XY Carriage Design

The XY Carriage is the hardware that carries the Extruder Carriage back and forth in 2 dimensions. For my design, the Extruder Carriage is moving in the X (short) direction and is carried by the Y Carriage which enables the Extruder Carriage to travel in the Y (long) direction. The extruder carriage design, and it's evolution, is covered on the Hot Ends, Extruders & Carriages page.

X Rod Calculation
[note: it's easier to talk about this is you visualize the X rod vertically. the references to above/below in what follows will make sense.]
The calculation for the length of the Y (Support) Rods is stright foward, but, because it's a dual extruder design, it's easy to miss some measurements.
The extruder carriage has 2 extruder mounts that are X.mount (44mm) apart.
They are located X.edge (46mm) from the edge of the extruder carriage.
The total X height of the extruder cariage X. carriage is: X.carriage = (X.edge) * 2 + X.mount
We'll add an additional 2mm for clearance between the extruder carriage and the y carriage. X.carriage.clear = 2mm
The Build plate X dimension is X.build (212mm). We'll add 5mm to that on each side so the extruders can actually go over the edge. X.build.clear = 5mm.
Here's the fun part. For the lower extruder to be above the top edge of the build plate the space required is:
X.top = X.build.clear + X.mount + X.edge + X.carriage.clear = 5mm + 44mm + 46mm + 2mm = 97mm
The same calculation applies for the upper extruder to be below the bottom edge of the build plate. X.bot = X.top
Finally we have to add in the depth of the shaft mounts on each end of the rod X.Shaft.
X.rod = X.shaft + X.top + X.build + X.bot + X.shaft = 20mm + 97mm + 212mm + 97mm + 20mm = 446 mm

For the actual calculation, please consult the Dimensions spreadsheet.
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[following belongs on the hot ends/extruders/carriages page]
platform that carries the extruder(s). To minimize the moving weight they should really be Bowden style extruders with the drive motor mounted on the frame and only the hot end on the carriage, but there are examples of designs where direct drive extruders have been used.

Some of our inspiration for the XY Carriage comes from the following sources
OpenX - http://reprap.org/wiki/OpenX
The Goal is to create a lightweight, minimal x carriage. the carriage will have a large central opening to facilitate various hot end designs, and provide enough room to insulate the hot end. From that we followed the following:
00str00der - reprap.org/wiki/00str00der
in particular the reference to the Sheliak X-Carriage here: reprap.org/wiki/00str00der
PrismX 3D Printer Machine Source Code by Terawatt Industries - terawatt-industries.github.io/prismx-scad/
The PrismX - Open Source 3D Printer - http://prismx.terawattindustries.com/index.html
and http://store.terawattindustries.com/76-prismx-3d-printer.html
PrismX - http://reprap.org/wiki/Prismx
http://kuehlingkuehling.de/2013/02/13/the-kuhlingkuhling-reprap-industrial/
Ducted extruder carriage for Rapman - http://www.thingiverse.com/thing:15044
HX1-Mod Quick-Fit X-Carriage - http://www.thingiverse.com/thing:25974
Budaschnozzle X Carriage For Mendel90 - http://www.thingiverse.com/thing:31596
Orca V0.3, X Carriage, LM8UU - by doommeister, published Mar 25, 2012 - http://www.thingiverse.com/thing:19837
Simple modular x-carriage for Prusa (igus bushings) - by mattproc, published Feb 9, 2013 - http://www.thingiverse.com/thing:48761
Dual Jhead extruder & carriage, design for prusa air 2 - by Arexma, published Jun 4, 2013 - http://www.thingiverse.com/thing:98485

For Bowden Design info see Extruders & Hot Ends Page

[following belongs on the parts pages]
Linear Bearings & Rods
for background on Linear Bearings and Rods see http://reprap.org/wiki/Linear_bearing and
the RepRap forum - Finding Smooth Rods - http://forums.reprap.org/read.php?4,201725,205353

The traditional reprap build material is the 8mm smooth rod. It was sufficiently rigid for the initial machines. As machines have gotten bigger the rods should have gotten larger. A 10mm rod is 2x as stiff as an 8mm one. [Side Note: 12mm bearings are only marginally more expensive than 10mm ones - go larger!] Because of difficulties in aligining a pair of rods to guide a carriage, some builders have gone over to pre-assembled carriage and rail systems. Ground and smooth, chrome plated, hardened steel rods intended to be used as linear guides are available from a number of suppliers. It is also possible to use drill rod. Hardened Rod is not easy to cut and the ends should be ground smooth if you do. Consider getting cut to length rod from your supplier.

