RPM Calibration Adventures.

Successful coin calibration

The slots are just a little snug, and theres definitely some under extrusion, but its not terrible for an afternoon of fine tuning.

A 3D printed afternoon

The less glamorous side of the afternoon. Curling and improper bed leveling caused some issues. Once I found the magic of purple elmer's glue stick, i had zero curling and could focus on calibrating the Z-distance.

Just for fun

A pile of failure!

Starting on an untested, poorly documented printer with ABS may have been a little ambitious, (or sadistic) but my calibration efforts have finally started to pay off. One of the biggest problems I ran into was some odd behavior in the yellow ABS I was using. I ran into this strange issue where pauses of about 90 seconds or longer would cause a horrible jam and I'd have to take apart the whole hot end. The filament was a little oblong, but even correcting for that I still ran into jamming issues. I switched hot ends, with little luck. Switching to a different color made all the difference, even though its from the same manufacturer. Although brown isn't the most attractive color, it prints consistently and has made flow rate and extrusion width calibration much easier. 

Another necessary calibration task was properly orienting the x-y travel of the gantry to be as parallel as possible to the print bed. Using calipers, I got the toolhead plane to within about 10 thousandths of parallel which should be ok for our purposes.

Between these two operations, the RPM can achieve about 95-99% trueness on the nickel calibrator found here. I still have a long way to go, but its a good start.

RPM First Prints

Little octopi!

These guys are adorable. Experimenting with bed temp to alleviate warping. Printed in ColorFab yellow ABS.

Second Print

First layer height is way too high, but I let it finish anyway. PVA glue seems to accept a massive variation of Z height. Printed in ColorFab Yellow ABS.

First Print!

First completed print! It looks a little rough, but not as bad as some of the other printers I've built for the lab. The nickel fits almost perfectly, and slots are only slightly undersized, both probably due to shrinkage. Printed in ColorFab yellow ABS.

My parents came to visit and brought down the RPM so I can finally work on it in my spare time! Although my workshop is tiny, I make good use of the space and have a pretty fully featured tool set. The first prints are here! My thermistor in my cheap J-head failed and the hot end melted spectacularly quickly, so I've resorted to using the provided x-truder. Most forum posts complain about it, so I might have to move on to using the E3D Chimera I've had tucked away more quickly than I planned. Although the prints are pretty low quality, note that the stepper drivers were limited to 8x microstepping for the moment, and the nickel ALMOST fit perfectly on the first try in the calibration object. 

The RPM Build Log

Parts

I was supposed to receive an assembled, calibrated printer….

Guts

The gantry is assembled and all three axes are assembled. This took way longer than it should have, and I had to rebuild the gantry twice.

Movement

ACME screw linear motion is what drew me to the printer, and it looks beautiful. 

With only belts and belt hardware to go, the RPM is definitely an impressive piece of machinery. What a journey its been.

Workspace photo!

Welcome to my lab! Its a little cluttered, but it works well for me. Notice the suspended filament roll, soon to be replaced by a more permanent filament holding solution. See if you can find the other projects I'm working on.

Simple additions

Each corner of the gantry is supported by a leadscrew, which makes leveling it a nontrivial task. I labeled each corner and kept track of my progress in excel. Little labels like these help keep me on track!

Completing the parts list

The RPM did not come with any kind of extruder mount, just an aluminum block with m5 tapped holes. This is my solution! I had to re-drill mounting holes to allow for different extruder heights. The extruder itself is attached to a separate plate which can be easily swapped out without having to remove too many bolts. The holder can accept a different extruder, a paste extruder, a laser... pretty much anything.

Improvising..

Lost a heatsink for a few hours, but a screw with thermal tape applied to the head kept the driver cool enough to keep testing.

Adding functionality

Limit switches are important, but there's no accommodation for them in the design from q3d. This is my solution for the Z axis, its adjustable with a flathead screwdriver, and works pretty well.

Custom Z-Stop Bracket

I only needed double stick tape to affix the X and Y limit switches, but the Z switch needed something sturdier. 

Its alive!

The RPM survived the journey to my DC apartment. Now to make sure that the calibration held as well...

Cable Management

Everything is working, but the wires need a bit of TLC before I close up the back panel.

The Quintessential Building Devices (formerly QU-BD) Rapid Prototyping Mill ( or, RPM) is one of the most exciting and simultaneously most frustrating machines I've ever built. Originally sold as a interchangeable 3D printer and CNC router, the frame is machined from aluminum, uses beefy NEMA 23s, and ACME leadscrews for each axis of linear motion. With over a cubic foot of build volume, this was the most impressive 3D printer I had ever seen, and I immediately knew I needed to have it. I ordered an assembled, tested machine on Jan 1st, 2013, expecting a delivery of my first 3D printer somewhere in the April-May timeline. This company was the first to teach me of the realities of manufacturing, especially the value of supply chain management. I received a collection of machined parts, assorted screws, and electronics in November of 2014. Additionally, while waiting, I had built two 3D printers and designed a drop-in laser attachment for stereolithography in my research lab to keep my interest up.  In the projects section, you can see the progression, and my latest prints.