McWire (Death March: Do not build!!!)
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| Description | A guide to building and operation of a McWire RepStrap
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Contents
Intro
This is a guide that will help with the decision making and build process of the McWire RepStrap found here [1]. If you don't have access to printed parts, which as this point is time is most people, you have to bootstrap your reprap using a 3d printer build from standardized or commodity parts. The McWire device is probably the simplest and least expensive device to do that with, it is also considered the current 'official' and possibly best support device to bootstrap with. That being said it has some significant drawbacks.
- McWire Drawbacks
- Speed (It's slow): the McWire is much slower than the Mendel reprap to print objects. Because it uses threaded rods to move the different planes (X,Y,Z axes) it does so much slower than the belt driven Mendel. In total it will take approximately 200+ hours of print time to complete the printed parts for the mendel.
- Lack of re-use (additional cost): A few people have had success using the McWire for other purposes such as a CNC milling device with a mounted dremel. In fact that was the original purpose (the McWire is derived from Tom McGuire's original instructables.com concept). Officially and as described here the McWire is not a very good, durable, accurate and reliable CNC device. YMMV.
Why or Why Not Choose Mcwire
Not sure on whether a McWire is right for you? Hopefully this section can help.
Some Pros About McWire RepStrap
There are some definite advantages of going the McWire route.
Ability to convert too milling CNC - It's fairly easy to switch out different tool heads. The screw driven axis offer the torque needed for light milling.
Opportunity for cost savings - The free form design offers an opportunity to use things you may already have to build your machine. MDF instead of laser cut plastic? Rubber bands instead of springs? You get the Idea.
Parts or substitutions are easily obtained - Besides the electronics most of the parts can be bought at a local hardware store.
Build Platform Easily Accessible - The build platform is front and center. Not surrounded by a box.
Loose accuracy requirements - The McWire cartesian bot is very forgiving of sloppy workmanship. Because the motion is along extruded aluminum U-channel, if your bed isn't straight or square you'll still be fine. This is a design that's quite forgiving to jury-rigging.
Flexible Parts List - The McWire can usually be built out of whatever you can find locally. You'll need some iron, steel, or sturdy plastic pipe. Threaded might be easier, but you could make it work with glued together pipe too. The bearings can be any size that you can screw down. The lasercut plastic parts are easily cut yourself from MDF, cutting boards, plywood, ODF, whatever. The aluminum U-channel is one part that you might have a hard time finding a replacement for, but you can make pretty much any sized channel work.
Some Cons About McWire RepStrap
Slow Speed - The 1/4" - 20 screw drive is slow and this leads to builds that are not as fine or as fast as other machines. Some people have had some success with using 1/2-16 rod instead.
Not Standardized - No two McWires are built the same. McWire is a concept driven into reality by the individual maker. Your first parts list will not be your final parts list. The design presented on the Seedling website does not offer standardized measurements and may be subject to your printer's whims. Fortuntely, the design is relatively flexible without significant cost in functionality. Put simply: You can mess up pretty bad and still have a working printer.
Some Build and Design Experience Required - You need to be able to work with tools, measure accurately and cut (fairly) straight.
Where to Begin
In many ways, the McWire RepStrap (aka "Seedling") can seem like as monumental a task as building a Darwin or Mendel RepRap. Relax. Building your McWire is going to take work, but won't be as overwhelming as it may now seem. The greatest advantage you can give yourself is to Plan Ahead. Think about what you're going to do before you do it, and why. This falls within the same logic line as "Measure twice, cut once." You can save yourself significant time and money if you plan ahead
Beginning with the Cartesian Robot The Cartesian Robot can be a good place to start if you have the tools and materials available to you. Because the cartesian robot is a relatively flexible design, you can make design changes to accommodate your needs and what you have available to you.
Beginning with the Electronics If you can get ahold of the electronics you prefer to use, starting with their construction can be rewarding. You can build and test your electronics without having constructed the cartesian robot.
Beginning with the Toolhead Beginning with the toolhead (typically an extruder) will help you to get going once everything else is done.
