From RepRap
Revision as of 12:12, 6 April 2016 by WillAdams (talk | contribs) (Really small mill)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search


A MillStrap is a commercial or hobby milling machine used as a RepStrap. In other words, you fasten the extruder onto the spindle. A RepRap is basically a 3 axis positioning system, electronics, and an extruder. If you cannot find a set of Mendel parts, then you can buy a new or used Milling machine instead. Then you can either (indirectly) mill out all the parts of some RepStrap capable of printing plastic Mendel parts, or (directly) use the mill with EMCRepRap to print plastic Mendel parts.

What is the difference between a MillStrap and a RouterStrap and a EmcRepStrap ?

(You bolt an extruder to a MillStrap to make plastic Mendel parts. Going the other direction, some people use a Milling and Drilling Head to bolt a rotary tool to a RepRap to make a very light-duty CNC mill).



You can purchase a milling machine, and use it with as a RepStrap. In this case, your cost is the cost of the milling machine, extruder, and electronics.

Buy-Use-Sell (Complicated)

You can buy a used benchtop milling machines, use it to make a set of RepRap parts, and transfer the electronics, extruder, and motors to the new RepRap, and sell the used benchtop milling machine. In this case, your final cost is the shipping cost for the milling machine, plus the cost of the RepRap.


In this case, you can use the machine as a traditional RepRap, as a CNC Mill, and for Shape_Deposition_Manufacturing.


QU-BD Extruder Modified for 5/16 collet

Note that once you have a working CNC mill, you can make many parts of the RepRap Extruder by cutting them out of plastic with the milling spindle.

A simple modification to a QU-BD extruder will allow it to be held by a CNC mill.

This solidworks model can be held by a drill chuck or 5/16 collet. The 5/16inch tube is directly overtop of the hot tip so rotation in the vertical axis of the extruder wont cause the hot tip to move. File:SolidWorks QU-BD Extruder

This page is a development stub. Please enhance this page by adding information, cad files, nice big images, and well structured data!

Crystal Clear action run.png

Release status: unknown

No image available.png
CAD Models
External Link

Note: I need to clean this up.  --Sebastien Bailard 07:58, 22 February 2010 (UTC)

Traditional or CNC-Ready

For RepRapping, we need to mount stepper motors onto the x, y, and z axis of the benchtop mill. When researching a mill to buy, search for:

  • model-name and CNC-ready
  • model-name and CNC conversion
  • model-name and CNC kit

Really Big Mills

  • Really Big Mills (RBM) are ~7 feet tall, and made of steel. e.g. the American-made Bridgeport and its clones. Bridgeports weigh 1950 lb (885 kg) and you'll need to pay a team of two or three riggers to move it. Rigger: An advanced-class human who weighs ~200-500 pounds and knows how to move big heavy stuff without pulverizing himself or others. Non-Riggers must roll to save from "Crushed by heavy thing" (4d6 HP damage) with a -2 penalty when they attack an RBM without a Rigger in their party.
  • The RepRap electronics may be too low power to move the servos/steppers of a Bridgeport mill. If you have a Bridgeport, dear reader, just knock together a RepStrap. It's a weekend project.


  • suppliers
  • price
  • description

Sieg/Generic Mill-Drills

  • suppliers
  • price
  • description

Common conversions include:

Tormach, Bridgeport

  • suppliers
  • price
  • description

These are big machines. It will be fun and useful to design the electronic to drive them.

Despite this, they're very handy as RepStraps, bootstrap positioning systems for a RepRap extruder head, and will make great 3D printers.

Small benchtop CNC Mills

Taig Mill

See Taig Mill.

As a RepStrap, "more than adequate for building Mendel parts".

Sherline, Clisby

See Sherline Mill.

Clisby brand mills were somewhat popular modelmaking mills. They were inexpensive, and very small, and you may be able to source a used one and convert them to stepper motor operation. The Australian manufacturer may be out of business, while the American fork, Sherline, is still going strong.



There are several Unimat models. Unimat 1 This is a children's toy, made from plastic. Unimat 1 was originally designed and released by Emco Maier, an Austrian industrial machine tool company. It is a modular miniature scale machining system, with plastic head- and tailstocks, and (low voltage DC) motor mounts, that can be reconfigured around aluminium extrusions that constitute beds and colums. While it can be considered a child's machine, in the right hands it can produce fine miniature machine work in materials lighter than steel. Unimat 3 was a small-scale, but professional-grade, machining system. It was built around a small lathe with a cast iron bed with ground slides, 46mm centre height, 200mm between centres. It also had provision to fit a milling head to a post that bolts to overhang the bed, and a wide range of accessories. Out of production since 1990, there has been a version called Unimat 4 produced in Taiwan, CNC variations as well.


The Metaline is made from aluminium extrusions. The CNC version of the Unimat is probably an excellent RepStrap base.


This is a larger machine made by unimat, a small benchtop mill.


This is a Unimat1 clone with digital readout. It does not have stepper motor mounts.


Inexpensive, and look like a good bit of kit. There's no information about doing cnc conversions on them.


Smithy Industries

micRo & M3

Lumen Lab SyncRo M3

No longer produced, Lumenlab is in bankruptcy, but they are everywhere and they're still working fine.

"micRo ... can be used for both additive (printing) and subtractive (milling, cutting) fabrication."

Work Area: 10.5" x 12.5" x 2.75-4" ; $1294 (includes mechanical parts, motors) + cost of spindle or other tool, motor controller electronics, and the computer running EMC

It looks like the micRo supports toolheads of about the same size and weight as the Mendel. Does it make any sense to try to adapt RepRap toolheads to the micRo or vice versa?


In Yahoo groups are an active group

Next Wave Automation

Rockler Woodworking sells several CNC routers for under $4000 -- not including the spindle -- the CNC Shark from Next Wave Automation.

Really small mill

EBay (and Taobao for China) are potential sources for cheap CNC machines. Search eBay for CNC.

There are lot of plans for building your own small desktop CNC machine. It seems that even a relatively cheap, flimsy milling machine is more than adequate as a RepStraps.

Pages in category "MillStrap"

The following 7 pages are in this category, out of 7 total.