Z-Rods Follow-up and Instructions

11 09 2010

I received my new ACME Z-rods awhile ago and I am finally getting around to writing this up. They are super sturdy, super straight, super shiny, super smooth pieces of awesomeness. Installing them took a little while to figure out, but once I figured it out, they worked really well. It may look long, but it really doesn’t take all that long. Here’s how I did it:

The first and most important thing was to clean them. They had a lot of dust and metal shavings stuck to them. Luckily they were covered in lubricant so it kept them safe. I spent about half an hour cleaning each one very carefully. First I used a dry paper towel on them and cleaned them by hand. That took forever so I put them in a drill chuck, held the paper towel tightly around it and turned the drill on slowly. That cleaned the outside nicely, but the threads still had a lot of junk in them. So to clean the inside of the threads I put the drill in between my legs, folded over a paper towel and held it in the threads as I spun the drill with my legs. Only after the rods were perfectly clean did I stop cleaning. The cleaning step is extremely important for smooth easy travel. If there is any dirt left it could make the Z motor skip a step.

Then I took the delrin nuts and ran them through the rods a few times to make sure each rod and nut was extremely smooth. I used the drill for this, too.

Using a dremel or a hacksaw, take off approx. 10mm from the side of 2 of the delrin nuts. Make sure you don’t cut into the bolt holes. Make the cut parallel to the bolt holes.

The next step was to actually install them in the Makerbot. First take out the acrylic Z stage by tilting it and turning it so you can take it out. It is easier to take it out if you take off the plastruder first. Next you will need to take off the pulleys and the belt from the Z rods. Then you will need to take off the square wooden pieces that hold the top Z bearings. Take off all 4 bolts and set the wooden pieces aside. You won’t be needing these anymore, but its probably a good idea to keep them for the future. Now you should just be able to pull out the old rods. Take off the lowest nut and the highest bolt on each old rod to release the bearings. Push 4 bearings into the lower bearing area. You will not need any nuts to hold them in anymore. Next take the remaining bearings and make sure that they fit on the longer 8mm part of the new rods.

Put in each new rod with the shorter part down. Before you put each rod down all the way, screw a delrin nut onto it with the wide part up. Screw it about halfway up and then push it into the bottom bearing. Then push a bearing onto the top of the rod. It should push all the way to the threaded part of the rod and it should be pushed into the hole in the wood.

The next step is to level out all of the delrin nuts so that they are all at the same height (within a few mms at least). I used a carpenter’s level, but something a little smaller would be better.

Next take off the wooden squares that are attached to the acrylic Z stage. Once you take off the wooden pieces, put the bolts back on the Z stage. These will hold the Z stage onto the delrin nuts. The M3 nuts will be a press fit into the mounting holes on the delrin nuts.

The next step is optional, but highly recommended. Using a dremel with a high speed cutter or a sanding wheel cut out a larger hole where the nut used to go. This is to make room for the ACME rods which are much larger than the old ones. You can get away with not doing this, but you will get extra friction, noise, and quite possibly extra skipped steps. Keep in mind that once you do this step, you will not be able to go back to the old rods without a lot of hacking.

Now you can finally put the Z stage into the body of the bot. The bolts should press fit into the mounting holes in the delrin nuts. Now is a good time to attach the pulleys to the new Z rods. Also put the belt back on now. You can now test out the Z stage by spinning the rods and marvel at your near perfect Z travel. The Z stage will now move about TWICE as much as with the old rods with each turn. Keep this in mind!

Now you have to tell ReplicatorG that it needs to move the Z stepper different amounts to move the Z stage the same amount. There should be a machines.xml file in both the repg install directory and in the ~/.replicatorg directory. Depending on what version of repg you are using it will use a different machines.xml. machines.xml is the file that declares the settings for each machine. Open one of these in a text editor. You will need to change both files just to be safe. Under the “Cupcake CNC” tag or “Cupcake CNC w/ heated build platform” tag, depending on which one you are using, and where you see it says “<axis id=”z” length=”300″ maxfeedrate=”150″ scale=”320″/>”, change that to “<axis id=”z” length=”300″ maxfeedrate=”300″ scale=”157.480314960629921″/>”

Now open up repg and open the control panel. Move the Z axis and check to see if it is moving the correct amount. If it is then congratulations! You’ve successfully installed your ACME rods!

