Page 1 of 2 12 LastLast
Results 1 to 10 of 17
  1. #1
    300+ Forum Addict jmig's Avatar
    Join Date
    Apr 2007
    Location
    Lafayette, LA USA
    Posts
    440
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Tighting up controls

    It looks so sad to see a forum with no posts. Besides, this may be the perfect place to post this question.

    I have a DIY control stick, made to represent the real aircraft stick. I use plastic gears with a 1:3 ratio to get more movement in the pot. However, with the long moment (appox 24") the gear slack gives me about 1" inch on either side before control input is seen in MSFS. This makes for a lot of slop in a fighter cockpit.

    Anybody, have an idea on how to tighten up the slop? I have already set the FSUIPC slope to +3. Any more and I get a sudden movement from the aircraft. I have my Delta set to 1. I am using a higher grade (Borug) pot, than the standard Radio Shack variety, in order to get better control.

    I don't use MSFS to control the inputs. It all goes from the OpenCockpit USB Axes card through FSUIPC.
    Attached Images Attached Images
    John

    System:
    ASUS P5Q SE/R
    Intel Q9550 O/C to 3.4 GHz
    4 GB 1066 DDR2 RAM
    300 GB WD 10,000 RPM Raptor SATA Drive
    GeForce 8800 GT 512 KB RAM
    Matrox TH2Go with three 19" Sumsung 940 BX
    IR Track 4

  2. #2
    300+ Forum Addict



    Join Date
    Feb 2007
    Location
    California, USA
    Posts
    406
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    One approach is to pre-load the potentiometer shaft with a spring so that it has a torque on it. This keeps the tooth faces of gear on the potentiometer always in contact with its mating gear. You can use a "constant-torque" spring which is basically a spiral clock spring. Alternatively, you can use a pulley and a standard extension spring.

  3. Thanks jmig thanked for this post
  4. #3
    300+ Forum Addict jmig's Avatar
    Join Date
    Apr 2007
    Location
    Lafayette, LA USA
    Posts
    440
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Quote Originally Posted by Mike.Powell View Post
    One approach is to pre-load the potentiometer shaft with a spring so that it has a torque on it. This keeps the tooth faces of gear on the potentiometer always in contact with its mating gear. You can use a "constant-torque" spring which is basically a spiral clock spring. Alternatively, you can use a pulley and a standard extension spring.
    I don't think the spring idea will work, Mike. These potentiometers have to work in both directions. A spring would only apply tension in a single direction.

    The use of pulleys with an idler would probably work. In that way, i could take out any slack.
    John

    System:
    ASUS P5Q SE/R
    Intel Q9550 O/C to 3.4 GHz
    4 GB 1066 DDR2 RAM
    300 GB WD 10,000 RPM Raptor SATA Drive
    GeForce 8800 GT 512 KB RAM
    Matrox TH2Go with three 19" Sumsung 940 BX
    IR Track 4

  5. #4
    300+ Forum Addict



    Join Date
    Feb 2007
    Location
    California, USA
    Posts
    406
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    The spring doesn't prevent the pot from working in both directions. It just takes up the backlash in the gears. This is the same approach used internally with "string potentiometers".

  6. #5
    150+ Forum Groupie
    Join Date
    Jan 2007
    Location
    Saskatchewan,Canada
    Posts
    255
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    I wonder how hard it would be to take a standard 270deg. pot and make a string pot out of it ?? Add a small pulley and spring to the pot shaft ??

    It would certainly be much cheaper than buying a string pot.


    I once extended the stick on my MSSidewinder joystick and ran into the same problem. I ended up shortening the shaft so the base of the stick was just under my knees when sitting in the pit,, rather than having the shaft extended to the floor.
    In other words I didn't solve the problem.

    I saw a picture a while back of a commercially sold extension for a Saitek stick. It was quite eloborate with brackets and pulleys etc. Somehow translating the big movement to small movements the original short stick makes.
    I will look for it and post it if I find it.

  7. #6
    150+ Forum Groupie
    Join Date
    Jan 2007
    Location
    Saskatchewan,Canada
    Posts
    255
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Here is a link to Simcontrols.

    They sell that extended sitck and there are some good pictures that may give you some ideas.

    Like I said before,, rather elaborate,, there should be an easier way ??

    http://www.simcontrol.co.uk/newheli.htm

  8. Thanks Matt Olieman thanked for this post
  9. #7
    Executive Vice President, MyCockpit


    Matt Olieman's Avatar
    Join Date
    Oct 2005
    Location
    Ocala, FL USA
    Posts
    3,155
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Thumbs up

    Quote Originally Posted by spitfire9 View Post
    Here is a link to Simcontrols.

