Tuesday, December 11, 2012

Another view of the motor/pulley fixture. The hardwood cross members support and align the 3/8" bolt shaft. Industrial-grade pillow blocks are not in the budget.

 The fixture sits on the lower shelf of the utility table and is shimmed in position. The primary and secondary drive belts are from junked washing machines.

Next, we need a way to get wire to the turning tube. The base is again scrap plastic .707" Nylon. The floating casters, like everything else you see used in this project, are from a junk yard. The plastic carton is a seat for the operator, and is equipped with a cushion. The pedestal holding up the spool of wire is from a discarded MIG welder, as is the wire spool adapter support.

The wire transport must move with the operator as the coil is formed. When you're setting up to wind a coil, be sure to find a smooth flat surface for the transport. Bumps and stops are annoying, and show up in the finished product.

At this point, we address the wire itself. Cut off a piece of wire three turns around the spool and place on the ground. The diameter of the loop is called the cast of the wire. The surplus material I have has a twenty two inch cast and a very high tensile strength. Another way of saying it is very tough to work with. To make the wire more amenable, a wire straightened is modified to be be used as a wire bender or preformer. The new cast will form a circle very close to the conduit diameter, approximately 4 1/4".
The torque supplied by the over-sized head stock is enough to pull the wire through the bender to the tube form.

Inches per Pound of Wire

                                                                  Silicon                                                Stainless
                                      Aluminum           Bronze         Copper       Nickel          Steel

.020 "                               32,400               10,300             9800          9950            10950
.025 "                               22,300                7100               6750          6820             7550
.030 "                               14,420                4600               4360          4400             4880 
.035 "                               10,600                3380               3200          3240             3590
.040 "                                 8120                 2580               2450          2480             2750
.045 "   3/64 "                    6410                 2040               1940          1960             2170
.062 "   1/16 "                    3382                 1070               1020          1030             1140
.078 "   5/64 "                    2120                  675                 640             647              718
.093 "   3/32 "                    1510                  510                 455             460              510
.125 "    1/8 "                      825                   263                 249             252              279
.156 "   5/32 "                     530                   169                 160             162              179
.178 "   3/16 "                     377                   120                 114             115              127
.250 "    1/4 "                      206                    66                   62               63                70

Revised Headstock Design September 18, 2015

 Cutting the new sheave from a large square. Six passes with router were needed to make a complete cut on
one inch material. Below, an acrylic panel fastened to the bottom of the router acts as a circular guide around the center pin.

The original 16 inch flange/sheave is shown resting on the new sheave material. Why the bigger pulley ?

Slower travel speed and increased torque for large diameter wires are pluses. .052", .062" (1/16) and 3/32"
wires are more easily wound at slower speed.

The head stock design will determine your surface winding speed and torque for wire forming.
 The white plastic base is 1 inch thick HDPE sheet cut from a scrap square and bolted to a 4" schedule 80 flange. A router used for woodworking is indespensible for this work. Setup is
simple. The machine does it's job flawlessly, but keep a supply of garbage bags on hand. You will empty your ShopVac reservoir several times as your work progresses. 

Before final assembly with the mounting hardware, a router is used to create the groove for the drive belt. My thanks to redneckdiy.com for instructions on this method. The sheave is now ready for action.

The stub in the flange is schedule 80 stock. Standard PVC cement holds it in place. This is the interface between the fixture and the work piece.

The finished sheave has a inside diameter of 23 inches. Weight with hardware is 22.2 pounds. 

Note the small grey bracket to the right of the flange. This supports my Digital Turns Counter;
a pedometer compliments of the local health & wellness expo.

Saturday, November 24, 2012

This support bracket must hold the weight of the head stock, tube section and wire. It is held in place
on one side by a large C clamp. The other side floats, and is shimmed for proper belt tension after
the work piece is loaded.

                                          Two small casters support the work piece.

The tail stock is simple. The fixed casters support the tube and allow it to turn easily. Note the C clamp in the center. Easy on and easy off.

Let's wind some coil !

The operator guides the wire on to the rolling tube. The wire spacing is determined by the guide tool. As the wire is fed, the operator holds the tool against the tube; the wall thickness of the guide is the distance between the turns. The guide rubs against the adjacent turn and is pushed to the  left by the pitch of the wire. Clear enough ??  Some form of automation is called for here. Wind-time for a 10' section at 190"/minute surface travel speed is about one hour and forty five minutes.
Please note the use of loose-fitting gloves.

Exactly how large is large ? Here are the charts.

Here are links to schedule 40 and schedule 80 tube dimensional drawings,
from http://cantexinc.com.



                   A completed 10' section, made with 4" schedule 40 PVC electrical conduit.  It's supporting 1100 feet of .045" stainless steel wire.