Sliding Pen/knife/pencil Holder for Cnc or Pen Plotter

How to set up the pen/pencil or knife in a pen plotter or cnc machine so it does not rip the paper. This is called the sliding pen trick ,read on check it out.

hello my name is Walter and I have been building things for a very long time ,now that I have retired I am not under any employment contract I can release some of my tricks to make things work. I built my first cnc machine back in the day of the commodore 64,I used an expansion port board and BASIC (peek&poke) to make it run,Well now I use an arduino with GRBL along with step sticks to run my current machine (mini robo CNC),( hp 24 inch pen plotter rebuilt for todays technology) now what I am writing about is a simple device to stop an ink pen /pencil from ripping through the paper and destroying a perfect plot.

Now my friends ,take a real close look at the z axis, the second photo really shows the detail,what I have done is dissemble an ink pen ,cut the bottom section in half ,the bottom section is the part with the rubber grip on it,the part we want has got the glue gunk on it from previous use,now we should have 2 parts that we want A appox 1/2 the orig pen barrel and 2 the ink cartage that was removed.

Now using a hot melt glue gun glue the modified pen barrel onto the z axis ,insure the pointed end is downward and with the z full down there is approx 1/4 inch between the paper and the tip of the pen barrel. Now for some slip and slide action. Caution insure that the barrel does not move before the glue cools.

Now lets take a good look at what has been accomplished. Now if we use the electronics on our machine to drive the Z full down the pen barrel should NOT touch the paper.this my friends prevents the paper from ripping.Next Step

The first thing we are going to do is move the z axis up so the pen cartridge(the part with the ink in it) is all the way down in the barrel allowing the tip to stick out. now slide a rubber groumet or rubber band around the upper end of the pen cartridge so that if the z axis moves up the barrel will catch the rubber band or groumet and raise the pen cartridge up .What have we done?

So far we have the z axis set up so that with the z full down the paper wont rip. however we may want a darker line.

Now if we were using a felt tip pen the line would be ok,however we are using an ink pen so to make the lines darker we need to add some washers to increase the pressure, you will need some washers with a hole size the diameter of the to part of the ink cartridge,simply drop them onto of the rubber band or groumet. That's all hope my info helped please look at the pics real good so you have a firm understanding of what you are doing...