HOMEMADE BENCH TOP MILLING MACHINE

Practical homemade micro miller for low carbon steels, cast iron, wood, plastics and non-ferrous metals. Built from common materials and simple hand tools. This machine can be scaled up as desired and offers a noteworthy return on investment.

[A] Overview:

1. Minimum of 1 meter Aluminum T-Slot Extrusion
2. Fasteners and hardware to suite Extrusion Type
3. 1 x 90 Degree Bracket to Suite Extrusion Type
4. Steel / Masonite Plate
5. ~0.2 mm Plastic / Brass / UHMW-PE / POM PTFE Composite Sheet
6. Stainless Steel Threaded Rods to suite Extrusion Type
7. Brass / plastic / wood / aluminum nut to suit spindle / feed screw choice
8. Paint
9. Way / Hydraulic / Heavy Motor Oil
10. 160, 220 Grit Sand Paper
11. Glass Sheet / Mirror / Window Pane / Granite Tile, etc
12. Mild Steel Flat Bar to Suit
13. Steel / Hardwood Base Plate
14. Rubber Feet and or Mounting Bolts

[1] Basic Tools Required

[1.1.1] Hand Tools:

1. Hack Saw with a 24 TPI bi-metal Blade
2. File (Optional)
3. Paint Brush - 19 mm

[1.1.2] Power Tools and Accessories:

1. Corded Drilling Machine
2. Selection of Drill Bits to suit (⌀3.5, 4.8, 5, 7, 8, 12)
3. Step Drill ⌀4-32 mm
4. Hole Saws to suit i.e. ⌀43 mm, ⌀48 mm, etc.

[1.2] Optional Tools

1. 115 mm Angle Grinder
2. Bench Grinder
3. Small Carbide Round Burr, 3 mm Shank
4. Belt Sander
5. Metric Thread Taps
6. Pedestal Drill Press

[2] Spindle Suggestions

1. Mini Die Grinder / Rotary Tool
2. Drill / Power Tool with ⌀43 mm EU collar
3. 6 mm Die Grinder
4. Air Die Grinder
5. ER11 Spindle
6. 3/4" 20 TPI Drill/Mill Spindle ( In Development )

Terms:

Threaded Rod = All Thread

TPI = Teeth Per Inch (Hacksaw Blades)

Pedestal Drill = Column Drill Press

Masonite = press-board / Quart-board

UHMW-PE = Ultra High Molecular Weight Polyethylene

POM PTFE Composite = polyoxymethylene resins and polytetrafluoroethylene

Materials Selection Notes:

1. See the MaterialGuide_v1 attached or
2. Download the Project Guide attached below for the best building experience. Includes:
3. 3D CAD Models
4. A4 Print Ready Templates
5. Material Selection Guide [ UDM200b_MaterialGuide_v1_25-01-29 ]
6. NOTE ON CAD FILES - the files are of an early prototype and are currently being updated. However dimensions and 90% of bolt holes are the same.
7. A complete bill of materials will be made available once a popular design emerges
8. A builder is encouraged to deviate from these plans as needed; to suite different materials on hand, budget, methods of construction, etc.

Where to Buy:

1. Aluminum Profiles: mcmaster.com
2. Other Materials: any decent hardware store

Disclaimer:

This document and all attachments are provided 'as is' and with no guarantees of any kind whatsoever. This publication is intended for use by suitably competent persons; designs are replicated at your own risk. WARNING: Wear eye protection. Remove jewelry and loose clothing. Tie up long hair. Exposure to harmful substances may occur. Risk of physical injury. Not recommended for Children under the age of 13. Adult supervision is strongly advised. Follow standard safety precautions as with any power tool.

Design Features:

1. Machining accuracy of 0.049 mm or better*
2. Axis locks on all axis'
3. Sufficient weight and rigidity to tackle most materials
4. Absolutely no specialized tooling or materials are required for construction
5. Expands your workshop / making capabilities by a large margin
6. A full maker's experience.

Cost Reducing:

1. Build using only 1 linear meter of T-Slot Profile, 1 x 300x300x5 mm plate, a few off cuts of 12x12mm square bar and standard fasteners - as an option. (The mini mill covered in this instructable uses a few more materials)

Dimensions and Specifications (mm):

MACHINE HEIGHT: 300

TOTAL HEIGHT (WITH ROTARY TOOL): 500

MACHINE LxWxH: 450 x 350 x 500

X TRAVEL: 200

Y TRAVEL: 90

Z TRAVEL: ~ 65+

TABLE DIMENSIONS: 300 x 35

T-SLOT SIZE: 6 mm

WEIGHT: ~ 6 KG, EXCLUDING SPINDLE and SPINDLE BRACKET

ROTARY TOOL: 130W, 220VAC, 8000-30000 RPM

Comparing Assembly Methods:

1. Bolt Only - No Threading
2. Relies on threaded rods passing through components
3. when threads are a must, threaded nuts are held captive in oversize holes
4. More components are required overall
5. Shims may also be used to substitute captive nuts and bolts as desired
6. Higher assembly tolerances (more forgiving during assembly)
7. Bolt and Studs - Hand Threading
8. Fewer overall components are required
9. Fewer assembly steps
10. Can result in significant time savings
11. Tapping set required
12. Less room for error

*Relies on accuracy of aluminum profile used. Using ME16 Extrusions typically results in ± 0.03 mm level of precision.

