Arduino controlled automatically actuated grill block

[Daox]

Sadly, I didn't get around to bench testing the grill block this weekend. I ran into a snag. I was hoping to use a plastic flexible pushrod to actuate the grill block. These are the kind used on radio control airplanes and they look like the image below.



The problem is, that my bend radius is around 1" which is really tight. The plastic pushrod doesn't like to bend that tight. The outer tube ends up pinching the plastic rod inside and the door lock actuator won't have enough power to push it.

So, I'm now trying to think of other simple & cheap ideas here. If anyone is aware of a more flexible pushrod I'd love to hear about it. Otherwise I think I'm going to be stuck adding a 90 degree pivot arm to the assembly. It won't be expensive, but it will just add more complexity to the whole thing.

Doh, just had an idea while writing this. If I sanded down the inner rod it would have more clearance and would probably work just fine. I'll give that a try and see how it works out. Still open to other ideas though.

[bestclimb]

Bicycle brake/shifter cable and sheath?

Or use metal cable instead of the plastic push-rod in the same outer tube the short distance from the end of the housing to the actuator and the throw for the lever should be ok. You can use some heat with the cable in the actuator to get the bend with out the binding.

Edit, JBweld to secure the pushrod ends to the cable, and a drimel like tool to cut the cable without fraying.

[aerohead]

My thought is that you're going to encounter binding anytime you 'push.'
This setup will be great for tension loads,but in compression,unless you had a mirror-image push-pull cable (as in an outboard motor steering system) it will tend to bind up inside the sheath.
In HVAC,rooftop package AC units have an outside air damper which is controlled by an electric motor and bell-crank which can rotate in either direction to modulate the airflow.

[gone-ot]

A microprocessor can "drive" a stepper-motor BOTH forward AND backward.

[Daox]

I sanded down the pushrod last night. It seems like it should work. The next step is mounting it up.

[a8ksh4]

Cool project... I'm looking forward to seeing how this works.

[ron]

Im in as well. ive had the bones for my CTD aero-nose cut for some time now and planned on a operable grill block of somekind ,this may fit the bill.

[Daox]

I worked on the grill block again last night. Its really starting to get near to its end form.

Here is a shot of the actual pushrods I used. I picked them up at a local hobby store. They're made for radio control airplanes. By the time I had sanded mine down those ridges were completely gone on the grey pieces. I only sanded it down in the area of the bend.




This is the first pushrod mounting piece. As you can probably tell, there isn't a ton of extra space to work with.






I had to file down the connecting piece between the two rods so it would fit around the hardware.




This is the other pushrod mounting point. It will make the 90 degree bend that is needed to get the pushrod out of the way of the actuating door flap.




And finally I threw the pushrod in to show how it'll be mounted.

[AndrzejM]

Awesome! I can't wait to see it working.

[Daox]

I think its about time for an update. I took the time today to glue the pushrod to the brackets. I held the pushrod in place with a wire while the glue dried. Its still curing, so I don't know how well its going to hold yet. I still think adding another bracket on the long side is a good idea to stop the pushrod from flexing right at the glue joint.

Anyway, lets see some pics.