Disclaimer

This blog is for entertainment purposes only, and is not meant to teach you how to build anything. The author is not responsible for any accident, injury, or loss that occurs as a result of reading this blog. Read this blog at your own risk.

Monday, September 15, 2014

Brake/Rudder pedals - part 6

Pedals, pedals, pedals! (12.0 hrs)

I started the day machining the last few steel pieces I didn't get to do last week.

The first parts I worked on were the hinges for the pedals, these were merely steel cylinders to be welded at the bottom of the pedals' vertical tubes.


Testing hinge for proper fit

Same hinge on bottom of pedal's tube, where it will be welded.


My good friend and Long EZ builder, Walter brought up a valid point about my original rudder cable attachment design. His concern was that the constant back and forth motion of the pedals might work loose the bolt securing the rudder cable adjustment tab. Walter has the gift for finding the most unusual failure modes, and this time he had me worrying about it as well, so I ended up modifying the design from a bolt, to a fixed stub and a cotter pin.


New rudder cable attachment point design


This new concept required additional lathe and mill work.


Drilling the cotter pin hole to 0.067" (1.7 mm) 


Rudder attachment point completed


The way I planned on adjusting the rudder cable to compensate for pedal adjustments, was to make a steel plate with holes every ½(1.3 cm), matching the adjustability of the brackets. The plates would connect to the pedals via the pins I just made.


0.063" (1.6 mm) 4130 steel sheet on the "chopping block"

Machining action shot

Plate as it came off the mill...

... and after a little cleanup.

This is how the plates will connect to the pedals


With the plates done, all the pieces were finally on hand, and the time had come for putting them together.


Let's make some pedals!


With all the design changes I have made thus far, the brake/rudder assembly looks quite different now, so before we move forward I’d better show you its latest incarnation...


Left pedal, seen from the left fuselage sidewall.

Same thing, opposite view.


The welding session took all afternoon, and preheating the thicker steel parts made them a lot easier to weld, as I had anticipated.

I started by welding the pedal hinges...


This hinge is getting ready to be welded. The hinge in the background is already welded.

View of both hinges welded


... then the rudder cable connectors to the actual pedals...


Preheating the much thicker end piece

Completed weld still glowing

Both pedal tops done


... followed by welding the pedals to the pedal’s shafts...


Magnet holding tubes in proper alignment

Finished pedals


...and lastly the pedal’s flanges...


Well... actually these are the completed pedals.

After letting them cool down a bit, I put them all together at last...







... then sat them down in the fuselage to see how they fit...


Looking for the perfect place to put them

Left side

Right side


Now, I have two options as far as how to position them. 

Option 1: I can lay them along the sidewalls, affording me more room to stretch my legs in flight (good).


Looks odd, but feels pretty good.

A view from the front seat


Option 2: I can lay them parallel to the aircraft centerline, allowing my feet to be straight when pushing on the pedals (good) but reducing the space I have to get around them in flight in order to stretch my legs (not so good).


Reduced space for getting past the pedal

Looks more "normal" perhaps

This configuration wastes a lot of space


I don’t know. What do you think?

Should there be a third option perhaps?

So far I have only tried option 1, and it feels pretty good. The bottom half of my legs rest against the sidewalls quite naturally, my heels brace against the F-22 stubs that stick out of the floor, and my feet act on the pedals parallel to the master cylinder shaft.

I’ll do more testing this week, after I get back from Ireland.




Friday, September 05, 2014

Brake/Rudder pedals - part 5

Making all the little bits (7.0 hrs)

I really like the brake/rudder pedal design I came up with, and although actual use might eventually dictate small modifications, for the time being the EZ shop R&D department (Research and Development) has been shut down, while the Manufacturing branch is ramping up production of the system's components.

To maximize leg room in the nose, I had planned on mounting the brake assemblies as close to the outer sidewalls as possible, which means they would be at a roughly 12˚ angle with the airplane centerline. I had also decided to remove the F22 stubs that were part of the original brake design.


While it looks bigger in the photo, the angle is barely 12˚.

One of the improvements I had considered, was to weld the top horizontal tube at a 12˚ angle to make it parallel to the bulkheads. This would prevent my feet from getting a little twisted while pressing the pedals.

After sitting in the plane for sometime though, it turned out that all of these changes were unnecessary. My left leg rested more naturally against the sidewall, and easily activated the brake pedal along the bracket centerline, this arrangement also eliminated any concerns of side loads being applied to the master cylinder piston. Furthermore, the little stubs felt pretty comfortable to rest the bottom of my heels against, marking the correct foot position for best brake activation. So, I decided to make no further changes, and leave everything as it was.

The brackets will bolt to plywood anchors. I am still using the same plywood piece I had purchased for the firewall a few years back.


Aviation grade plywood leftover from the firewall

These will become the anchor points for the brackets

A 45˚ chamfer was added to ease laying the fiberglass

3 holes were drilled


These plywood pieces will be floxed to the nose floor, then fiberglassed over. In order to have good attachment points for the bolts, I followed my friend Ary’s lead, and purchased some Tee nuts inserts for wood from McMaster-Carr.


Tee Nut

These worked very well, and were easy to install.


Tee nuts about to be installed.

Tee nuts installed with the help of a small hammer

The Tee nuts seem to hold very well

I couldn't resist putting the assembly together


I made two new flanges out of 0.100” (2.5mm) thick 4130 steel on the CNC mill.


Holes pre-drilled

Holes enlarged to final size, and engraving done.

Flange getting cut, one 0.007" (0.18mm) slice at a time.

The umbilical cord is coming off next

Here's the new born all cleaned up


A little lathe work was necessary to create the bullet-like nose of the master cylinder rod extensions.


Creating the rounded nose that will press on the flange

Drilling a hole for the set screw


The pedal vertical components were drilled, and cut on the mill.


While CNC was non strictly necessary here, it helped increase the consistency of the parts.


The slider piece had its three slots CNC cut as well.


These were fun to watch getting cut

Slider nearly finished, before final cutting.


Lastly, the rudder cable attachment point was made on the lathe.


Tapping the rudder cable attachment point for an AN-4 bolt

Rudder cable will connect here


There will be an adjustable piece connecting the top of the brake pedal to the actual rudder cable, but I will design it and machine it when I get back from Europe.

Unfortunately, I ran out of time before I could finish making all the parts, and I had to leave on another trip. So, there will still be a tiny bit of machining to be done next week, before the welding session begins, and I can turn all these parts into actual pedals.


Almost all the parts for the pedals are finished

I'm pretty happy with the quality and consistency of these parts

It will take a long welding session to turn all of this into pedals


One of the issues I had welding 0.100” (2.5mm) thick steel plates to 0.035” (0.89mm) steel tubing, is that the tube melted before the plate was ready to fuse. I was still able to weld them by directing the TIG torch, and the heat, mostly toward the plate. This however was not a great solution, and though successful, the welds turned out very ugly. 


What I should have done was to preheat the parts before welding them, and this is exactly what I intend to do next week using a propane torch.