New Mods, Same Printrbot Plus V2
I decided to go ahead and do a complete overhaul on my printrbot plus V2 in anticipation of the dual extruder production version that should be coming out soon. First to go was my old belts and pulleys. I eagerly replaced them with GT2 6mm wide belts for the X and Y axis’s and why I was at it is put on a set of 20 tooth aluminum GT2 pulleys. I felt like I could do more to tweak my bot for better resolution so I went about seeing what else I could upgrade while I had it torn apart. The majority of parts were purchased via eBay seller: nrg24seven So far I am very happy with pricing and the quality of the parts I purchased. Good sellers are hard to find especially on eBay.
I’ve never been a big fan of the tensioner setup on the V2’s, so I went about figuring out a new idler setup primarily for the X axis. I wanted something that was easy to adjust and didn’t require to much modification or custom fab work. One issue is finding a location to mount the idler without interfering with my current setup. I came up with a idler that mounts to the outside of the oversized washers on my current X idler setup. I used two pieces of aluminum and quickly CNC’d out the two side mount pieces. Once those were mounted all I had to do was thread on a nylock nut which will serve two purposes. The first purpose will be to hold on the X axis idler that is mounted in the stock location and the 2nd use is to adjust the newly added idler. That way I can quickly adjust the tension as needed. I will attach some pictures asap.
**As a side note if you have a stock plus or LC you will need to get about 2 -1″ washers with 2 608 bearings to make this setup which will replace the stock printrbot idler. I will go into further details and how to later on.
After that it was time to tackle my stock couplers. I have been and probably always will be a fan of spider couplers as I have tried many different kinds and I’m always led back to them. However I recently bought some couplers that look much like the ones used for CNC machine and usually have been known to be too springy for 3D printers. These look just like them except inturnally they are different. You can adjust the amount of spring and tension that they have which allows you to be able to fine tune your couplers. I bought them at the correct size for the rods I’m using but, I always add a little PTFE tape or plumbers thread tape as it assures that there is a solid grip between the shaft, rod and coupler. This can also be used if your coupler holes are a little too big for your rods or shafts. Just make sure to wrap them very tight when applying the PTFE tape. That way the tape will bond better with itself as well as the threaded rod.
I also just recently got some bowden tubing that is supposed to be better than PTFE tubing. I was able to get about 30 plus FT of it. Quick tests look good so far but, I will post new information once tested side by side. I have my dual extruder setup so I will run standard PTFE on one extruder and the new bowden tubing on the other.
After tinkering around a bit and trying to figure out a better non printed way of fixing how the nuts that the z axis rides on to move up and down. I was looking in some of my bins and I noticed a pile of wing nuts. Then it hit me, if I use the 1inch nuts on the bottom, a spring on top of that ND then an upside down wing nut on the top. The wing nut fits perfectly in the stock grooves with little movement. I had to loosen up a couple screws so that I could set the desired tension on each side. So far it looks great but the real test will come when I start printing. If this setup doesn’t work as expected then I might toy around with a wing nut on the bottom. I don’t know why I hadn’t thought of this earlier as it works perfectly with the stock notches. Here’s a few pics of it so far.
Update: October 28th 2013
I tested out several different variations of this setup and I’ve recently found that the wing nut is best under the platform. However I still need something at the top end to stabilize the rods more effectively. I will more than likely solve that issue with the first few prints I make. I will follow up with the final design as well as STL files.
I got an idea from another member of the dual extruder beta testers. The idea was to split the fan mount and latch on the dual extruder setup so you can feed in New filament without un-latching the other side. I had some spare birch so I went about making two seperate fan mounts. Since the stock fan holes are soo close together, I couldn’t use the same style and just split it into 2 separate pieces. About half way down I widened the mount so I could space the fan holes out a little bit while still allowing the needed space for the stock setup. I just got done cutting the 2 pieces out and I’m about ready to test fit. I will post some pictures after I’m done mocking it up.
