Low gear ratio belted gearbox for 3D Sets Rancher RC

Just to clarify - this model contains changed files only (based on Model 6 v 1.1.2), to build the whole thing you need other parts from one of the Rancher models from 3DSets: https://3dsets.com/product-category/3dprintable-models/3d-printable-car-models/rancher-4x4-lineup/ 

I can not guarantee that the provided model will work, print correctly or that it will be durable - it works for me (at least for now). 

Inserting the gearbox requires to disassemble the front windshield. Also the Font floor mats won't fit with the modified gearbox (for now I didn't made an upgrade to that).

Keep in mind that due to low gear ratio (32:1 instead of the default belted ratio 8:1) RC model will be slower (compared to the geared gearbox 29.4:1 ratio), but it will have an excellent crawling capabilities.

Recommended setups:

• Standard belted gearbox (8:1) - use the proposed by 3DSets (or bigger) brushless motor, for an emergency solutions you can use a 540 motor 55T paired with 1080 ESC (the motor will work on normal rides quite well, but will get super hot if you try to use it for crawling)
• Standard geared gearbox (29.4:1) - use the default setup proposed by 3DSets (but you can use a 21T 540 motor with 1080 ESC) or a Hobbywing Fusion brushless combo (risky due to high engine torque).
• Low ratio belted gearbox (32:1) - it should be able to work with 21T 540 motor or Hobbywing fusion without problems.

It is recommended to use more durable filament for the pulleys (and more heat resistant) like PC Blend - after a long ride with PLA pulleys I've noticed that the pulleys got loose in the bearings. This happened probably because on the slightly warmer PLA pulleys (after constant 15 min. ride near vmax) the forces acting during rotation slightly crushed the shaft in the bearings.

Bearings and pulleys must fit tight, feel free to slightly scale up the pulleys if they are loose - without that the gearbox would rattle loudly, and it will probably break in a short time.

On models Gearbox Housing - front Fusion.3mf and Box Front D_mod.3mf the two horizontal holes are spaced by 25mm (for 540/550 motors), other holes are spaced by 25.4mm (for Hobbywing Fusion motors).

Print the required models using the default 3DSets presets for the same part types.

For (29.4:1 ratio) Geared gearbox modification print the following file:

• Gearbox Housing - front Fusion.3mf - this plate allows using a Hobbywing Fusion motor with geared gearbox. Keep in mind that due to high engine torque the gears and shafts may not last very long. Fusion motors don't get hot (with this gear ratio), so there is (probably) no need for printing the part with high temperature resistant materials like ABS.
• Use M3x8 (instead of M3x10 screws) for mounting the Hobbywing Fusion

For Belted gearbox you have two main options:

1 - Longer Box Middle - useful only if you plan to use a standard 8:1 ratio gearbox but shorter by 42mm, the reason is that on the -48mm version the Box Middle would extend past the Box Front D, and that would look odd.

Print Box Middle -42mm.3mf and Shaft Long -42mm.3mf and a recommended Motor pulley - 14T sprocket.3mf (described further).

With this setup and 8:1 ratio gearbox I recommend printing also the Box Front C_front.3mf instead of the standard part, because it has extra screw holes on the bottom for rigidity (use two M3 nuts and M3x12 screws) and it has a corrected hole depth (original model has a slight error on one hole).

2 - Short Box Middle - the go to if you want a 32:1 gear ratio gearbox

Print files:

Box Middle-Mount -48mm.3mf
Shaft long -48mm.3mf
Box Front B_mod.3mf
Box Front C_rear.3mf
Box Front C_front.3mf
Box Front D_mod.3mf
Pulley new.3mf (2x)

For both options you need to print:

Dashboard.3mf
Windscreen frame.3mf

Chose one of the motor pulleys:

Motor pulley - nuts.3mf / do not use it with the 8:1 gearbox, even with brushed motor the torque will quickly damage the pulley shaft hole (see picture)
Motor pulley - 14T sprocket.3mf / more reliable version, requires 14T sprocket - same as it is mentioned in the 3DSets Model 7: Buggy

If you are using an older Hobbywing fusion (which is 63-64mm long) you may need to print the following parts:

Front panel mount.3mf / nothed version, without it the longer motor will not fit (see pictures)

If your motor interferes with the servo you may need to print:

Servo washer -4mm.3mf / place it between the servo and chassis (to lower down the servo)
Ball joint servo -4mm.3mf / if the servo is lower, we need to shorten the ball joint :)

In the cross section pictures you can inspect how to assemble the modified gearbox, all the red and yellow parts are modified, all green parts you have to print from the original 3DSets files listed below.

Original Gearbox Housing files:

Box Front A.stl
Box Front B.stl (original)
Box Rear A.stl
Box Rear B.stl
Box Front A Cover.stl
Box Front B Cover.stl (2x)
Box Front C Cover.stl (2x)

All the original pulleys (with two extra Pulley Shaft small S or L size) except:

Shaft Long.stl
Pulley 1 - Motor - A.stl
Pulley 1 - Motor - B.stl

Required extra screws and stuff:

bearings - 4x (same type as the others: 10x15x4)
timing belts - 2x (same type: HTD 144-3M-06)
M3x8 - 2-4x (for mounting the Hobbywing Fusion to the Box Front D_mod)
M3x10 - 2x (for connectingthe modified Box Front B_mod to Box Front C)
M3x12 - 5x (for Box Front D_mod and extra rigidity on Box Front C/Box Middle)
M3x16 - 2x (for connectingthe modified Box Front B_mod to Box Front C)
M3x25 - 4x (or 8?)
Respective amount of nuts