[Potatohead908]

I am on a mission to create a tool for work. What I need is around a 15:1 reduction, a 90 degree transition in drive angle and the driven shaft will move up to half an inch along the driving shaft. This drive mechanism will be driven by a cordless drill. I am thinking I will need to make a worm gear set with an extra-long worm to allow the worm gear to move along the worm axis. The worm has to be less than .375" OD and the worm gear less than 1" OD. The other option is a helical gear set.

My questions are 1) Have any of you seen this type of drivetrain? 2) Do you think this is possible without being prone to failure? 3) Do you know of a supplier that sells worm or helical gears in "stock" form so I can cut to my needed dimensions?

[elbruz]

Just a have look at www.maedler.de . Or Small Mechanical Components: Precision Gears, Gear Assemblies, Timing Belts, Timing Belt Pulleys and Couplings - SDP/SI . Hope it helps.

[Eldon_Joh]

i have a left and a right gearbox from an electric wheelchair that is something like 15:1 reduction.
the first stage is a hypoid gear, that also backdrives.

not sure what you mean by the driven shaft will move up to half an inch along the driving shaft.
edit: a long worm will work fine use a larger than normal shaft and bushings for the bearings, the shaft will simply slide through the gearbox..keep in mind that the gear ratio will change.
it would also be possible for the worm itself to slide through the bushing, but the contact area will be a third or so what a smooth shaft would be