Just Another RepRap

Something’s wrong here, and I’m not sure what it is. There are a bunch of things it could be, and I’m frustrated.

Tonight, again, I watched the MakerBot plastruder push the heater barrel right out of another PTFE insulator.. First it had extruded a small amount, then the entire barrel pushed out. I should create a gallery of PTFE insulators..

I was just ready to print out the test piece that I’d read about for months. I had just tightened up all of the belts, and I was convinced everything was going to work great.

Unfortunately, the barrel is now caked in this seemingly unremovable glaze that’s practically filled the grooves to the point where it seems smooth, which is why it’s not getting a grip anymore. Actually, I don’t know that. I suspect the thermistor is giving inaccurate results, but I’m not sure which way. When I saw it push out, I’d told it to be at 220C. If it was actually colder than that, the plastic would have been tougher to push through the nozzle so the motor would have pushed the heater barrel out (I DID see it extrude some through the barrel, so at least some of it melted). Or it could be way hotter than that, and have affected the PTFE. I don’t know.

I’m burnt for a while. This is extremely frustrating. The extruder needs to be strong as steel, and there needs to be some ability to detect when we’re pushing waaay harder than we should need to, so firmware can stop the motor before it tears the extruder apart. I’m tempted to use some of my Mendel supply of brass rod and PTFE rod to create another extruder from scratch (and use kaptan tape instead of fire cement, since that’s what the MakerBot’s extruder uses), but then I also have to use more nicrome wire, which I don’t have too much of. Agh.

Frustrated. Hulk mad. RepStrap no work. 🙁

[Update: Before giving up for the night, I clamped the existing heater barrel down in a vice, and successfully ran an M6 die from my new metric tap & die kit along the barrel, completely cutting away all of that awful glaze. Later I plan to cut off another piece of PTFE, drill it on both sides, use the M6 tap, and rebuild the insulator again. I do not plan to turn anything on though until I can find our meat thermometer, borrow one from a friend, or buy one at the store, so I can see what temperature the barrel actually is when I tell it to go to 220C.]

After printing the K block (see my previous post) with the RepStrap, I immediately went ahead attempting to print my first Mendel part. I ambitiously chose the pinch-wheel-bracket-NEMA17_604-bearing_1off.stl file, which is the green part of the following picture:

The green part is what I need to print

I’ve had varying amounts of success and failure. I have several aborted attempts. Since these were aborted, most of these are just the bottom part of the above piece:

You leave the thing alone for one minute...

Multiple levels of failure

Almost good enough!

This was a very fast print, but it almost wrecked the extruder

The bottom of one of the failures before clearing away the raft

The one on the right is closest. I took a spare ruined PTFE rod and stuck it in the piece on the left (and then fed a piece of ABS filament through it) for illustration purposes.

So, the above one on the right is the closest I’ve come to a functional piece. Worst case, I’d drill through the top, sand off the rough parts, and make it work, but it’d feel better to print it correctly. Clearly I need to do some kind of configuration for this device that I haven’t done (I thought we’d calibrated it but I’ll try again).

Video:

About two weeks ago I almost posted a blog entry titled “%*@$-ing surreal!!”, whose first sentence was “Ok, my head’s about to explode”. I decided to hold off posting it just a bit – here’s a bit of back story behind that, that post, then more..

(Quick glossary for friends reading this that don’t know the terms: a RepRap can print most of its own parts, and is made from parts printed by another RepRap. A RepStrap is a device you make out of whatever you have lying around, that works just well enough to bootstrap you into the system by letting you print out the necessary pieces for a RepRap (so a RepStrap might be made out of wood, or might be a modified existing machine you have, or you could theoretically make one out of Lego bricks, etc)). Darwin is the name of the first version of RepRap, and Mendel is the name of the 2nd version of RepRap.

First of all I’ve been acquiring parts for and building my Mendel RepRap since October 29th, when I threw my hat over the wall and ordered most of the 3rd generation electronics. I really wanted to make a Mendel at this point, not a Darwin, and since there were no Mendel-like RepStraps in the world, I was initially torn – I didn’t want to build a Darwin and then immediately go ahead and build a Mendel (cost and time).

