View Full Version : Cool new gram scale
SurfCity
03-13-2008, 01:26 PM
More fun toys. I just got my new gram scale, a $35 item from GramScales.com (http://www.gramscales.com/product_info.php?cPath=25&products_id=521) that's literally the size of a CD jewel case. This model will weigh objects up to 500 grams in tenths of a gram. They have hundredths-gram models, but I figured that was total overkill for helicopters; it's not like we're launching a space probe or something.
Anyway, I've been weighing everything from Post-It notes (0.01 gram) to paper clips (0.03 gram), just for the fun of it. The photos below show a few more practical uses. You'll see the fiberglass canopy vs. the light plastic canopy, plus the Logictech 2100 gyro and 3100 servo.
Buzzkill
03-13-2008, 02:00 PM
Sweet !! How do you like that 2100 gyro combo?
SurfCity
03-13-2008, 02:35 PM
Sweet !! How do you like that 2100 gyro combo?
Don't know; I haven't built my heli yet, although it looks promising powered up and programmed on the bench. The Logictech manual says the gyro should lie flat and suggests keeping it 10 cm away from the motor and belt, which would put it on the nose of the battery tray. Out there, it would be sensitive and accessible, but where does the battery then go? The perfect place would be a battery tray above it, but that means fabricating a part. And so on. So I'm fiddling.
Buzzkill
03-13-2008, 03:33 PM
You can put the gyro on the end of the battery tray and still have room to slide the battery behind it. I have one setup like that.
I like the Align battery tray modded onto the frame myself.
SurfCity
03-13-2008, 04:42 PM
You can put the gyro on the end of the battery tray and still have room to slide the battery behind it. I have one setup like that.
How's your CG with that setup?
Buzzkill
03-13-2008, 08:36 PM
Better than with the gyro under the frame. My other setup with the Align battery tray allows you to "adjust" the battery position, making it even better and the ability to do the same with different brad batteries.
mjr_larkin
03-13-2008, 11:13 PM
where is the "ideal" CG? Is it ideal to have the CG be directly under the main shaft?
SurfCity
03-14-2008, 12:25 AM
where is the "ideal" CG? Is it ideal to have the CG be directly under the main shaft?
That's what I would think. And to achieve that on a tail-heavy heli like the 200, weight is needed at the front. I also assume that a high CG is preferable to low.
unfortunately, especially with a heli this small, you really need a hundredth gram scale. I have a 10th gram scale too and its not that useful. When you try to balance the small parts, you will see. Balance a set of blades using the scale and then try balancing them by putting a bolt through them and putting them on two glasses or whatever. Its easy for the scale to show tailblades weighing both 3.4 grams but one might weight 3.35 grams and one might weight 3.43 grams. And thats quite a big difference.
More fun toys. I just got my new gram scale, a $35 item from GramScales.com (http://www.gramscales.com/product_info.php?cPath=25&products_id=521) that's literally the size of a CD jewel case. This model will weigh objects up to 500 grams in tenths of a gram. They have hundredths-gram models, but I figured that was total overkill for helicopters; it's not like we're launching a space probe or something.
Anyway, I've been weighing everything from Post-It notes (0.01 gram) to paper clips (0.03 gram), just for the fun of it. The photos below show a few more practical uses. You'll see the fiberglass canopy vs. the light plastic canopy, plus the Logictech 2100 gyro and 3100 servo.
SurfCity
03-14-2008, 01:35 PM
Its easy for the scale to show tailblades weighing both 3.4 grams but one might weight 3.35 grams and one might weight 3.43 grams. And thats quite a big difference.
This is very interesting. If eight hundredths of a gram is a big difference in blade balance, then I need better scales. I know it's a tiny heli with tiny tolerances, but this is smaller than I expected.
This is very interesting. If eight hundredths of a gram is a big difference in blade balance, then I need better scales. I know it's a tiny heli with tiny tolerances, but this is smaller than I expected.
It is, I didn't think it would be either, but I can weight to flybar paddles and you can see one will start at like 3.4 and then end at 3.5 when it settles, the other might just start and end at 3.5, so who knows what they are really weighing. The parts are so small that without 100th gram accuracy, you won't really get them balanced properly.