While a number of components are specialty items, many are commodity parts which may be available at mainstream vendors. Some potential vendors include:
International / U.S. / Internet
- Makerslide Europe
- Reactive Substance
- MixShop (Canada)
- accora (Canada)
- Phidgets (Canada)
- Go Tronic (France)
- Thingibox (Spain)
- Oriental Motor Co., Ltd (Japan, but offices pretty much world-wide)
- Zapp Automation (UK)
- RobotDigg (China) --- Notable for having motors w/ Acme screw shafts and other custom parts
- dumpsterCNC --- ACME, UN and Metric Components, Trapezoidal Parts, Clamp-on Couplers; and Shaft Collars
- Evil Mad Scientist --- DIY and open source hardware
Specialty hardware stores
- Misumi U.S.
- VXB (bearings)
- FScoupling.com (flexible shaft and other couplings)
- HPC (Europe) --- site is available in English, French and Italian
- B&B Manufacturing --- Timing Belt Pulleys & Timing Belts
- Biedler's Belts --- GT2 belts
- Ace Hardware --- check for a store local to you
- True Value --- check for a store local to you
- Home Depot --- the "ship-to-store" option is useful for parts not available locally and doesn't incur shipping charges
- Radio Shack
- DigiKey (Canada)
- Soigeneris --- also carries milling bits, and other mill and lathe supplies , as well as software
- Harvey Tool --- site has an option for finding a local distributor
- Garr Tool Company
- Tools Today
- RobbJack --- very nice interface for selecting bits --- product pages include basic feed/speed data
- Micro-Mark --- Milling Machine Only Tooling --- a model-making tool company, they have a number of small specialty bits well-suited for use on small mills, including some very affordable fly-cutters for surfacing a spoil board or stock.
- LakeShore Carbide.com --- Full selection of U.S. made, quality end mills at reasonable prices
- Sorotec (Germany)
- End Mill 1-Flute lapped Ø3,0mm Z1
- 30 degree angle x 1/4" carbide bits engraving and scoring tools --- engraving in aluminum, note it is a 1/4" shank and I use a Dewalt DW 660 
- (5) 1/8" (.1250") 2 FLUTE CARBIDE ENDMILLS - NEW 
- Garr Tool Series 620MEDP#41030 1/8"x3x1" --- excellent quality, long narrow bit w/ a long cutting length which makes workholding and fixturing much easier, and puts making through cuts (w/ many passes) on 1" material feasible.
Strategizing on purchases so as to save on shipping and handling is a useful technique to help keep expenses in check.
If all else fails, many items are available on eBay, or Amazon.
There is a separate list of specific vendors on the Upgrade Overview page.
Specialty Local Vendors
Please list specialty local vendors which don't have a sales presence on the internet below by their geography.
- Pacific Fasteners Ltd. --- Burnaby, BC, Canada, locations in Vancouver, Toronto and Seattle
- United Kingdom
- Clerkenwell Screws --- 109 Clerkenwell Road, Clerkenwell London, EC1R 5BY
- United States
Additional / Commodity Items
There are a number of other items which one may need or will find useful:
- Extra M3 and M5 washers --- these are pricey in low quantities, and are generally useful
- Lock washers (Note especially their suggested use for “Tensioning the Machine” in Assembly troubleshooting) and other miscellaneous hardware, esp. for Belt Anchors
- M5 socket cap screw assortment --- automotive stores usually have a plastic organizer filled w/ various sizes --- saves a lot of time and gas and cash if you do much upgrading
- Zip ties or other fasteners
- Electrical cable/wiring --- 18 or 20 gauge. 4 (or more) conductor 18 gauge security cable is sold in bulk by the foot at most hardware stores, e.g., Home Depot's 18-4 CL3R Security Cbl Shld 1' @ 0.63, Part number 0000-249-865 Ed0345.18.10 <A>, listed in bulk on their site. Also available from All Electronics - Shielded 5 conductor 22 AWG with drain @ 0.33 per foot.
- Cable Management system
- End mills
- Material for an electronic enclosure
- Some way to cool the stepper drivers such as a fan and/or heat sinks
Thread on this here: What else should I have on hand?