This page details rotary tools, spindles and routers. There is a list of other potential spindles on the Spindle Overview page.
- 1 Concerns
- 2 Maintenance
- 3 Key Considerations
- 4 Machine Types
- 5 Speed
- 6 Alternative/Temporary Mounts
- 7 Design considerations
- 8 Compatibility
- 9 100 to 999 Watts
- 10 1KW and over
- 11 List of Videos
- 12 Collets and Adapters
- 13 Spindle Control
- 14 Other spindles/Sources
- 15 Other mounts
- 16 D.I.Y.
- Air-flow / heat dissipation Several of the brackets below are made of aluminum so as to facilitate the latter.
- Water cooling adds complexity.
- Mounting it plumb to the machine Discussion of techniques for doing so on the forums in Aligning DW660 to be perfectly vertical. An interesting technique for this is to use spacers as shown in Re: Bits you use. The professional tool for this is a “spindle square” --- the construction of which is shown in Making a spindle square. Cf. Squaring the Spindle N.B. How vertical a spindle is mounted, and to what degree it is held immovable while cutting can have a strong effect on cut quality.
- Weight Moving to a larger spindle can require that one (re)adjust the machine as noted in Fine Tuning --- Motor Current. Two kilograms is, if not past the upper limit of weight, very close to it.
- Wear/Maintenance --- How To Tighten Up A Sloppy Second Hand Dremel --- this may be useful to do on even a brand-new unit. Spindles may use brushes in their motors which require replacing. Bearings may need replacing as well: Bosch Colt started squeaking, so I replaced the bearings.
- Dust Collection --- See the Dust Shoe overview page for a list of implementations.
- Rotation Direction --- Note that this is typically clockwise from the top of the machine.
- RPM --- this can be measured in various ways.
Note: One can use longer bolts in the universal spindle mounts to accommodate larger spindles. Specifics are noted below.
Collets will wear with use and require replacement as well.
"What good quality, metal-bodied, small/compact/trim rotary tool/cut-out tool/router/spindle with collet size between 6.35 and 3mm is available w/ a diameter of <70mm, and a power rating of >100 Watts (500 or more is highly desirable and arguably a reasonable minimum), and a weight of <2Kg?".
- Smaller diameters are better (move the endmill closer to the axis of movement)
- More power is better w/in reason
- low runout (captured in the phrase "good quality" above) is the most important characteristic.
- A suitable collet size is a key consideration, and the want of it will require either an adapter (which complicates things and may increase runout) or a custom collet (which adds to the cost).
- Rotary Tool --- the prototypical hobbyist tool. Dremel is the most-recognized brand name and widely available. A small hand-held unit intended for small, delicate work. Collets are typically aluminum sleeves available in a variety of diameters shaped to fit the machine's shaft end and held in place by a nut, 0.125" is typical..
- Cut-out Tool --- A commercial tool intended to cut drywall, as a class was inaugurated by the RotoZip Spiral Saw. Collets are similar to rotary tools, but typically only 0.125" and 0.25" diameters are available.
- Router --- The first powered woodworking tool, it allowed a woodworker to use a collection of small bits to create profiles which used to require either individual hand planes, or a combination plane such as a Stanley 45 which was viewed by most as finicky and difficult to set up. Routers are now available in a number of different sizes, w/ various terms being used to describe a over-lapping ranges of devices. Collets are usually specific to a machine and the stock collets are typically only available in 0.25" or larger sizes. Custom collets of various types are available, some of which afford conveniences like to industry-standards such as ER.
- Spindle --- the generic term for any device for spinning an Endmill mounted on a machine, it's also used to signify a unit which is intended for being so mounted. Previously, only expensive, high-quality commercial units were available, but spindles suited for hobby-level equipment have become available of late. Usually these use industry standard collets such as ER.
The sort of collet and sizes in which they are available is a significant concern in selection and can dramatically affect the final price of a unit. It may be best to consider the sorts of cutting which one wishes to do, select an Endmill and match the spindle choice to that.
One additional concern is how different power ratings are measured. Commercial/Industrial spindles are rated for their sustained output (root mean square, RMS power). Consumer devices such as rotary and cut-out tools and routers are typically rated at their (theoretical) peak horsepower. For example the Makita RT070x-series has (as the name implies) a 700 Watt power rating, but is described as being 1.25 HP, which ~=933 Watts. The table below should use actual power ratings rather than peak so as to allow comparisons --- please update (with references) if any peak ratings are found.
