Has anyone ever taken there servo and installed it to a gear box. Servo city recommends there technicians install but they also sell separate? I have emailed servo city to ask what was involved but no responce yet.
Yes, I have assembled three of the power gearboxes. If you follow the assembly instructions you will have no problem. You’ll need a light duty soldering iron (15 watt) and some basic tools (screw drivers etc).
A couple of years ago I wrote an article for the AMYA Model Yachting Quarterly Journal (Issue #140) reviewing the SPG800 Servo Power Gearbox. In the article I stressed reading, then re-reading the assembly instructions before starting the assembly process. Do this and the gearbox will work perfectly.
I’d allocate about an hour to assemble a gearbox, at least for your first gearbox. By the time I got to my third gearbox, it was a 15-20 minute chore.
If your time is worth more than $30/hr then get the pre-assembled gearboxes. Having a pre-assembled gearbox arrive can be a load off you mind. I’ll probably buy the pre-assembled gearboxes for my next purchase.
I would probably buy it pre assembled but I already have a 815bb so i would just use that. What is the smallest srevo I could use with the gear box? I would assume you could not use the basic standard servo that comes with the radio? What would be the most ratio you would need for a IOM or do you just go full on 5:1 and have more than enought power with less speed?
synriga, What a useful link (how did you ever find that obscure paper?). Thanks for solving my mystery of the Condor MS-747WB.
yar
synriga, What a useful link (how did you ever find that obscure paper?). Thanks for solving my mystery of the Condor MS-747WB.[/QUOTE]
I’ve developed a few useful research skills while I’ve been working on my Masters degree.
The SPG800 power gear box only accepts an HS-800 series servo (805 and 815). The SPG700 gearbox uses the HS-700 series servos. The SPG400 kit provides the greatest flexibility as it uses standard size servos (4xx, 6xx).
You can use any standard size Hitec servo on the SPG400. While you can put an $8.99 HS-311 servo in the SPG400 power gearbox and end up with a 250in-oz servo for $50, selecting a higher torque servo would pay off in the long run.
I suggest the 5:1 metal gears. The delrin (plastic) gears will work fine as long as you don’t have a high load or any binding problems. I stripped 2 sets of the plastic gears before switching to the 5:1 metal gears. Once those plastic gears have 1 or 2 teeth stripped, the gears are worthless.
As far as speed. I’m using the 5:1 gears with a HSR-5995TG servo in my S/B (Santa Barbara) with 1080sqin sail area. I can sheet in faster than any of the other S/Bs.
I got the HS805 today from ServoCity. It looks like a suitable replacement for the vintage 747. I like it.
But my mind is now on gearboxes and I know my level of involvement with this hobby will lead me towards getting one soon.
I figure if its good enough for a Santa Barbara… syringa, the one you use is here (last one on the list, and 5:1 metal in the dropboxes)? I ask since it starts as a HSR-5995TG (what you said) but in the same dropboxes its a HS-5995TG (no R). Same thing? Just checking.
thanks yar
Has anyone ever deduced what the ideal transit time(full in to full out) should be for racing? I saw a website the other day that had the wind pressure per sq. ft. for different wind speeds. With these two bits of info a person should be able to rough out which servo to use. I was thinking that a 5 to 1 reduction on an 815 or 805 would result in very slow sheeting but then I’ve converted mine to a winch. With an arm it should be faster.
Don
There’s possibly no ideal except 0.0 seconds; anything else is a compromise.
The larger the boat, the slower the servo transit speed you can get away with. My venerable Star 45 still runs her original Vortex sail-winch. It takes around 4 seconds for maximum transit. I’ve never thought that the slow winch speed was all that detrimental to the performance of the boat; it certainly has never detracted from the fun of sailing her. All out racers might take issue with a 4 second transit, but for my purposes it’s fine. In actual use, the slower winch speeds seem to smooth out the sheeting operation and produce a more graceful effect. It’s not as herky-jerky a movement & adds to the scale realism. I suppose a faster winch speed would ultimately be superior, since you can always slow things down if need be. As for there being an “ideal” winch speed, I guess that would be as fast as possible as long as you meet your power “overkill” factor.
Happy Yachting - Kip
Unless you are sailing a multihull where BOTH torque and speed are essential ! Otherwise you may find your boat floating upsidedown if you are using a slow winch !
I believe the quickest is the RMG sailwinch. this winch also has plenty of power for any rc yacht
I use a hitec 815 in my IOM and it works good with 2;1 purchase? I was wondering if I could do a 3:1 or 4:1 to make a difference. I know if i do more purchases then the arm get shorter? Has anyone else tried this.
Andrew
When you start messing it around you gain some and lose some. You can get more travel with purchases but the get a lot of line running around. If you get enough travel now then you can use a shorter arm and gain some effective torque back by going to more pulleys. Each of those turnings represents some friction but if you use good pulleys the loss isn’t too much.
I did one with a triple purchase earlier this year. It looked kind of neat but in the end wasn’t necessary.
Short answer is that you can do it and it does work.
-Barry
Hi Andrew,
If I had a choice, I would use a longer arm and no pulley. The reason is simple. There is no friction in an arm.
So make the arm as long as you can and use the fewest number of pulleys to do the job.
John,
your advise is very good, the problem I am having is that I must turn into the wind for the sails to come in. Even in light winds the servo (815) does not pull in the sails on a reach or run, I did not think this is right? Also when the sails are close hauled, there is lots of servo hum,The arm is straight in line with the line so it should be little tension? Last week I ran out of battery power due to all this hum? So I thought pullies, and shorter arm would work good.
Andrew
Hi Andrew,
the 815 should have plenty of power to pull in your sails. I would suspect that it is not getting enough power. Are your batteries fully charged? Are the batteries good? Are you running it on 6V? Are you using a Y harness?
Are you using a return elastic? Is that putting too much resistance into the system?
John
Yes, Yes, yes, yes, and no? I am using 6v with y harness, batteries are charged and good 5 sanyo ni-mh 2500 1.2 volts. The elastic return is one of those retactors used for ID bages at work and is not very strong. I am using pulley’s? I wish I had other boats to compare with?
Andrew, it should be possible to narrow down the issue to mechanical or electrical.
If you go into the winch compartment and pull the sheet manually, how does it feel? Does it need a lot of effort? ie too much friction or resistance in the system - if, yes, then redesign the sheet lead system to symplify it and reduce the number of pulleys.
If the sheet feels like it moves easily, then you have either an electrical problem or maybe a wornout winch servo.
Maybe Don or someone else on the forum with more electrical experience than me could advise on how to read current and voltage of the servo under load and what would be reasonable values.
Also check for poor soldered joints, “black wire”, or corroded contacts. . .overly thin connector wire… anything that could interfere with current flow.
John,
the set up I have is with the sail arm located in front of the mast. There is a turning block on the end of a 5" arm. The sheet is attached to the bulk head by the mast then turns around the arm turning bloc then back to the bulkhead out through a gomit to the back of the boat around a turning bloc to pull in sheet? I might try to scan in a drawing if this does notexplain well enough. Servo is fairly new so I do not think it is that?
Andrew