AndyAndrews

My advice to all on this is to make certain your scales are individually calibrated and verify that they actually HOLD calibration before using this to calculate CG. I think FW is being a little harsh on them by calling it a POS. Someone spent a lot of money and time making this device and it is done really well. I think they have issues with the inherent design of the scales though. None of my scales would read the same weight consistantly. Maybe it is the cone. Bottom line don't trust without verifying.

FalconWings

My Feedback: (57)

Andy what do you mean by calibrating? Setting them to zero is not calibration it is merely zeroizing. For real calibration you'd have to buy a set of calibrating weights, and keep a log of calibration intervals.
I hope there was no expectation for an average hobbyist to have to get involved with calibrating scales.......JMHO.

I know how to do this but naaaaaahhhhh. Thats not what I purchased.

AndyAndrews

Falcon, I mean exactly what I said. I know what calibration means lol. In the manual they give the proceedure to actually "calibrate" the scales. Not just set them back to Zero. I did this with calibration weights and in intervals (trust me this took a lot of time) and it wouldn't hold calibration after numerous attempts.

FalconWings

My Feedback: (57)

Gonna give that a try Andy. Im not very optimisitic but Im willing to try.

number27

another over complication of doing a simple c of g. before this wonderful item came along how did we all do c of g.

AndyAndrews

Hey it's a great idea that was going to make weighing and CG an easier task if it worked. I applaud the efforts.

Gaspar

Harry, please contact me by email Monday (sales(at)xicoy.com), I'm out of town this weekend.

Gaspar

Quandry

Hey folks, I've done a few planes with the CG machine and just some suggestions to try if you are hitting issues:

* Place the sensors on a solid floor, eg tiled or concrete. If you use it up on a table you can get some movement on the sensors. If you need to boost up the nose or mains to get the model level use something very solid with no movement in it.
* Put your wheels in the centre of the sensor and always measure centre to centre.
* Check that you don't have your left and right sensors mixed up, it makes a difference!

Not saying that will fix the problems in this thread but just throwing it out there to try and help some folks.

Geoff

btw, a buddy and I checked a few planes via the manual method and the CG machine and the models we balanced worked out just fine.

causeitflies

How does switching the left and right sensors make a difference?

FenderBean

I'm bringing mine to Kentucky jets so if anyone would like to give it a try on their jet feel free to hit me up. I'm starting a database so if anyone needs one I have or would like to contribute let me know as well.

Sekhet

My Feedback: (1)

After reading through this thread and doing some research, I came to the conclusion that I have to have this piece of kit in my hobby room!

LA jetguy

Its a must in the shop / Hobby room.. I actually have two sets one in the car to help pilots at the field....... you don't know how many pilots fly planes or jets that are not properly balanced and do not know about it... They complain how bad they fly and land ...

David..

drac1

My Feedback: (4)

I was considering purchasing, but not so sure now as it seems like a lot of hassle.

We shouldn't have to be calibrating the scales unless they are dropped or damaged somehow. The unit should come calibrated and ready to go. Also, shouldn't have to be placing the wheels in the exact centre of the scales to get a correct weight. Anywhere on the scales should work.

If you have to double check the calcs, may as well just do it the way you have been.

I'll follow along and see what else comes up before committing.

marc s

Harry - blue-tac

marcs

HarryC

My Feedback: (1)

? ..

marc s

To fix the angle sensors to the surfaces.....

marcs

AndyAndrews

I ended up with three postal scales that I bought at Staples that were 100% calibrated out of the box. I had all of the stuff already to check and they passed.

lxfly

Got the balancer 3 weeks ago and checked/rebalanced 3 planes (2 Sprint that already have flown afterwards and 1 small Futura) I had to make small corrections to my CGs, knowing from further balancing and flying that the planes were nose heavy.

Tare is no problem, just 1 touch and is acceptable to compensate normal drifting. I tested the 3 balances with a 500g weight, difference only 1-2g. I made a simple wooden construction with measurement lines to level the plane and a small weight with a little pin to measure the distance from CG to mains. with these little helpers everything is working fine. Distance measuring is done with plane adjusted on balances and plane leveled.

As in a former thread said, I use some wooden pieces of different thickness under the nose balance to level plane.