Education
There are a number of websites in which builders have documented their experience putting together a McWire build. You may gain significant insight by going over their experiences. Here are the links to some of the sites:
Plan
Execute
Suggested Tools
Parts List
Online
An example McMaster Carr Parts List
---begin paste---
1 95462A033 1 91083A033 1 90275A714 1 90494A030 1 91083A030 1 90273A581 3 91034A100 1 98273A255 2 8735K111 1 88805K57 1 9001K34 3 4549K606 1 4549K595 2 4549K602 3 44605K115 1 68095K121 1 44605K155 2 44605K105 2 98847A029
---end paste----
Complete detail for informational purposes:
1 95462A033 1 Pack Zinc-plated Grade 5 Steel Hex Nut, 1/2"-13 Thread Size, 3/4" Width, 7/16" Height
2 91083A033 1 Pack Plain Steel Type A Sae Flat Washer, 1/2" Screw Size, 1-1/16" Od, .07"-.13" Thick
3 90275A714 1 Pack Zinc-pltd Stl Flat Head Slotted Machine Screw, 1/2"-13 Thread, 1-1/4" Length
4 90494A030 1 Pack Plain Grade 2 Steel Thin Hex Nut, 5/16"-18 Thread Size, 1/2" Width, 3/16" Height
5 91083A030 1 Pack Plain Steel Type A Sae Flat Washer, 5/16" Screw Size, 11/16" Od, .05"-.08" Thick
6 90273A581 1 Pack Zinc-plated Stl Flat Head Phil Machine Screw, 5/16"-18 Thread, 3/4" Length
7 91034A100 3 Each Black-oxide Steel Coupling Nut, 1/4"-20 Thread Size, 5/8" Length, 1/2" Width
8 98273A255 1 Pack 410 Ss Type 23 Thread-cutting Screw, 10-24 Thread, 1/2" Length
10 8735K111 2 Ft. Bar Made Of Teflon(r) Ptfe, Rectangular Bar, 1/8" Thick, 1/2" Wide, 2' Length
11 88805K57 1 Each Architectural Aluminum (alloy 6063), 90 Deg Angle, 1/8" Thk, 1-1/2" X 1-1/2" Legs, 8' L
13 9001K34 1 Each Architectural Aluminum (alloy 6063), U-channel, 1/8" Thk, 3/4" Base X 3/4" Legs, 8' L
16 4549K606 3 Each Std-wall Galv Welded Steel Thrd Pipe Nipple, 3/4" Pipe, 12"l,thrded Ends,17/32"l Thread, Sch 40
17 4549K595 1 Each Std-wall Galv Welded Steel Thrd Pipe Nipple, 3/4" Sz, 3"l, Thrded Ends,17/32"l Thread, Sch 40
18 4549K602 2 Each Std-wall Galv Welded Steel Thrd Pipe Nipple, 3/4" Pipe, 6"l, Thrded Ends,17/32"l Thread, Sch 40
19 44605K115 3 Each Low-pressure Blk Malleable Iron Thrd Fitting, 3/4" Pipe Size, 90 Degree Elbow, 150 Psi
20 68095K121 1 Each Low-pressure Forged Steel Flange, Threaded, 3/4" Pipe Size X 3-7/8" Od, 150 Psi
21 44605K155 1 Each Low-pressure Blk Malleable Iron Thrd Fitting, 3/4" Pipe Size, Tee, 150 Psi
22 44605K105 2 Each Cast Iron,125 Psi,3/4"pipe,round Head Cap
23 98847A029 2 Each 18-8 Stainless Steel Threaded Rod, 1/4"-20 Thread, 3' Length
Electronics
1 Mother Board
3 Motor Drivers
1 Extruder Board
1 ATX Power Supply
1 USB Cable
Local Hardware Store
Costruction Method
Build and measure as you go. Substitutions where ever.
Structure
Sleds
Electronics
Wiring
Software
Wiki build notes below here!
Files and Parts
Generic/Daughter_part and CarrotStraightener. (As a gentle style recommendation, it's good to try to keep all your parts and files on the RepRap wiki rather than scattered around so that Mr. Bunny doesn't have to use a scripts and so on to get stuff back onto the wiki.) File:Uploaded files example.zip
Photos and Drawings
Captioned
Links can be put in captions.
Flicker Example
<flickr>2967868906|right</flickr>
Working Notes
Project Lead(s): Mr. Bunny Wiki-maintainers and helpers:
Forum thread?
Tooling
Description of tooling requirements.
Process
What is making the part like?