One option is to simply zip tie the machine in place and support it w/ a plastic mold: http://rettgergalactic.com/blog/2014/02/quick-shapeoko-dw660-spindle-mount/
An elegant solution is to cut up a pair of hose clamps, bending the ends over and drilling holes so that they may be used w/ the universal spindle mount as shown in Jacob's Shapeoko 2 #6316.
Or rearrange parts and use hose clamps: http://www.shapeoko.com/forum/viewtopic.php?f=10&t=5475&p=40420
Commercial mounts are most easily found by searching for "<router/spindle diameter>mm spindle mount" --- eBay has many listings for 52, 65, and 80mm units.
As noted elsewhere, mount hole spacing is consistent and compatible between the ShapeOko 1, 2 and 3. Unfortunately, other dimensions aren’t so standardized.
- holes could be drilled and tapped to allow accessories to be attached
- the horizontal placement of the router
- placement of the vacuum hose, or select a particular crevice tool to always use
Hardware can be placed so that second tools are not needed (use a rectangular slot and place an insertion nut in it, or put a hex nut in a suitably sized channel. Another possibility is to use quick-release hardware: http://www.kippusa.com/us/en/Products/Latches/Adjustable-Latches/K0050-Adjustable-Latches-with-a-movable-hook-clamp/K0050-SVA-Adjustable-Latches-with-a-movable-hook-clamp-Style-A.html
Please note that the hole spacing for the inner pair of holes on the Shapeoko 3 is the same as that as on the ShapeOko 2, or for the MakerSlide used for the ShapeOko 1, so mounts are compatible between the machine designs if no other geometry interferes.
100 to 999 Watts
A note on the low-end rotary tools --- pretty much anything w/ at least 100 Watts of power (or 0.8 Amps @ 110VAC) will be workable --- there are probably too many re-badged variants (Sears Craftsman effect) to list them all, unless there is some extra-ordinary reason to warrant a listing (the tools currently listed are shown due to their widespread availability while still being a good value). Depending on one's patience and expectations and materials, one could go much lower (there's a 9-volt DC tool which would probably be quite kid-safe / friendly) if one took light enough cuts.
Cautionary discussion: Running long jobs using default shapeoko (1/2) rotary tool.
Note that one may be able to use designs for cylindrical spindles based on their diameter.
|Category||Type||Collet size(s)||Power rating (see Note below)||Speed||Power Supply||Weight||Noise rating||Notes||CAD/Mount||Purchase Link / Specific Model|
|Rotary tool||Generic||1/8"||120 Watts (1.0 amps)||8,000 -- 30,000 r.p.m.||120v AC||80 db||This is the tool included with the ShapeOko 2||This tool has two different/distinct diameters, so will not mount plumb in the stock mounts --- one can make up the narrower diameter using a suitable size of zip tie around the tool aligned with the lower mount.||Oddly, it's not listed on http://www.altocraft.com, but does show up on eBay regularly: Altocraft 100 Pc Electric Grinder W/ Blow Case|
|Rotary tool||Generic||1/16" and 1/8"||144 Watts (1.2 amps)||8,000 -- 35,000 r.p.m.||110v AC||Great starter tool and will take you further than you might expect. These are prone to working great and then dying all of the sudden.||Spindle Mount||Harbor Freight: Variable Speed Rotary Tool Kit|
