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Comments: This page is the result of my research into parts availability for building a HobbyCNC Controller. The basis for this list of parts is based on the concepts outlined on the HobbyCNC web page. There are a number of options that can be chosen during the design and construction of this controller. Please refer to the Notes section at the bottom of this page for information on those options.
The Notes section at the bottom of this page contains considerable information regarding the selection of parts and the concepts used in compiling this list. Please examine the Notes carefully before purchasing any parts.
The vendor part numbers in the table are links to the parts on the vendors' web sites. Please contact me at netboss@NOSPAM-REMOVE-THISmypage.net with any broken links, errors, omissions, comments or additional information.
The information on this page may be freely distributed so long as said distribution is not for profit or charge. Links to this page are encouraged. The information contained herein is believed to be accurate at the time of publication, however no warranties, expressed or implied are offered. The reader assumes all responsibility for the use of the information on this site.
See the Notes section on this page for information regarding how this table is organized. All prices are in US dollars.
HOW TO USE THIS TABLE: This table is divided into 5 columnar sections, most of which have subsections. Starting at the left, the first column contains a description of the item listed on that line. The second column references any notes which pertain to this item. Sections 3 through 7 are each comprised of 3 subsections which contain information about the Part #, Price and Total (price x number of pieces needed for the HobbyCNC controller). The Part #'s are hyperlinks to the web page for that item on the vendor's web site. The final vendor "Other" is for vendors who offer only 1 or 2 items. The vendor's name and web site are contained in the Notes. The Total column is explained later in this paragraph. The 8th section is comprised of 6 subsections. The first 5 of these subsections have one column for each vendor. Generally speaking, the lowest price vendor is selected and the number of pieces needed for the controller is listed in this vendor's column. I will now offer an explanation of the Total columns under the vendors' section and the rightmost column, also labeled Total. The number of pieces needed is multiplied by the price for the vendor selected. This price is then entered into the Total column for that vendor and the left most Total column. Only one vendor is selected for each item and only that vendor will have a dollar amount entered into the Total column for that item. The final row in the table lists the totals for each vendor with the left most column showing the total amount for the parts needed to construct the HobbyCNC controller.
Not all parts needed for the construction of the controller are listed in this table. Most notably missing are low cost parts that can easily be obtained locally. These include four 4-40 x 1/4" screws for the controller board standoffs. These can be obtained at a local hardware store for about 5 cents each. Also omitted is heat shrink tubing. A number of local stores (including Home Depot) and online vendors offer heat shrink tubing assortments.
Some of the small parts (nuts, Molex pins, etc.) are sold only in large quantities (i.e. 50 or 100 pieces). Be sure to check each vendor's minimum quantity before deciding where to buy these parts.
A. These items are obtained from HobbyCNC. The prices shown on this page are based upon the construction of a 4 axis controller for a router, lathe or mill. Costs for a 3 axis controller will be somewhat lower than represented here. The prices shown for the HobbyCNC controller board and stepper motors include the shipping charges for delivery within the United States. Please refer to the HobbyCNC web site for shipping charges outside the United States. However, the remainder of the parts listed do not include shipping charges. Shipping charges for the additional parts will most likely be in the neighborhood of $30.00.
The author suggests that a 4 axis controller board be purchased and the controller case be constructed for 4 axis (openings for cables, connectors, etc.) even if only 3 axis are to be used. The additional cost will be minimal and the future addition of a 4th axis will require only the purchase of a 4th stepper motor, additional connectors and construction of a 4th motor cable.
B. The 5 conductor cable is used to connect the controller to the stepper motors. The 2 conductor cable is used for connecting the controller to limit switches, spindle/coolant control, etc. 24 feet of the 5 conductor cable will provide for 4, 6 foot cables for 4 stepper motors. The selection of 24 feet of 2 conductor cable is somewhat arbitrary and should be adjusted according to your needs. All Electronics is the only vendor who offers these cables in cut lengths, with a minimum order of 10 feet.
C. Heat sinks are required for the driver chips on the controller board. The HobbyCNC design suggests the use of a single piece of 1/8" x 1" aluminum bar approximately 7" long. The cost of ordering this amount of metal online will most likely result in shipping charges which make the price for this item unreasonable. Local vendors may require minimum purchases. The author has offered an alternative in two forms. The heat sinks from All Electronics are almost exactly the size necessary for 2 of the driver chips. Little modification of these will be needed and the fins should offer superior cooling when compared with a plain aluminum strip. Although heat sinks from other vendors are listed, they would require extensive modification and it is recommended that they be used only as a last resort.
Heat sinks for the TO-220 devices are not called for in the HobbyCNC design. They are included in this list only as an option. If they are used, be sure to keep them electrically isolated (don't let them touch one another). Considerable modification of the heat sinks will be needed to use them on the HobbyCNC board. So long as adequate cooling is provided for the controller, these should not be necessary. In fact, if they are needed, the controller probably lacks sufficient cooling.
It is not necessary to electrically isolate the heat sinks for the driver chips from one another. However, do keep them isolated from heat sinks on the TO-220 devices, should those heat sinks be used.
Be sure to use heat sink grease (thermal compound, All Electronics item number TG-150).
