Indexing a large prime number, 127 for example.

[Norman Bain]

Ok elf: I'll bite ... what is the thingy in the image used for?

[Bob La Londe]

holy crap three of them? to avoid the mind numbing (its numb enough), I skimmed through.....I'm guessing even a still of 18:18 would capture the essence of it?

Not having a DRO shouldn't be end of the world, an excel program of the X/Y's would suffice...but of course be a lot more tedious

Actually, in the video(s) he did show a short spreadsheet with coordinates for a bolt circle that he'd printed out. I'd do it in CAD myself.

His DRO didn't just give a read out. It would calculate the coordinates for a bolt circle for you. Just enter start angle, number of holes and center diameter. I'm not surprised. The DRO on my lathe has quite a bit of math capability built in as well. Someday I'll have to read the manual.

[Bob La Londe]

And then you have to punch and drill them with great accuracy. That's the rub.

Nah, you do it on the mill. Even without a DRO you can still read the dials. Just have to account for the backlash of your machine. Spot drill then drill.

[Bob La Londe]

That's an interesting indexer. How do you use it? It looks a lot like some tool post drills I have half made from ER collet chucks for my lathe. Well except for that massive indexing plate in the way. LOL.

Isn't that what you use spotting drills for?

[Mcgyver]

His DRO didn't just give a read out. It would calculate the coordinates for a bolt circle for you. Just enter start angle, number of holes and center diameterl.

I know what you mean, I have one that does the same....was just saying not having a DRO wouldn't stop one for this approach, you can use excel to easily generate coordinates. That's assuming MHB ddoesn't go to 127 lol

[CCWKen]

Doesn't anyone use a computer anymore??? Any arbitrary number of indexing holes can be calculated easily. Any 2d Cad program can do it in a few seconds.

BS flag waving. It takes three months to years to learn a new language and draw with CAD software. I had a career in computers but I've gotten frustrated with every CAD sample I've tried. Those of us that think Paint.Net is challenging have no chance with CAD.

[Normanv]

J. Tiers, post no. 7 has the simplest answer. That is what I did to produce these dividing plates for my rotary table. I have just used them to produce a set of gears for a model traction engine and they worked perfectly. My interpretation of perfectly is to cut 31 teeth on a 30 tooth gear. The last one did not remove any metal.
P.S. How the hell do you post images? URL? what is that all about?

[Bob La Londe]

BS flag waving. It takes three months to years to learn a new language and draw with CAD software. I had a career in computers but I've gotten frustrated with every CAD sample I've tried. Those of us that think Paint.Net is challenging have no chance with CAD.

Not so much anymore. Some are more intuitive than others. Add on that so many other users are now posting misc help videos on-line and I suspect anybody who approached it with their attention focused could learn the basics of some programs in a few hours to a day. Oddly enough I probably wouldn't even use a proper "CAD" program for this. I'd use a the CAD capabilities in one of my CAM programs. CamBam. Its not free, but with a 40 executions time limit you can do a lot of work with it before your demo period expires. Hmmm... this might be a good project for a screen capture video. If I have time I'll make one and post it for you in the next few days.

[elf]

That's an interesting indexer. How do you use it? It looks a lot like some tool post drills I have half made from ER collet chucks for my lathe. Well except for that massive indexing plate in the way. LOL.

The ER25 collet chuck is the spindle for a rose engine and the indexing plate is called a rosette. The indexing holes are used to move the cut starting point on the workpiece a division of the pattern. In the rosette shown, the pattern repeats three times. The number of the divisions of the pattern is shown above the holes.

Here are several completed boxes: