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Post by chipbutty on Nov 11, 2010 16:33:10 GMT -5
That all sounds good. I popped the 14t pinion in the heli today. Got the screws in the mail but the washers are too small so the bolt head goes through the holes on the servo itself. So I've ordered some decent M2 washers with dimensions which should work. Fitting mini servos on this heli isn't quite as straight forward as I anticipated! I have never actually "tached" my 425, but I am running a 1470kv motor with 15T pinion, 50T primary, 20T OW, and 61T main. I think I 'calculated' it at around 2800 and it flys really well. I had a 16T pinion in it for a few flights and the head speed was scary fast, but it was real hard on batteries. I was only getting 3:30 flights with a 6s 2500mah battery.
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Post by chipbutty on Nov 11, 2010 16:34:09 GMT -5
At least the link adjustment tool doubles up for other uses ;D
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Post by Jerrymac on Nov 12, 2010 2:14:08 GMT -5
Hehe, that should get you a lot of 'built in' expo since you would have to move the top of those sticks a long way. You could fly "fists" like Justin Chi, lmao.
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Post by chipbutty on Nov 16, 2010 16:10:37 GMT -5
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Post by dunkonu23 on Nov 16, 2010 17:41:18 GMT -5
Next item to curse... link lengths... offset on servo arms... BUT, it will all be in the past soon and soon you'll power it up, set it up, and fly it. You'll be happy.
Scott
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Post by gauiman on Nov 16, 2010 18:09:49 GMT -5
I just installed my Spektrum DS821's without a hitch, Im glad I choose the DS821's. I was ready to file down the adapter plates to fit them. My next step is to curse the offset on the servo arms too like dunk mentioned lol. Is anyone using Raptor links & what kind of wheels are you using Ive seen some nice metal ones here www.readyheli.com/search.asp?keyword=wheelschipbutty nice job on the servo install!!!
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Post by chipbutty on Nov 16, 2010 18:14:54 GMT -5
I'm not happy unless I'm cursing something ;D Next item to curse... link lengths... offset on servo arms... BUT, it will all be in the past soon and soon you'll power it up, set it up, and fly it. You'll be happy. Scott
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Post by chipbutty on Nov 16, 2010 18:18:11 GMT -5
Dare I ask what the offset issue is? No doubt I'm about to come across it. Next item to curse... link lengths... offset on servo arms... BUT, it will all be in the past soon and soon you'll power it up, set it up, and fly it. You'll be happy. Scott
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Post by gauiman on Nov 16, 2010 18:31:45 GMT -5
Dare I ask what the offset issue is? No doubt I'm about to come across it. Next item to curse... link lengths... offset on servo arms... BUT, it will all be in the past soon and soon you'll power it up, set it up, and fly it. You'll be happy. Scott Check out the Finless build video on servos below video.helifreak.com/tmp/eaa3278c72fee99375ac30e064f10899/servos.wmv
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Post by chipbutty on Nov 16, 2010 19:12:12 GMT -5
Cheers. You know I downloaded those a while ago but completely forgot about them. It maybe useful if I actually watched them.
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Post by Jerrymac on Nov 17, 2010 1:10:19 GMT -5
Chip, if you look at the elevator arm, and the pitch and roll arms you will see that the balls are not straight across the center. They are off set. There has been a lot of discussion over the years about this, mainly, why do you need to match the offset. Simple answer is; That is how Gaui designed it. The easiest way I found to match the offset is with the Custom Heli Parts CF servo plates. They have the offset built in, and better yet, the plate is slotted so you can can rotate it to get the servo center without using sub-trim. If you check the pics of my 425 in the photo section here you can see them. They attach to your existing servo horn. ReadyHeli used to carry them, but I just checked and they don't have them now, at least not the right part # as CHP. But you can get them direct from CHP. customheliparts.com/store/index.php?route=product/product&path=46&product_id=99Gauiman ( sorry guys, I don't know your real names ) JR makes some large servo wheels that are more than big enough to drill the holes in the right place, and they fit the DS821's. I know this for sure as I have some of them in my parts box. I got them a while back at HeliDirect, but they don't stock them anymore. Somebody that carries JR servos should have them I would think. Hope this helps guys, Jerry
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Post by dunkonu23 on Nov 17, 2010 2:46:35 GMT -5
Like Jerry, I didn't worry about the servo offset. I bought something where you don't have to worry about it--the CNC bell cranks! Scott
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Post by Jerrymac on Nov 17, 2010 3:26:54 GMT -5
Yeah Scott, that is the easiest way, but, the reason I didn't mention it is because it opens a whole new can of worms, lol.
The Gaui CNC bell cranks have no offset, but, some of the after market CNC bell cranks still have the offset built in them so they still require that it be matched on the servo horns. It all depends on which ones you use.
The Gaui CNC ones are more expensive, but they are the ones to use for the easiest set-up.
