Push/pull controls

[Ronson2k9]

It's Blender..

http://www.blender.org/

It's a GPL 3D modeling studio.. I use it for a lot of different things including sci-fi modeling and artwork but lately I'm mostly using it for flight sim stuff. You can import FSX aircraft into blender but so far there isn't an export - there still working on one.

Speaking of the Cessna throttle group.

There are a few options with the control function in how we'll set up the controls.

Option 1
- The control will stay in position till you pull/push on it. Turning the control will give you a fine tune but will not physically move the control.

Option 2
- The control will move when you push or pull or turn the knob and still give you fine adjust.

Option 3
- This applies to the other 2. You can position the threaded rod and pot so that you can adjust as soon as you move the control. That is the threaded rod extends out past the pot at it's off/zero setting. So the pot is farther away from the back of the MIP and the adjustment nut is half way down the possible threads it can move along. This will let you pull and adjust back if you like or adjust forward without pulling on the control. I was thinking that would be a good option as you may want to fine tune at any position. Of course you can only move the adjustment from zero forward to begin with but once you have moved it you can then adjust right away.

Option 1 and 2 require two different set ups so it's important to decide which you would like first.. I've got option 1/3 on the drawing board right now. I have option 2 in sketch form but haven't incorporated 3 in that yet.

[Ronson2k9]

Well I got the design done.

It will take a few more parts to add the added tuning function but I think I did it as economically as possible.

The primary principal is the friction brace. That will keep the friction to move the pot arm/control nut much less then to move the control itself. There is a free floating tube that will not turn I'm hoping. Steps can be taken to ensure that doesn't happen but they perhaps aren't that necessary. It's okay if the tube turns but would be better from a wear and tear standpoint to keep it just moving in one direction.

Control Knob...



The knob is made from wood and can be drilled to form the shape of the Prop Pitch control. On the inside are 2 drilled holes one small hole to accept the fine adjust rod and stopper (to make sure the threaded rod turns when you turn the knob). The larger one to hold the brass control rod. It will float inside the knob with two plastic bushings helping to keep it from turning when you turn the knob for fine adjust. I'm hoping the friction brace will help keep the brass rod from turning as well.

This is Knob Cross Section.


Onto the back end.

This is behind the MIP or perhaps if you like can be installed in a rack mount plate (making for easy adjust or repair if needed).

I'm working from the 3" through of the pot as a guide so that is the maximum length the control arm can move including the fine adjust. As yet I don't have the actual items on hand so can't offer dimensional info but you can get the idea of the working and make your measurements based on your materials.

As the outer control tube is free floating the friction brace can work as hard as you would like to hold it in place without preventing the fine adjust from working. I even built in an adjustable friction brace so you can set the amount to your liking.



FRICTION BRACE

I figure I would make that out of a masonite sandwich with 2 rubber washers the same inner diameter as the outer diameter of the OCT (Outer Control Tube). Then cutting them and removing about 1/8 chunk from them this will allow them clamp adjusting the friction on the OCT. The sandwich is to hold the washers in place. The 'Bread' is 1/8" larger then the OCT diameter and the 'Meat' of the sandwich is the outer diameter of the rubber washers. The brace is then glued together (making the sandwich). Then cut in half and sanded on the edge of the friction area to give room for the clamp to work. The brace is drilled and with the rubber washers inserted it's slide into place in the brace brackets.

The rest of the design is pretty much what I've talked about before. There is added mounting plate (wood) so you can bolt it from the front of the MIP. That screw does double duty holding the Pot Guard and Pot as well. Which is screwed from the inside out. Remember to counter sink the screws so the control nut has free passage.

This would probably be a lot more effective as a worm gear and transmission as that would let you set the travel distance and eliminate most of the work but more complex to design. Parts perhaps harder to find.

There is some sheet metal in this design but you could substitute wood if you like.

If anyone has any questions or suggestions pass them along please. I'm hoping to begin building one of these this weekend so I'll be able to bring some parts lists and dimensional info hopefully.

Ron

[kermit]

Hi,
As soon as I have my cockpit installed I can make some pictures of a exploded view of a orginal Mixture controll
regards Henk

[Ronson2k9]

Hi,
As soon as I have my cockpit installed I can make some pictures of a exploded view of a orginal Mixture controll
regards Henk

If you could tell us what the actual control does. Not to say that we don't know what they are for but how the control acts when in use. That would be quite helpful too.

It would be cool to get the actual control and hook it up. I wouldn't want to cannibalize it though. I'm thinking the section I have where the pot is located would work just as well with the control cable instead of the rod that is the design now.

It's a bit of a hit and miss to the measurements as it all depends on what I can find at the hardware store to build it with. To that end it's the same for everyone else too. Once I get some of the materials though. I'll be able to put numbers to the drawing to take some of the experimentation element out of the design.

I still think a worm gear would do a much better job. I just don't know where locally I would find it. It would need to be small enough to fit in the space but big enough to do the job. Rotary 100k pots are easier to find though so you gain on that but perhaps loose on the other.. hehe..

[kermit]

It will be up for sale shortly together with a prop rpm control and throttle all orginal aircraft hardware,
I have purchased a real cockpit section of a Cessna 172 with the orginal controlls logbooks and other hardware , but still waiting on delivery.
I have already had the control opened up for adjustment to a pod and for my own curiosity

The innertube has a smal metal ball that locks thru a small hole to the outerhousing(that has a threaded inside wall and that in combination with the ball works as a fine adjustment) when the pushbutton with a small long pin isn`t pressed.

