67
edits
Gimbal Project: Difference between revisions
no edit summary
No edit summary |
No edit summary |
||
| Line 138: | Line 138: | ||
made from a 7" long piece of 3/4" EMT that has had two holes and a notch cut in | made from a 7" long piece of 3/4" EMT that has had two holes and a notch cut in | ||
the bottom.<br/> | the bottom.<br/> | ||
<br/>A PDF file of the part drawing is available: [[ | <br/>A PDF file of the part drawing is available: [[media:stick_stub.pdf]] The completed stick | ||
stub should look like this:<br/> | stub should look like this:<br/> | ||
<br/> | <br/> | ||
[[file:stick_stub.png]]<br/> | [[file:stick_stub.png]]<br/> | ||
<br/>The stick stub is just that - a stub. | <br/>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 | 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 | The stick stub also provides the mechanical interconnect for the roll and pitch | ||
axes.<br/> | axes.<br/> | ||
<br/>The next part is the roll axis actuator rod. This is just a fancy name | <br/>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 | 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:</ | threaded on the other. It looks like this:<br/> | ||
<br/> | |||
< | [[file:roll_axis_acutator_rod.png]]<br/> | ||
<br/>[[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 | details of making the rod. The hole is sized for a #10 screw. When | ||
installed, it looks like this:</ | installed, it looks like this:<br/> | ||
< | <br/> | ||
[[file:roll_actuator_installed.png]]<br/> | |||
< | <br/>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 | 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 | about 1-1/4" long You'll use a "stop-nut" which is basically a regular nut | ||
| Line 164: | Line 163: | ||
tighten the screw down enough to take the slop out, but not enough to bind up | 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 | the mechanism. Stop-nuts allow this - the nylon ring ensures that they | ||
won't loosen over time.</ | won't loosen over time.<br/> | ||
<br/> | |||
< | [[file:roll_axis_pushrod_connection.jpg]]<br/> | ||
<br/>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 | 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 | the stack. They'll be the washers that will rub on the inside of the stick | ||
| Line 174: | Line 172: | ||
rubbing against the inside wall of the stick stub. Take the metal washers | 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 | 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.</ | each side that gives the closest to center fit.<br/> | ||
< | <br/>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 | 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 | 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).</ | were drilled for 1/4" and #10 bolts (not on the same clevis).<br/> | ||
< | <br/> | ||
[[file:clevis_fork.png]]<br/> | |||
< | <br/>Next up, making the wooden bearing blocks for the gimbal...<br/> | ||
< | <br/>First, you're going to need to download the drawing for the bearing parts.<br/> | ||
< | <br/>[[media:pitch%20axis%20bearing%20drawing.dxf]] pitch axis bearing drawing.dxf | ||
- This drawing was saved in AutoCAD 2004 DXF format. You shouldn't have | - This drawing was saved in AutoCAD 2004 DXF format. You shouldn't have | ||
any problems reading it using any of the freely available CAD programs, you can | any problems reading it using any of the freely available CAD programs, you can | ||
download a PDF of the plan | download a PDF of the plan [[media:pitch%20axis%20bearing%20drawing.pdf]]<br/> | ||
The drawing will print full size on a single 11x17 sheet. <br/> | |||
The drawing will print full size on a single 11x17 sheet. </ | <br/>The blocks are made from 5/8" Birch plywood. However, any good quality | ||
< | 5/8" (or close) plywood will work.<br/> | ||
5/8" (or close) plywood will work.</ | |||
< | <br/>Please take your time cutting out the bearing blocks. <br/> | ||
< | <br/>Here are some recommendations that should help you get a more accurate | ||
result:</ | result:<br/> | ||
< | <br/> | ||
* When drilling the three mounting holes in the bearing base, it would be | |||
a good idea to drill both parts at the same time to ensure that the holes | a good idea to drill both parts at the same time to ensure that the holes | ||
are placed identically in both parts. The bearings must be square and | are placed identically in both parts. The bearings must be square and | ||
aligned to one another or the pitch axis bearing shaft will bind. | aligned to one another or the pitch axis bearing shaft will bind. | ||
* When creating the parts with the bearing holes in them, it is far safer | |||
and more accurate to drill all the small holes and the two large holes | and more accurate to drill all the small holes and the two large holes | ||
<em>before </em>you cut the parts to shape. Trust me, you don't want | <em>before </em>you cut the parts to shape. Trust me, you don't want | ||
to be boring a near 1" diameter hole in a part with nearly no material to | to be boring a near 1" diameter hole in a part with nearly no material to | ||
hang on to while the drill does its job. :) | hang on to while the drill does its job. :) | ||
* The large bearing holes are specified at .95". The easiest way to | |||
reach that size is to use a 7/8" Forstner or Spade bit. This will get | reach that size is to use a 7/8" Forstner or Spade bit. This will get | ||
you to .875" The remainder can be sanded away with a small drum sander | you to .875" The remainder can be sanded away with a small drum sander | ||
| Line 214: | Line 212: | ||
to the point where they're just a little bit loose around the 3/4" EMT | to the point where they're just a little bit loose around the 3/4" EMT | ||
conduit that makes up the pitch axis bearing. Make sure that when | conduit that makes up the pitch axis bearing. Make sure that when | ||
