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jit's build: Frame

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This page pertains to the Bukobot v1. Some portions may be useful to v2 owners. For more information, see here.


Find these:

From top to bottom, these are the frame top, frame bottom, two frame sides, and the electronics holder support.

Some of your frame pieces may be shorter.

Place the frame top and bottom parts next to each other, and compare their lengths. They must be exactly the same length.

Place the two frame sides next to each other, and compare their lengths. They must be exactly the same length.

Using your square, examine the cut ends of all four of those extrusions. They must all be exactly square.

Find this in bag 9:

Electronics Mount Support

From this last kit, take out the M5x16mm button-head screw and matching washer and nut, and set the rest of the kit aside for now.

(If you have the Azteeg X1 instead, this kit is the same except for the printed plastic part.)

Using the smallest aluminum piece, the electronics mount support:

Note that two washers are shown here. Your kit should come with two M5 washers for this purpose (although earlier kits may not).

Connect this to the frame bottom piece (don't tighten it yet):

If you only have one M5 washer, slide the electronics mount support over until the screw is near the end of the large extrusion with the open end of the electronics mount facing up. Look into the end of the slot and watch the screw while you slowly tighten it. If the end of the screw comes into contact with the bottom of the slot before you can fully tighten the screw, then your washer is too thin and you need a thicker one, or you need two washers. Washers can vary a lot in thickness.

Never drive the end of a steel screw into an aluminum surface. It will leave a mark. And, will probably result in an unreliable attachment.

When that is resolved, move the electronics mount support to the position shown above and tighten the screw enough so that it won't flop around. You will readjust its position later.

Z Mounts & Bottom Brackets

Next, find these, bags 10 (Z Axis Mount) and 2 (frame brackets bottoms) respectively:

(The current motor mounts look different, but work the same way)

Assemble Mounts

From the Z axis kit, take out the four motor mounts, the Z endstop sub-kit, eight M5x16mm button-head screws and eight M5 nuts, and set the rest of the kit aside for now.

Clean up the holes in these plastic parts that take M5 screws (see the image below for a hint). The screws should slip through the holes easily.

Apply two M5x16mm screws and two nuts to each of the four motor mount pieces, properly seating the nuts and then backing them off as before. Set these aside.

Assemble Bracket Bottoms

Apply nuts and screws to all the holes in the 4 rectangular frame bracket bottom pieces shown next. These are paired up, where in each pair, one of each pair has a foot attached. Most of the holes get M5x10mm screws, but one corner of one piece in the pair gets a longer M5x16 screw for the frame foot. The following are the first pair to assemble:

Above is a view of the pieces from the side that will go against the extrusions, and this is a view of the other side:

Below are images of a different (later?) style of mount

Frame Bracket Bottoms

Set aside the motor mounts for now. Attach the two rectangular pieces to one of the frame side pieces in the usual way:

(Make sure you are using a frame side piece, and not the frame top! The frame top is the same length as the frame bottom. The length of the two frame side pieces may be different than the length of the top piece.)

Check that the lower edges of the rectangular parts are fairly flush with the end of the extrusion. Also check that the frame foot is straight.

Attach the frame bottom:

Before you tap the frame bottom extrusion in, make sure the four slots (two on each side) are properly aligned with the rectangular plastic pieces. If not, adjust the position of one of the rectangular plastic pieces on the frame side piece.

It is also recommended that you check that the center two nuts of each corner piece do not freely rotate in their seats as you will not be able to slide anything down the channel to get these nuts to grab. If the nuts do rotate you can apply small slither of cloth tape or gaffer tape around the outside edge of the nut to make it slightly bigger.

Using the mallet, tap the frame bottom in until it is flush. Tighten the 8 horizontal screws (four on each side).

To get the bottom and side extrusions aligned exactly along the bottom surface, lay the currently unattached top extrusion piece down on a flat surface and then lay the corner join on top of this extrusion as shown below (you are simply using the top extrusion as an elevated flat surface). The vertical frame nuts of the join should be loose so the side extrusion can slide up and down. Then press down on either the bottom extrusion or the side extrusion until the corner is flush against the top extrusion piece on which the join is resting. Tighten remaining screws.


Top view:

Check that your assembly matches the above, and that nothing is flipped around backwards or mirrored.

Closely examine the place where the two extrusions touch. They must touch, with no gap. Pick the whole assembly up and look at the opposite side of the frame bottom, where they touch; they must touch, with no gap. It is very important that these two metal pieces are firmly against each other, as this contact is what assures that the X axis and the Z axis are perpendicular. If they are not perpendicular, then your printer will print weird parts.

Now assemble these:

Flipped over:

Add these parts to the remaining frame side piece (not the top piece):

Attach Y Axis

Before we attach the frame right side, we need to attach the Y axis to the frame bottom. The Y axis stepper motor goes out toward the back, on the same side as the bottom bracket feet. The two nuts hanging from the bottom channels of the Y axis slide into the top channel of the frame bottom extrusion:

Loosen the screw holding the electronics mount support and swing it back towards the bracket foot, and out of the way. Then slide the Y axis until it is roughly in the middle of the frame bottom, and slide the Y axis forward or backward until the two hidden screws become visible through the two holes in the Y axis extrusion. Reach through the holes with your hex driver and tighten the screws. We will adjust the position of the Y axis later.

