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Ever thought of getting into 3D printing but want to try it first for low cost? Part Three.
Now for a few little tips that have to do with the hot bed, and wiring and the routing of the wires. They say you learn by your mistakes, so let’s hope these tips help you to not make any serious mistakes by going too fast and getting the assembly out of order. I found it best to route the wires for the right front stepper motor of the machine to the back rear right through the hole in behind the motor, and then come out of the hole with the power pack wires and come across the rear of the machine as in the photos below.
The rest of the wire routing is pretty much as described, but don't cover the wires with the flexible curly cover until all the wires are connected, that way it's easier to trace wich wire goes where. The hot bed and nozzle wires should attach as I have shown in the photos below:
You can do this after you have all the wires from the Hot bed and hot end wrapped in the curly protective plastic. Notice that I used a small tie strap around the wires coming from the hotbed through the small hole in the bed to stop them getting chaffed every time the bed moves. Also remember to move the bed back and forwards to make sure you have enough wire before you finally tighten the wing nuts, you'll find extra screws and nuts and wing nuts in the packets for this. Just take your time and follow the wireing diagram carefully when your connecting the wires and I'm sure you'll do fine.
Another thing to note, make sure enough wire is showing past the covering when you connect the power wires to the circuit board because you don't want the screw to tighten on the plastic coating around the wire, that could cause the wire to come loose and make some serious arcing and eventually burn the wire and could possibly cause a fire, so strip enough wire and tighten the screw holding the wire tight and check it periodically just to be safe. I really do think there should be a better way of connecting wires to these boards, I was thinking I might make a male to female connector just like we have on cars.
Hot Bed Tweaks.
Now on a printer that cost under $200 you cant expect the best hot bed in the world, so this one is made out of a peice of aluminum drilled and has the heating element glued to the underside. We should remember that there are a lot of more expensive printers that don't even come with a hot hed heater, so we should think of this as a bonus. Now if it was made from cast aluminum it would be nice and flat and our prints would probably stick a lot better, but the problem with this bed is it's so thin it tends to bow in the middle when it gets hot, the four corners are held by the adjusters so the surface tension can only go one way and so it pulls down very slightly, just enough to make your filament loose if your printing near the center of the plate, even if its printing great near the front or back.
So I remembered I had a couple of old glass shelves knocking around here that were leftovers from when I cut some other shelves to size on my Motorized tile saw, so I cut them and filed them off on the cut edges and used one of those and a few clamps from the dollar store to hold it in place. You could probably get a $2 picture frame from the dollar store and use that glass too I bet, Just make sure you sand the sharp edges of the glass so you don't cut yourself everytime you clean the glass. Now I tried glue sticks and then masking tape of all kinds but I admit I didn't try that milor film stuff because where I live no one stocks it and I wanted to try my first print so bad. I saw a guy on You Tube trying hair spray and I thought maybe I should give that a try, so off to the dollar store again (honestly this isn't a plug for them) to find some firm hold hair spray. I found one for $2 and headed home to try it.
Now I tried a few different methods of applying the hair spray, so what works for me might not work for you, YMMV here's what works for me. I take it outside and spray the glass back and forth one way then the other, not too much and not too little, then i leave it to dry and reinstall it on the hot bed.
Before you level the hot bed, check that the two Z microswitch screws are loose on the underside of the travel carriage and the switch can move up or down easily, this will make the final adjustments a little easier. Now your hot bed is probably way out of adjustment, so what I did first was, I tightened the bed screws up so the bed came down as much is shown in the phoros below, you'll see the springs getting squashed. I watched how much thread was sticking out of the bottom of the wing nuts to keep it kind of equal so the bed would be almost level with the nozzle. I moved the nozzle to the center of the glass and placed a piece of card under it as shown. You may have to raise the nozzle up or lower it by hand using the two threaded Z rods on either side until the nozzle just rests lightly on the piece of card. Make sure you use a ruler or tape measure to keep the Z carriage an equal distance above the stepper motors on both sides. You should be able to slide the card from under the nozzle without the table moving up or down when you insert it again, you should just feel it holding the card lightly.
The next step is the total leveling of the bed :-) Use a tape measure on top of the stepper motors to check both sides of the Z axis to ensure they are both at the same height as shown below, Then level the four corners of the hot bed using the wing nuts. Firstly go slowly, Move the nozzle carrier to the left front corner while moving the hot bed towards the back of the printer, stop just about an inch in on both axis. Use the piece of card or similar to do the bed screw adjustments here too but this time use the wing nuts to adjust until you get the same results you had when you did the center of the glass/bed. When that's correct move to the right front side and check that, adjusting up or down on the wing nuts until the card just touches but doesn't make the bed move up or down. Proceed to do the 4 corners the same way and then do a quick recheck to make sure nothing was gained or lost while the others were being adjusted. When your satisfied with your bed leveling and the Z axis measures the same both sides , move the Z axis microswitch up under the Z carriage until the switch closes fully and tighten the screws as shown below.
Most of the different knobs and things I made to make this printer better will be listed at the end of this blog with full credits given to the great guys at http://www.thingiverse.com it's these people that give their time freely that makes 3Dprinting and design what it is today, they deserve a big hand and our thanks, and if we can support their efforts we should.
Next blog is all about our first print, yippee