I’ve been surfing around looking the net looking for some idea’s for my radial arm saw reprap project. Initially, I was thinking that a belt drive would be the way to go, but than I thought it would be interesting us a rack a pinion. It seems like racks and pinions arrangements are a bit pricey so that got me thinking about making a rack with my cnc metal shaper project. It would be nice to have a clapper that could have a fixed automatic downfeed to it so I it would be easy to make a rack. Something basically that could do a simple automatic down feed to a fixed depth.
I have functional Ammco shaper as well as a a carcass of a parted out Ammco metal shaper I picked up cheap off of ebay. I want keep one shaper classic so to speak and basically pimp out the carcass with cnc.
The plan is to basically to machine a new clapper assembly specifically to mount a stepper motor. I figured this would be a project that I could mount on my classic shaper and get use out of, while I get the rest of pimpy made. I probably should be do this out of cast iron, but I’m using steel that I have on hand instead… (I hope I don’t regret that). The first piece that I’m working on machining is the dovetail assembly that fits into the ram. I got a piece of 4″ round and offset it in my 4 jaw chuck. It was a interesting experience since my lathe isn’t bolt to the floor. The vibration from the imbalance was causing it to walk. I was getting pretty good surface finish with carbide but it seems like my poor logan is groaning a bit with the increased cutting forces. So… I switched back HSS using my diamond tool holder. I’m experience some pretty bad tearing with that. I’m still roughing things out on the first side (which fits into the ram). I basically need a 1.125 tight fitting diameter. I don’t know if I can achieve that turning. I did a quick check for taper and it seems like lathe is cutting straight, so I’m wondering if I should go to size with tool post grinder. Hopefully, I can grind it straight enough that I wound have to do this from centers…
In the mean time, the thing that got me started down this path, a rack and pinion for my radial arm saw reprap has presented itself with another solution. I’ve seen people making rack drives from threaded rod. In researching this I across some posts from Mike Everman on making a fixture for machining the pinion racks. This guy has done a bunch of things that I find rather interesting…. Here are some links…
Fixture for makeing a gear to mesh with threaded rod.
Very interesting belt drive application
Differential Roller Screw
Servo Nut Drive.
oldham coupling animation.
Eddy Current Brake
Anyway I go this threaded rod rack route, I have some acme rod from a scrapped garage door opener that would be fun to use. Using a fixture/tap solution unfortunately wouldn’t work.
In that cnczone there’s an interesting link on threading in the lathe. http://www.bedair.org/Worm/Worm.html At some point this would be fun to try. Anyway… rapidly running out of christmas vacation ;(
One other very interesting post I’ve run across was this:http://blog.ponoko.com/2010/11/16/ten-rules-for-maker-businesses-by-wireds-chris-anderson-%E2%80%94-rule-1/