For the builders

[Rattus]

Hope this is in the right section and not out of line.

To the builders out there great and small.
These sounds like a juvenile questions but, rotaries are a different world.

1. Do you fabricate your own cams?
2. Are there sources for cams besides going through the few suppliers that offer them?
3. Is the stroke length governed by the pin offset from center on the cam in mm?

Trying to gain some working knowledge of these and might hack the shop owners knock-offs. lol

[tattooedpirate2]

Me personally, I use cranks and connecting rods as well as a slide in my machines. As far as direct drive rotaries, I use to build them 25 years ago. Building a cam is real easy with the right tools. If you don't have a mill you can get a cheap drill press from harbor freight and a machinists cross slide vise and make a mill for about a hundred bucks. The cam is off center measured and thats where you drill your shaft hole for the needle pin and bearing. I measure in from the edge of the crank myself, its easier. You need an edge finder to do this. But if this is to much to do send me your drawing and I will make you one. What kind of motor are you using? I use one from Radio Shack that is super powerful and inexspensive on my Blunderbuss Machine. Most machine shops use metric measurements for sizing its easier than the inch. I'm an inch man myself that's all I have ever used.

[Rattus]

I'm in the data collection and thinking stage for any of this. I was thinking of first hacking the shop owners stealth knock-offs. He mentioned that he's like a longer stroke and I'm digging what Otto has done. Then move on to a complete machine. I think that I know what motor your using.

Post or PM me on what some cam's would cost from you. Looking for a 4 - 4.5mm stroke conversion.

I wish that I had time for a drive. I see your about 6.5 hrs from me. Love to pick your brain. lol

[Administrator]

If you do this I would also suggest making new bases and tube chucks for them as the current ones are one of the downfalls of that machine.

[Rattus]

If you do this I would also suggest making new bases and tube chucks for them as the current ones are one of the downfalls of that machine.

I hear what your saying. I dislike those chucks. might as well just go for the ground up approach at that point. Kind like using an old Supreme frame and only saving the side plate.

[Administrator]

Maybe a nice blued steel or brass base would make it look nice.

"If you have to buy Chinese you should at least buy it from an American"

[Administrator]

Could get Seth C. to make you a chuck like this?

[Rattus]

That would be sweet.


OK here's another question. While I plan on buying from at least three of the builders on this site, my mind goes wild and I like to tinker.

My question is: What are the key factors on motor selection? Torque and how much? RPM? stuff like that. I'm looking over several motors and just wondering..would that work or would that make a hamburger machine?

[Administrator]

Cost, weight, longevity of the bearings or bushings in the motor. This is a good question since each builder will have thier own theories. It has also been brought up before (I think by Mike Metaxa) to think less about the motor and more about the drive system. Do you have a heavy cam that works like a fly wheel or is it light and balanced what type and size of bearings are you using, etc. I am only adding this cause I know some of the builders pride them selfs on having at least a little proprietary info they need to keep. Hopefully a few of them will chime in with some info.

[Rattus]

Cost, weight, longevity of the bearings or bushings in the motor. This is a good question since each builder will have thier own theories. It has also been brought up before (I think by Mike Metaxa) to think less about the motor and more about the drive system. Do you have a heavy cam that works like a fly wheel or is it light and balanced what type and size of bearings are you using, etc. I am only adding this cause I know some of the builders pride them selfs on having at least a little proprietary info they need to keep. Hopefully a few of them will chime in with some info.

Ahhhhhhh my brain! LOL

I was trying to see if this was talked about before I asked.

Weight and size is one for my preferences and that goes for the whole machine as well. Moving to lighter stuff.

The whole flywheel is unknown.
I would like to make a direct drive and something along the lines of a a-bar setup with spring, like a shag canister comes to mind.
I'll leave the piston and slide systems to the other guys for now and just buy one of theirs. lol