So, I decided I’d throw caution to the wind and just plunge ahead acquiring parts for a Mendel, doing all of the assembly that I could before requiring RepRapped parts, and eventually I’d figure something out. The closest thing I had to an exit strategy was posting a picture of all of the purchased and assembled parts I had, and begging someone who wanted to grow our community to print me parts (with the true promise that I have a bunch of friends lined up behind me waiting for me to print them parts).

While building and not having any real access to RP parts, a rationalization started to build in my mind. Rather than feeling like I should have gone down the longer path of building a RepStrap of my own design (which would be destined to fail, by the way – I’m married, with four children, and it’s amazing I have any time at all for any of this.. my building experience is ok, but not great..), I’d convinced myself that it’d be even better to not build a RepStrap, my rationale being that the quicker I get on the actual RepRap platform, the sooner I’ll be able to apply my creativity and design to that platform, to make things better for everyone (rather than just designing, building, becoming attached to, and then enhancing my own tangent RepStrap design, which I’d only really needed to get on the RepRap platform in the first place). Some people have done amazing innovative work on their RepStrap platforms, don’t get me wrong, but I really wanted to get to a RepRap soon.

On Sunday, November 22nd, I was explaining my new rationalization to my dad and my friend Kevin on the way to the football game we were attending (Go Pats!). After describing my desire/justification to bypass the RepStrap process, I said:

“Don’t get me wrong, if someone dropped a MakerBot on my desk tomorrow, I wouldn’t say no, it’s just that I want to spend my time/energy on getting a Mendel.”.

Now, here’s the post I was going to post on November 24th, two days later:

Title: %*@$-ing surreal!!

Ok, my head’s about to explode.

Today after lunch, two coworkers returned from some talk and said…

…that there are MakerBots in the building, that we can go ask for. And take.

(For anyone following this blog that doesn’t know, a MakerBot is a RepStrap build by a company called MakerBot Industries in New York. It’s like a RepRap kit. It can’t print another one of itself, but it can print a RepRap, which could then print another RepRap).

The parts are sitting on my desk right now. They bought three, for groups to build. It’s part of a technology library they have here, to foster creativity/imagination/etc.

Chris and I picked it up, opened the box, and plan to build as much of it as we can on Saturday.

I still can’t quite believe it. It went from “yeah, no I think you can just walk upstairs and ask for one”, to “no, umm, really?”, to a bunch of discussion, to “why not, let’s go ask”, and then bam – parts all over the desk.

What’s really killing me is three (fully assembled) Stepper Motor Driver v2.3 packages, sitting right here, next to a window on my screen that’s checking the website every 30 minutes to make sure they’re still out of stock on Stepper Motor Driver v2.3 boards. >:(

I fully expect to wake up and wonder how I believed any of this was real.

🙂 Two days after I told Kev that I wouldn’t say no if someone dropped a MakerBot on my desk, and someone literally dropped a MakerBot on my desk.

That Saturday, at Chris’s house, from 11:30am until 4:30am, we built the MakerBot that will someday print out parts for many Mendels.

(BruceW, if you’re reading this, keep printing. 🙂 Larry and potentially I will still need them, as will others in the new england group. I’m not so good at reliably printing parts yet (after many, many attempts). And theoretically we don’t get to keep this MakerBot forever).

This whole thing has been a big (but useful!) change in direction for me. Before I was building. Now I’m printing, with a functional 3D printer. It feels a bit like reading the last chapter of a book before reading the rest. I’m now stuck figuring out what temperature to print what at, how to get something to print without it being destroyed by the printer (or destroying the printer), etc. But I’ll get back to that fire cement soon enough.

So, many of the blog posts after this will reflect my use of a functional RepStrap, and the problems involved in printing. Hopefully it won’t take long before I get enough parts printed (either by myself or from others) that I complete my Mendel and I’m talking about things I printed with my own instance of the Mendel RepRap. 🙂

p.s. After a few failed attempts to print whistles and minimugs, here was the first successful print. (I’m now going to save the minimug tradition for when I get my Mendel printing):