Now you can print something! Keep in mind that any previous .s3g files, like the ones you print from the sd card with will not work because they contain the machines.xml for the old rods. So if you try to print from the sd card with an old file, it will move about twice as much as it should in the Z axis.

I’ll post pictures of before upgrade and after upgrade sometime soon…

Advertisements




The newest RepRap – Huxley

4 09 2010

The newest version of RepRap has been announced. It will be a continuation of the Mini-mendel and it will be named “Huxley”. You can see the wiki page here: http://reprap.org/wiki/Huxley





New Z Rods

22 08 2010

I’ve just bought a new set of Z rods for my Makerbot to improve the quality of my prints. If you look closely at prints from my Makerbot (http://www.flickr.com/photos/49325300@N07/4778528559/) you can see that there are lines about 1mm tall that go in and out of the object. This is called Z wobble, waviness, etc and its from the Z rods on Makerbots not being perfectly straight. This is mostly a design flaw that could have been avoided, but it also could have been avoided by using high quality ACME rods instead of plain old threaded rods. The threaded rods it uses are not meant to move things accurately. They are meant to hold nuts that hold stuff. Therefore the threads don’t have to be very accurate or very straight. The Z axis on a Makerbot is directly driven from the threaded rods which means that any imperfections in the rod will directly affect the print.

When you’re someone like me who is obsessed with getting $15,000 dollar quality on my Makerbot, this Z wobble is very annoying. So I went for it and bought some replacement ACME rods off of ebay. For anyone else who is interested, here’s the link: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=330462274481 You might have to search for “makerbot upgrade” on ebay because this ebay auction is going to expire soon. I made an offer of $60 bucks and they took the offer so I ended up getting it for <$70 bucks, with shipping. I see this as a pretty good deal.

I haven’t received my new rods yet (I just ordered them a few days ago), but I will post when I do.





Makerbot ≈ Instrument

22 08 2010

Some people may say that owning a Makerbot as a 3D printer is silly. They say that it requires too much skill and time to operate for it to be a real consumer item. Well I say that owning a Makerbot is very similar to owning a musical instrument.

How useful is a musical instrument when you don’t know how to play it? About as useful as a Makerbot is not knowing how to operate it. On a piano, most people can figure out how to play a simple song nicely. On a Makerbot most people can figure out how to print a simple object. To play a complex tune on a piano, it takes considerably more time and effort. To print a complex or high-res object on a Makerbot it takes work and time.

Instruments are coincidentally in the same price range as a Makerbot.

Also, if an instrument has a loose nut or something is falling off, you don’t bring it to someone to fix it, you would just tighten the nut yourself. This is the same with a Makerbot. Other things like refrigerators, dishwashers, and computers are the type of things you would bring to a specialist to fix. Why does a 3D printer have to fall into that category? If you understand your 3D printer the way you understand your drum set or piano why would you need to bring it to someone to have it fixed.

I make music with plastic. A new type of specialist. A Makerbotter.





The state of the Bot

13 08 2010

Ok I finally decided to take some pictures and video of my bot to show off. I’ve got some on flickr here: http://www.flickr.com/photos/49325300@N07/

Here’s a picture of the Makerbot. I like to call it iMakerbot. I have it outfitted with some nice shiny new orange printed Z pulleys. I also have an orange Z crank which you can barely see here. On the extruder side of things, I have a super awesome Makergear 0.4mm bighead nozzle assembly with a hybrid PEEK/PTFE insert. I’m just using the standard acrylic platform that came with my bot. Next to it you can see I have a little orange box attached. That’s for catching the test extrusion for automated printing. No more operator stop involved in every single print. The thingiverse entry for that is here: http://thingiverse.com/thing:3777

I’m able to print with both PLA and ABS. Right now I like orange ABS the best but I also have some natural and some blue.

