RepRap – LHelge

The RepRap is printing!

The RepRap build is moving along I haven’t installed the heated bed yet since I need a 24 V power supply, capable of delivering 10 A, first. I found a small pack of four 200 x 200 mm mirrors at IKEA named Sörli that will be perfect for a heated build surface. But for now I will print on a cold printbed. I measured the build volume without risk of hitting anything, it’s around 180x180x100 mm, so the mirrors will be perfect!

For the first real print after installing the hotend I put kapton tape directly on the aluminum sheet. The print wouldn’t stick at all, the printer just smeared a large blob of heated plastic around. I’ve read that blue painters tape is the preferred surface when printing PLA without heated bed so I bought two different brands of tape, Tesa and Kip at the local Hornbach store.

So far I have only used the KIP-tape and I would say it works great. I’ll come back with a comparison when I’ve tried them both. Most people recommend Scotch blue 2090 but I haven’t found a supplier for that brand here.

I ordered a 0.35 mm J-Head MK V-B hotend from www.hotends.com. Most of it was already assembled, I just needed to insert the resistor and thermistor and put some kapton tape on it, then I could mount it to the extruder. I’ve also ordered some thermal grease that I will put on the resistor and thermistor when it arrives, but for now, the printer works fine without it.

Here are some pictures on my first print, maybe you could guess what it is?

Finished print — Finished and assembled print, the outer part is mounted with two ball bearings and can be moved by a servo.

Finised print 2 — The same part from above. Servo cable neatly hidden in the aluminum tube.

When generating the g-code for the printer you can choose how much infill you like to have. This particular print have the outer 3 layers solid and the inside have a 40% rectilinear infill which saves plastic filament, print time and weight but the parts are still very strong. This infill pattern is not as demanding on the printer as the honeycomb.

I will soon write another post about the thing I am printing together with the STL-files and a complete BoM.

The RepRap is alive!

I have previously written about my RepRap build, now its starting to come together. The last part I need before i can make my first print is the hotend that I’ve ordered from www.hotends.com

I use a RAMPS 1.4 board that, I ordered from 3D Gadgets, to control the stepper motors. RAMPS is an Arduino based RepRap controller that you can flash with several different firmwares. My first try was Marlin which seems to work fine. Since I dont have any hotend and temperature sensor I had to make some firmware hacks to get the thing moving. But I did!

And some picture of how it looks right now.

Picture of my RepRap — My RepRap including motors and RAMPS controller. It’s just put together to see if it works.

The steppers are pretty small but I got them very cheap. Let’s hope the have enough power not to loose steps while printing. A worst case solution could be to crank up the current and put heatsinks on them, or just buy bigger ones.

RAMPS 1.4 have 5 Pololu stepper drivers to be able to control X, Y, Z, E0 & E1.I only use one extruder and the Z axis have two motors connected in paralell on one of the driver. Maybe I’ll change the firmware so I can use one driver for each motor instead, but I don’t think that is necessary right now since the load on the Z-axis is very low.

Z-Motor — One of the stepper motors controlling the Z-axis

Y-Motor — The motor controlling the Y-axis

X-carriage — The carriage and extruder moving in the X-axis

X-Endstop — Each axis have a mechanical microswitch for endstop.

Right now I only have 3 endstops which is enough for the controller to find the home position (coordinate 0, 0, 0). It’s probably safer to have 6 endstops, one for each end of each axis, maybe I’ll add 3 more in the future.

Extruder-top — Top view of the extruder, you could see the hobbed bolt inside which grips the filament

I use Wade’s Geared Extruder I hope my small stepper motors are strong enough for this extruder.

Filament — A 1 kg roll of white 3 mm PLA filament

I will start out with PLA plastic for my first prints, from what I’ve read I think ABS is more likely to warp because of uneven cooling. I think PLA will work great until I have my heatbed working.

Updates on the RepRap build

Last week I received 5 NEMA 17 stepper motors for my Prusa Mendel RepRap. They are pretty small and I’m a bit worried that they will be to weak for some parts of the printer (mainly the extruder) but I have to wait and see.

I also ordered a complete RAMPS kit and 1 kg of plastic filament from 3D Gadgets. The shipment from china with FedEx was super fast but since I work office-hours it seems impossible for FedEx to deliver it to me.

I hope I’ll find a solution to get my package and will post some pictures on both RAMPS and the steppers when it arrives.

I also discovered that I could run the whole RepRap on 24 V using RAMPS or that I could divide it so the steppers and extruder run on 12 V using the 5 A fuse on the board and the heatbed running on 24 V using the 11 A fuse allowing me to push 264 W of power into the heatbed. Should be enough.

