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Gimbal Project: Difference between revisions
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Back in May 2009 I had spent some time tossing ideas back and forth with a nice gent by the name of Jentron on the #flightgear [[IRC|IRC channel]] (irc.flightgear.org). We were discussing the various methods that could be used to create a very inexpensive gimbal assembly for pitch & roll control in a home built flight simulator [[cockpit]]. | |||
Back in May 2009 I had spent some time tossing ideas back and forth with a nice gent by the name of Jentron on the #flightgear IRC channel (irc.flightgear.org). We were discussing the various methods that could be used to create a very inexpensive gimbal assembly for pitch & roll control in a home built flight simulator cockpit. | |||
This is what Jentron developed: | This is what Jentron developed: | ||
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Below is instructions on how you can construct this gimbal for use in your cockpit! | Below is instructions on how you can construct this gimbal for use in your cockpit! | ||
== Building instructions == | |||
Here's information on how my version of the Jentron Gimbal Mk II was built and how you can build your own. | Here's information on how my version of the Jentron Gimbal Mk II was built and how you can build your own. | ||
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One important thing to note - the gimbal is designed to be mounted underneath the cockpit floor. This is what it looks like from above, in the "operating" position: | One important thing to note - the gimbal is designed to be mounted underneath the cockpit floor. This is what it looks like from above, in the "operating" position: | ||
[[file:jentron_mk2-3.jpg]] | [[file:jentron_mk2-3.jpg|400px]] | ||
This article will only cover the ins and outs of the gimbal itself. The reason for this is that your application may be a bit different and you'll need to adjust other parts of the design to fit your situation. | This article will only cover the ins and outs of the gimbal itself. The reason for this is that your application may be a bit different and you'll need to adjust other parts of the design to fit your situation. | ||
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The completed stick stub should look like this: | The completed stick stub should look like this: | ||
[[file:stick_stub.png]] | [[file:stick_stub.png|400px]] | ||
The stick stub is just that - a stub. Your flight grip and lower stick or "stick box" will attach to this using another 3/4" EMT mating connector. The stick stub also provides the mechanical interconnect for the roll and pitch axes. | The stick stub is just that - a stub. Your flight grip and lower stick or "stick box" will attach to this using another 3/4" EMT mating connector. The stick stub also provides the mechanical interconnect for the roll and pitch axes. | ||
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The next part is the roll axis actuator rod. This is just a fancy name for a 6.75" long bit of 1/4" steel rod that you've flatted on one end and threaded on the other. It looks like this: | The next part is the roll axis actuator rod. This is just a fancy name for a 6.75" long bit of 1/4" steel rod that you've flatted on one end and threaded on the other. It looks like this: | ||
[[file:roll_axis_acutator_rod.png]] | [[file:roll_axis_acutator_rod.png|400px]] | ||
[[medial:roll_axis_actuator_rod.pdf]]Here is a PDF file that shows the details of making the rod. The hole is sized for a #10 screw. When installed, it looks like this: | [[medial:roll_axis_actuator_rod.pdf]]Here is a PDF file that shows the details of making the rod. The hole is sized for a #10 screw. When installed, it looks like this: | ||
[[file:roll_actuator_installed.png]] | [[file:roll_actuator_installed.png|400px]] | ||
The screw is not shown. The attachment will take bit of experimenting with to get it centered in the stick stub. You want a #10 screw that's about 1-1/4" long You'll use a "stop-nut" which is basically a regular nut with a nylon ring pressed into the top. The idea is to allow you to tighten the screw down enough to take the slop out, but not enough to bind up the mechanism. Stop-nuts allow this - the nylon ring ensures that they won't loosen over time. | The screw is not shown. The attachment will take bit of experimenting with to get it centered in the stick stub. You want a #10 screw that's about 1-1/4" long You'll use a "stop-nut" which is basically a regular nut with a nylon ring pressed into the top. The idea is to allow you to tighten the screw down enough to take the slop out, but not enough to bind up the mechanism. Stop-nuts allow this - the nylon ring ensures that they won't loosen over time. | ||
[[file:roll_axis_pushrod_connection.jpg]] | [[file:roll_axis_pushrod_connection.jpg|400px]] | ||
To center the rod in the stick stub, you'll need to get two #10 nylon washers and a few #10 zinc washers. Place the nylon washers on the "outside" of the stack. They'll be the washers that will rub on the inside of the stick stub. The nylon won't produce the noise that a metal washer would when rubbing against the inside wall of the stick stub. Take the metal washers and stack them on either side of the rod until you've got the right number on each side that gives the closest to center fit. | To center the rod in the stick stub, you'll need to get two #10 nylon washers and a few #10 zinc washers. Place the nylon washers on the "outside" of the stack. They'll be the washers that will rub on the inside of the stick stub. The nylon won't produce the noise that a metal washer would when rubbing against the inside wall of the stick stub. Take the metal washers and stack them on either side of the rod until you've got the right number on each side that gives the closest to center fit. | ||
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The clevis fork is made by taking a 1/4" extruded aluminum turnbuckle and cutting off the left-hand threaded end. You then drill a hole that's the appropriate size for the bolt you're going to use. In my case the holes were drilled for 1/4" and #10 bolts (not on the same clevis). | The clevis fork is made by taking a 1/4" extruded aluminum turnbuckle and cutting off the left-hand threaded end. You then drill a hole that's the appropriate size for the bolt you're going to use. In my case the holes were drilled for 1/4" and #10 bolts (not on the same clevis). | ||
