Adding Power Downfeed to Your Shaper |
|||||||||||||||||
 |
For operations where automatic cross feed is not used it is necessary to hand crank the downfeed handle to adjust the depth of cut at the start of each ram stroke. Cutting dovetails and slots are examples. The power downfeed just about eliminates that tedious operation and if a dial indicator is installed one has a good visual indication of where the tool tip is. First a driver must be added to rotate the downfeed screw. I chose a Sears electric screwdriver since the price was right. The one used is a 3 volt model and runs at a no load speed of about 180 RPM at full voltage. To control the speed for jogging or stepping the screwdriver was modified by removing (sawing off) the battery holding portion of the unit. The cut was made just above the built-in switch at a point near the motor terminals. The switch was discarded. Now the power from an external adjustable voltage power supply can be connected through a reversing switch arrangement to the terminals. Note that there are differences in the Sears models and you will have to adjust to what you find. | ||||||||||||||||
| A couple of new parts will be required as are pictured. The ID of the upper end of the PVC tube had to be enlarged slightly to allow a nice fit of the drive device. Not shown are three holes tapped 6-32 and spaced 120 degrees near the top and bottom edges to lock the motor to tube and tube to new slide block. This makes for easy removal should you want to put the handle back on. One other change was to mill a 1/4 inch hex about 1/2 inch long on the upper end of your downfeed screw. This allows easy grabbing by the driver socket. The .75 inch hole near the lower end of the tube is a dial sight window for convienence. |  |
||||||||||||||||
 |
|||||||||||||||||
| A tricky but necessary mounting bracket for the microswitch needs to be installed on the turned portion of the crank bearing support. The best description is shown in a couple of photos. The position of the bracket on the bearing support circumference must be adjustable because the length of ram stroke determines the cam location and requires a repositioning of the microswitch. | |||||||||||||||||
 |
|||||||||||||||||
| If that sounds cloudy, it will become clear when operating the machine! Mine is just a snug fit and can be muscled without tools to any position. | |||||||||||||||||
|
|
|||||||||||||||||
| Wiring | |||||||||||||||||
 |
 |
||||||||||||||||
| The wiring is as basic as it can get. A variac adjusted DC power supply, about 6 volts and 3 amperes allows an easily adustable down feed rate. You may prefer a variable voltage supply and eliminate the variac. The drawings show all. Just for the record, I built a PWM type speed controller and found it to be no better or worse than the simple one described, and a lot more complex. | |||||||||||||||||
|
|
|||||||||||||||||
| More Ideas | |||||||||||||||||
 |
One more thing, the photo shows some neat things I learned from a Rudy Kouhoupt article in HSM. The taper pin hinge, a new clapper block with the tool bit held so that it's cutting edge is in line with the center of the hinge pin, and his neat vise which fits the shaper table. All are valuable hints.
The spring idea is nice for positive action especially in short stroke applications for internal work. It allows locking the clapper as well. ( I don't know where that idea originated ). When I want to index something, I add some angles and mount a spin indexer (5C) as dictated by the job on the table. A support to the floor helps! |
||||||||||||||||
| Richard 2004 | |||||||||||||||||