When the button is pressed the metalball sinks in a little dent on the pushbutton pin, so the innertube is releasing itself from the outerhousing.
on the innertube they have connected the cable that goes to the carb or mixturevalve.

When the button isn`t pressed , a smal spring under the knob will push the knob with pin back,
therefore locks the ball under tension between the innertube and the outerhousing.


I have connected that cable who is free turning on the innertube to the pod
greetz

[Ronson2k9]

Pretty cool.. Love to see pics of your new 'hardware' when you get a chance. I know if I got something like that I would want to dig right into it.. It's a good idea to take some pics though just so you have a record of where you started from.

That information on the controls is a bit more detailed that I had been hoping for. I was mostly wanting to know..

How far the handles pull out?
How many rotations there are before it requires a movement by pulling?
Actual measurements of the controls as I'm only guessing from my parts manual?
Does the control move in and out if turned?

That kind of thing. I could be interested in your controls when you have them available as there are many here that would be I'm sure? Depending on where you live and so on??

If I could get the data on them before you sell though that would be really quite cool..

Thanks in advance?
Ron

[kermit]

Hi Ron,
I will make pictures when I`m collecting the cessna, uptill its in working order.
Here some more details about the controls, I bought the controls from ebay and made them work with the Simkits CCU.
Simkits is asking 265 euro ex vat a piece for them,I did it for less

Mind before I could us them I had some pods go up in smoke and flames before I could figure out the connections, After 3 days you could still smell the burned pods

How far the handles pull out?
its now being limited to the pod being 6 cm full in to full out, but can go to 8 cm
But the CCU has calibrated to full in and full out, with Flight one`s cessna 172 you can really fine tune the controlls

How many rotations there are before it requires a movement by pulling?because off the above limitations (6cm) 26 turns full in to full out
pulling is not a part fine tuning, it goes from 0 to 100 % motor-rpm without the need of pulling.

Actual measurements of the controls as I'm only guessing from my parts manual?Do you want all the measurement? I will do that tomorrow if I have the time

Does the control move in and out if turned
Yes ,when turned the control moves in and out

greetz

[Ronson2k9]

Cool and thanks. I had a feeling about the controls moving in and out as that would also tell you where the control is set. 8cm is about 3-1/4 inches at full so the 2-1/2 inches is good too. I had earlier thought of the control moving when turning. It will take a bit of re-write of the design to get it to do that. I think I can design it to do that though.

The outer tube would move the pot and the control nut would stay stationary. Then when you turn the rod that moves the control and the outer tube as well as the pot.

Looking forward to your C172 pics.. and those of the controls?

[kermit]

You have to make sure that the outertube stays put,
it is your controll body that has to be fastened to the in the instrument panel ,
take a look on the simkits-site and look for the control, that the way I did it
greetz

[Ronson2k9]

Okay.. In the previous design the control would be able to rotate and do a fine tune but the design kept the control stationary . We have found out from Kermit that this is incorrect from a prototype standpoint. So there is just a little work to get it to move the control as well when being turned.

A few things will stay the same. It's basically all the same parts with a few added on.

THE FRICTION BRACE

I deleted the friction brace. However given the difficulties with the CHYoke at times it might be a good idea to add a UHMW/Nylon washer to both sides to make sure the rod can move smoothly through the port in the MIP

BRASS CONTROL ROD

This is now where the pot movement will be coming from. So you will need to lengthen it so it can move the full length of the pot travel. You will need two stoppers and a bushing/eyelet (for the POT connection). Besides holding the bushing/eyelet in place for the pot control. One is also to stop the control rod from sliding out of the MIP.

THE THREADED ROD

This is now going to move the control when you turn or push/pull the knob. You will still need the nut to be free travel but you want more resistance on the nut so that when you turn the knob it moves the control and POT are as well. The threaded rod need not go all the way to the knob if you can't find threaded nylon rod. You can find nylon bolts that could serve in this instance they would need to be perhaps 4+ inches long to allow for securing to the control rod safely.

You can use an eyelet instead of a drilled (stopper with set screw removed) bushing so long is the out diameter is less then that of the control nut and the inner diameter is big enough to slide over the tube.

THE CONTROL NUT.

In this instance the nut is no longer connected to the pot arm. That pot arm connection will from a stopper on the brass tubing. The nut now will move the entire control when you turn the knob. You want to increase the resistance on the nut to move by clamping the nut in the guard a bit harder then in the previous design.

I also can perhaps replace the UHMW with masonite (shiny side to the control nut) so you can have more friction on the nut but not too much as the control nut must move when being pulled (unlike in MK1 when it moved as the control was rotated). The only friction in this design comes from the nut. So in many ways it's a simpler design. UHMW should give a more solid feel (resistance will be constant) so if you can find it could be worth using over the masonite.

-------------------------------------------------------------------------

This version although more prototypical is a bit of a balancing act to get all the frictions to work with each other. As there is more happening in that regard.

In Design 1 (Friction from..)

Friction Brace > friction from moving the pot/control nut

In Design 2 (Friction from..)

Threaded rod + control rod > Pot arm travel/control nut

Hopefully I haven't confused everyone..

I'll make up a drawing of this design too as it is a bit easier to understand that way.

Edit: This is the new drawing.


Both designs should work well.. I now it's just a question of building them.

I'm thinking because of the challenge and the prototypical nature and the added benefit from knowing where the control is set the second design stands out pretty strong.. That's the way I'm going to make mine anyway.

Just for fun.. The parts manual shows them not evenly spaced but I think I can manage them if they are..


I did enjoy the brain bending on this design.. If you have any questions or other comments feel free. Photos of my build will be up shortly.