    They sell that extended sitck and there are some good pictures that may give you some ideas.

    Like I said before,, rather elaborate,, there should be an easier way ??

    http://www.simcontrol.co.uk/newheli.htm

    WOW, that's quite impressive!!!! Thanks for the link. Please, someone, go put that in the "Builder Links"

  10. #8
    2000+ Poster - Never Leaves the Sim Trevor Hale's Avatar
    Join Date
    Nov 2005
    Location
    Ontario, Canada
    Posts
    2,432
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Quote Originally Posted by jmig View Post
    It looks so sad to see a forum with no posts. Besides, this may be the perfect place to post this question.

    I have a DIY control stick, made to represent the real aircraft stick. I use plastic gears with a 1:3 ratio to get more movement in the pot. However, with the long moment (appox 24") the gear slack gives me about 1" inch on either side before control input is seen in MSFS. This makes for a lot of slop in a fighter cockpit.

    Anybody, have an idea on how to tighten up the slop? I have already set the FSUIPC slope to +3. Any more and I get a sudden movement from the aircraft. I have my Delta set to 1. I am using a higher grade (Borug) pot, than the standard Radio Shack variety, in order to get better control.

    I don't use MSFS to control the inputs. It all goes from the OpenCockpit USB Axes card through FSUIPC.
    Jim the reason there are no posts here, is we just created this forum Yesterday. I assure you that Gwyn (Westozy) will be along to put his $0.02 in worth. shortly. keep your eye's peeled.
    ________________________
    Trevor Hale

  11. #9
    300+ Forum Addict



    Join Date
    Feb 2007
    Location
    California, USA
    Posts
    406
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Quote Originally Posted by spitfire9 View Post
    I wonder how hard it would be to take a standard 270deg. pot and make a string pot out of it ?? Add a small pulley and spring to the pot shaft ??
    Not hard at all. In fact string and cams are used to good effect in a floor mounted stick I'm working on right now. Here's an almost useful photograph of an early prototype:



    This a view from the bottom, so the mechanism is upside down. You can't see the potentiometer, just the wood knob on its shaft just to the left and a bit below the right-most white idler pulley. The bigh chunk of wood with all the bolt heads in it pivots fore and aft with stick movement. The string wraps around the knob a couple of times and turns the pot. The trick is to choose the appropriate diameter of the knob for the radius of the string cam (the curved wood piece just to the left of the knob). With the right diemnsions, a 40 degree movement of the shift results in a 270 degree movement of the pot.

    I'm about to start building the third prototype of this project. It will be the project in the "Joysticks" chapter of an upcoming book on recreational flight sims. (Assuming I don't die of old age first. I write sloooowly.)

    Random useful facts if you want to go down this path:

    Use a Bourns model 6639S potentiometer: low torque, tight mechanical tolerance, 10 million turn lifespan.

    Always minimize lateral force on the pot's shaft to allow the pot to live out its spec'd lifespan. That's why the idler pulleys are used.

    Use low stretch string. I use 80# woven fishing line.

    Use replacement closet door wheels for pulleys. They have integral ball bearings and cost about $5 for a pack of two at your local hardware store. Inner diameter is 1/4" so you can mount them using standard 1/4" bolts.

    Use a standard instrument knob for the pot then work your math backward to find the radius of the string cam. I got a couple of nice plastic knobs with non-slip groves that grab the string nicely. (Much better than the wood knob in the picture.)

  12. Thanks Trevor Hale, Sunday, jmig, Matt Olieman thanked for this post
  13. #10
    150+ Forum Groupie
    Join Date
    Jan 2007
    Location
    Saskatchewan,Canada
    Posts
    255
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Thats exactly what I was thinking about Mike.

    Great idea !

Page 1 of 2 12 LastLast

Similar Threads

  1. PFC Controls on ebay
    By Cessna170 in forum Off Site Articles For Sale
    Replies: 0
    Last Post: 06-24-2009, 01:31 PM
  2. FlightLink Controls
    By davek in forum General Builder Questions All Aircraft Types
    Replies: 0
    Last Post: 05-29-2009, 08:33 PM
  3. Help please! Saitek controls
    By Drewsta in forum Computer Hardware Setup
    Replies: 7
    Last Post: 08-09-2008, 11:32 PM
  4. mixture controls
    By gokhotit in forum FS2Phidget Users
    Replies: 4
    Last Post: 04-25-2007, 04:48 PM