To buy before first print:

Extruder
Power supply
Endstops
Piece of glass to use as print surface.

Prusa Mendel printbed

I put together a heated printbed for my Reprap using three parallel 10 Ω 100 W power resistors. The resistors are screwed onto a 220 mm x 200 mm x 5 mm aluminum sheet. This will make the whole printbed a 3.3 Ω 300 W heating element.

Printbed power resistors — Three 100 W power resistors connected in parallel will act as a heating element.

On top of the sheet I will place a 220 mm x 220 mm sheet of glass to use as a print surface.

When printing the printbed should be between 60° C and 110° C depending on which plastic is used.

Since the main voltage used on the reprap is 12 V, maximum power that can be achieved is

[latex]
\frac{U^2}{R} = \frac{12^2}{3.3} = 44 W
[/latex]

My guess is that it will take at least two eternities before it gets hot enough, but for a start I’ll use the printbed temperature logic built into the RAMPS controller card.

Later on I think I’ll build my own temperature controller with either a step-up or a separate power source with a higher voltage to get more power out of the printbed.

Not much happening right now

It’s been a while since I had any updates here. I’ve had a lot to do and, no energy to work on any of the projects here for a while. I think that the first project I’ll resume when the summer is over is my Prusa Mendel RepRap.

Whit this done I could start making parts for really cool multicopters.

RepRap Prusa Mendel

To mount the sensors on the large outrunner as i wrote about in this post I got a couple of 3D printed plastic parts for holding the hall sensors at exactly 17.14°.

Plastic sensor brackets printed on 3D Printer

This raised my interest for 3D printing and I started to do some research on which printers that were available. There are several different projects that sell a kit that only needs assembly for example the MakerBot but I decided to go with the RepRap that is a more DIY kind of printer. The main reason of this is that the RepRap seemed to have the highest buildvolume/price ratio and the community around the RepRap is very large and helpful.

There are several different versions of the RepRap but when I started this build a couple of months ago most people seemed to be building the upgraded Prusa Mendel with LM8UU linear bearings, upgraded z-axis couplings and slight changes in som other plastic parts. The nice thing with a RepRap is that once you’ve built your machine you can print most of the parts needed to build another one. Therefore there are a lot of people around the world selling the plastic parts on for example ebay.

The RepRap can print two different kinds of plastic:

ABS (Acrylonitrile Butadiene Styrene)
Is made from petroleum and has a quite high melting point. This is the kind of plastic which LEGO blocks are made of. This plastic is softer than PLA and more flexible.

PLA (PolyLactic Acid)
This plastic is made from corn starch and has a lower melting point than ABS and is a little bit harder but more brittle.

I decided to go with parts in ABS, I’m not sure yet if that was a good choice since I’ve heard that it’s more difficult to produce good quality prints with this plastic. I ordered the plastic parts from a dutch guy on eBay and the first parts I got were pretty bat prints all parts were ugly and the x-axis mounts were so warped the were unusable.

Warped x-axis mounts — The x-axis mounts are to warped to insert the x-axis smooth rods in the corresponding holes.

Luckily enough the guy I bought them from were kind enough to send me a new set of parts which were good enough.

Apart from the plastic parts you need what is caled Vitamins, this is all the parts that you cant print on another RepRap. For the Prusa Mendel this is:

About 6 m M8 threaded rod
About 3 m 8 mm smooth rod
A big pile of nuts, screws and washers M3, M4 and M8
A couple of 608zz ball bearings and LM8UU linear bearings
Printbed
5 Nema 17 stepper motors
Electronics (for example RAMPS or Sanguinololu)
~200-300W 12V power supply

The current status of my build is that I’ve acquired and assembled the first five parts in this list, the rest will be bought when I can spare the money.

The threaded rod, nuts, screws and washers I bought at a local hardware stores (Bauhaus and Hornbach) and the bearings are from eBay. The smooth rods are from a Swedish webshop called Maskindelen.

To get good quality prints you need a heated printbed and most of the Prusa Mendel DIY kits you can buy includes a heater built on a pcb but since I had a nice sheet of 5 mm aluminum left from the motor mount on the E-Puch, I decided to build my own. The aluminum will be used to spread the heat from three 100 W power resistors mounted underneath the bed. On top of this I will place a 220 x 220 mm piece of glass to print on.

For the rest of the parts I’m pretty sure I’ll buy a Prusa Mendel electronics kit from ReprapWorld togehter with a 12V 348W MeanWell PSU from Sure Electronics on eBay.