Springbok Flyer

Renė,

Have you left your planes just standing on the sensors, without switching the unit off - and checked if the settings change. On mine, if I leave it on, with the plane on it - the settings change.

Try it, look after 5 minutes, if your results are still the same.....

Jan

wfield0455

My Feedback: (7)

I have noticed this as well. However, over time mine always settles down to a very similar result. Also, while he Caclulated correction weight may change by a large amount on heavy models, the actuall shift in CG measurement has always been small (a couple of mm) for me.
I've been using 3 postal scale and a spreadsheet to do an almost identical process for years and it's proven to be 100% reliable as long as your scales work

This is what I do;

1) Set the scales out near where they will be used on a solid, level surface and allow them to adjust to any temperature changes from where they may have been stored. It's been my experience that small electronic devices such as these scales aren't always 100% temperature stable so if I bring them out of my car into a house to CG a model, I let them sit and acclimate to their new environment for a few minutes before using them.

2) While allowing the scales to acclimate to their new environment, carefully measure the airplane.
I use an inexpensive lazer level to project a line between the mains to make it easy to get an accurate measurement from the nose/tail wheel to the center of the mains. I also set it under the plane to project a dot onto the wing to measure the mains to CG distance.

3) Carefully set the airplane onto the scales, making certain the scales are well centered under each wheel.
I take a look at the weight screen as a sanity check to verify that all of the scales seem to be giving reasonable readings before going any further.

4) With the plane on the scales, allow a moment or two for any changes in the CG stop.

5) Find a weight that approximately matches the calculated correction weight and place it on the model and go back to step 4.


I expect that the recommended CG for any of my models is simply a safe starting point and that I may need to make adjustments based on test flying the model.

I purchased this unit because it's much more compact and portable than the postal scales I had been using and so far it seems to work just fine. Still, you can't just take some half baked measurements, toss the model on the scales without zeroing them and read a CG in 2 minutes and expect it to be perfect.. It's a tool and it needs to be used carefully to get accurate results.

Springbok Flyer

Wayne,

I concur 100% with you - I do the same and even more.

However, after all is said and done - when simply leaving my models to sit on the sensors - the cg position will change by +-20mm, and it will not settle back. If anything, it will keep on changing, the longer I leave it.

Cheers,

Jan

causeitflies

I have one sensor that is totally wacked. Sometimes it is 100g light, sometimes 100g heavy and occasionally more than 500g out. I have calibrated it many times and even took the cap off and re-adjusted it. The plane is large so I don't want to hang it or try to teeter balance it on a straight edge or tube.

I will use the bad sensor on one of the mains (near CG where it's not as critical) after measuring the weight with a good sensor. I will add some weight to it to trick the device so I can get this thing balanced for KY. I didn't bargain on spending this much time just to get this thing to work. The other two sensors are very consistent and within a few grams of each other.

wfield0455

My Feedback: (7)

Jan,
Mine doesn't change nearly that much. Mine seems to drift slowly to a final reading over a period of about a minute and it seems to repeatably calculate the same CG to within 2 - 3 mm each time, Depending on the weight of the model (I CG'd a 115lb UAS on mine) that 2 - 3mm differnce can amount to a pretty large calculated correction weigh difference though. I also am in the habit of checking how well the scales remained zeroed after I'm done by lifting the plane off the scales and then looking back into the weight menu. Mine are always still zeroed quite well after a CG session.

I can't say if I got particularly good scales or if you got at least 1 particularly bad one. Still, I would think that if your unit varies by as much as 20mm you must have at least 1 bad scale or something.

I'd suggest filling a plastic cup or something similar with about 1 Kg of lead shot or such. Just pick one of the scales at random, zero it, put a cup on it and then add weigh until it reads 1Kg. Move it from scale to scale and see if they all read the same. Leave it on each scale for a few minutes and see how much the reading changes. If one of them reads very differently or varies by a great deal over a period of 10 minutes or so, you've identified a bogus scale.

Wayne

drac1

My Feedback: (4)

Has anyone contacted the manufacturer about the problems with the scales? If so, what has been their response?

AndyAndrews

Don't waste your time with it. Got to Staples and get three digital postal scales. About $90 each.