Wednesday, September 19, 2012

Upgrading The 3D Printer And Hexy Build Notes (Prusa RepRap)

What a busy couple of weeks I have had. Many upgrades for the printer have arrived, and work continues on understanding and possibly building Hexy before my Kickstarter version arrives from Arcbotics. In this post I will cover the upgrades I have made to the printer; why I made the upgrades, their cost; and finally show some updated Hexy prints to show off the new accuracy.

First; I was printing the Seej Starter Set, in preparation for taking my printer to work on my last day. While doing so, the printer gave up the ghost. Badly. First, the z-axis was homing and went right down through the printer bed. So after a break and calming down, I put the z-axis back together, calibrated; and went to home it again. Same thing, it went right down through the printer bed; which was saved by being spring loaded. This time though; the z-axis couple snapped in half.

So, because of this complete printer failure and needing to order new parts anyway; I decided to do the upgrades that are suggested to get good accuracy. Mainly, G2 pulleys. So I ordered:

 So that is $63.00 plus shipping came out to around $75.00 all said. I also ended up buying a new metric hex set for ~$10.00 because I stripped a set working with the Motor Shaft Coupling. I purchased all of this from Ultimachine which is where I get all my parts/PLA.

 Moving along... I rebuilt with my new drive belts. The nice thing about the GT2 is that they are meant for this type of machine instead of the old T5 belts which aren't. It is also nice to go from a printed pulley to an aluminum one. So at the end of the day, the change is getting rid of printed parts (vitamins), lowering how much of the printer can be re-printed. I wouldn't suggest anyone build one of these without this immediate upgrade. In a moment, you'll see the stark contrast in quality.

So first, the change to the coupler:

On the left, the printed coupler, on the right, the new aluminum one.

On the left, the printed pulley, on the right, the new aluminum one.

With the upgrades installed, it's like a new printer!

Printer, with new pulley/belt and new shaft coupling.

So with an upgraded printer, it was timing to do a comparison print and produce a part for Hexy. This part should hold two small servos; which I just happen to have received from Hobby King today. My apologies for the following photo being upside down. What you see if a servo measured with a caliper compared to the Hexy piece it should fit it. The problem being the hole is the exact size of the servo, so it doesn't fit! Either does the screw, as predicted by the guys at Arcbotics.

One thing we can note in the picture below though; is the Hexy part on the left (right if the picture was flipped). That part was produced under the old belt/pulley/coupling system by the exact same STL file, and as you can see is obviously way too big.

So the current plan is to work a bit from on calibrating the printer to see if that resolves the issue of the Hexy piece now being slightly too small; unless the error is in the STL file. Regardless, I am very happy with the prints being produced; especially with so little changes to configuration. I'll be posting in the Arcbotics forum to see if the STL can be resolved further and to provide them more feedback. Next chance I get, I'll be reproducing an entire leg of parts for Hexy, and trying to print the Seej set again.

Monday, September 03, 2012

RepRap Rebuilt! A 3D Printer Story

So it has been a long time since I made a real post; but we won't dwell on it. Instead, let us get to the good stuff and share some information!

This post regards my long term rebuild of my Prusa Mendel Reprap, which I decided to do back in March. If you saw my previous blog posts, you will have seen the state of the printer. It worked, but it didn't print well and there were wires everywhere. I even used some CAT5 as motor wire.

Because of the setup, the printer experienced many problems:
  1. Wires would catch during the printing run.
  2. The printer could not be moved.
  3. The RAMPS (Arduino Mega + Shield) kept getting bumped around, etc.
So, I took the entire thing apart and took the following steps:
  1. All wires now use connectors (pictured below).  These are available at Ultamachine:
  2. The power supply and RAMPS are mounted on a small piece of wood, which is mounted to the reprap (pictured below)
  3. The thermistor, print head, and extruder motor now share the ribbon cable, instead of 3 wires handing intermingled in the machine.
With the changes in place, the printer actually printed really well with no calibration. The controller computer was also updated; (1ghz/512MB -> Core i3 + 2GB). Going forward, I don't recommend hooking a reprap up to an older machine like that unless you are going to "slice" on a different machine. I consider the connectors to be a big upgrade, it should be easy to swap out, adjust and generally maintain all of the connections.

Here are a couple pictures:

Well, that is the 3D printer post. I've been printing some Hexy parts to calibrate it; and I'm very happy. It prints better than it ever did before!

I have a post coming up with some code in it that is pretty exciting, and I'm continuing to experiment with the printer while waiting for my Hexy. Don't forget about my little tracked bot! A model is needed for the sensor mount to make the line following more smooth!

That is all for now!

Sunday, September 02, 2012

Quick Post About Hexy

Hello, just a quick post about Hexy the robot.

I was recalibrating the printer after finishing up the rebuild and wanted to do some printing. Since I was curious about the sizing of Hexy and also my ability to print parts for it; I decided to grab the STL files and get printing.

There was trouble; not all of the stl files were ready, some of them needed to be run through first. It took me a while to figure this out; but once I found it everything went smoothly.