All materials are cut to size according to the cut list, holes drilled, chamfered, deburred and sharp edges broken.

All faces making contact with an aluminum surface should be 'trued up' by sanding (or scraping) the surface to an acceptable level of flatness.

Remember: the accuracy of the machine stems entirely from how well each component is made to interact with the Profile Extrusions. And so, it is helpful to ensure that all parts are prepared as carefully as possible and that high quality aluminum extrusions are used.

Purpose of Column Design

The column forms the main structure of the milling machine and all other assemblies are fitted to it. Every force acting on and through the mill will almost certainly pass through this assembly and so the design should reflect that. There are a few main challenges to consider. Firstly, the two sliding planes must meet at 90 degrees. The extrusion's faces which are exposed outwards must be flat relative to the same vertical plane - there can be no twists or bends in either piece relative to one other. And, lastly, the structure must overcome forces that would otherwise cause bending or separation of the two perpendicular extrusions.

In keeping with the original design principles of affordability and accessibility, this approach has been conservative. For added performance the width of the column side panels and be increased and larger aluminum sections used.

Reducing Friction and Wear

Avoiding metal on metal contact - whenever two metal surfaces are to slide or rotate about each other, steps are take to keep the respective parts from touching. The main method employed to do this in this build is by adding a layer op plastic and effectively two oil films - one on either side of the plastic divider. This method has two main drawbacks, there is increased deflection in all axis' due to there being two individual oil film layers and the plastics used are not hard wearing nor self lubricating. One solution will be to use engineering plastics like those mentioned in the materials break down.

SUMMARY OF PARTS USED

M8 SS Threaded Rod / Bolt 150 mm AND 400 mm in length

M8 Brass Nuts

Plated Steel washers

Fibre Washers

4.3 mm Unhardened Nickle Plated BBs

Mild Steel Cutouts left over from drilling

Mild steel handle fashioned from 5 mm thick flat bar

M5x25 mm SS Grub Screws

DIY THRUST BEARINGS

Here, a method of easily producing your own thrust ball bearings is demonstrated. There are several disadvantages the biggest of which is producing an evenly deformed washer. If the set up is not perfectly centered and square to the force applied, the washer warps and is not suitable for use. A better approach is using flat washers only and holding the rolling elements captive in a ring or cage.

The fiber-washers tend to deform over time but offer smoother operation and have performed well in testing, better options may be stainless steel or brass. The rolling elements are 4.3 mm unhardened steel BB's. As shown, tape is wrapped around the assembly to retain the rolling elements and oil (grease is used in the open type). A further improvement would be a layer of PTFE plumbers tape between the rolling elements and outside layer of tape. These designs are experimental and don't outperform standard thrust bearings of course.

BRASS NUT AND SS THREADS

The brass nut and stainless steel threaded rod paring offers almost zero backlash in this case. Traditionally a faster wearing material like brass or bronze is used with hardened spindles to significantly reduce wear in the expensive part, rendering the nut as a wear item instead. In this scenario the nut is a similar cost to the spindle and so focus can be shifted to other benefits such as helping to maintain reliable accuracy over time, less backlash out of the box and smooth, quite operation. Decent lubrication is still required.

Forming Internal Threads Without a Tap

Internal threads may be achieved by embedding a suitably sized nut into an appropriately sized hole. There are two basic methods of retaining the nut without gluing or brazing. First, by means of a slightly undersized hole (Selecting a drill size the same diameter as the across the flats dimension i.e. spanner size will usually be a good starting point) into which the nut is carefully pressed. Or by drilling the hole to the same size as the nut and clamping it in place. Each method has a distinct advantage over the other. The pressed in method maintains a low profile and the clamping method is better for strong, reliable threads. Each of the 3 Axis' is locked by means of a bolt passing through a clamped nut, in these instances a nylon locking nut is used. The nylon ring is first drilled out and a hole drilled to match the profile of the nut, taking care to drill slightly shallow so that a portion of the nut is raised above the clamping face. The nut is placed in the hole with the thin walled rim left over from removing the nylon facing inward. This will allow the wall to crumple as force is applied making for a seamless fit between parts when bolted together.

Back Gib ( Short ) - Table:

When installing the table assembly, first thread one of the stud nuts all the way to the upper limit, raise the plate and fix it in the raised position using the second nut from below. Now you are ready to slot in the table. Once in, the full range of thread is available for clamping pressure adjustment. Leveling of this plate is achieved by clamping the plate between the 4 nuts once the correct level and sufficient pre-load is set.

In this example, the plate has had a number of spot holes drilled and one through hole for oil to pass through from the top and lubricate the back sliding surfaces of the table.

Ruler Scales:

Steel rulers are held in place by magnets - leaving them adjustable. Alternatively, one can fix them to the feed screw brackets for a more permanent solution.

Two sizes are shown here.

Euro spindle neck mount - ø43mm

1. Accepts the standardized 43mm diameter collar.
2. Such as routers motors, geared drills and spindle motors
3. Off the shelf brackets are available

Custom Size - ø48 mm

1. Suits pictured model of Mini Die Grinder

HORIZONTAL MILLING and More Coming Soon. Stay Tuned! This instructable will be updated regularly.

The UDM-200 Micro Milling Machine is Open Source. If you'd like to learn more about this project, feel free to visit: https://libreindustrial.cc/

1. LIBRE INDUSTRAL DESIGNS are licensed under CC BY-SA 4.0