Refer also to the comments here about improving the strength of the Y-axis joint.

Move the electronics mount support all the way to the left, pointing out the back and perpendicular to the frame bottom. Tighten that screw.

Now attach the frame right piece. Line up the free end of the frame bottom piece with the two vertex pieces already attached to the frame right piece, and insert. Check the alignment, and tap with the mallet until flush. As before, check that the fit is solid, top and bottom, with no gaps. Tighten all of the M5 screws.

Install Motor Mounts

Install all of the Z motor mounts. Insert one mirror pair of the Z axis motor mounts into the top end of each frame side piece, and slide them down until they are stopped by the rectangular vertex pieces, as shown farther down the page. Tighten.

Z Axis Endstop

Now assemble the Z axis endstop as shown below.

The adjustment wheel has a hexagonal depression on it for its nut. If the nut doesn't fit, use the adjustment screw to drive the nut into the part before assembling the rest of the endstop.

Bottom view:

Top view:

Note the nut under the head of the long M3 flat-head screw. Unfortunately you may not be able to install this nut if your kit was supplied with an M3 screw which is not threaded along its entire length (and the hole isn't big enough to fit an M4 nut). The purpose of this nut is to prevent the screw from rotating when the adjuster wheel is turned. You may need to use a balldriver to hold the screw in place when making fine Z-axis endstop adjustments if you can't fit the nut.

As before, you can drill out the smaller hole of the microswitch with a 2.5mm drill so that the screw passes through easily.

Front view:

Back view:

Install the Z axis endstop onto the right frame piece (the last extrusion you added). Tighten. You will adjust the exact location of this later.

At this point, carefully check that everything shown above has been installed, and is oriented correctly. The two plastic feet attached to the frame bottom are pointing toward the back.

Frame Brackets Top

Now find this in bag 1:

Add the eight M5x10mm screws and eight nuts to the frame upper vertex pieces, as we did with the other frame pieces. Insert the vertex parts into the ends of the frame upper extrusion:

Back view:

There are no vertex top pieces on the back.

Don't tighten the screws yet. Adjust the position of the vertex pieces on the frame top until they fit into the tops of the frame side pieces.

With the vertex pieces on the front, join the top frame piece onto the rest of the frame. Walk each end down, a millimeter at a time, keeping the two ends even. Adjust the vertex pieces sideways as needed. When everything is flush, tighten the screws. Make sure that there are no gaps between the metal pieces, as this would affect the perpendicularity of the axes.

Now that the printer has three feet, it can stand on its own without falling over. Check that everything is properly aligned and the connections flush, and all the screws tight.

You may find that the printer has little weight on the Y axis foot, and tends to rock backwards onto the Y axis motor. As you add more parts to the printer, it will stop doing this.

Center & Square-Up Y Axis

Loosen the two screws holding the Y axis in place, and move it to the exact center of the frame bottom piece (measure it). Tighten one of the two screws enough so that the Y axis won't slide around, but can still be rotated around a vertical axis. Then use a square to make the Y axis exactly perpendicular with the bottom frame. Tighten both screws, without losing this alignment.

The above shows one way to use a square to help make the Y axis perpendicular.

If you have a Duo you might consider the following idea rather than “centering” your Y-axis (you still want it perpendicular however): With two extruders it is useful to be able purge both hot-ends without having to move the X-axis to each side of the print bed. Unfortunately this is not possible when the Y-axis is positioned in the center of the frame (another 10mm in frame width would have been very useful for the Duo). Instead, to accomplish this you need to:
* position the X axis end-stop all the way to the left of the frame so that the end-stop switch clicks when the X-carriage is around 2-3mm from the frame edge (don't worry the end-stop switch is only used when homing and the X-carriage doesn't approach the stop at high speed; in all other circumstances the controller ensures that the motor is never moved to less than 0 position)
* then position the Y axis so that the nozzle of the right-hand extrude just clears the edge of the Helios heated bed indent (i.e., imagine X represents the nozzle and the line is the edge of the hot bed /----\_X___/----\_____/----\ )
This does mean you will lose 5mm off the right-side of your print area for your left extruder unless you position you glass slightly to the left of center on the hot bed - which is not a problem for PLA (and you'll get varying results if you try to print right to the edge of the heated bed glass with ABS anyway); however it does mean that you can easily work on both your extruders without having to move the X-carriage around. Remember to set you X-Max in Repetier-Host and Bed Center in Slic3r correctly to avoid hitting the right-hand side of the frame (i.e. set these to 5-6mm less then what they would otherwise be).

If you ever bang into the printer and jar it, check to make sure the Y axis is still square. Also check it every time you transport the printer, even if it's only across the room. This adjustment is the only thing keeping the Y axis perpendicular with the X axis.

Prev: Y axis < Up to Jitsbuild > Next: Z axis

The contents of this page may be re-used under any of the following licenses: The Creative Commons Attribution-ShareAlike 3.0 Unported License (CC BY-SA 3.0), or the GNU Free Documentation License (GFDL, version 1.2 or later). Nothing on any of these pages is there to tell you what to do, only what other people have already done.

jitsbuild-frame.txt · Last modified: 2014/01/25 17:42 by jit