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HomeAircraftHelicopterHIROBOHirobo Freya › Servo Wheel Drill Guide
02-02-2010 02:34 AM  8 years agoPost 1
GMPheli

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W. Bridgewater, MA USA

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So I am progressing nicely with the build of my Freya. I am setting up the linkages now. Does anyone have servo wheel drill guides for the Freya that has the proper radius and offset for no binding? I bought this Freya used and although I do have the manual, it makes no mention of drill guides. It just gives a recommended radius and then says to make sure that it is at 90 degrees to the center of the wheel. A lot easier said than done. How have you all drilled your servo wheels? I also have the collective push pull upgrade bellcrank and need to get that servo wheel set up too. Does anyone know what radius to use here?

Thanks
Alan

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02-02-2010 03:12 AM  8 years agoPost 2
Dr.Ben

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Richmond, VA, USA

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Alan,

For the Freya on the cyclics, choose a "star" and the hole position which gives you maximum swashplate travel at 100% ATV/AFR. Keep both rods down to the servo identical and choose your wheel accordingly for ball placement there. Once you know that radius, you can copy it to a solid wheel if you desire. It's generally the equivalent of one hole in from equal radius to the p/p bellcranks. In strictest sense, you should have a very small amount of differential drilled into the wheel. In practice on THIS model, the distance from the p/p bellcranks avoids any functionally statistical binding at full travel, which is why Hirobo doesn't specify its use in the instructions (they DO on the Eagle3 VPUS, for example). In eCCPM models this is a much bigger deal, because by the time you go to full collective and then add cyclic in on top of that, any error in the p/p parallelogram can really induce binding loads on the servo wheel.

The collective is easy; match the radius of the p/p bellcrank to the servo arm, and the travel is perfect.

Ben Minor

Peak Aircraft/Team Minicopter Team Futaba Team Kontronik USA

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02-02-2010 03:46 AM  8 years agoPost 3
GMPheli

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W. Bridgewater, MA USA

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Thanks Dr.Ben!!!

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02-03-2010 05:22 PM  8 years agoPost 4
John Benario

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Las Vegas

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If you are interested, I can drill you perfect differential servo wheels.

John Benario

Team highest quality
Futaba radios
Cool Power fuel
John's Ultimate building school

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02-03-2010 06:04 PM  8 years agoPost 5
Dr.Ben

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Richmond, VA, USA

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John,

Given the desire to use zero subtrim, how do you know exactly where to position the holes on the wheel without having his servos in the model beside you and locked at their electronic centers?

Or are you speaking of a template wheel to copy over onto his own wheels?

Ben

Peak Aircraft/Team Minicopter Team Futaba Team Kontronik USA

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02-03-2010 10:11 PM  8 years agoPost 6
GMPheli

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W. Bridgewater, MA USA

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Wow, thats awesome, John. Thank you! May I ask how you do it? I was thinking and what I had planned to do was pretty much what Dr. Ben suggested. Try it with one pushrod and an old arm first, to get the distance, then drill your wheel for one pushrod (at neutral). Now mark the wheel about where you think the other ball will go(of course at the same distance). Hitch everything up and adjust this mark by eye by just watching thru the hole in the link, and seeing if it is staying centered over said mark as you move the servo to extremes. But if you have a jig all set up, then heck ya!!!

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02-03-2010 10:57 PM  8 years agoPost 7
John Benario

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Las Vegas

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Use trig to figure out the angles, and then use a rotary table on the vertical mill to get the exact angles.

I did this for myself when I flew the freya some years back.

Email if interested.

John

Team highest quality
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John's Ultimate building school

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02-03-2010 11:18 PM  8 years agoPost 8
Hillstreet

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Marietta, Georgia USA

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Servo Wheels
Having worked side by side with John setting up my Evo's, a Trex 600, a Outrage Velocity and seeing his SDX, you just cant eyeball and drill servo wheels. While some might assume that close is ok, any discrepancies caused by inaccurate measuring, drilling and spacing on the wheel, will cause binding. It might appear that this is being over analytical, but rest assured John's heli's are built right and do not experience binding issues. Just my 2 cents. Hope you get your Freya set up correctly.

Hillstreet

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02-03-2010 11:46 PM  8 years agoPost 9
John Benario

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Las Vegas

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I went downstairs and found my Freya servo wheels. It is kind of hard to tell, because my camera is so sucky (look I can't be spending money high tech devices like cameras when I am spending my money on WW2 vintage machine tools!), but you can see that the balls are offset slightly from being 180 degrees apart.

John Benario

Team highest quality
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John's Ultimate building school

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02-04-2010 12:12 AM  8 years agoPost 10
GMPheli

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W. Bridgewater, MA USA

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I am sure I could learn the trig, but I do not have access to the tools you have. I realize the balls need to be slightly offset, this is what makes it so hard. And Hillstreet, I don't plan on eyeballing the location of the balls, please reread what I wrote. You will still have to measure to set the lengths the same. When you have it right, the ball link from the pushrod that is not connected will stay exactly centered over your mark (at the correct distance out which you have to measure) when you manually move the servo to extremes. This is what you have to eyeball. This will be much greater than what is needed for an eccpm setup, let alone an mccpm. And if it does not bind at these extremes, then it will surely not bind at operating range. Anyways John, I will give it a shot and if I can't get it, then I will contact you. And Dr. Ben, I thought subtrim was only an issue on eccpm setups. What does it affect on mccpm?
Thanks
Alan

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02-04-2010 04:42 AM  8 years agoPost 11
abgraham

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Deep South Texas

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Drill Jig
GMPHeli, this thread might help:

https://rc.runryder.com/t298430p2/

Here's how I created a drill jig for my HPM Sceadu:
I found an easy way to set it up was to cut a piece of clear plastic from some packaging then scribing two lines 90 degrees to each other(one long and one short) with a hobby knife. Measure from the intersection on the small line and mark where the servo wheel screw will go. Drill a hole for the servo arm screw with a small thumb drill. Then, where the two lines intersect, drill a small hole. This will be the hole in the servo wheel where the ball will be.