|Rotary tool||Generic||1mm--3.2mm collet sizes||170 Watts||8,000 -- 35,000 r.p.m.||230v AC||Fusion 360 models:||Maplin (UK): 170W Variable Speed Rotary Tool with LCD|
|Rotary tool||Brand-name||1/32" -- 1/8"||138 Watts (1.15 amps)||15,000 -- 35,000 r.p.m.||110v AC||IMO, gives you no advantage over the knockoff||CAD||Dremel 200 Series Rotary Tool|
|Rotary tool||Brand-name||1/8" (3 smaller sizes, 1/32", 1/16" and 1/8" available)||192 Watts (1.6 amps)||5,000 -- 35,000 r.p.m.||110v AC||1 lb. 7¼ ozs. (660g)||The Dremel 4200 is a new version of the 4000 with new features, but has the same power rating / motor.||http://www.shapeoko.com/forum/viewtopic.php?f=5&t=6793&p=55950#p55950||Dremel 4000 High Performance Rotary Tool|
|Rotary tool - high-end||Brand-name||240 Watts (2.0 amps)||12,000/24,000/30,000 r.p.m.||110v AC||better than a Dremel is the Black & Decker 3 Speed RTX Rotary Tool, RTX-B||Black & Decker 3 Speed Rotary Tool RTX-B|
|Rotary tool - high-end||Brand-name||6 high concentrically steel collets, 1/32-, 1/16-, 5/64-, 3/3-2, 7/64-, 1/8-inch||100 Watts (1/8 hp)||5,000--20,000 r.p.m.||110--120v AC||1.3 pounds, 9 inches long||Proxxon 38481 IB/E Professional Rotary Tool Dust Shoe for Proxxon Mount Other Proxxon IB/E users? And an example job
Discussion of disassembling one to mount it more directly and re-wiring to allow for control through the electronics: http://reprap.org/wiki/Proxxon_Micromot_50
|Mini spindle||Kress 530FM||ER11 and 3.175mm (1/8"), 4mm and 6mm collets||530 Watt||29000 1/min||230 V||1.3 kg||Very loud||Diameter: 43mm|
|Mini spindle||Kress 800FME||ER11 and 3.175mm (1/8"), 4mm and 6mm collets||800 Watt||10000 -- 29000 1/min||110V (US) 230 V (Europe --- this may be a different sub-model)||1.4 kg||Diameter: 43mm||Vendors:|
|Cut-Out Tool||Brand-name||1/8" and 1/4"||600 Watts (5.0 amps)||30,000 r.p.m.||110v AC||3.2 lbs.||The DW660 - great upgrade from the dremel knockoff, allows you to use a router speed controller with some success, also gets you into the 1/4" shank game!||DW660
|Dewalt DW660 Cut-Out Tool|
|Spindle||O.E.M./Krt motor (China)||ER11 Collet (3.175mm)||500 Watts||0--10 r.p.m.||AC110V/AC220V±10% 50/60Hz (10A)||Chinese 500W spindle||SVG spindle mount||CNC Spindle Motor 500W & power supply & 57. 5mm mounting bracket for PCB engraving w/ collet ER11|
|Spindle||O.E.M. (China)||ER11 Collet (3.175mm)||400 Watts (Torque:500mN.m)||3,000--12,000 r.p.m.||12--48VDC||~1.99 pounds||Re: Quiet Cut Spindle take apart and review||Motor Length: 186mm
|CNC W Spindle Motor ER11 & Power Supply & Speed Controller & Mount bracket
Wiring diagram correction: http://www.shapeoko.com/forum/viewtopic.php?f=21&t=5492&p=55551
|Spindle||O.E.M. (China)||ER11 Collet (3.175mm)||600 Watts (5.0 amps)||3000--12000 r.p.m.||24-110V DC (7.8A)||~4.17 pounds||||Includes Spindle Mount Bracket||Air cooled 600W Spindle motor|
|Spindle||O.E.M. (China)||ER11 3.175mm , 4mm ,6mm||800 Watts (1 HP)||10--20rpm||220V||800w Chinese spindle||Re: Cutting stainless steel?||Dimensions:
|Spindle||GMT/UGRA CNC||ER11 Collet||800 Watts (1 HP)||6000--20 r.p.m.||220V 3 Phase (Inverter Output Voltage)||3KG||||GMT Air Cooled CNC Spindle|
|Cut-Out Tool||Brand-name||1/8" and 1/4"||480 Watts (4 amps)||30,000 r.p.m.||110v AC||Rotozip RZ2000 - 52
Used successfully on Tony's ShapeOko #1894F.
|RotoZip SCS 01 Mounting Brackets|
|Cut-Out Tool||Generic||1/8" and 1/4"||420 Watts (3.5 amps)||28,000 r.p.m.||110v AC||Harbor Freight clone HF cutout tool is cutting alum plate like a champ.
