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I'm building a roban 800 size Md 500 .. anyone have a good method to get ideal pitch setups.. seems to be alot of mechanical servo travel to deal with..

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  • I'm building a roban 800 size Md 500 .. anyone have a good method to get ideal pitch setups.. seems to be alot of mechanical servo travel to deal with..

    I'm using futaba cgy760 and futaba transmitter..

  • #2
    Well, you’re in the right place for expert advice Titason! These guys sure got me on the right track & I’m still asking. Often.
    1. For me, ideal pitch setup always starts with measuring my fixed swashplate link with a mic..ball center to ball center..then adjusting the other 2 links below the swashplate to match EXACTLY! Roban’s manuals say 35mm but I’ve not found that to be quite accurate. The idea is to have your swashplate perfectly level @ 90 degrees to the main shaft when measured through a full 360 degrees rotation.
    2. I then move each of the 3 linkage “L” levers to exactly 90 degrees to their pivots, then tape each lever’s servo control rod to the side of the frame. No servos connected at this point. If # 1 was correctly measured & set, the swashplate should appear eyeball level. Don’t worry about swashplate to rotorhead linkages yet...if swashplate to shaft is not perfect at this point then the blade grips can’t be set perfectly.
    3. Here’s where folks differ I’ve found: Once you install the servos, need to get them at neutral, obviously. I just plug ‘em into my receiver for this. No FBL yet. I leave them powered up at neutral, then install my servo arms 90 degrees to the pushrod. Some folks say 90 degrees to the servo. Your choice. Either way, make use of the numbers on the servo arms to choose the best match between the R & L servos so when installed both arms look like a mirror image to each other.
    4. Adjust each servo to “L” lever rod length to maintain the 90degree angle on the “L” lever. Roban gives 81mm & 112mm measurements for these but I’ve not found them to be exact. However, the 2 outside servos rod lengths should be equal or very nearly so.
    5. If all done correctly, your swashplate will be level. I use my digital guage to verify before proceeding. Now install your head, & set ONE of the grip pushrods to attain an exact zero pitch angle on the grip. I leave the blade bolts in place & just eyeball that the bolt is centered on the main shaft when viewed. When it looks good, remove that pushrod & measure ball holes center length with your mic. Set the other rods to that measurement.
    6. Reinstall the grip pushrods. Now, all the blade bolts should appear a perfect center on the main shaft when viewed from the grip end.

    That should help you get started, I hope!

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    • #3

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      • #4
        Excellent.. I've setup align trex heli for years but this roban setup was just frustrating me.. appreciate the help..

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        • #5
          Welcome. I’ve found that Roban does a good job Loctiting their mechanics but check anyway. None of my Roban helis had the side frames secured with locking compound but all the critical components were good.
          My first Roban was the AH-1W Cobra & I spent hours dialing the mechanics in. The hard way. My second Roban was a B407 & I had a level swash & zero’d grips in an hour...& it’s a 4 blade head. That was done before the first servo was installed, then just a matter of adjusting servo rods to keep it square up top.

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          • #6
            Your system worked great on getting the swash and head linkages setup.. the only problem I have is way to much mechanical travel on setting pitch to around +10/-4 I'm using the futaba cgy760 and futaba transmitter.. I tried knocking down travel endpoints to70 .. I put servo linkages on the inner most hole on servo connectors.. also on counterclockwise rotation do you need to change gyro settings different than for clockwise

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            • #7
              Yes on the CCW change from CW, definitely. I’m not familiar with your Futaba gyro but in my Demon & IKON FBLs endpoints are set in the gyro...not the Tx. Your manual should be specific what Tx settings need to be.

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              • #8
                I'll check that again.. Thanks

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                • #9
                  I do know that CGY760 has the receiver built in & requires a Futaba programming box that’s specific to that gyro. I’ve also noticed you can buy that gyro with or without the programmer, but if I remember correctly Futaba hasn’t released PC programming option yet. Your programmer should list setup menu items to follow that will eventually get to the servo endpoints.

