When a Problem Comes Along…

When dealing with filament-based printers, while all essentially do the same thing – melt plastic and push it through a computer-controlled nozzle, there are many different ways of accomplishing this and I’ll highlight a few.

Most filament printers can be classified into two groups – Cartesian and Delta. In a Cartesian printer there are three axes, X (left/right), Y (forward/back) and Z (up/down):Axis

Two of the most popular of the Cartesian printers are Prusa i2 and i3 styles, or as I like to call them the A and the L styles because their frames look like those letters when viewed from the side. The picture above is of my original FrankenPrusa i2. It’s a little difficult to make out, but this is essentially an A-Frame which is obvious when viewed from the size. Its biggest disadvantage is the inability to make very tall prints, as the X-axis carriage can only go so high before the angled bars restrict movement. The i3 (or L-shape) removes this limitation by mounting the Z axes to a stiff vertical mount and re-orienting the X-axis rods accordingly. As seen below, this allows for virtually unlimited height, just cut a taller frame and use taller rods.

20160426_224846

The biggest disadvantage to this design is that the head and the build plate are both moving (see the video in my Printing a Printer… post), often in opposing directions at the same time. This simultaneous motion can affect the accuracy of the print, especially if there are a lot of directional changes.

The Delta-style machines were designed to remove part of this extra motion. A Delta consists of three towers arranged 120 degrees apart around a circle in a triangle formation, or like the Greek letter Delta, where it got it’s name. The build plate stays stationary while the three towers move a set of connected arms up and down in coordination to move the print head. One downside to the Delta is the need to convert the Cartesian coordinates in the g-code file to Polar. This requires extra processing power that some of the low-cost printer controller boards just don’t have.

Back in the Cartesian world, the CoreXY design takes out the counter motion by moving the build plate up and down rather than the extruder/hot end and limiting all X and Y motion to one plane. This allows for more precise placement of the print head and is one reason why I selected that style. The other reason is because in my attempt to build a Delta-style machine, I purchased a lot of extruded aluminum and this let me reuse the extrusion, motors, belts, screws and fittings and electronics. The additional materials I needed to purchase were minimal compared to building from scratch.

BUILD LOG

Starting with this entry, I’ll be adding my build log to the end of my main article. Today I put the frame together and quickly discovered something. My design was going to be larger than the reference design in all directions. The G&C uses a standard 8″ (or roughly 200mm) square build plate, while I am using a 12″ (or 300mm) square plate. This means that each dimension will be about 100mm longer to accommodate. While discussing this with the designer, he mentioned that the frame pieces should be 10cm longer. In my head, I translated that to 10mm longer and cut the pieces accordingly. I measured twice and cut once, but didn’t check my conversions twice or do a sanity check. The result means I have to get new extrusion and cut them to the correct size. The featured picture is the initial frame assembly before I noted my mistake. So I am at somewhat of a standstill until I get the new metal in, but I’ll find something I can do.

Next blog I’ll get to the actual extruder and my choices for that most important piece – and maybe more construction!

Here I Go Again…

Printing a Printer

The word “RepRap” comes from the term “replicating rapid prototyper” and one of the original ideas and ultimate goal is for a 3D printer to be able to replicate itself. And while we aren’t quite there yet, there are some designs that come surprisingly close. The G&C CoreXY has a lot of printable parts, and to save costs I am using my i3 FrankenPrusa to do the printing, with the occasional assist from the printers at MidSouth Makers, the local makerspace that services the Memphis/Mid-South area:

 

The Printing Primer

There are many different types of 3D printers around, from industrial types used by government or corporate research and development departments that can run hundreds of thousands of dollars down to the “consumer” level that may now only run a couple of hundred dollars. For this blog I will be discussing the consumer level printers, specifically the “Fused Deposition Modelling” (FDM) type.