 Linear Bearings

McMaster
Fixed-Alignment Linear Ball Bearing
Closed, High Temperature Steel, for 10 mm Shaft Diameter
http://www.mcmaster.com/#63255k46/=sxc55o
63255K46 $18.17 Each
Metric Frelon-Lined Linear Bearing
Tight Clearance, Closed, 6061-T6 Aluminum, for 12mm Shaft Diameter
http://www.mcmaster.com/#60605k93/=sxcf71
$18.48 Each - 60605K93

VxB - http://www.vxb.com
LB10UU 10mm Ball Bushing 10x19x29 Linear Motion Bearings - Price: $2.95
Ball circuit: 4 - Size: 10mm x 19mm x 29mm
LM10UU Linear Motion 10mm Ball Bushing - Price: $2.95
Ball circuit: 4 - Size: 10mm x 19mm x 29mm
Diameter is 10mm, Bearing outer Diameter is 19mm and Bearing Length is 29mm.

internet/ebay suppliers
2pcs 19mm x 10mm x 29mm Cylinder LM10UU Linear Motion Ball Bearings -  Price: $5.99   
http://www.sourcingmap.com/2pcs-19mm-10mm-29mm-cylinder-lm10uu-linear-motion-ball-bearings-p-471034.html?utm_source=google&utm_medium=froogle&utm_campaign=usfroogle&gclid=CPbQ2Pih1b8CFQxp7AodYiEAZg
Double Side Rubber Seal 10mm x 19mm x 55mm Linear Motion Bearing LM10LUU - Price: $7.95   
http://www.sourcingmap.com/double-side-rubber-seal-10mm-19mm-55mm-linear-motion-bearing-lm10luu-p-298072.html?utm_source=google&utm_medium=froogle&utm_campaign=usfroogle&gclid=CNmo-oCi1b8CFQto7AodFT4AIw

http://www.ebay.com/usr/jsbgreatbearings
(Qty.1) LM10UU linear motion ball bearings 10x19x29 mm LM10 linear bearing
http://www.ebay.com/itm/like/141312111496?lpid=82
q1 - $2.81, q2 - $5.30, q10 - $16.47 - free ship
(Qty.1) LM12UU linear motion ball bearings 12x21x30 mm LM12 linear bearing
http://www.ebay.com/itm/Qty-1-LM12UU-linear-motion-ball-bearings-12x21x30-mm-LM12-linear-bearing-/141312127088
q1 - $2.99, q2 - $5.50, q10 - $17.17 - free ship
-- no stock for LMxxLUU

http://myworld.ebay.com/jamesbondtb/
10pcs LM10UU 10mm Linear Ball Bearing Bush Bushing
q2 - $5.00, q10 - $10.00, q12 - $12.50 - free ship
4PCS LM10LUU 10mm Linear Ball Bearing Bush Bushing New (long!)
q1 - $6.00, q2 - $8.00, q4 - $16.00 - free ship
2pcs LM12UU 12mm Linear Ball Bearing Bush Bushing
q2 - $5.00, q10 - $11.50, q12 - $13.00 - free ship
2pcs LM12LUU 12mm Long Linear Motion Bearing Ball Bush (long!)
q2 - $8.00, q4 - $15.00 - free ship

Misumi - shaft - http://us.misumi-ec.com/vona2/mech/M0100000000/M0101000000/
Misumi - bearings - http://us.misumi-ec.com/vona2/detail/110300026540/
Misumi 12mm linear bearings - used to DL the cad files
LMUMF12L - $40.02 - 12x30x21 - single length
LMUWMF12 - $26.01 - 12x57x21 - double length

Rails & Carriages
Another approach thats gaining traction is to use a rail and carriage system that's manufactured for linear motion applications and available off the shelf. It typically has the advantage of minimal alignment issues. The two suppliers noted here offer a dry lubricated slide (think teflon). There are many who offer ball slides but those are significantly more expensive.

Igus - Drylin Line of rails and carriages - http://www.igus.com/drylin
PBCLinear (used in the A1) - http://www.pbclinear.com/Gliding-Surface-Technology--Plain-Bearing-Linear-Motion

Contact Information
Contact me using: fpirz (at) media (dash) conversions (dot) net

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