Another Redneck Linear, but this one gets the job done! This very universal Linear can be used with several sizes of motors from 270, 360, 370, 380 up to the 540. Uses 5/16-18 all thread rod and spinning hex nuts for motion. You are only limited with the linear travel by how long of threaded rod you can get. Has a range of gear ratios that can be uses to get the right speed and power you need. Will mount up several different ways and has mounts for miniature micro switches. Can mount up and push or pull through a bulkhead. You can use all or part of the linear depending on what you need it to do. Small enough to fit beside a 2 by 4 with motor laid on side. With motor speed controller linear could be used to move about anything with remote control. The liner has two different A cases depending on the motor you want to use. The 540 case will handle most motors with 25mm mounting holes 1.409" case and 10mm bearing housing (550 will work with larger pinion gears, but you better fasten it down good!). The 380 A case will handle motors with 16 and17mm bolt centers, max motor OD of 1.092". The 540 case will go down to 93-14 gears and the 380 will go down to 93-10 gear ratio. Just added a .PDF gear ratio chart that shows what gears you can use and their ratio. The spool (A gear - B gear) sandwiches a drilled Team Associated slipper clutch style spur gear with 1.25" octagon in between the halves with 5/16-18 hex nuts inside for contact with all threaded rod. Uses two 18x12x4mm sealed RC truck bearing on the spool. The Team associated gear I found easily on Amazon, they have a 93, 87, 84 and 75 tooth 42P gears. To figure the speed of the linear use the following example. The motor I am using is a Mabuchi RS540SH-7520 (purchased 4 of them new off ebay for $12.60), it is a 7.2V, 12A, 312 g-cm of torque at 19,000 RPM. The gearing is a 93 spur gear and a 14 tooth pinion, divide the pinion teeth by the spur teeth you get .1505 multiplier. Multiply your motor RPM times this number (or the spool is turning .1505 (15.05 percent) of the motor speed). 19,000 RPM times .1505, that is 2860 RPM that the spool is turning at the threaded rod. Take the RPM's at the rod times the thread pitch of the all threaded rod which is .05556 (that is how far it moves with one revolution of the spool). The rod moves 158.8" inches per minute, divided by 60 seconds is 2.648" of movement per second. With the 84-33 gear ratio and this motor it would have 6.91" of travel per second. That is wipin right along! If you use smaller motors with lower RPM things will slow up a lot, you will need torque to get taller ratios and speed. With the 540 motor and 93-14 gears with the liner case chucked in my vise it dead lifted a 5lb hammer and didn't even strain. But the RS540 is a powerful high Amp motor. Need to talk about how to wire it up and the micro switches. You have to understand that I know just enough about electricity to get me in trouble! So please research your motor and ratings of switches to be safe. The RS540 motor is rated at 12Amps DC Volts. If you use micro switches to run the motor itself, be sure they are rated for 12Amps at DC volts not VAC. Big difference, most sub-miniature micro switches will only handle a fraction of the DC Amps that the switch will work with in AC Amps. I am using an Arduino board and a 2 channel relay to control the linear. The micro switches cut off the low 5 volts, .020 amps of the Arduino board through the relay, not the 12A of the motor. When get more time I will do some different wiring schematics for automotive relays and toggle switches, but there is already a lot of info online on this subject. The micro switches have holders that will go on at several angles, and the case will rotate for placement of motor on top or sides. The switch triggers have 5/16 nut inside and one for a jam nut. Can be adjusted up and down the rod for the right shut off point of motor with switch. Linear uses #4x3/8, #4x1/2 and a couple #4x3/4" sheet metal screws. Uses 1/4-20 bolts in the mounting bracket and yoke. You will need to drill with a "F" bit and tap the yoke to 5/18-18 thread. Sill working on this so stay tuned for updates as I use it and get the switches working. I tried printing some gears but they didn't turn out round enough or strong enough to work with that powerful of a motor at 19,000RPM. Just added some Team Associated Spur Gears to download. You will have to try them and see if they will work for the smaller motors. I would use a metal or plastic manufactured 48P pinion gear for the motor. Have fun and be safe! Update June 2015: Hey everyone I found a really nice motor from Jameco #2144673 Mabuchi RS555PH-2330. The motor has 380 g-cm of torque and does it at a slower 5050 rpm. Much easier to manage and only 4amps at 12-30 volts. The motors are $3.95 each. I am using one on a new project lifting a 15lb metal blade on a RC Dozer and it has a lot more power than the RS540.