I painted the bot with a few coats of white spray paint and a few coats of shiny clear protective spray paint. It gives it a really nice hard smooth finish that’s impervious to water and 3 in 1 oil. I also outlined the Makerbot Industries with a sharpie. I just painted the outside of all the parts with the white and the inside with just some clear paint for water protection. I highly recommend going the spray paint route with a Makerbot. It is easy, quick, cheap, and it turns out really really nicely. It looks even better and shinier in person.

I’m thinking about upgrading my Z rods because I’m getting a ton of Z wobble which is both annoying and problematic for tuning skeinforge. The Z wobble shows up even more when I do higher quality prints which ruins their high quality attributes.





Support Material – Sand?

12 05 2010

I just came up with an idea for having support material on a Makerbot or RepRap. The idea is quite simple, but I think it could work.

The idea is that you would have the whole platform essentially be a box that would be filled up with a bit of super-fine sand each time a new layer is deposited. The entire build area would be surrounded by a barrier to keep the sand in. Each time a new layer is deposited, a new layer of sand is added so that the sand level is just below the last layer of plastic. This would mean that the plastic couldn’t sag more than one layer thickness.

The sand could be deposited in a number of different ways. One idea would be a whole bunch of sand in a bucket above the machine and a valve just releases the sand while the platform moves below to evenly disperse it. The platform would shake to get a flat layer after the sand is deposited. Another way would be the same idea, but with a worm drive to push the sand at an even rate down. The first idea would rely on gravity, but the second one would be motor driven. Or you could have the bucket at the side of the platform (so it’s not in the way) and deposit the sand, then just have the platform shake violently for more time to get the sand flat.

The only problems I foresee with this are that it’s inaccurate and messy. The sand would have to be really really fine and controlled extremely carefully to get high precision. The sand would also make this less likely to be on a desktop. I’m sure it would create a big mess if there was an accident. This is the main reason I’m hesitant to try this. Another problem this might cause is inadequate layer adhesion. The sand could get in between the layers and make them not stick well. This would be especially bad with really fine sand.

I might try it at some point, but just add the sand by hand. I could add a manual stop after each layer then press yes to continue after I’m done. This would take forever, but it would be a great proof of concept.

Another thing I might try is cornstarch instead of sand. It would be smoother. I could wipe each layer of cornstarch with a brush to make sure its flat. This is another idea I like. If you had a brush that was the width of the surface and it wiped the cornstarch or sand after each new support layer.

Thats the basic idea of things. Sorry if my ideas are a bit scattered…





The Extruder Works!

10 05 2010

I built the extruder that I posted about last and I have been testing it for a while now. I’m just using ABS for now because I’ll have to change a few things for it to work with PLA.

I changed a few things from the design I posted. First off, I didn’t have any PEEK (and it’s really expensive so I didn’t want to buy any) so I just used some PTFE. I’ve got a block of PTFE that is a half-inch thick. I just drilled the requisite holes using the original washer as a template. This worked really well to get the spacing right.

Also, I just used some nichrome wire and wrapped it around the barrel in one layer instead of using a HeatCore. It was much easier than making a new HeatCore.

And also, instead of some fancy insulator, I just used a piece of PTFE. That was all I had around, so that’s what I used. I just drilled a 3ish mm hole in it and carve a little out at the bottom so it would sit well on the top of the barrel.

And finally, because I’ve been having problems with plastic leaking around the nozzle threads, I just soldered the nozzle onto the barrel. The one thing I hope is that the solder isn’t melting. If it is, it could short the nichrome, clog the nozzle, and a bunch of other bad stuff.

This extruder has been working well for ABS so I might try it with some PLA soon. I was thinking I could remove the PTFE insulator at the top and see if that makes it work nicely. The ABS has been leaking around the PTFE at the top a little, and that could cause a pretty substantial jam with the PLA. I was thinking I could add a small metal pipe just above the barrel to guide the filament into the barrel. It would be cooled with a heat sink to make sure it stays below PLA’s glass transition temp.

Anyway, that’s the newest update on my extruder escapades.