UPDATE: As I look at this project a year or so after I published it here and now have learned the site............This project is a mess and I put alot of effort into it. So I am going to clean it up a bit and make it easier to read and understand, correct a few steps I see now and work on getting a better project for you all to see.
Me and a friend were talking about auto feed screw guns and how they were huge and expensive. I have not got as far as to make this auto feed but it is why I used the circular bottle for later fabrication of auto feed. I am close with trying to build a drum style hand held auto screw gun to hold and dispense 8 screws (for the everyday home user) This Idea is more like a simple one screw at a time Idea that covers 3 tools you can buy in the store. I have designed this to be a "screw guide" like the tool you can buy that has the sheath to hold the screw while drilling. Also I have made it so it will drive a flush screw every time and self retract, no matter what size the screw. Also I have designed it around a magnetic "fast change" bit with bearings to independently spin.so in seconds can go from Philips to Flathead. Everything in this project is recycled or something I had laying around the house. The only thing I did pay for was bearings and inner/outer race so I could make the outside hand held part free floating. If there are any questions about this project I'll be more than glad to answer them. I do things a little differently than some, When I build I do it the same way I play instruments. I don't know the chords or sheet music and I play everything by ear so you will find in this project I really didn't measure anything or plan anything out so I will do my best to explain my trial and error tactics and how I got what I ended up with. I do apologize for that.
Step 1: Core/housing
So this would be my first step to the project. I didn't think to take photos until after I started so I'm thinking Ill go back and build a second bearing set up to show how I did it. First I took my bit holder and when I went to the store I just looked for a bearing set up to fit the bit holder diameter snugly. Then I wrapped it in electrical tape so it would fit snug into the housing(pic#3) I made. Once I had figured out the housing and had guides on each side for a later part. I had to fit an end cap and also something to fit into the front and hold the bit and bearings inside the housing.(picture #6&7) I collect random junk and old pill bottles from people for project and the locking tops on the bottles and reverse threads made this project much easier also I used small screws from a tore down R/C car.
Step 2: Stop Some Undesired Rotation/movements
My next step once I felt ok with my core was to make it so the core and outer sheath would move independently backward and forward but not spin independent. Here is where a lot of trial and error came into play. Picture #1 shows my next part that just so happens to be the same diameter as the outer shell, It was the only bottle I had with the size I wanted. The added piece in picture #1 is shaped that way solely so it will bend just enough to fit inside of the outer shell and slide into the tracks on my core to stop any independent spinning.. Also the outer shell for this to work was split half way up to allow a slight expansion when put together. If I had what I needed then I would have just used a larger outside so I had to make it work.
Step 3: Backstop
Next step once I had my core and outer shell fitted I needed a back stop so the inside piston did not want to push flush to the cap of the shell. This is where the dual threaded sides help a lot. The stopper threads inside the edge of the bottle allowing for the cap to still be put on without interfering.
Step 4: Connection Pieces
Next was finding a way for the core to move but not push out the back of the shell when the spring is set inside. So now I turn to random R/C car parts and little prefabricated parts I could use. And of course I could not find two identical parts to keep my core and outer shell together so I had to fabricate 2 different pieces to keep them together and fit the track to keep shell and core together.
Step 5: Cap/spring Guide
This I would say was the hardest and most annoying part of the project. This step was finding out what should hold my spring yet allow it to still compress smoothly and not bottom out and stop my screw from driving in the full amount. Huge trial and error point of the project. I went with 3 different ways before I noticed the plastic core of a CD disk holder was perfect to fit a screw and also prefabricated to be straight and smooth inner core.. First was plastic tubing I found to "Grip" the screw head when it touched the wall and cutting out the smooth action. Next I took a toilet paper roll and made my own tube..........that's not my style so I nixed that. I ended up just going with the same style as picture #2 just with the core tube from a CD holder. The end of the CD "pole" also was beveled giving me an edge to fit into the cap so it would not push through the top.
Step 6: Testing
The spring inside I grabbed out of my toilet paper roll holder lol its perfect for this application. Once everything was done and put together I sat and compressed it about 30-40 times and slowly took it apart and rebuilt all while shaving off small parts and making everything fit and work together smoothly.
Step 7: Finishing Idea
At the end of this project I have a top I can put on that will make it flush every time with any size screw also I decided to make a second top that will when drilling leave just enough of the screw every time to hang things on your wall, this is the same depth never fail every time. so I guess it might look goofy but it does serve the purpose of the 3 tools I have selected to cover. Also its all recycled items (besides Bearings under $2) and can be used by anyone easily. also the way its build for the outer shell to not spin you can hold this and drive screws in with maximum stability and universal to any drill. Like I said before if anyone has any questions I will gladly answer them. Next project of this kind will be my "Home" Version of an affordable auto feed screw gun as close to this size as possible. Some things in the pictures are not the end result, maybe just different material but the idea itself does not change.