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                  • #10
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ID:	264262 Just a couple of pics of my projects.. The roban md500 800 size getting pitch settings...electronics setup.... Also my roban 700 size conversion heli with trex700 with roban head and spin blades.. flies great..the spin blades are very smooth and stable..
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                    • #11
                      Titason, could you measure your servo arm’s center screw to linkage ball center? They look too long to me but just could be the photo’s perspective. Mine are 14mm & keep me within my IKON’s recommended servo travel guidelines. Doesn’t appear those arms allow you to chose a closer hole, either. The goal is to attain a +12 degree and -12 degree collective travel range in initial setup (not final setting) without the need to reduce the servos endpoints in the FBL too far. Don’t know what Futaba recommends, but if you see something on the order of 40% at the +12 and -12 then you will see less than the 40% at final pitch of +10 and -4, obviously. May need to swap to a shorter servo arm: unless you have a machine shop I personally wouldn’t recommend drilling new holes by hand as the #1 and #3 arms need to be identical. That’s just my opinion, of course!

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                      • #12
                        Thanks . outer hole is 21mm inner hole is 17mm.. only problem I've had is elevator linkage contacts elevator swash on inner hole at negative pitch.. I don't think I can adjust that with different arm.. I did set other linkages to the inner holes and left elevator linkage on the outside one still had way to much travel my percent of swash adjustment was like 17 percent .. Click image for larger version

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                        • #13
                          Originally posted by Titason View Post
                          Thanks . outer hole is 21mm inner hole is 17mm.. only problem I've had is elevator linkage contacts elevator swash on inner hole at negative pitch.. I don't think I can adjust that with different arm.. I did set other linkages to the inner holes and left elevator linkage on the outside one still had way to much travel my percent of swash adjustment was like 17 percent .. Click image for larger version  Name:	15950934831226252163262922917859.jpg Views:	0 Size:	102.4 KB ID:	264317
                          Oh wow, you have to get some different horns, that is way too much throw adjustments, I used the small round nylon servo on the inner holes on my AH-6 and the nylon straight horns on the inner holes on the Magnum PI and still had to dial everything way back, I know nylon servo horns are not recommended for these big helis, but I have had no problems with my 800 size Magnum PI and AH-6
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                          • #14
                            Ditto DCCORSAIR....Way too much servo horn! None of my linkages hit anything at my 14mm setting & I’m using nylon horns as well. I had asked that question awhile back on another thread & the responses were all positive on the nylon vs metal. No disaster stories. I believe the tensile strength of nylon exceeds the sheer force required to separate the nylon ball link assemblies so I’m comfortable with ‘em.

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                            • #15
                              Yea ill give that ago where do you get those.. nice heli .. have seen that magnum pi heli flying around Oahu..

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                              • #16
                                Should be able to order the horns online from most all rc supply vendors, including Amazon. Need to know your servos spline tooth count,’tho. Probably written on your horns & will be something like “24T”.

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                                • #17
                                  Just a quick question on setting pitch on asymmetrical blades.. This is the technique I've been using.. Is there any different way this should be done.. Click image for larger version

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                                  • #18
                                    That’s the same pitch gauge I use & works great. I set it’s reference mode on the top of the motor can. Just be sure to reset it’s reference perpendicular to each blade each time you remove & install it. Don’t leave it in place on a blade then rotate the blade to a different position, in other words....unless you’re positive your reference calibration surface is level on all axis. If you do change those servo horns will need to start over with your FBL setup so any pitch settings done now will change also.

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                                    • #19
                                      Just a quick update was able to get some nylon horns and get adjustments down to acceptable limits for my pitch settings at around 38% with +10/-4 finals.. what a difference.. Really appreciate your help on this..1 Click image for larger version

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                                      • #20
                                        Just a question on how tight blades should be tighten on the blade grips particularly on scale setups with multiple blades.. I Always have mine basically little if any movement I Know centrifugal force's are at work but new to this type of setup don't want to overdue it.

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