arduino, robots, cameras, and life

On my self sourced prusa I have been going back and forth on how best to tension the belts lately. I had a zip tie hack that actually worked out fairly well, but it had a fair bit of slop in it, and I think that helped set up some vibrations and Generally keep it from being the best it can be.
I love my local hardware store. I went there (twice) today and on the first walk there I remembered this piece of hardware that is generally used to tension screen doors to keep them square. I checked one out and I think it will be perfect for my y belt. I may even throw one on my x axis, but I’m not sure if I need it.
Here’s a pic

As you can see in the pic I have been experimenting with a very light y stage. It is perforated hardboard that they sell for hanging tools. The actual bed will go on top of there with 4, 5mm bolts and have the glass and hbp clipped to it.

I have also gone with a double wide skate bearing for the idler end of the x and y axis. If the two ends are aligned, then you don’t need anything else keeping the belt “on” the pulleys. Simple tension holds them there. This has made things much smoother and simpler compared to using fender washers.

I don’t remember who tweeted it, but I saw a tweet a week or so ago saying that the makerbot grab bags were a good deal. I looked at them and bought three. I figured that at $9 each they would be a good deal.
even if they had nothing but the ftdi cable.
I got my box today and Wow!

I got two of the grab bag #1 and one #2. Each of the #1′s had TWO ftdi cables, two early nozzles, 5 pfte barrels, 2 brass barrels, a bunch of thermistors, pulleys, a fan, and some plastic build plates. They said that the grab bag could or could not include those items, but I didn’t think it would come close to having them all!

The second grab bag was similarly stocked, with a ton of pulleys, belts, some rods, some wooden build platforms and a ton of fasteners and plastic bearings.

They said it in the description, but I want to reiterate it: If you are a cupcake operator, you should probably get this. It is a great source of spare parts that would have cost you hundreds to buy a few weeks ago from makerbot. It will hopefully keep your bot printing for a long time to come.

If you are not a cupcake operator: it’s still a damn good deal.

Thanks makerbot!

It’s been a busy start to the summer! I was able to go to Maker Faire, and now that I’m back I’ve spent every spare second on my bike or at the new hackerspace in town. One benefit of being a hackerspace member is that I finally have a place to keep my big /noisy / messy projects!

Here’s a pic of where it stands right now. I have everything together, but it’s not wired up yet. I’m also replacing the clonedel parts as fast as I can. They are causing more trouble than they are worth right now.
Here’s a link to solid state depot’s wiki on my prusa.

Here’s a pic of my monster e-stop button. It came out of a printing press. It is wildly overkill, but it looks cool. It is currently wired up to the psu, so if the switch is tripped, it cuts power to the machine. dead stop.

I’ll update more when I do more. I’ve been learning how to use a lathe in order to drill out some hot ends. It’s been exciting so far…

Let’s give this a try!
Tonight I prepped 4 3ohm 10 watt aluminum resistors with in two parallel pairs with solid copper wire. I gave it 12 volts of juice and it got plenty hot quickly, so hopefully this back of the matchbook effort will pay off.

I don’t have the aluminum plate with me, so I only prepped the electronics. This is what they look like.

And here is a closeup of one resistor.

I have been reading a few other blogs about other peoples diy hbp builds and I was getting really confused. Hydraraptor is using 9(!) 48ohm resistors on his reprap hbp. That seemed really high, considering the people doing it with nichrome wire only have about 6 ohms total.

Then I realized that Hydraraptor is using 240VAC. That seems dangerous, and in one of his posts he mentions how one of his resistors failed and ended up melting a bunch of his circuit breakers. Yikes, that’s not for me.

My plan is to set this up on an aluminum plate with the stock thermistor from the makerbot kit. I’m still unable to print because of some extruder issues, but this is a good distraction while I try to figure that out. I’m also going to try building one with nichrome wire. IF it works as well then it’ll be lower profile than this resistor configuration.

I recently bought a molded reprap prusa mendel kit from Metrix create space. They are a hacker space in Seattle, Wa. The molded kits cost anywhere from a third to half of what a set of printed parts cost because they take far less time to produce. One downside of the printing method is that parts will end up sloppier and require some more post processing.

Here is what the base looked like as it arrived.

Here is the other three parts, unprocessed.

The next picture is where you can start to see the disadvantages of this method. There is a lot of plastic on the bearing holder (purple) that needs to be cut away, and you can see the way that the miniscus on the big gear has made the entire gear cupped. I want to clearly state: none of those are deal breakers. This is a great deal, and even the RP parts require a fair bit of processing. I was surprised when these parts came in, but after thinking about it I don’t think I should be. They appear to be functional, and that’s all that really matters to me. As long as they last long enough to print their replacements, I’ll be happy!

Hit the jump for how to build it!