Method of attaching rods to rotor

[Storm_Eagle]

I would drill & tap the rods and install threaded studs, like in the cam drawing, then drill & tap slightly larger mating hols in the rotor grooves, fill the holes with epoxy or JB Weld and press the rod stud assembly into the grooves. Once the epoxy sets it will never come apart.

That would make it permanent. That is why i don't want to use adhesives so i can dissasemble it after if needed.

You five pins. The spacing on the rotor allows for fasteners to be drilled and tapped from the far side. Just cross drill the holes and tap the rods just like your drawing. If you can't have an exposed hole on the rotor, just plug after fastening the rods.

The plugs as stated above would make it permanent (or at least needing to drill out the plugs if you want to dissassemble it). And both the outer rotor surface and the rod surface is critical to be "airtight", that is why i dont want external holes. And that is why i will be using ground bars as stock for both the rods and the rotor part.

Cut dovetails in the rods and mating dovetails in the core Tapped hole on the end that intersect both the core and the rods will prevent sliding out. Alternatively, an interference fit or Loctite..

How do i make sure the dovetails pull the rods tightly into the groves? I'm doubting that i can keep the tolerances so tight that it will be a interference fit on my benchtop mill. Or how do you even measure the wedge part of the dovetail to see how close you are?

 

[piper184]

It would be helpful to know what this assembly will be used for.
Airtight: At what pressure?
Most adhesive products can be released with heat. What temperatures will this be subject to?

Drilling and tapping for screws from the opposite side seems the most practical thing to do. Most thread locking compounds will also seal to some degree. Is there some functionality other than airtightness that precludes the use of countersunk screws?

 

[hman]

That would make it permanent. That is why i don't want to use adhesives so i can dissasemble it after if needed.

The plugs as stated above would make it permanent (or at least needing to drill out the plugs if you want to dissassemble it). And both the outer rotor surface and the rod surface is critical to be "airtight", that is why i dont want external holes. And that is why i will be using ground bars as stock for both the rods and the rotor part.

How do i make sure the dovetails pull the rods tightly into the groves? I'm doubting that i can keep the tolerances so tight that it will be a interference fit on my benchtop mill. Or how do you even measure the wedge part of the dovetail to see how close you are?

I'm not too sure, but I'm concerned that the use of an adhesive like epoxy might at least partially insulate the rods from the rotor ... especially since the assembly is intended for grounding, so good conductivity is vital

My approach would be to use stainless steel hose clamps (one near each end of the rotor) to hold the rods in place within the rotor grooves. If the overlap area is long enough, you could even use 3 or 4 hose clamps.

 

[piper184]

Are the rods for grounding as in electrical or is he attaching ground rods, as in precision ground?

 

[Storm_Eagle]

Are the rods for grounding as in electrical or is he attaching ground rods, as in precision ground?

precision ground

 

[piper184]

How about if you moved the mounting studs closer to the ends of the rotor and then used either a tapered pin or a set screw with a taper on the tip to go into a tapered hole in the stud?

A tapered pin might be difficult to remove since it will be going into a blind hole but a set screw with a taper could easily be removed, even if thread lock was used. They could be made flush or recessed from the end of the rotor.

With the tapered hole in the stud set just a hair short of the center line of the screw hole, as you torque the set screw it would force the stud towards the center of the rotor.

 

[GL]

Is this turning in use? If so, how fast? Can you make a cap plate on both ends, drill and tap the rod ends and screw through the cap to get retention against the rotor and longitudinal control. Assuming rods are not hard. Do the rods control pressure behind them against the rotor? Your first idea is maybe fiddly. Need to put all the parts in the layout to check interferences. Sometimes magic becomes the only easy answer before something real shows up.

 

[Firstram]

Magnets, the answer is always magnets!

 

[Eddyde]

How about if you moved the mounting studs closer to the ends of the rotor and then used either a tapered pin or a set screw with a taper on the tip to go into a tapered hole in the stud?

A tapered pin might be difficult to remove since it will be going into a blind hole but a set screw with a taper could easily be removed, even if thread lock was used. They could be made flush or recessed from the end of the rotor.

With the tapered hole in the stud set just a hair short of the center line of the screw hole, as you torque the set screw it would force the stud towards the center of the rotor.

I think this would be the easiest and if using set screws, the most secure way to make the rods removable. Setscrews are available with a 90°Cone-point. I would flatten the top of the stud so the contact with the hole is concentric with the tip of the screw, a slight countersink in the hole should suffice. The trickiest part would be offsetting the hole in the stud just slightly, so it is pulled towards the center of the rotor, when the screw is tightened.

 

[Eddyde]

Magnets, the answer is always magnets!

Another great idea, especially in combination with a couple of blind locating pins.