[[file:clevis_fork.png]] | [[file:clevis_fork.png|400px]] | ||
Next up, making the wooden bearing blocks for the gimbal... First, you're going to need to download the drawing for the bearing parts. | Next up, making the wooden bearing blocks for the gimbal... First, you're going to need to download the drawing for the bearing parts. | ||
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Here is an exploded illustration that shows you how the pitch axis bearings are assembled: | Here is an exploded illustration that shows you how the pitch axis bearings are assembled: | ||
[[file:pab_exploded.jpg]] | [[file:pab_exploded.jpg|400px]] | ||
The bearing is assembled using three 1-3/4" #10 pan head screws and three #10 nylon ringed stop-nuts. It's important that you don't use any washers on this because the washers will actually rub on the bearing shaft when it's installed. The base is attached using two 1-1/2" #8 flat head wood screws. You should countersink the holes for them as shown in the model above. | The bearing is assembled using three 1-3/4" #10 pan head screws and three #10 nylon ringed stop-nuts. It's important that you don't use any washers on this because the washers will actually rub on the bearing shaft when it's installed. The base is attached using two 1-1/2" #8 flat head wood screws. You should countersink the holes for them as shown in the model above. | ||
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You'll now want to make the pitch axis bearings. They consist of two short lengths of 3/4" EMT conduit cut to a length that will allow them to fully seat in the EMT mating connectors on the gimbal box and extend at least two inches on the pitch actuator side and about 1/2" on the roll axis actuator side. Below are examples that show you roughly how it should look. Pitch axis connection end: | You'll now want to make the pitch axis bearings. They consist of two short lengths of 3/4" EMT conduit cut to a length that will allow them to fully seat in the EMT mating connectors on the gimbal box and extend at least two inches on the pitch actuator side and about 1/2" on the roll axis actuator side. Below are examples that show you roughly how it should look. Pitch axis connection end: | ||
[[file:pitch_axis_bearing_detail.jpg]] | [[file:pitch_axis_bearing_detail.jpg|400px]] | ||
You'll note here how the centering rod for the pitch axis is mounted to the bearing. I'm using a #8 eye bolt that has a locknut on both sides to hold it in place. I chose a #8 because the eye is perfectly sized for a 1/4" bolt. You can also just barely see the Du-Bro ball-link that I'm using to connect the pitch axis to the potentiometer that connects to the computer. The ball-links are very inexpensive and very handy to use. The ones I chose are threaded and have a long enough reach for them to be able to pass through the side of the clevis fork. You can see the nut for the ball on the inside. | You'll note here how the centering rod for the pitch axis is mounted to the bearing. I'm using a #8 eye bolt that has a locknut on both sides to hold it in place. I chose a #8 because the eye is perfectly sized for a 1/4" bolt. You can also just barely see the Du-Bro ball-link that I'm using to connect the pitch axis to the potentiometer that connects to the computer. The ball-links are very inexpensive and very handy to use. The ones I chose are threaded and have a long enough reach for them to be able to pass through the side of the clevis fork. You can see the nut for the ball on the inside. | ||
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Roll axis connection end: | Roll axis connection end: | ||
[[file:roll_axis_pushrod_and_center_interconnect.jpg]] | [[file:roll_axis_pushrod_and_center_interconnect.jpg|400px]] | ||
Here you can see why the roll axis side of the pitch axis bearing needs to be so short. When you move the stick to the far left, the back end of the clevis fork can't come in contact with the bearing tube. | Here you can see why the roll axis side of the pitch axis bearing needs to be so short. When you move the stick to the far left, the back end of the clevis fork can't come in contact with the bearing tube. | ||
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In my design the steel rod is 10" long. Your application may and probably will vary. Here's a picture of the assembly: | In my design the steel rod is 10" long. Your application may and probably will vary. Here's a picture of the assembly: | ||
[[file:roll_axis_centering_and_pot.jpg]] | [[file:roll_axis_centering_and_pot.jpg|400px]] | ||
As you can see, the whole thing is very simple. A 1x1 L bracket is bolted in place and has a 5/16" hole to allow the rod to pass through it. | As you can see, the whole thing is very simple. A 1x1 L bracket is bolted in place and has a 5/16" hole to allow the rod to pass through it. | ||
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That's really all there is to it! Below you'll find various pictures of the assembly that will help out in building your own. | That's really all there is to it! Below you'll find various pictures of the assembly that will help out in building your own. | ||
[[file:roll_axis_pushrod_and_center_interconnect-2.jpg]] | [[file:roll_axis_pushrod_and_center_interconnect-2.jpg|400px]] [[file:pitch_axis_pushrod_and_pot.jpg|400px]] | ||
[[file:pitch_axis_pushrod_and_pot.jpg | |||
[[file: | [[file:pitch_axis_pushrod_and_pot-2.jpg|400px]] [[file:pitch_axis_bearing_detail.jpg|400px]] | ||
[[file:gimbal_box_detail.jpg]] | [[file:pitch_axis_bearing_detail-2.jpg|400px]] [[file:gimbal_box_detail.jpg|400px]] | ||
[[file:roll_axis_pushrod_connection-2.jpg]] | [[file:roll_axis_pushrod_connection-2.jpg|400px]] | ||
[[Category:Hardware|Gimbal Build a simple pitch & roll gimbal]] | [[Category:Hardware|Gimbal Build a simple pitch & roll gimbal]] | ||
[[Category:Howto|Gimbal Build a simple pitch & roll gimbal]] | [[Category:Howto|Gimbal Build a simple pitch & roll gimbal]] | ||