When creating 3D objects via computer there are generally two ways to do it – via a subtractive process where the Computer Numeric Control (CNC) controls an item with a blade or cutting bit like a router or spindle and the material is cut away and the 3D item is left behind. The other method is via an additive process where material is built up layer by layer to form the object. There are pros and cons to both but for the home user the additive process generally wastes less material, is overall safer and is less expensive to get into.

Most inexpensive 3D printers are of the FDM type. The best way I heard it described is a “computer-controlled hot glue gun” and that is a fairly apt description. Essentially an FDM 3D printer takes a plastic filament, feeds it into a heated chamber where it is melted and forced out through a smaller nozzle to create a strand. That strand, still in a melted state, is deposited onto the build surface via directions given to it by a small microcontroller that tells it where to move the print head. Layer by layer more plastic is laid down until an object is formed. If you look at the picture below, the red, green, yellow and pink pieces are all 3D printed by the FDM process. If you look closely you can see the striations as each layer is printed, and if you look at the pink pieces on the buildplate and in the video above, you can see the hatchwork of the interior portion of the print, or the “infill”:

corexyPieces

The heated chamber is referred to as the “hot end” and the device that drives the filament into the hotend and eventually out the nozzle is known as the “extruder”.

In my next build log post, I actually start to put stuff together and discuss cartesian vs polar, some of the different styles of FDM printing and why I chose CoreXY vs other designs.

 

It’s Time to Come Together!

On March 23rd, the first 3D Printer Meetup was held, sponsored by 3D Hubs. We had a great turnout with many different kinds of printers from a MendelMax 1.5 to a Lulzbot Taz 3D, a couple of Chinese kits and my own (in)famous FrankenPrusa (parts sourced and built on my own, like the new printer build I’m chronicling in this blog). I know of several people with a Delta-style printer like a mini Kossel or Rostock and would like to get them to come out as well, as those are fascinating machines to watch print.

One of the nice things was attracting users who did not have a printer of their own, but were interested in the technology. This hobby can seem daunting to the uninitiated, but it really is not and demystifying it is one of the goals of this meetup, and I am glad to say that, at least for a few people, we were able to meet that goal.

One of the other goals was to learn from each other, and we were able to do that as well. We looked at each others’ printers (and drooled at the dual-head Taz ), picked up some tips and techniques (and generally marveled at how FrankenPrusa was able to print with a loose frame, angled x-axis motor and general unfinished look). It was a great night and I met some really awesome people. I really look forward to another one soon – and hopefully I’ll have FrankenCore completed and ready to show off!

You Got To Be Startin’ Somethin’

Welcome to my blog about 3d Printing in the Memphis/MidSouth area. I have been a 3D printing enthusiast for several years and have built several printers along the way. My first was a Prusa i2 variant as seen in my “FrankenPrusa Lives” video (please excuse the “scary”/annoying music, I was trying to be “artistic” and failed miserably):

Shortly after it made its first couple of prints, I tore it completely down and built an i3 variant, but still kept the FrankenPrusa moniker. This one can be seen in action in this timelapse where I was printing the parts for my third printer build, a mini Kossel (a delta/triangular) variant named FrankenKossel (sensing a pattern  here? The naming convention is a story I’ll save for another post):

 

However, I was not satisfied with the build – it was much harder to calibrate and just didn’t feel as solid, so I tore that down and have embarked on the construction of a new printer – the G&C CoreXY printer by Filipe Campos that I am naming FrankenCore. However, mine will be somewhat larger with a 300 mm^3 build volume, as opposed to the roughly 200mm^3 volume of Filipe’s original.

While this blog will detail the build, I will also be posting about other activities relating to 3D Printing in Memphis and Mid-South, starting with the first 3D Printer meetup being held on Wednesday, 3/23/2016 at the MidSouth Makers makerspace at 7:00pm. If you are interested, click here to sign up!

I will also be posting my opinions/reviews about different equipment and materials, my experiences and other thoughts about 3D printing. Also, I welcome any feedback you have – please email me at dchamberlin@midsouthmakers.org. Thank you for stopping by and I hope you enjoy this blog!

Danny