3-D Printer ChamberAugust 28, 2013
About 6 months ago I got a new 3-D Printer, a Replicator 2 from Makerbot. While the printer does a good job, it does have it’s flaws.
The first issue is sound. While the printer is is only a little louder than a normal ink jet printer, it can take more than 12 hours to do a single print. Over time, especially when sleeping, the noise can be more than a little bit annoying. Most 3-D Printer owners never do anything about the noise, other than locate it in a good part of the house, and it is never a problem. But this is me! Two of the more interesting flaws are not unique to this printer, but hinder almost all 3-D printers at the hobbyist level. Being the inventive type of person that I am, I set about solving some of these issues.
The second issue is one of temperature. When the plastic is extruded, layer by layer, it comes out of the nozzle at about 220 deg. C. It then starts to cool. If it doesn’t cool just right, the print can warp as different parts of the print cool and contract at different rates. With some practice, this can be managed, and warping kept to a minimum. But drafts and other things can also effect print warping. An open window near the printer could, in theory, cause problems should a cold breeze come in. Some of the better 3-D printers are somewhat enclosed to help minimize this issue. I thought I could do better.
My solution to both of these issues is to build a chamber for the printer. This chamber is basically a box that the printer goes into, and insulation makes it both soundproof and allows some elevated and consistent temperatures inside the box.
I should mention at this point that running this kind of printer at elevated temperatures is not considered advisable by many. And they very well might be right. But this is an experiment, and much experimenting remains. So don’t do what I’m doing, unless you want to experiment also. And don’t complain that I’m doing it wrong, either, since I freely admit that I might be! I also admit that much of this is severe overkill. If it’s worth doing, then it’s worth overdoing!
There is a lot to this chamber, so be patient while I describe the construction and features.
The main box is built from 0.75 inch plywood. The wood is joined with rabbet joints and glue, and are very solid. Then, on the inside, the joints are sealed with a thick layer of caulk. The reason for all of this is to make a very sound-proof box, and joints are the weak link in soundproofing.
The door is made from two layers of 0.75 inch plywood and 0.5 inch laminated glass. The glass is that thick (and laminated) for soundproofing. I used two layers of plywood because the glass is so frickin’ heavy! The glass is almost as heavy as all of the wood combined. The glass is held in place, sandwiched between the plywood in something like a rabbet joint, and sealed with lots of caulk. I used a piano hinge, but I would use something else if I had it to do over again. The hinge is too flimsy under the huge weight of the glass, and the door sags. The door is held closed using two adjustable latches. Due to the sag of the door, I made three “door lifters”, which you can see in blue in the pictures. These are a ball bearing and a ramp. As the door is closed, these lift the door level.
The door is sealed with two layers of weatherstripping. The first layer is for the plywood to plywood seal and is a 0.5 inch wide strip of normal self-adhesive rubber that you can buy at your local big-box hardware store. The second layer is more of a spongy foam, that seals between the plywood door and the fiberglass. It is about an inch wide and 0.5 inch thick.
Lining most of the chamber is 2 inch thick rigid fiberglass insulation, wrapped in whatever fabric I could get on sale. This form of insulation is commonly used for sound isolation. Normally the fabric should be as thin as possible, but what I used is quite thick. For this application the type of fabric isn’t so important. The fabric wrapped panels are held in place using just a couple of drywall screws and some large 3-D printed washers (they look like silver gears in the pictures).
The printer itself is on a vibration isolated platform. I did not want vibrations from the motors to couple mechanically to the plywood and re-radiate into the room, so the printer rests on a plywood platform that is isolated from the rest of the box. The isolation medium is “rubber mulch”. Essentially shredded rubber tires that is commonly used instead of sand on playgrounds. There is a wooden tray that holds about 3 inches of the rubber. On top of that is a plywood platform, and the printer sits on top of that.
Above the Replicator 2 is a frame made from aluminum T-Slots. It is suspended from the ceiling by elastic bands. Mounted on the frame are some fans, and LED lighting. Future experiments might call for mounting a heater on the frame as well. The LED lighting is similar to the lights already on the Makerbot, except more of them. There are 60 RGB LED’s on the frame, all pointed straight down. The elastic bands is to offer some vibration isolation so fan vibration doesn’t couple to the plywood.
The filament spool is located on top of the chamber, outside of the soundproofing and heat. There are two t-slot “towers” with a 0.75 inch diameter steel tube, which the spools are placed on. Fancy latches lock the rod in place so it won’t accidentally come off. The latches look cumbersome, but they actually work very nicely. Adding and removing spools is easy, and it can handle any size of filament spool. I can store several spools at once on the same rod, so switching between filament is fairly easy. I should note that I live in a place where the air is dry. I have yet to have issues with too much humidity effecting filament.
The filament is guided through the chamber roof by a 3-D printed “spike”. This spike is solid PLA and keeps the filament from getting pressed on by the fiberglass insulation while trying to minimize the amount of noise that is allowed to escape the chamber. On the top of the chamber is a cup that holds some acoustic foam, and the filament runs through that foam. The foam is nice because it not only blocks some sound from below, but it also removes any dust that has settled on the filament.
I have made several modifications to the Replicator 2, specifically with this chamber in mind. Mostly because of the expected elevated temperatures. On the extruder stepper motor I have attached a heat sink using thermally conductive epoxy. Combined with the fans on the suspended frame, this helps keep that motor cool. On the Y Stepper Motor I have also added a heat sink, but in this case I have also added a 40 mm fan and some ducting. In testing, this has reduced the motor temperature by 40 degrees F! I also changed the extruder fan. The old fan was starting to go, the bearings were making bad noises. The new fan pushes more air, and ironically is a lot quieter.
I have not changed to aluminum arms or extruder upgrade, although I am keeping a close eye on things in case I need those.
Now on to the performance: I have had the chamber working for about a week and I couldn’t be more pleased. There are some issues, but on a whole it works very well.
With my head 1 foot away from the door, I literally cannot hear the printer when it is running. The normal ambient room noise completely masks any sounds coming from the printer. If I press my ear against the chamber I can hear something, but it is very quiet.
The lights are very bright. Bright enough that I need to work on a way to dim them. But that is a good thing, because the lights included with the printer are not enough by themselves when the printer is in the chamber (and normal room light is mostly blocked).
One potential major issue is that it takes quite a bit of force to pull the filament through the now longer feed tube. The tube is bent more than before, which isn’t helping. It is currently working, but just barely. I have started working on an auxiliary filament feed motor. A simple sensor mounts on the extruder and detects when the printer is trying to pull filament. At that point, an extra motor mounted just under the spool will push more filament down.
Another potential issue is that the insulation might be too good. Without any extra heaters, the chamber reaches about 100 deg F after about 2 hours of printing. I have not done any longer prints just yet, so I don’t know if it will get much hotter. If this becomes an issue I will have to install coolers as well as heaters. I know how to do that, but would prefer to avoid it if I can.
This is a work in progress. I still have a lot of work to do on this chamber, but early results are very promising. The next thing is the aux filament feed motor. After that will be some stuff for temperature control. I will report on that later.
As I add things to Thingiverse, I will add links below. If I am adding things too slow, request something in the comments. I don’t plan on adding everything to Thingiverse since some of it is too specific to this chamber, but if you ask for it I’ll put it up.
Multiple Spool Holder: http://www.thingiverse.com/thing:143537
Filament Extruder Guide: http://www.thingiverse.com/thing:143502
Extruded T-Slot 80 mm Fan Mount: http://www.thingiverse.com/thing:143553