Push/pull controls

[Kerbo]

I found these little diagrams that help understand the locking mechanism for the controls with a button and provides some important dimensions.

http://www.acsproductsaz.com/790ball.htm
http://www.acsproductsaz.com/790.htm

[Ronson2k9]

Thanks and cool.

I got the measurements pretty darn close I'd say. Given that I was working from a blow up of the MIP in C206 Parts Manual. Some of the other stuff I got from photos. There is a 3" travel on the linear pot so you really can't make that longer. Most if not nearly all of the build is out of wood except the brass tubing and the nylon rod. I tried finding that Home Depot but they didn't have it. There is a fixture place that sells industrial fixtures I had went to before for another project. I had forgot about but found again when looking. All they sell is nuts and bolts and stuff like that. Including a complete selection of Nylon. Don't know if I can threaded rod in that but a long enough bolt will do. I tied it at Canadian tire even though it was the wrong size and it's so smooth it will work perfectly for this.

My model is drawn to scale BTW that is the computer model I have. It's 1 BU (Blender Unit) to each cm so it's no problem making a 'Scale' drawing of it.

I'll take the drawings (links you posted) and check them against mine and make changes as needed.

It would be cool to get the release button working. But remember we are working with wood here. The button install would need to come before anything else. I had thought of the electro magnet as a way to release the friction on the control rod. You could almost use a bicycle brake system if you wanted to. Hooking up a cable to button. It would make it pretty complex then though.

Could make it a fake though maybe. That is the button depresses but doesn't do anything more. Would need to add a spring to the interior of the knob and a cap and button of course.

What do you think of the idea..

1 - Make it work using an electro magnet?
2 - Make it work using bike braking?
3 - Make it look like it works with a spring?
4 - Make it a non moving button?

Personally I like #3.. Would make it a bit harder to build but not to much harder. This only applies to the Prop and Mis controls...

[Kerbo]

I'd be happy as long as it looks and acts like the real thing. For my sim I am going simple for the throttle/prop/mixture controls for now and will revisit them later. I have too many pieces started already.

[Ronson2k9]

All righty.. I'm thinking that will require a spring and a cap on both ends of the knob. The cap on the back end can be the faring though. That will require the control rod to be attached to the faring and not inside the knob (need room for the spring and button - also trying to keep it simple).

I was thinking of putting the rod in there anyway (well attaching it to that). Just didnt' want the control coming apart when being pulled. So will need some good gluing to get this right.

For the button I was thinking maybe a twist top bottle top (if the dimensions are right) probably not though. So a piece of sculpted doweling will do the trick I'm thinking. Well 2 of course. There are lots of things you can do to nylon but one if the things you can't is Paint..

We can put the button on a pin (piece of doweling) that will both hold the spring in place and keep the button going straight in and out. Could be easier then trying to hollow out the button so that it can accept a larger diameter spring. I'm thinking the real one pushes on something in the control anyway. It will act like the spring in a ball point pen with out the click.. (I don't think it locks open in the real one). Could use some UHMW plastic tape around the pin to make sure it never sticks to the socket it will fit into. Always not be ready for such things. In this case as when it's closed .. It's closed.. So no going back when knob has been assembled. Unless I put a nut in the end of the knob and a threaded rod to connect the two parts.. UGGG.. There should be a way to get it together without glue.. To save making more knobs and stuff. Probably with metal parts in this time as you want them to stay together till you unscrew them .. You don't want the knob coming off the faring when in use.. hehe A little bit of locktite should take care of that. I'll see what I can come up with...

The knob is getting more complex now hehe..

I'll be back later with a new cross section and dimensions now that I've got the info from those sites you hipped me to.

[Kerbo]

I'm looking forward to what you come up with, keep us posted.

[Ronson2k9]

Well this is what I have so far.

Side Cutaway Ortho


3/4 Cutaway Ghost Ortho


So far it's an enclosed design as it's a question of getting the two main parts to mate and still let it come apart. Also I don't want to tempt it coming loose inside as turning (push/pulling) could cause over time. So while building it to come apart to fix also means that it can come apart at anytime.. While an enclosed design has more strength it also means that you would need to be prepared to rebuild if need be. I myself don't think that you would but you never know..

Basically the design incorporates a spring for the button.
- Button is on a shaft that is partially prevented from full insertion by the knob and full retraction by the washer and screw. It is also under tension that should keep the button from sagging.

Precise drilling is a must and is perhaps done first before anything else. The knob can then be held in place while details are created. Then the other parts are added as the knob is assembled and painted.

When looking at the drawings from the site they seemed a bit less accurate then I had originally thought. They don't quite give enough detail to show the size of the knob. As there are ridges and bumps you can only guess if they are included in the drawing so The length from MIP to the tip is what would be the most accurate.

Myself I'm working on the assumption that all the knobs when pushed all the way in are at the same length from the MIP. It just seems to make sense to me. They are different sizes and of course textures. Should be able make easily if you have a drill press and a good set of bits. Forstner bits would be preferable if you have them for the interior drilling anyway.

Addons to the design.

The pocket that the spring sits in could be susceptible to binding on the spring when pushed..
- You could add an exterior collar around the spring that is free floating in the pocket so the spring doesn't bind
- Beveling the pocket could also work to that end as well.
You would need to augment the diameter of the spring pocket to accommodate.

Still to do.

Need to find a way to lock the tubing/threaded rod into the flange that is holding them. To keep the knob from turning them loose. A keyway could work or a set screw that goes all the way through from the outside. Being able to hide that though would be something I'd want to do.

Care must be taken to make sure all parts line up correctly
- Brass tube
- Knob Flange
- Knob
- Knob button

If any of them are out of position that would be bad. That's why drill first and detail after. If you mess up the drilling you haven't spent all that time detailing.. Not that we aren't all talented people. A small jig to keep everything in position to do the detail work would make that a hole lot easier/safer. A countersunk piece of ply with a carriage bolt should do nicely.
Any other thoughts bring them on..

Drawing with measurements to follow - baring any suggested changes..?

Ron