The long line lines up with its corresponding link on the x lever.

With the radio powered up and servos centered and the x lever centered, drill a small hole in the servo wheel for the ball.

Then flip it over and do the other side.

(Easier done than said)
You could also use this Trig Calculator to check your measurments:

http://www.carbidedepot.com/formulas-trigright.asp

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02-04-2010 10:22 AM  8 years agoPost 12
Mike0251

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Hills of the Blue Ridge VA

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Keep in mind that these kits are created for the common man. Having the tools like John has is a wonderful thing but 99% do not. That being said a good machinist scale is a must as well as a set of dial calipers with rod end attachments. That will allow you to have each linkage exactly the same as the other. Using the large round blank servo wheels and the bird powered up and set in neutral you can then place the linkages up again the servo wheel and check for your 90 deg requirement and how they fall against the wheel. Adjust them in or out to get the final lay, both of the same. These wheels have diameter marks on them as that is a requirement per the book as well. Armed with that you should be able to get that so close that the common man will never see an issue to worry about. No template required. The machinist scale, depending on your eyesight, is good for 3 decimal places in accuracy. Just a thought for you.

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02-04-2010 05:33 PM  8 years agoPost 13
John Benario

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Las Vegas

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Gary Wright years ago had a 90 degree jig that would hold the pushrod at 90 degrees to the servo arm's radius. There may still be some floating around.

John Benario

Team highest quality
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John's Ultimate building school

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02-04-2010 05:47 PM  8 years agoPost 14
Dr.Ben

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Richmond, VA, USA

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eCCPm or mCCPM, the use of subtrim always skews servo travel to one side, making total servo arm travel different in one direction versus the other. I will agree that it has no where near the potential deleterious effects on a mCCPM model that it can (will) on an eCCPM model, but I simply hate doing it because I can always take the time and effort to NOT have to use it. That's me and my PITA OCD.

John, an ali template for the differential with a center hole bored for a snug fit on the servo screw would help out alot of guys. You could probably make several at once and stack drill them.

I tried Gary's tool. It wasn't accurate enough. Too much slop between the rod wiggling under the o ring retainer and, way more annoying, the fact that the slot for the servo screw was oversized for the 2.6mm screws that Futaba uses in some of their servos.

Ben Minor

Peak Aircraft/Team Minicopter Team Futaba Team Kontronik USA

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02-05-2010 02:16 PM  8 years agoPost 15
John Benario

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Las Vegas

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Alan, I have been thinking how to duplicate Gary's tool, in a manner that would be precise. I think I can do it.

Two questions:

Are you using a 92XX servo with the 2.6 mm bolt/screw or a 93/94XX with a 3 mm bolt?

Would you be willing to cover my expense for the endmill I need?

I'll make it and send it to you to try out.

John Benario

Team highest quality
Futaba radios
Cool Power fuel
John's Ultimate building school

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02-05-2010 09:23 PM  8 years agoPost 16
GMPheli

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W. Bridgewater, MA USA

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I am using 9252's
How much will the end mill cost?
Thanks
Alan

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02-06-2010 03:21 AM  8 years agoPost 17
Dr.Ben

rrMaster

Richmond, VA, USA

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A LOT less than your time is worth, I can assure you.

Ben Minor

Peak Aircraft/Team Minicopter Team Futaba Team Kontronik USA

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02-06-2010 05:04 AM  8 years agoPost 18
Ace Dude

rrProfessor

USA

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Have you seen this?

  

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02-06-2010 03:02 PM  8 years agoPost 19
rlink2

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ga,usa

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sdx
hey john what servos, engines and, blades would you recommend for the sdx?

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02-07-2010 02:00 PM  8 years agoPost 20
GMPheli

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W. Bridgewater, MA USA

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Well I got the ailerons done and they came out good. I used the procedure I had described above. Center both the linkages and the servo. Measure or use identical length rods and rotate the servo wheel on the splines to get one of the lines on the wheel to be perpindicular to the bellcrank. Now measure and drill the distance you plan to use, but offset it ever so slightly (around a mm). Set up the one rod with everything centered, measure this rod and duplicate. Now this is the cool part, you don't have to measure angles, we are just going to "dial" it in by changing the lengths of both rods evenly until you can move the servo to extremes and the ball link stays centered over the same spot on the wheel (which has to be the same distance as the other ball link). The circles on the wheels make this easy. Just take a fine point sharpie marker, and trace the ball link hole (with no ball) centered over the circle, (or in this case half way between the 10 and 12.5 circle). Move the servo to extremes, and holding the pushrod in the proper spot see if the hole stays centered or changes. This is the ultimate goal of measuring angles, right?. Just adjust both rods evenly until it does. The sharpie pen will wash right off with alcohol making it quick. It only took me a turn and a half from my original position to get it to work. (of course I went the wrong way the first time). I don't have the head on, so I just laid the heli on my lap with the landing gear hanging off of my kness. This let the light in so you can see what you are doing. You may have to use a little subtrim because you are guessing at the offset, and this is where the error will show. You could even use the wheel to make a template (It would be nice to have servo wheel drill guides included with the kit, though)
Thanks for everyones help.
Can't wait to get this thing in the air!
Alan

Ace Dude that tool is cool. Where do you get them?

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HomeAircraftHelicopterHIROBOHirobo Freya › Servo Wheel Drill Guide
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