I am looking for a strong reliable way to attach a globe motor to a small gear. In previous years we have bored out the gear to the diameter of the globe motor shaft and then ramed set screwed onto the flats of the motor shaft. This method worked but it wasn t very reliable and constantly came loose. I was also thinking of somehow boring out the gear to the same shape as the globe motor shaft but i couldn t find a good way of doing this with our limited machine shop capability. If anyone has any info about how to attach gears to the globe please let me know.
Last year, my ascending system used two globe motors. I did what you want to do, I bored the two ends of the main drum with the shape of the output shaft, the motor just slid in, and that was it, no set screws to worry about. It was however, a pain in the butt to mill by hand (which is what I did) - but it is possible. Of course, if you could, and the design permits (mine did not) you could always use wire EDM, or water jet like the above person mentioned, also do not forget about CNC milling, as it would have worked for what I needed it to if we had a CNC mill large enough. I think using the technique you used in the past was good in a pinch, but I would constantly be worried about the set screws. Globe motors rock, and I had two, because everyone was afraid to use them (no side loads are tolerable) - so remember that!! don’t just cantilever the gear without proper shaft support, or you will eat the gearhead in a second! Good luck with your project.
We have used the globe motors for several different applications.
We had a square hole EDM’ed out of the center of a sprocket than had a square block made that fit the square hole and the oval shaft of the globe motor. It was sweet. Very precise EDM’ing.
We use globe motors on our satellite dish feed assy. In order to insure that there is no slipping of the gear, a small hole is drilled through the gear and motor output shaft and a drill rod (drill blank) or roll pin is inserted to hold the two together.
The tool you are looking for is called a broach. A broach with the appropriate width will give the shape hole you need. I don’t think broaches are terribly expensive, though I must admit our machine shop has never made us pay for one.
Either that or find an EDM shop nearby. It is a small enough job you might get it done for free if you ask nicely and the machine is idle at the moment.
I never thaught to use a broach…that would definately would have been easier than doing it manually on the mill…I think our team is getting ready to buy a press (in the past to put key ways in gears we sent it out to a mentors shop, but never did I realize they created that size broach. A note about drill rod,before I knew what drill rod was…I tried cutting it on a gravity feed band saw…not soon after was I getting yelled at for wasting the blade…and I wondered why it wasnt cutting…silly me. I learned my lesson.
I believe they are made, but not on large scale, not at least from what I found. I believe it would fall under the “oval double radius” broach. I found a company that makes custom broaches, but you can bet it would cost a lot of money, and probably time. So, I’m not upset that I spent so much time on the mill, I learned a few new tricks doing it that way.
I always thought a broach was something you used to finish what was already roughed in. (i.e. an edm or wire operation needs to be finished with a broach to make it smooth and accurate.) Any professional machine ops out there to answer?
I am no professsional machinist but I have done keyway broaching. It is basically a “staircase” of cutting edges and with each “step” it takes off a little more material. For the keyway, you start with the round bore, but the broach does the entirety of the slot. They have hexagon broaches too. You start with the round hole and on the broach may be like a foot long and on each step the cutter gets a little larger and a little more hex shaped and by the time it gets all the way through you have a full hex. I really thought there were Double D broaches, but I could be wrong.
There are various kinds of broaches. We have one that was specially purchased to make a hole that fit the old Van Door motor shaft. Our sponsor provided it, so I have no idea how much it cost. I’m not sure whether or not it will fit the new Slider motor, though the output shaft is obviously different. Our sponsor also has a set of key way broaches which we have used occasionally. They all work as sandrag has described
hey I was just wondering, how, exactly, did you guys get the sprocket to fit with the globe motors, like did you guys use hub or hubless sprockets? Thanks.
I used the globe motor like a lathe and turned it down… Hooked it up to a 12V, put the gearhead in a vice, and held a file against it. It fits an FP pinion now, but sadly its too small due to some smoothing files that probably shouldn’t have been made. Epoxy stripped twice, what do you think about JB weld on the armature? Would it hold? I cant see easily putting a pin into the FP gear without screwing up some teeth bigtime.