Automatically actuated grill block - Mk3

[gone-ot]

I do NOT know exactly what the torsional loads might be at highway speeds (+50% for headwinds!) but end activation could "un-snap" your connections (unless your plan is to ultimately glue them together). A center activation would greatly reduce that torsional load, whatever it is.

[Daox]

Again, thought provoking ideas Old Tele Man. Perhaps I should bias the blade pivot point so that the wind holds it shut at speed? With the blade open, it won't take much force to keep it in that position. The door lock actuator has some friction to overcome with the gearing inside of it, so it will help hold the block in place at what ever position its at, but a little help never hurt.

[Daox]

Here are a couple more pictures. I got the actuator mounting bracket designed.





Here it is with the actuator shown. This more accurately shows the scale of things. The grill block is not that large. The entire assembly is only 3" tall and 9" wide currently. It will get larger to add some sort of mounting provision. I just haven't gotten that far.





Next step is designing the linkage between the actuator and the blade. This has been proving tricky as I'm running out of room.

[samwichse]

At this point, wouldn't a rotary actuator actually be better/easier to interface?

Red Dot-Red Dot Electric Operated Rotary Sealed Servo Actuator 12V 4-Pin - 71R3576 - RD-5-9063-0P-71R3576

[Daox]

It is quite possible that a servo would work better for the application, especially if it were smaller in size. The reason I keep going to the door lock actuator is price. These door lock actuators are $5 shipped. How cheap can you get servos for? If you can link me to a good priced one I'd definitely be interested. The whole thing will be arduino controlled, so controlling it is not an issue.

[samwichse]

20KG Metal Gear High Torque Wide Angle Digital Waterproof Servo for RC Robot PZ | eBay

Claims 20kg force on a 1cm arm. Derate by 50% and double the arm length and you're still looking at 5kg, that should be enough, right?

Waterproof, all metal geartrain, works on 5v. $14.89 + $8 shipping

Also:
Towerpro MG958 55g 20KG High Torque Digital Metal Gear Servo | eBay

20kg, metal gear, not waterproof, $14.83, free shipping

Lots of pretty cheap options on ebay for servos nowadays.

[Daox]

I actually have some radio control servos kicking around the house. I bet even those little ones have enough power to actuate the grill. I'm not sure about holding it in place... but we'll see. I can design it so the wind speed holds it shut. I like the servo idea though. Also, I looked on amazon and you can get 2X micro servos for about $8. Its WAY smaller than the door lock actuator and would be much easier to integrate into the design. Thanks for the idea!

https://www.amazon.com/TowerPro-SG90...ds=micro+servo

[gone-ot]

"It takes a COMMUNITY to design a grill block."

[Daox]

Originally Posted by Old Tele man

"It takes a COMMUNITY to design a grill block."

It certainly helps to have a wealth of knowledge kick in their ideas! Thanks guys.

I dug through my radio control stuff and found a micro servo. Its really quite small (mechanical pencil in the picture for scale) but does have a pretty great amount of holding power. I was a bit surprised about that. The gearing must be a pretty tall ratio. Anyways, I think I should be able to mount it directly inline with the lever arm that actuates the blade.

[RoadCyclist]

Daox already answered this for me but asked I post my question here:

Quote (Originally by RoadCyclist)---
Hey, I was reading you Arduino grill block thread and was wondering: How are you programming the Arduino? Is it linked to the engine computer? Also, how are you powering the servo and MC?

I'm asking because I have an Arduino and can do some simple tricks with it, and was thinking about copying your design if that's all right with you, assuming it works out.