MiniMill DownFeed HandWheel Mod

This hand-wheel mod was made specifically for a LittleMachineShop Model 3900 HiTorque Mini Mill, but is should fit similar models, or other makes and models of bench top mill that use the sane type of three-spoke down-feed crank.

CAUTION : It is NOT necessary to remove the three-spoke crank to install this hand-wheel. However, if you do remove the three-spoke crank from your mill, be aware that there is a spring and ball bearing under the hub set screw which will fall out and get lost if you are not careful. I did remove the three-spoke crank from my mill for the purpose of getting accurate dimensions, and to facilitate test-fitting prints.

Note that I have included a dimensioned drawing of the three-spoke crank so you can see if you have an identical version.

Ideally, this print could have been made in two circular halves. However, this resulted in a print that was too big to fit my printer, so I broke each circular half into three sections, and overlapped the inner and outer sections for greater strength. 

Assembly

In addition to the 3D printed parts, the following fasteners are required :

• M3 x 16 SHCS (qty 12)
• M3 nuts (qty 12)

Assembly of the hand-wheel is straightforward. Note that there is a total of six printed pieces - three “inner” (closer to the mill) pieces, and three “outer” farthest from the mill) pieces. The “inner” pieces can be further identified by the presence of hexagonal holes for the M3 nuts.

Begin assembly by placing one "inner" and one “outer” piece together so that they form a socket for one of the handle knobs, and screw the two pieces together with M3 screws and nuts. DO NOT OVERTIGHTEN or you risk cracking the plastic. Repeat this for the two other inner/outer pairs to form three sub-assemblies (see photos). Each of the sub-assemblies can then be placed over each of the three crank knobs, and then screwed together for final assembly.

Print Instructions

Print the parts in PETG using the 3mf files provided; otherwise :

• 0.3mm layer height
• perimeters = 3
• infill = 15% grid
• supports required under the socket holes

Note that the provided 3mf file print one “set” of an inner and outer section; three such sets are required.

CAD

The OnShape 3D CAD files for this are here :

https://cad.onshape.com/documents/74e0398e244695e605089b53/w/207d03a9e9261926831a000b/e/90b48852e46abfeb71b63983