, > taking around a 6 inch move to hit full speed, but its otherwise running > well for now. > > > > The other things I always say is to use compound curves. > Those are not as easy in openscad. Variations of a cylinder and sphere > are available as macro's but true beziers take much longer to render, > after you study up on the library that does that. I haven't gotten that > familiar with it yet. There also is not that much room to play in. I'm > modified > somewhat, the png I sent, and the prusa will have another done in about > 4 hours. > I concentrated on stiffening up the left and right edges, where the warpage > was showing,but there is no real room to get artsie. And since that's > all flying > weight, every gram counts. > > Thank you for the advice. Take care and stay well, Chris. > [...] > > Cheers, Gene Heskett. > -- > "There are four boxes to be used in defense of liberty: > soap, ballot, jury, and ammo. Please use in that order." > -Ed Howdershelt (Author, 1940) > If we desire respect for the law, we must first make the law respectable. > - Louis D. Brandeis > Genes Web page <http://geneslinuxbox.net:6309/> > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
