I think you could use the diagram you have and modify the shafts and eliminate the numeral dials without changing much else, no?
Robert
I imagine this could be done fairly easily. That would not only eliminate the numerical dials, but it would eliminate the need for the pinion gears on the top end of the transmission shafts as well. It would also eliminate the need for the "Spider Spring" and all the steel balls that hold the numerical dials in place.
But if you look on the first page of this thread at the video on how this thing works, you might take note that it's important to have the balls and spider spring holding the numerical dials in place, which in turn, hold the transmission shafts in place, when they aren't being locked in by the locking gear.
In other words, changing anything on this design could potentially have cascading effects that could result in other problems. For all we know the original prototype model had these problems and was prone to jamming up? Maybe that's part of the reason they redesigned it?
Changing things without being clear on what the consequences are could result in trouble down the road.
How determined are you to make exact replicas of parts? Parts are designed with ease of manufacturing in mind. The purpose of the vee shaped protrusion in the bore of the gear is to follow the keyway on the shaft. A conically pointed pin inserted through the bushing and brazed in place could accomplish the same goal.
I agree, there is a lot of opportunity here for some design changes that would make things much easier for a hobby machinist to be sure.
I don't know what Racer's full purpose is. Nor am convinced of his conviction to the project at this point.
I'm thinking that anyone who takes this project on would probably do well to stick to the original design. Unless they are only interested in building a single unique hand-made calculator for their own personal accomplishment and satisfaction.
Seems to me the latter would be a terrible waste of effort. For just a little more effort making it correctly could result in a potential for some real profit down the road. Apparently there are people willing to pay good money to have their repaired. If a machinist put in the effort to do this project by the book it could result in a potential pay off in the long haul.
Let's face it, no matter how we approach this project it's going to be at least a year long (if we're LUCKY!) Maybe longer than that.
This isn't a project you're going to want to look back on and say, "
Darn I wish I would have taken the time to do it right".
Probably better off just doing it right from the get go.
Forty dollars a gear? Once you are set up to make them, it could potentially pan out.
Just say'in.
Especially for someone just starting out in life like Racer. This is an opportunity he really shouldn't pass up. He won't have time to do this after he graduates and starts working full-time. And if he does it now, he could get himself set up in a Curta Calculator repair business and even sell the "Replicas" that he makes. This could turn out to be a full time career if someone takes it seriously.
Look around. I just came from a web site where people are selling Curta Calculators for as much as $5,000. A working replica will easily bring in a grand. In fact, it's hard to find even used beat up one for much under $1000.
Although some people do get lucky. I just read a post on the Curta forum where a guy just picked one up at an antique store for $10. No kidding! Apparently the owner of the shop had no clue what it was worth. And the photo of the one he got appears to be immaculate.