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Post by chipbutty on Nov 17, 2010 5:55:45 GMT -5
Thanks Jerry. I never knew it was going to get this complicated. Why have Gaui done this? Seems like an unnessesary added level of frustration. So I now have to buy more bell cranks or try and machine new holes on the horns that may or may not work with the MKS servo horns. Also, I don't know if the parts you linked to would fit my servos. I just checked with them and they charge $27 to ship to the UK! I can't afford that unfortunately. These are the servo horns I have. The circle one is no go as it's very small. And when I said I was only happy when cursing something. I take that back ;D
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Post by dunkonu23 on Nov 17, 2010 6:11:30 GMT -5
Watch the finless video on the 550. Specifically, there's a section where he shows an easier way to get an offset on the servo arms. I believe it involves taking the corresponding bell crank and using it to mark drilling locations on the servo arm.
Scott
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Post by chipbutty on Nov 17, 2010 6:38:37 GMT -5
Hi Scott - What time is it there? Didn't expect you on here! I took a look at the Finless vid. I'll see if that's feasible. If I mess up I need to find out what horns will fit MKS servos. Buzzflyer is the only stockist of Gaui 425/550 stuff and I had a look at the Gaui CNC Pitch & Roll Arm Set - 204612 and CNC Elevator Lever - 204614 ( www.buzzflyer.co.uk/GAUI-Hurricane-425-Spares/c-1-151). As I understand it they don't have any offset so I won't need to do anything with my servo horns? Cost of the CNC bits comes to £28 ($45). Pricey, so I'll take another look at that Finless vid and see what horns will fit MKS. If you get the chance to take a look at the Buzzflyer web site they sell the RTF Gaui 425 with the same MKS servos and judging from the pictures they appear to have done nothing about the offset! I don't think I'd like to fly it. www.buzzflyer.co.uk/RC-Helicopters/GAUI-Hurricane-425-RTF/p-70-1550/Watch the finless video on the 550. Specifically, there's a section where he shows an easier way to get an offset on the servo arms. I believe it involves taking the corresponding bell crank and using it to mark drilling locations on the servo arm. Scott
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Post by chipbutty on Nov 17, 2010 8:16:47 GMT -5
I see they also do an offset for Futaba. I know MKS servos accept some Futaba horns so that may be a cheaper option than going CNC. I've emailed MKS to find out if they would fit. I have a feeling that they won't. But It would be great if they do as Ready Heli have them in stock and the cost is $11 to the UK including shipping. I like the sound of that! Only draw back would be the two week wait. In the meantime I've ordered some large round Futaba horns to see if they work. One thing I'm wondering about the offset issue is why someone hasn't manufactured a plastic arm for the elevator with additional holes so you can go straight? Then you could just use the extra holes on the pitch and aileron and go all plastic with the arms. Or am I missing something here. No doubt Gaui would've done that if if they thought it was a better option so maybe it's a geometry issue. The easiest way I found to match the offset is with the Custom Heli Parts CF servo plates. They have the offset built in, and better yet, the plate is slotted so you can can rotate it to get the servo center without using sub-trim. If you check the pics of my 425 in the photo section here you can see them. They attach to your existing servo horn. ReadyHeli used to carry them, but I just checked and they don't have them now, at least not the right part # as CHP. But you can get them direct from CHP. customheliparts.com/store/index.php?route=product/product&path=46&product_id=99Jerry
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Post by Jerrymac on Nov 18, 2010 2:47:14 GMT -5
There are some other ways to do it. I don't have any close-up pics of the servos on my 550, and it is out in the back of my truck right now, but I will try to take a pic of it tomorrow before work. When I built it the CHP servo plates were out of stock and so were the large JR servo wheels.
What I did was use a piece of 2mm thick kind of nylon/plastic and cut out a circle with a hole saw the size of a large servo wheel. Then I cut a small hole in the center to fit around the "rib" of the small servo horn. I mounted the new 'wheel' onto the servo horn with screws, then drilled the offset holes in it and mounted the link balls to it.
You could probably do something similar with the large Futaba horns if they do not fit the splines on your servos. Simply cut the center out where the splines are and mount the rest of the horn to your original servo horn, then drill the offset holes in it.
I realize it might sound kind of "mickey mouse", but it is actually not much different than mounting the CHP CF horns to your existing servos horns. I have been flying my 550 for 2 years now with my "Jerry-Rigged" servo wheels on it with no problems yet.
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Post by chipbutty on Nov 18, 2010 6:13:58 GMT -5
At first I thought those CHP servo plates were actual horns then realised they attach themselves to the horn itself. That's sleep deprivation for you.
That's a great tip if the Futaba splines don't fit. I'll definitely give that a go if I need to. Btw, I ordered 8 large C type Futaba horns just in case! Those things are hard to get hold of. I just object to paying £28/$45 for the CNC arms. In my opinion you shouldn't have to fork out more money when you've already bought the kit. Would be nice if Gaui supplied their own CHP style plates with the kit.
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Post by chipbutty on Nov 19, 2010 8:29:45 GMT -5
They fit the MKS splines perfectly On with the build.
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