After I took some measurements on accuracy it was less than desirable. Going to slow it down when i get a dust shoe to keep the shop clean of alum chips. I love the HF spindle though.
|Harbor Freight: Electric Cutout Tool|
|Compact Router||Brand-name||1/4" other sizes available:||840 Watts (7.0 amps)||16,000 -- 27,000 r.p.m.||110v AC||3.3 lbs. (4.1 lbs. including base)||71 db (further testing here)||The DWP611 - better choice than the DW660, I think it's a tad bit quieter, but seems to be more robust, with less plastic and more metal. If using a speed control system, it is possible to modify the 611 to bypass the built-in variable speed control and to place the optical sensor within the router housing.
Variable speed, the actual no load speeds of one unit were measured as:
1: 15820 2: 16960 3: 18950 4: 21280 5: 24270 6: 27080
||Dewalt 1-1/4 HP Max Torque Variable Speed Compact Router with LEDs --- DW611 is fixed-base, DWP611PK incl. plunge base.
Also available is the DNP-611, the bare motor unit w/ no accessories beyond collet wrench, and 1/4" collet and nut.
|Compact Router||Generic||6mm + 8 mm (3.175mm (1/8) collar adapter available separately for 12 euros)||850 Watts||11,500 -- 32.000 r.p.m.||230V AC / 50Hz||1600 grams||CauCau 850w||Diameter : 44mm
Diameter total: 70mm Length: 270 mm aluminium spindle mount available separately
|Universal Router / CNC Spindle = CauCau 850 W (eBay UK)|
|Compact Router||Brand-name||1/4" Note that a custom 1/8" collet is not available from the manufacturer, but see Elaire Corporation Makita Style Router Collets. Previously, there was: 1/8" collet (adapter)s which fit with some filing Astro Pneumatic Tool Co 200-283 Slot 1/4-1/8-Inch Collet Reducer||700 Watts||10,000 -- 30,000 r.p.m.||120v AC||1.4kg (3 lbs.) (cord increases this to 1.5 kg?)||The Makita RT0700C/0701C(X) - seems to be similar in kind to the DWP611. Same sort of aluminium housing and speed control, but without the two LEDs underneath. The 0701 is slightly newer and is intended for the North American market. The 0700 is still available as a 220V model for Europe and other localities which use that voltage. This requires the use of a different motor and attendant parts and some indicate that it requiresa different collet. Another difference for the two models seems to be the screw layout for the base(s), w/ the newer 0701 having a standard Porter Cable layout.
Variable speed, the actual no load speeds of one unit were measured as:
1: 9470 2: 12280 3: 16870 4: 22175 5: 27035 6: 29800
Discussion of relative merits: Re: spindle choice
Diameter: 65 mm Files:
|Home Depot: Makita
Requires a shim if using the stock SO3 69mm diameter mount. 2mm noted as being too thick.
|Trim Router||Brand-name||1/4"||660 Watts||20,000 -- 30,000 r.p.m.||120 V AC 5.5 Amps||Ridgid 2401||Mounts||Ridgid|
|Trim Router||Generic||1/4" (MLCS steel adapter bushing 1/8" or Elaire Corporation Reducing Collets or StewMac brass adapter --- see list below for more and commentary)||Watts (3.4 amps)||26,000 r.p.m.||110v AC||Re: Treating spindles as a consumable||Harbor Freight (HF) Trim Router --- details on using the stock mount w/ strapping (thread now includes .svg file for a mount and dust shoe). Alternately, one can use the stock mount by using longer bolts 70--75mm.||Harbor Freight: 1/4" Trim Router|
|Carving Tool||Generic||1/8" and 3/16"||15,000 -- 20,000 r.p.m.||110v AC||The Chinese Foredom knockoff - This is a pretty good little spindle. For the most part you can only get to 3/16" shank, which isn't really an advantage over 1/8" because the bits are so hard to find, but what it does get you is "off-site" power. It uses a flexible wand connected to an AC motor. The motor turns between 15-20k RPM. I used one of these for about 6 months before it died. You can see it in my phone dock video (see list of videos below). The foredom knockoff is to-date my favorite choice *IF* I could get it with a 1/4" collett. It's good enough that I've contemplating buying a non-knockoff foredom handpiece just to see if it's any better, but at $355 I'm not sure that's ever going to happen. Because of what EJ was talking about (mounting the majority of the weight) off the machine, gives some great advantages. One that wasn't mentioned is the fact that the tool itself is closer to the z-axis, creating less of a lever arm.|
|DC Spindle||Generic||180 Watts||15,000 -- 20,000 r.p.m.||48v||This is ninja quiet!||The 180w DC spindle (48v) - And IMO does a nice job with simple engraving features, but is SERIOUSLY lacking in the power category. Don't plan to cut much (or anything) with this. I don't do PCB engraving, but imagine this thing would be great.|
|DC Spindle||Generic||1/4" ER-11||300 Watts (6.25 amps)||3,000 -- 12,000 r.p.m.||48v||~1.73 pounds||The 300w DC spindle (48v) - This is the second quietest spindle on the list. It's still lacking in power compared to even the knockoff dremel, but can manage to cut through most woods & plastics if treated nicely (1/32" (0.79375 mm) depth pass). It also has a 1/4" ER-11 collett option, but IMO is worthless because of the lack of power. Blog post about it here.|
|DC Spindle||Inventables||ER-11 (1/8", 3/16" and 1/4")||300 Watts (6.25 amps)||3,000 -- 12,000 r.p.m.||48v||Blog post about it here.||Dimensions:
DC Spindle Mounting Block --- note this is only suitable if one has redesigned the Z-axis to suit, otherwise the stock universal mounts work (but may require some adjustment).
