The Atlas 7B Shaper arrived about four months ago now. Each time it has been started it shorts out. The problem is the new switch that was installed. The attached wires were the source of the short, so the first fix was wrapping them in electrician's tape. This did not short out as quickly, but eventually shorted out after a few minutes of movement. The gap between the main driving gear and the back of the switch is small and this switch has terminals sticking out the back.
A new switch was purchased from Ace Hardware with two wires coming out of one end. These wires were shortened. Both these wires and the motor wires were bared and joined with wire nuts. A little measuring showed that there was sufficient room in front of the main gear to fit the switch and the nuts. The nuts were taped to the back of the switch with electrician's tape. The switch was installed with the ground wire trapped between the machine and the switch plate. The machine was run without shorting out.
Learning how to use the shaper was the next task. A few books are available, one purchased and two downloaded pdfs. Setting the length of stroke is the first task. This is done with a crank handle attached to a square shaft on the just below the switch inside of a knurled knob. The length of stroke should be the length of the material plus 1/4" at the front of the workpiece and 1/8" at the back of the work. The handle/lock at the top of the shaper is then released. A square ended shaft is to its right and turning this adjusts the position of the shaper cutting tool. After setting the stroke length, the shaper was manually moved to the rightmost or stroke beginning. This was adjusted so the cutting tool was 1/4" from the front edge of the workpiece.
The worktable can be moved back and forth by a square ended shaft with a graduated dial just to the left and below the switch. It was adjusted so the tool was just in front of the workpiece. The tool height is adjusted in small increments by the handle on top. It was adjusted to just touch the top of the small block in the vise. The machine was started and the handle for tightening the belts was pushed to the right engaging the head movement. To engage the crossfeed a small knob is turned counterclockwise (a clockwise turn causes the table to move away from the operator) causing the table to move toward the operator. Cutting was good, though the cuts were too far apart. Learning how to adjust this movement is the next lesson.
Noticed that black dust was accumulating below the belt on the back side of the shaper. This is the belt that connects the large top pulley to the small bottom pulley. I had thought these two pulleys were sufficiently aligned. Using a straight edge indicated the bottom pulley needed to move away from the shaper about 1/16". The pulley was adjusted as indicated.
A cheat sheet was made for the shaper. It has a diagram of the shaper indicating all of the 'knobs' that can be adjusted to affect cutting. Each is labeled with a letter and a phrase describes the utility of that knob. Also indicated on the diagram are the various places where oil should be applied (and one for grease). Now that the winter is past this should be the first order of business before beginning work on either the South Bend carriage stop or tool holder.
Spent some time this morning (6/5) continuing to learn how to use the shaper. The first challenge was adjusting the length of stroke. The large knurled nut was loosened with some effort and the shaft in its center was rotated clockwise (about one turn per 1/4" additional stroke). The knurled nut is then tightened. The handle on top is loosened and the shaft on top is then rotated to move the beginning of the cut to the correct position. A few times back and forth gave the right length of cut with sufficient overlap at both ends. Then the distance of automatic movement of the table was adjusted. The only way I know to do this is to loosen the nut on the eccentric and move this nut in or out relative to the center of the eccentric wheel. It was adjusted to give a small movement. I am guessing about 0.005" (bad guess, it is about 0.010"). The tee nut is difficult to slide and may require some lubrication.
There has to be a better way to make this adjustment!! The scale on the table movement shaft might indicate that this is where this is done, but I have yet to figure it out. Nope, as seen on YouTube this is the only way to adjust this movement. You should be able to read out the distance moved on the scale as the movement takes place on the return stroke.
With these parameters set the down feed was set to about 0.005" and cutting commenced. The cuts left no obvious grooves between strokes, but chatter could be seen and felt across the face of the work.
I read the Kay Fisher columns on Shaper tools. The tool I am using may be part of the problem. It is a right knife tool, which is usually used for vertical cuts on the side of the work. I need to make a round nose tool with no rake. The Armstrong tool holder will provide the 14° rake and the grinding should provide about 7° clearance if the bottom of the tool is aligned with the wheel center. This is a multipurpose tool used for roughing and finish cuts. It is the most commonly used tool as it will cut in both directions, eliminating the need to move the table back by hand after each pass.
I ground a round nose tool from a Sherline HSS blank. After grinding it needed cleanup on the ground face. This was done with 150 grit paper and left a pretty decent finish on the ground curved face. The top face was slightly ground (maybe it should have been left alone) and then sanded with 150 grit, honed with 220 and 320 grit and finally sanded with 1500 grit paper. This left a nice polish on the top face.
This new bit was put in the Armstrong holder, which was placed as far into the lantern tool post as possible. A couple of cuts across the part, advancing about 0.010" per pass and a depth of 0.003-0.005", resulted in significant chatter. The fern-like finish can be seen in the left photo below. The round nose tool was extended almost 1" from the holder and its vibration during cutting was fairly obvious. So this tool was cut in half with a Dremel and cutting wheel. The shortened version was returned to the Armstrong tool holder exposing about 3/8". No vibration could be seen, but as the photo on the right shows there was still a lot of chatter.
Reading up on Shaper chatter it seems as if I should continue to work on sharpening the round nose bit. The front or bottom face should probably be sanded to a finer grit. A leather strop may also be helpful. I should also explore different feed rates, especially slower feeds. Maybe even use real cutting fluid instead of the oil I tried because it was handy.
A few new things were tried. After a little consideration the clearance might not be sufficient. The Armstrong tool holder angles the tool at > 7° and the clearance is only 7°. The heel of the tool looked very close to contacting the work upon visual inspection. So I increased the angle of the table on the grinder and reground the clearance. I then carefully sanded the clearance and the top face of the tool with successively 150, 220, 320, 400, 600, 1000, & 1500 grit sand paper. Cutting then proceeded as before. There was little change in the amount of chatter as seen in photo lower left. I then lowered the speed one step (the lowest the machine can go). Chatter was improved as seen in the lower right photo (0.005" depth of cut). The picture below shows the improvement. It is still not as smooth as it should be. Oil, cutting depth of 0.007", of 0.002" resulted in no improvement. Difficult to see in the lower left photo is the "bump" in cutting at the beginning of the cut. This was not affected by any of the modifications discussed above.
