garageFab.cc

This is mini-router assembly in progress. The Y, Z and X stage are already assembled, working on the base now. I wanted to do a video timelapse of the whole thing, but as I went into several dead ends where I had to go back a couple of steps and re-assemble or re-align something differently, I thought I'll do clean timelapse when there are documented steps.

I've also had several issues with the assembly that aren't showstoppers but are still important:

This weekend I tested the linear drive with ACME leadscrew positioned in the center of sliding element profile. In summary, with good alignment of shaft mounts, it works extremely smooth without any visibly detectable backlash. When shaft mounts are not well aligned, the torque needed for rotation gets uneven unless there is a small axial slack.

Over the last couple of weeks I tested the linear motion design where leadscrew is located in the center of the sliding element profile. This allows the room for leadnuts to move and be precisely aligned parallel to the rail, which eliminates entire host of problems like whipping, high friction, uneven torque that I had when the leadnuts were essentially fixed to the corner of the sliding elements once and for all. Because leadscrews moved, I also had to modify the shaft/leadscrew mounts, the motor mount and the belt holder thingy. So far I tested center shaft arrangement with 1/4" all-thread leadscrew and the belt drive. Both appear to work well. I have not yet tested ACME leadscrew with delrin nut, the arrangement with belt-connected dual leadscrews and shaft-connected dual belts.

Milling plywood was relatively easy. Plastic - a bit more difficult. First, I tried cutting shapes out of black 1/8" thick sheet of what turned out to be polyethylene, according to this plastic id table. I used the same high speed cutter as for plywood - Dremel #194, speed setting 4 and 0.03" depth passes at about 9 IPM. There was a lot of plastic swarf. Then I tried milling a 3/8" thick cutting board made from HDPE. The stuff started melting and forming blobs around the bit, even though I used recommended speed setting (4). After  experiments with speed and feedrate, and online research (good plastic milling info), I switched bits. I wanted to cut gears for RepRap extruder out of HDPE, so I got some small diameter bits on eBay to try.

Finally, here goes: minirouter and first tests with Dremel on plywood. The router had actually been assembled for weeks - it only took me several evenings to assemble it, but few problems came up and I spent time trying to fix them, then fixes/workarounds resulted in new problems and so on. The same flaws and weak spots mentioned in the previous post still remain in the design. Couplings is one of them, and non-alignable leadnut is the other.

 

I haven't posted in a while, but have done a few things:

Taken apart the drilling contraption since I didn't really need it when the angle no longer had to be accurate; enlarged to 1/4" the holes on the angle from drilling contraption. This created a nice pile of Contraptor parts, ready for the next project. Made several sliding elements of different sizes - full, half, "quarter", installed Delrin nuts in some of them. Revisited the whipping rod/nylon couplings problem and decided to switch over to 0.250"ID aluminum tube for couplings. Tried to couple this tube to 10-24 rod, unsuccessfully. Searched for more powerful but still cheap steppers with lower coil current. Plotted the next contraption to be built.