This is another Y-Carriage for the Tevo Tarantula. This replaces both acrylic parts of the Y-Carriage. The part is designed for those people who are using either the stock roller hardware or a MGN12H Linear Rail for the y-Axis.
This Y Carriage is part of my Heat Bed Assembly:
The carriage is designed to remove the common stress points for other designs, which occur commonly at the point of attachment (corners of the mounting plate). It also uses the engineering concept of the I-beam to provide maximum stiffness along each arm, while reducing the overall weight of a printed part to be as close to the original acrylic part as convenient to the design.
This design achieved greater stiffness than even a 4mm Aluminum Plate (though could not improve on Alu's weight reduction).
1x Lower Plate
2x Top Plate (or) Top Plate_NoSupp
8x M3x15 Bolts
8x M3 Nuts
All original Y hardware for rollers/linear rail
Optional - 8x M3 Washers
The original version included fillets in the design and these created drastic overhangs that ended up with significant stringing. However, it was not unusable, as the printed version shown in the pictures is the original design. But in an effort to reduce potential problems or at a minimum to reduce the requirement for post-processing, I have switched the fillets to chamfers and the angle should be less than 45deg. This is true for all models.
The top plate was redesigned to remove the embedded holes for the screws/bolt. I did this to remove the required support material for those sections (it was horrible to remove). It should look much cleaner now, and the design has ample room for the screw heads to show above.
However, there was a design issue that I could not resolve. I wanted to ensure that my design maintained the original print profile and did not increase the height of the print surface. This requires a small section at the tips of the top plate to be printed with supports. However, I have also included in the files a no support version, but to remove the requirement for supports, I had to increase the height of the build plate by 5mm. I don't know if people will care, so I included both files.
I printed my part using the above settings. Recommended Material ABS. PLA is also acceptable as heat under the bed is not a major Issue. I printed in PETG, but have noticed that the rigidity of PETG is not what I had wanted.
Designed for a line width of 0.4, with 4 loops, plus 1.6mm walls all around (8 layers top and bottom). Given the size of both parts, I highly recommend printing with a brim of at least 10 loops. This will help to reduce the chance of the part lifting up due to thermal stresses. [My Glass plate made a nasty sound as it relaxed when I released my PETG prints]
To help adjust settings, I have provided a settings test, so that you can verify that your printer can produce the part as required, without getting halfway into a 10hr print.
Infill percentage is your choice. Maximum stiffness will be achieved at 100% infill, but that increases the overall mass of the part. The expected mass with 100% infill is about 280g. This is about 80g more than original mass of both acrylic pieces. I am betting that reducing infill can bring me to within a comparable weight without affecting stiffness too much.
Last note for testing: there is a length test print, that you can do to ensure that your length scaling between the x-y axis are equal. The print is 209mm which is the distance between the holes at the corner of the build plate, and the corners of the top plate as printed. If it does not print at 209mm investigate the scaling on your x-y dimensions.
The parts are intended to fit together without any necessary post-processing. There is no tolerance, so it is a snug fit. But they create a very good friction fit as designed. to ensure that your printer does not require any scaling for the printed fit, I have included a fit test piece; Pint either the settings test piece, or the bottom plate first, and then the test piece to verify that your print will be adequate.
The parts are designed to be assembled with 8x 15mm M3 Hex Head Fasteners; 4 per top plate.
Assemble the wheels to the base plate first using all the stock Tevo hardware. Then attach the top plates. Once you have assembled all the parts for the Y-Carriage, slide the mount onto the aluminum extrusions. (Alternately if you do not want to remove the y-belt idlers, you could assemble the top plate in place, tightening all the screws once they are in place on each side of the aluminum extrusion.) Once on the aluminum extrusion, attach the y belt and tension down with your choice of clips and tensioner. Then attach to hot-plate with stock Tevo screws and springs. You can use your choice of thumb screws, however, I have produced a matching set to keep the style of the y-carriage the same
Note if you fit the parts together before you have attached the hardware (like I did... even after writing my own instructions) you have two options: first, you can use a small pair of pliers to hold the nut in place. It was tight but did work. Alternately, you could switch the nut and flat washer to the bottom and have the screw head facing up; the hole was small enough that this wasn't going to cause a problem.
The design was tested using a simple static stress-strain analysis within Fusion 360. The wheel mounting points were held in place as constraints and a force of 0.1N was applied to the end of a single arm to determine deformation. Notes on the simulation can be found at the link below.
This was compared with the original acrylic. The plate as designed should have a more than 10X increase in the stiffness versus the original.
A comparison of other y Carriages can be found on the Tevo Tarantula users facebook group (https://www.facebook.com/groups/TEVO.3dprinter.owners/permalink/1659864224107545)