I have an HP Laserjet 1018 printer. I am printing my circuit designs on a transparent paper, when I do so the output isn't totally dark. I have to go over it with a black marker so its totally black. What I want to do is print the first time the circuit then the second time the same circuit in the same position over the first printed circuit. When I try printing the second time the circuits are not aligned with each other. How can I print the circuits aligned with each other.
We have no way to make friction based paper feed repeatable. The placement can become more consistent if all parts are cleaned, but it doesn't help original uncertainty nor tear and wear.
Your options: 1) Explore printer driver settings - is there any settings for darkness
Use less glossy paper which takes more ink powder
if you use transparencies be sure you have the right side getting the ink powder
Assemble and fasten manually two transparent copies together.
I have used always trick 4 (=manually aligned 2 separate copies) for photoresist applications because one has too much microscopic holes. It works if the feeding happens uniformly after it starts. It's useless if the feed is slippery.
The comment by user287001 is of sufficient value to be considered an answer. User287001 moved his comment to an answer while I typed this!
Mechanically, it is nearly impossible to have a printer perform in the manner you require. I was an offset press (lithography) operator during the last century. It was possible to adjust the paper guides and pick-up system to create the alignment required but involved multiple adjustments and was valid for only the one print job.
Additionally, if you intend to create two copies and fasten then together (a good alternative), it is advisable to mirror one of the copies and flip the transparency over.
If not flipped, the two layers have a displacement equal to the thickness of the transparency. If flipped, the two layers will be in contact with each other, eliminating fringe illumination and diffraction that might be caused by the material thickness.