You may be curious; so here are some leg pieces for Hexy; printed in blue PLA.

That's all for now. I'm prepping a full post on the rebuild reprap; my robot progress, and another project that is coming along very nicely.

Sunday, January 08, 2012

3D Printer Build Post 2 (RepRap Prusa Mendel)

My long journey concerning this printer has turned out to be a glorious one. With objects coming off the printer with a pretty high quality; and my ability to design objects starting to form, it became time to share the progress and information. I will answer my own questions from the end of the previous post; outline more of the printer build, and share the general experience. Also, I will address the budget with an update.

Alright, so let's see it!

Above is my RepRap (Prusa) as it sits today. It is half converted over to version 2. I chose to do this conversion to understand the printer better, and more importantly to improve the prints. The original build calls for using printed clamps on the axis; and the plastic simply slides. This is fine; but the clamps have to be replaced periodically and you just don't get accurate movement. So I printed a new X-axis, new Z-axis, some stabilizers and purchased a set of LM8UU shaft bearings to mount the new parts. Here are closeups of the new X-axis and Z-axis.

You can see the role of the LM8UU bearing. The Y-axis still uses the old printed clips. You can see them in this picture for comparison.

Obviously the shaft bearing works way better. although the clip design is really good and it works surprisingly well as a printable solution. To complete this tour of the upgrades, we can compare the old Z-axis to the new one, and show the Dremel work I did on the z-axis coupler at the top. I cut out the center so I could separately tighten the two ends. Here are the pictures.

The last upgrade to talk about is visible at the top of the first picture. I printed a mount for a large Ultimachine spool of PLA. I haven't gotten to the spool yet (finishing up the clear PLA), but it's ready to 'spin' now.

With all of that said, it would be wise to update the budget. The budget previously stood at $782.00, and I did some upgrades and had to purchase the LM8UU bearings.
  • Upgrades - Free. Printed on my printer.
  • LM8UU bearings - $15.00 w/shipping (Ebay)
  • Additional PLA - $76.95 w/shipping (Ultimachine Blue PLA Spool)
  • Razor blades and Miscellaneous like zip ties.
This brings the total for the current setup to ~$900.00. This is a ready to print state with a full spool of blue PLA.

The next topic to cover are notes from my build. A LOT of work goes into getting the printer 'correct'; once it is built there are a whole new set of challenges ahead.
  • Do the axis move correctly? Does telling each of them to move 10cm move them exactly 10cm? This will be adjusted in firmware until it is as correct as you have patience for.
  • Do the axis move smoothly, or do they jerk? You'll end up printing tension mounts for your belts and converting over to LM8UU so that your prints don't start 'shifting' mid print when something skips.
  • Is the whole thing rigid enough and on a rigid base? Get a good print going and a bad table or weak frame tightening will cause the frame, the table or both to shake.
  • Is the bed level and is the print head setup to be the correct distance from the print bed when home? Instructions say 1 or 2 sheets of paper; yep. Easy :-(
  • Does the Z-axis wobble? This is why I did the work on the z-axis couplers and added the stabilizers at the bottom. Without that work the rods wobble and the print wobbles as it goes up.
  • Does the extruder push through 10cm of plastic when told to? This has to be adjusted physically (is your hobbed bolt working properly?) and in firmware.
  • Are the motor steppers AC adjusted correctly? Too high; they'll overheat (and burn you!), too low and they'll miss steps. I added heat sinks; but ended up not needing them.
  • Is your software configured correctly? Correct filament width; correct temperature settings for your filament? Correct fill settings? Correct layer height/width? I spent weeks on this.
Finally, we do want to print things. Where do these magical things come from? Well, I'm not going to really cover the printer firmware/software except to provide some links. I use Sprinter for firmware with Pronterface/Skeinforge for my software; it is running on Windows Tablet Edition (2001). This is because I'm using an ancient computer I had in the basement for printing.

The best place to find things to print is Thingiverse. The software uses STL files that are representations of 3d models. The software then cuts the model into layers and modifies as needed in order to print. Frequently you will have to add supports that you cut away/etc; in order to make a print work. Here are some objects on Thingiverse that I really like:
You can see my thingiverse profile here:
If you follow it; you can see what I've printed (some) and what I like. I haven't uploaded anything(yet).

To take it further, you will want to design your own objects. I have been using OpenSCAD to design things. Although I use the term 'use' lightly, I'm still learning. OpenSCAD is a programmer's design tool; you write scripts that generate objects. Once done, you can export them to STL, have them sliced and run them off the printer.

To wrap this up; here is an object I designed in OpenSCAD and printed. Just a small business card holder. I hope to parametrize it and print a larger one as a stand from my Kindle DX.

If you are looking for some good videos of the reprap in action, checkout this guys channel on Youtube. He has filming setup, where as I don't.

A great video of his:

That wraps up this post; and hopefully opens the door for many more. Feel free to send me questions or feedback. I hope everyone had a great holiday and came into the new year with a sense of renewal and determination!

Create a "GG Button" With an IOT Button on Discord

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