D. No heat sink is required for the bridge rectifier in the HobbyCNC design. However, a close examination of the photos on the HobbyCNC web site shows that the bridge rectifier is mounted so as to be elevated off the surface of the case. A CPU heat sink from a dead computer makes a very nice heat sink for the bridge rectifier with slight modification. Other suitable heat sinks are listed here for the convenience of the reader. After drilling an appropriate size hole through the heat sink, mate the flat side of the heat sink to the flat side of the bridge rectifier using thermal compound. Mount the heat sink/bridge rectifier assembly to the case by passing an appropriate size screw through the case, heat sink and bridge rectifier, securing the assembly with a lock washer and nut. Do not over tighten the assembly as the bridge rectifier can be damages by excessive tightening.
E. There are a number of options for connecting the power cord. The author's design calls for a power receptacle of the style found on most desktop computers. The receptacle from All Electronics includes a fuse holder. If a receptacle with an integrated fuse is chosen, only one additional fuse holder is needed (for the DC supply).
The use of a power receptacle is optional, the power cord may be passed through one of the panels of the case and wired directly to the AC fuse and transformer. If this method is used be sure to use a strain relief grommet where the power cord enters the case.
F. A half circle style mounting bracket for the large electrolytic filter capacitor is the most practical choice if the capacitor is mounted horizontally in the case. However, the author has been able to find half circle brackets only for the 2 inch diameter capacitor (2" bracket = Newark #95F2822). The alternative for a 2 1/2 inch diameter capacitor is to use a bracket designed for vertical mounting of the capacitor. This would require affixing the bracket to one of the panels of the case. This is not a particularly practical design. A half circle bracket can be easily constructed from a strip of aluminum or plastic. Do not use metals other than aluminum as they can cause an electrolytic reaction between the metal and the aluminum case of the capacitor. Although most large can capacitors have a plastic coating on the outer case, if this coating is compromised in some way, such a reaction can occur. Although not a particularly elegant solution, a half circle bracket can be constructed from an aluminum pop can.
Be sure that the capacitor can is not crushed or deformed by the mounting bracket.
G. The use of nylon standoffs is suggested so that the potential of the standoff creating a short is eliminated. Nylon standoffs and nuts are listed for mounting the male end of the standoff to the board. The female end should be mounted to the case. Metal 4-40 x 1/4" screws, which may be obtained locally, may be used for this end.
Use caution when tightening the nut and screw to the nylon standoff. They require only slightly more than finger tightening. Excessive tightening can result in a snapped post or stripped threads. The friction fit of nylon threads are such that lock washers are generally not needed.
H. These screws can be purchased at your local hardware store. Hardware stores generally carry only metal screws, but this is satisfactory for mounting the female end of the standoff to the case.
I. The power cords listed here are the style used with most desktop computers and require a matching receptacle on the case. See note E for alternate methods.
J. The author uses spiral wrap to prevent chafing of the stepper motor, limit switch etc. cables, where the cables contact moving surfaces. Careful routing and securing of these cables can eliminate the need for this item.
K. These connectors can be used to connect the stepper motors (5 conductor) and/or limit switches etc. (2 conductor) to the controller. It is recommended that connectors be used on the motor end of the motor cables. Optionally, connectors may be used on the limit switch etc. cables. The connectors listed here provide for snap-in mounting on the case panels should the use of connectors on that end of the cables be used. Alternately, cables can be connected via terminal strip(s) as described in Note L. An additional method is the elimination of any connectors at the case end of the cables, running the cables through holes in the panels of the case. If this option is used, be sure to provide adequate stain relief where the cables pass through the panels.
L. These terminal strips are included as an alternative to connectors at the case end of cables. Although this is a 12 position terminal strip, it is easily cut to any size. Other sizes are available. The use of these terminal strips on the case for connection of auxiliary input/output signals (limit switches, spindle control, etc) makes the connection of these devices very convenient. The terminal strips can also be used on the router, mill or lathe as a common junction point for auxiliary signals.
M. Research on the web will show a number of specifications for the amperage capacity of various size wires. Because the hookup wire is in an essentially "free air" environment (as opposed to being enclosed in a conduit or multi-conductor cable), 18 gauge wire should be sufficient for the maximum 10 amps provided by the controllers power supply.
The vendor for the wire listed in the "Other" column is www.ba-electronics.com.
N. In choosing a parallel cable remember that it must be a "straight through" cable (pin1 to pin 1, pin 2 to pin 2, etc.). Do not use a Laplink or similar cable. These cables have some pins that are crossed. Also use caution when purchasing a cable labeled as a "Printer cable". Some printer cables have a Centronics connector on one end. The cable for the HobbyCNC controller must have a DB-25 male connector on each end.
Parallel cables generally come in 6 foot lengths. Mouser offers parallel cables in 6, 10 and 25 foot lengths. Mouser 10 foot,601-30-9510, 25 foot, 601-30-9525.
O. The Molex connectors in this list require the use of a special crimping tool to attach the pins to the wire. There are several reasonably priced crimpers listed at www.action-electronics.com. The author has successfully used small needle nose pliers to crimp the Molex pins, however the process is very tedious and prone to ruining pins. The use of a magnifying glass or magnifying headset is suggested if this method is attempted. If this method is used, the author recommends soldering the connection after the connection is crimped (the author actually solders all crimped connections, no matter how they are made). Be very careful not to use excess solder as excess solder can flow into the connection portion of the pin, making the pin unusable. If the crimps are soldered, it is suggested that a trial connection of the male and female pins be performed before the pins are inserted into the housings.