|Palm Router||brand-name||1/4" (Other sizes available from Precise Bits)||672 Watts (5.6 amps)||16,000 -- 35,000 r.p.m.||110v||3.3 lbs.||The Colt - This thing is a MONSTER! It's loud as hell, and weighs more than any of the others (excepting the heaver Dewalt ), and is pretty big, but it can really tear some stuff up. Cat saw it run first hand on one of my prototype machines when he was in Chicago last month and could attest to it's sheer power. I used a 1/4" 2 flute Onsrud bit and tore through a piece of maple at 1/4" depth pass without the Colt even flinching. Discussion in the forums here. European model is GKF-600. Notable features include:
Variable speed, the actual no load speeds of one unit were measured as:
1: 12500 2: 14000 3: 16350 4: 19150 5: 23700 6: 29600
|K2CNC Colt Router Mount
Colt spindle mount on Inventables.com --- note that this mount interferes w/ the Z-axis travel on a stock Shapeoko 2 and will need to be moved out for most usages. Thingiverse: Bosch Colt Spindle Mount for Shapeoko 2
|Mini spindle||generic||ER20||800 Watts (7.27 amps)||6,000--24,000 r.p.m.||110v||The next one on my list is the 800w water cooled VFD. At $379, it's pricey, but this one runs off 110v, so the need for a 220v drop isn't required. The 220v versions are about the same price, but most people don't have 220v available and would have to pay an electrician to get it installed.||aliexpress|
1KW and over
|Category||Type||Collet size(s)||Power rating (see Note below)||Speed||Power Supply||Weight||Noise rating||Notes||CAD||Purchase Link / Specific Model|
|Mini spindle||generic||ER11 and 3.175mm (1/8"), 4mm and 6mm collets||1500 Watts (13.63 amps)||19,200--24,000 r.p.m.||DC --- requires VFD||~6kg||Chinese spindle (the 2nd best thing I've done for my Shapeoko more details in Spindle 1.5 KW 220V 400Hz + Huanyang Inverter (HY01D523B)||Diameter: 80mm|
|Mini spindle||Fräs-Spindel Kress 1050 (available in two different models as noted)||ER11 and 3.175mm (1/8"), 4mm and 6mm collets||1050 Watt||5000 - 25000 1/min (1050 FME-1, the 1050 FME model has a lowest possible speed of 10,000 RPM)||230 V||1.7 kg||Re: Zerblatt's build
Variable speed, the actual no load speeds of one (FME-1) unit were measured as:
1: 4998 2: 7332 3: 12000 4: 15678 5: 20028 6: 24840
Note: Watt ratings converted to amps using Volts / Watts / Amps Converter on http://www.supercircuits.com.
List of Videos
Collets and Adapters
A collet is a holding device that forms a collar around the endmill to be held and exerts clamping force on the tool when tightened, usually by means of a tapered outer collar. Adapters are sleeves which fit w/in collets allowing them to hold smaller size bits.
Collets are either industry-standard, specific to a given design, or a custom aftermarket part. The aftermarket collets are made to higher standards, usually of better steel, and will reduce runout. They also avoid the need to use adapters.
There are some vendors which make collets for specific machines as listed above.
There are also industry standard forms which some machines use allowing for a certain level of interchangeability.
