"Why Don't He Ever Write?"; How A Vertical Mill Is Like A Typewriter

This is the funniest line out of Dances With Wolves--one of those films that was breathtaking when I first saw in the theaters, but has rapidly declined in my perception. Great cinematography can cover a host of other evils.

Some of you are probably asking yourselves, "Gee, why doesn't Clayton respond in a more timely manner (or at all) to my emails?" Well, it isn't for lack of interest, but lack of time. A few days ago, someone emailed me to ask if, instead of a caster set for his Losmandy GM-8, could I build basically a version with a flat bottom? He didn't have a place to roll his mount--but he sure wanted to keep the dirt and bugs out of the hollow legs. I agreed to try and make a set for him--and then I asked on the Losmandy users mailing list if anyone else needed such--and I immediately received three requests for information.

Voila! You can read about it here.



They share some parts with the ScopeRoller 8 product--and they can be field upgraded to the ScopeRoller 8. I intend to do likewise for other mounts as demand arises. (Although at the moment, the Losmandy tripods are the only ones with this dirt and bug gathering problem.)

It looks like a trivial change to make this, but most of the work was figuring out to optimize manufacturing to minimize the number of parts and the number of processes.

Another project that is keeping me busy involves a company that I would rather not name quite yet. They are a manufacturer of high-end telescope tripods, and would like me to offer a caster set for their product. This is a bit different from the other products that I make because it has a rather different interface--in some ways, easier, in some ways, harder.

The big difference is that I am using my vertical mill to make this product. I have to produce a recessed rectangle that will produce a somewhat close fit (say, +- .05") to particular dimensions--and I need to put a hole in the center, again, within perhaps +- .05". The recessed rectangle is about .1" deep.

This is well within the tolerances of this vertical mill, but there's a bit of learning involved. You see, you have to figure out exactly where to drop the cutting bit to start excavating. First you find out where the edge of the plastic is that you are going to be excavating. Then you move the cutting tool a certain distance in from the edge. Then you start cutting. This part wasn't difficult.

The more difficult part--and where a vertical mill is like a typewriter--is figuring out how to exactly center the cutting tool in the middle of the recessed area. For those of you too young to have ever learned to use a typewriter, one of the things that you learned to do in typing class was how to center a title.

"Hey, how hard can that be? You just hit ALT-C--and bang! It's centered!"

Well, on a typewriter, you would see how many spaces there were between the left and right margins, and divide that by two. Then you would count the number of characters in the phrase that you wanted to center. Then you would divide that number of characters by two. Then you would subtract the second number from the first number, to figure out how many columns you had to space over before you started typing the centered title.

Same thing on a vertical mill. If you have a space that is 1.40" wide, and your end mill is .25" in diameter, you start at one side of the space, and move the carriage over (1.4/2)-(.25/2). That's puts you in the center of the space.

Another discovery: there wasn't enough room in the Y dimension of the mill to get the part that I was excavating all the way over, because the vise that holds the part on the mill table was in the way. But there's always a way to get around these sort of problems--I turned the vise 90 degrees from its normal position, and now I have enough room to do the cutting in one operation.