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jit's build: Y carriage

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


You will need from bag 14:

Note: The Bukobots smaller than 8” have a different carriage design. The Y carriage is a single piece of flat aluminum (the “Y carriage Y-Plate”), and not four pieces that have to be assembled together and aligned; also, the kit shown above may be different. If you have this smaller carriage, skip down to here.

8" Carriage

These four pieces of aluminum are needed:

Note that there is another straight aluminum piece of the same length in your kit, but with a hole drilled near one end. You don't want that one now.

T-Plate & U-Plate Screws

Start by putting the 8mm screws (the shorter screws in the bag) into the slotted holes in the flat parts as shown:

Their heads should be flush with the flat plates. It might be a tight fit; just screw them in. Then add the eight nuts, making them flush with the ends of the screws - this leaves space so the nuts fit into the channel.

Attach T-Plate to Channels

Turn the smaller “T-Plate” flat piece over, and slide the two nuts on one side into the channel of one of the straight pieces:

Try to make the end of the straight piece flush with the edge of the flat piece. Simultaneously, use a carpenter's square or T-square, or some other object with a known accurate right angle on it, to square up the corner. (The corner of a shelf is used here.) When the parts are flush and square, tighten the screws. You may have to get a good grip on the metal pieces with one hand while turning the screw with the other, as they will probably try to shift as you tighten.

The nuts may freewheel inside the channel when you turn the screws. To prevent this, jam a small flat-blade screwdriver next to the nut (don't use your expensive ball-end hex driver for this!). One side of the nut will grab the screwdriver blade as you turn the screw, the other side will push it out; use the grabbing side. Don't forget to remove the screwdriver afterwards.

Attach the other side of this T-Plate piece to the other channel. Make it square and flush in the same way. If you don't have a square object that fits between the two arms, check that they are parallel by measuring the distance between them with a ruler, at both ends.

Attach U-Plate to Channels

The remaining flat piece, the U-Plate, connects into the other end of the channels. To set its position, use your platform (heated or unheated bed) as a gauge.

(If you have a heated platform: Remember that the heated bed is one of the more expensive single components of your kit. Don't damage it by applying excessive forces to it during the following procedure.)

Lay the bed upside down on a cushioned surface:

Find your platform mount kit and get out the three flat-head screws (in the small bag with the orange pieces, bag 14b). There should be two long ones and one short one. Lift up the bed and insert the screws through from the underside, as shown above. The heads of the screws fit into chamfered holes.

Set the metal parts on a flat surface (not the heated bed), screw heads facing up, and slide the four nuts on the last flat part into the channels in the straight pieces. Tighten the four screws, and then back them off just until the four nuts slide freely in the channels.

Gently set this assembly onto the inverted bed:

Line up the two holes in the loose half of the metal assembly with the two longer flat-head screws at one end of the bed, and pass the screws through the holes. Then shift the other part of the metal assembly until the third flat-head screw lines up with its hole. Check that all three screws are vertical and not tilted. (The shorter screw may not be long enough to reach the hole in the T-Plate, so just peer down the hole and look for the screw.)

When everything lines up, apply just enough pressure to the flat metal piece to prevent it sliding over the straight pieces, and gently tighten the four loose screws, just until you feel some drag on the screws - you don't want to press down on the bed so much that you damage it. Then carefully lift the metal assembly off the screws and move it to another flat surface, and tighten the screws the rest of the way.

Move the assembly back to the bed and check that everything still lines up. Then set this assembly aside.

Lift the bed off of the three flat-head screws and put it back in its protective packaging. Put the three screws back in their bag, but don't put the bag away just yet.

Completing the Y Carriage

Attach the Standoff

From the platform mounting kit, you will need the M3 button-head screw and the M3x14mm standoff. Put the rest of that sub-kit aside for now.

The screw and the standoff go at the end of the carriage that has one hole. The screw goes on the bottom of the carriage plate and the standoff goes on the top, pointing up. (The slots in the long aluminum pieces face up, unless you don't have the long aluminum pieces, in which case it doesn't matter.)

Make sure this screw is tight, and check it occasionally when you're using the printer. If it loosens, the back end of the platform will wobble excessively and mess up your prints.

Many of the following images don't show the standoff. They should.

Assemble the Bearings

Find the remaining linear bearing hardware: linear bearings, bearing holders, 5Mx10mm button-head screws, and nuts (four of each). Trim the holders if needed, and assemble them as described in jitsbuild x carriage. Don't apply cable ties at this time. Set these assemblies aside for now.

Y Tensioner Clearance

Find this:

Attaching the Y tensioner to the Y carriage must be done with care. There is very little clearance under the Y carriage, and the screws protruding beneath it might collide with another part while the carriage is moving. To prevent this, you could cut 2mm off the end of the Y tensioner attachment screws, or you can simply put a 2mm spacer under the head of each screw. This kit provides M3 nuts to act as spacers, one nut per screw.

Alternatively, if you have the parts, you can substitute a stack of washers instead of the nut. A stack of three M3 flat steel washers fits quite well: two 7mm diameter washers, and one 9mm diameter fender washer. These are the same kinds of M3 washers used elsewhere on the printer. They fit better than the nut, and make it easier to adjust the tensioner.

The nut spacer is shown on the left, and the alternative spacer made of washers is shown on the right:

Choose which method you will use, and put the chosen spacers on the three M3x20 button-head screws.

Attach the Bearing Assemblies and Tensioner parts

Attach the bearing assemblies and the tensioner parts to the metal assembly as shown. The exact positioning of these tensioner parts will be determined later when assembling the Y axis.

Get out one of the precision steel rods and use it to make sure the linear bearings are straight before you tighten the screws on the bearing holders. Make sure you insert the nice end of the rod, and don't bang the end of the rod against the bearing balls inside.

Bottom view:

Note the nut on the long flat-head screw, between the two plastic parts. It fits into a hexagonal depression on the rectangular plastic part.

The small white semicircular printed plastic part on the end of the long screw is the Y synchromesh tensioner. Without the synchromesh cable in place, this part is likely to fall off and get lost. So put it back in the bag for now.

Top view, with the kit-provided nuts as spacers:

Top view, using washers instead for the spacers:

Next: Y front end < Up to Jitsbuild > Next: Y 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-y-carriage.txt · Last modified: 2014/01/25 17:41 by jit