- PreciseBits - has collet kits to fit several different routers including the DeWalt 611.
- STUBBY ER Collet Chuck ER-11 Manual Collet Chucks --- 1/2" or 5/8" shank which provides an ER-11 collet suitable for small bits.
- Elaire Corporation Router Collets --- available for Bosch, Porter Cable and Milwaukee. Please note that this company will custom craft collets as noted in: Re: Custom 1/8" Collet for Makita RT0701C Trim Router and may have collets for routers which are not listed, contact them. Please compare with Re: Makita RT0701C Collets/Endmills. See also Elaire Corporation Makita Style Router Collets.
Some machines may share collet designs. Noted instance(s) of compatibility:
- Dewalt DW660 and RotoZip --- the latter are available at: Lowes.com
- Black and Decker Spare Parts --- 3/8" collet cone suitable for Makita
In addition, it is possible to use adapters to allow a collet to hold a bit which otherwise would not fit:
- RotoZip Chuck Adapter --- works w/ the DNP/DWP611.
- Trend CLT/SLV/3263 Collet sleeve 3.2mm to 6.35mm (eBay UK)
- MLCS steel adapter bushing 1/8" --- steel with a single slot (for the 1/8"--1/4" size)
- Lee Valley Bushing Adapters
- Elaire Corporation Reducing Collets
- Stewart-MacDonald Adapter Collet --- brass with 4 slots for the 1/8"--1/4" size --- the additional slots and symmetry may help reduce runout and allow it to spin truer.
- IMService Sleeve-Adaptor 1/4 to 1/8
- K2CNC 8th Combo .25" & .25" --- interesting brass design which uses a set screw
Cautionary note on collet adapter sleeves: Warning regarding Collet Adapters. One concern about the brass adapters is the differing thermal properties of brass vs. tool steel.
It's also possible to directly control a spindle using the electronics: Spindle Control.
Single-speed spindles can also be controlled using a router speed control as noted in Less Power on the Dewalt DW660 page.
One concern with using speed control on the DW660 (and similar units) is that it is cooled by a fan on the motor shaft, which works fine at high speed and low to moderate torque. When you reduce the speed and increase the torque (by using closed-loop speed control), the cooling becomes insufficient.
Another option is to use an external tool to monitor the R.P.M. as mentioned on the forums: http://www.shapeoko.com/forum/viewtopic.php?f=7&t=4788&start=1330#p45186 and documented in Simple RPM Detector.
- MLCS Rocky 30 Trim Router Amazon --- seems to be a rebadged Makita RT-0701 — but in black to match the Shapeoko 3
- 3Speed spindle
- Wolfgang Engineering 12-volt DC Spindle --- best suited for PCBs. Forum discussion
- http://www.grizzly.com/products/H7790 --- metal body 1/4" trim router $46.95 --- 440W/2.1 amps, 30,000 RPM, 4.04lbs.
- http://www.grizzly.com/products/H7791 --- plastic body 1/4" trim router $44.95
- http://www.harborfreight.com/flexible-shaft-grinder-and-carver-40432.html --- http://www.shapeoko.com/forum/viewtopic.php?f=7&t=258&p=38230
- Re: Recommendation: Spindle solutions available in europe?
- best tool for uk builds
- Re: Source: Kress 1050 42, 43 mm motor mount? Frässpindelhalter 43mm
- UK Bosch GFK600 (for sale on Screwfix in the UK
- Dewalt D26200 --- DWP611 equivalent
- Amazon UK
- Dust Shoe
- K2CNC CNC Spindle Router Mounts --- Products include: Porter Cable 892, 7518 CNC Router Mounts, Hitachi Router Mount, Bosch 1617EVS and Colt Router Mounts.
- Spindle View Dust Shoe for 64mm spindle by akhlut
- http://www.amazon.co.uk/gp/product/B0001P19QI 
- Forum discussion: Idea For A DIY Spindle
- plans on MIT to make a spindle
- http://www.openbuilds.com/builds/890kv-ox-rc-spindle.411/ 
- https://www.reddit.com/r/shapeoko/comments/427g8u/is_the_shapeoko_3_more_rigid_than_a_stepcraft_and/cz92919 --- discussion of using a treadmill DZc motor, and various pulley options
- http://www.cnczone.com/forums/vertical-mill-lathe-project-log/41200-bt30-spindle-project.html