Making a little headway on test fitting everything. Once I get the prototype how I want it I will remake any needed pieces and more than likely paint it to match the rest of my bot. Here is a picture of where I’m at today.
After mocking up the other side I started thinking about different kind of fan mounts. I have a couple fans that are a little bit bigger than the stock ones. I’ve decided to wait until I get my dual extruder plus up and running again before exploring these options any further. Mostly due to time in which I don’t have much of. I will update when I either come up with a more feesable option that will more then likely be printed.
Soon I will add the results of how these modifications effect my print resolution. I will also add documentation on how to add these mods to your printrbot.
Update: October 22nd 2013
I still need a little bit more information before actually firing up the plus v2 so I started working on bracing the x axis. The v1 had a solid piece of birch that accompanied the x axis rods which helped to stabilize the bridge. When the V2’s came out the re-design didn’t include this piece so I decided to go ahead and make my own. I grabbed 4 L shaped steel brackets. Two of them are larger than the others. After that I grabbed some half inch aluminum tubing as well as some custom machines bolts that for inside the aluminum tubing which allows them to be easily mounted. This is the first version and didn’t take to much time as I had all the required parts laying around the prototyping lab. After installing everything I am actually amazed at how much stronger the bridge is. My next few steps include beefing up the x rod mounts and the y axis bearing mounts.
Recently I decided to beef up the brackets to all steel ones. Even though the old setup worked perfectly fine, I’m all about overkill. I kept the longer L shaped steel brackets and added an extra one were needed instead of the smaller 90 degree ones. Changing these two brackets made an aesthetic difference as well as made everything super sturdy. This modification took a lot of wiggle out of the X Bridge. Next I plan on changing out the x axis rod mouth to something a little more sturdy. You can also find a similar but printable version of the x axis stabilizer on Thingiverse.com I recommend this mod to anyone who has a printrbot plus or LC as its made a difference in the strength of the entire x bridge.
Update: October 28th 2013
Getting all my endstops or homing switches and order I realized that leveling the bed on the printrbot Plus is a pain. I was aware of this issue in the past but until lately it never bothered me so much. So I decided to redesign the platform and due to prior mods it wasn’t as easy as originally anticipated. The modifications I’m referring to is half square aluminum runners that go the full length of the bed mount and sub-mount. Originally I had glass with blue painters tape on top but I was tired of it cracking or breaking due to temperature changes. I could buy high temperature glass but I figured, why if I already have Lexan sheets. Lexan works great with PLA which is what I primarily will be using as my heatbed runs on an 24 volt setup from a prior setup. I need to set aside some money for an oversized heatbed.
So I found a fairly thick piece that is between 1/4″ to 1/2″ thick. I wanted to use the thickest piece possible so it would help assure it is as flat as possible. Lexan has been used in the past with great results when laying down PLA. I took the springs out of the setup and firmly mounted the sub-mount to the wood bed. Then I built stand-offs that mount the wood bed to the piece of Lexan. Doing this helped to clear the extra bolt heads from the half boxed aluminum runners. I then replaced springs with little pieces of rubber that are used in CD/DVD players to produce shock protection in case they are bumped. I might add some rubber hose gaskets as well to give it a little more room for adjustments if needed.
I later decided to take off once again the stock printrbot LC bolt adjusters as they sit too tall and interfere with the fans mounted on the dual extruder beta. That’s one thing I hope and have recommended that be changed for the production version. The way it is setup makes it for almost any fan you may buy other than the clear printrbot ones not fit right as they sit level with the extruder tips. I will have to print some sort of new latch and fan mount assembly that will relocate the fans to a better position. It also has birch wood side pieces that come down the sides with no real purpose. I will add the new pictures as soon as I am able to take some new ones.
Update: October 30th 2013
Here’s some new pictures since I upgraded the bed. I’m also testing out frog tape to print on as I’ve heard of great results using it.
Posted from RepRap Squad HQ