you're sanding the parts to shape, you do them in assembled pairs. | you're sanding the parts to shape, you do them in assembled pairs. | ||
* If you'd rather not sand the holes to size, you can still get good | |||
results by boring a 1" diameter hole instead of a .95" hole. The fit | results by boring a 1" diameter hole instead of a .95" hole. The fit | ||
will only be a tiny bit looser than what I've specified and it won't affect | will only be a tiny bit looser than what I've specified and it won't affect | ||
how the gimbal operates. | how the gimbal operates. | ||
< | <br/>Here is an exploded illustration that shows you how the pitch axis bearings | ||
are assembled:<br/> | |||
<br/> | |||
[[file:pab_exploded.jpg]]<br/> | |||
<br/>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 | 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 | this because the washers will actually rub on the bearing shaft when it's | ||
| Line 236: | Line 234: | ||
your bearing block layout, you'll also want to mark out the space needed to | your bearing block layout, you'll also want to mark out the space needed to | ||
allow the gimbal box to protrude up through the cockpit floor. In my | allow the gimbal box to protrude up through the cockpit floor. In my | ||
version I'm using a hole that's 5-1/2" wide and 5-1/4" high.</ | version I'm using a hole that's 5-1/2" wide and 5-1/4" high.<br/> | ||
< | <br/>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 | 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 | 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. | 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.</ | Below are examples that show you roughly how it should look.<br/> | ||
< | <br/>Pitch axis connection end:<br/> | ||
< | <br/>[[file:pitch_axis_bearing_detail.jpg]]<br/> | ||
< | <br/>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 | 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" | it in place. I chose a #8 because the eye is perfectly sized for a 1/4" | ||
| Line 254: | Line 252: | ||
chose are threaded and have a long enough reach for them to be able to pass | 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 | through the side of the clevis fork. You can see the nut for the ball on | ||
the inside.</ | the inside.<br/> | ||
< | <br/>Roll axis connection end:<br/> | ||
< | <br/> | ||
[[file:roll_axis_pushrod_and_center_interconnect.jpg]]<br/> | |||
< | <br/>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 | 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.</ | clevis fork can't come in contact with the bearing tube.<br/> | ||
< | <br/>You can also see the roll axis potentiometer connection. Just like on | ||
the pitch axis, I'm using a Du-Bro ball-link on the clevis end, and a Du-Bro E/Z | the pitch axis, I'm using a Du-Bro ball-link on the clevis end, and a Du-Bro E/Z | ||
Connector on the potentiometer end. This is a very simple and very | Connector on the potentiometer end. This is a very simple and very | ||
reliable way to connect your axis pots to your stick gimbal.</ | reliable way to connect your axis pots to your stick gimbal.<br/> | ||
< | <br/>The last component I'm going to cover is the centering mechanism.<br/> | ||
< | <br/>The centering mech is very simple. It consists of a 1/4" steel rod | ||
that's been threaded on one end, a clevis fork made from a turnbuckle, a pair of | that's been threaded on one end, a clevis fork made from a turnbuckle, a pair of | ||
springs and some locking collars.</ | springs and some locking collars.<br/> | ||
< | <br/>In my design the steel rod is 10" long. Your application may and | ||
probably will vary. Here's a picture of the assembly:</ | probably will vary. Here's a picture of the assembly:<br/> | ||
< | <br/> | ||
[[file:roll_axis_centering_and_pot.jpg]]<br/> | |||
< | <br/>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. | bolted in place and has a 5/16" hole to allow the rod to pass through it. | ||
A collar on either end holds the spring in place. The springs are | A collar on either end holds the spring in place. The springs are | ||
compressed against the center bracket just slightly. This provides good | compressed against the center bracket just slightly. This provides good | ||
centering force for the gimbal. </ | centering force for the gimbal. <br/> | ||
< | <br/>One option you may want to consider is using two spring pairs. If you | ||
stack a lighter spring atop a heavier spring, your gimbal will have light force | stack a lighter spring atop a heavier spring, your gimbal will have light force | ||
around the center and it will increase as you move the controls. This | around the center and it will increase as you move the controls. This | ||
happens because small movements around the center only compress the light | happens because small movements around the center only compress the light | ||
spring, while movements toward the travel ranges compresses both the light and | spring, while movements toward the travel ranges compresses both the light and | ||
heavy springs.</ | heavy springs.<br/> | ||
< | <br/>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. If you've got | the assembly that will help out in building your own. If you've got | ||
questions please feel free to join the | questions please feel free to join the | ||
<a href="http://www.simpits.org/mailman/listinfo/simpits-tech">simpits-tech</a> | <a href="http://www.simpits.org/mailman/listinfo/simpits-tech">simpits-tech</a> | ||
mailing list!</ | mailing list! | ||
<br/> | |||
[[file:roll_axis_pushrod_and_center_interconnect-2.jpg]]<br/> | |||
< | <br/> | ||
< | [[file:pitch_axis_pushrod_and_pot.jpg]]<br/> | ||
< | <br/> | ||
< | [[file:pitch_axis_pushrod_and_pot-2.jpg]]<br/> | ||
< | <br/> | ||
< | [[file:pitch_axis_bearing_detail.jpg]]<br/> | ||
<br/> | |||
[[file:pitch_axis_bearing_detail-2.jpg]]<br/> | |||
<br/> | |||
[[file:gimbal_box_detail.jpg]]<br/> | |||
<br/> | |||
[[file:roll_axis_pushrod_connection-2.jpg]]<br/> | |||