Scale Capacity. Maximum hive weight?

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Paul's picture
Scale Capacity. Maximum hive weight?

What is the heaviest hive you have seen? The load cells in the Developers Kit are 50 Kg each that make a 200 Kg (440 lb) scale when 4 are used. A single 200 Kg load cell frame based on the USDA/NASA design is being tested. Should we consider using a 300 Kg or four 75 Kg load cells (660 lbs) instead?

Below is an email exchange - sorry we really do need to use the forums more ... What do you think?

On Wednesday, December 06, 2017 11:47:37 Carl wrote:
> As to 660 lb. - equates to a double deep and 12 shallow supers. Really?

On Thursday, December 07, 2017 12:04:56 Carl wrote:
> Did Bob indicate if the 400 lb.was on the hive at one time or did they exchange boxes during the flow? That’s at least 8 shallow supers (empty with comb drawn average 8-10 > lbs.) Most of our developers don’t exceed 200 lbs. Maybe we should distinguish categories for commercial vs. others.?

OK, I finally remembered to ask Bob about how heavy a hive could get. I stand corrected on part of my original response: The following is based on Bob's experience when he was beekeeping in the NW about 30 years ago:

First, in North Dakota (not South Dakota), averaging 300lb of honey from the hives was a "good" year, not an average year.

Carl asked if they exchange supers during the flow. Bob: That depends on the beekeeper. Some leave the supers on all season and harvest once. Some harvest repeatedly during the season. Obviously, if you don't have enough supers, you must pull the supers, extract and put the supers back on during the season.

What are the biggest hives? The biggest Bob has personally seen was 5 deep supers on top of a double deep. He said he was sure there were bigger, but that was the biggest he has seen. That year, they averaged 350 lbs of honey per hive.

Would some beekeepers exceed 440 lbs per hive? Bob: Yes.

Would a 660 lb scale handle all cases: Bob: that would handle 99%.

Carl is probably right that most of our developers don't exceed 200 lbs, but all of our developers are hobby or maybe sideline beekeepers, not commercial. As I mentioned, I saw Steve's hive hit 394 lbs in middle Georgia which is not noted for heavy honey flows, He was playing with different techniques, like checker boarding and maybe removing the queen.

From an engineering perspective, we use "worse case" and then design in a margin or error - sometimes called over kill. How much margin of error do you design in? Depends on whether it is consumer, industrial, avionics or military. In general, that would span from 50% to a factor of 10, depending on how high the price of failure.

I would like to see an minimum of 50% to 100% beyond the maximum design weight. If the scale is designed to take 440 lbs, I would like it to be able to operate to at lease 660 lbs.

This really impacts the frame design more than the choice of load cells, as it is easy to put in load cells that have more capacity (if they have the same footprint). Harder to beef up a frame, thicker, heavier, more expensive material, higher shipping costs.

It would be interesting to get a quote on CZL642-300 to compare to the CZL642-200. Same on the CZL602-50 and the CZL642-75. I am sure they charge a slight premium for the higher capacity cells, but they really cost the same to manufacture. In fact, I think there is slightly less machining (less metal removed) on the larger cells, assuming the same form factor.

If you could choose between two different scales that cost the same but one had a capacity of 400 lbs and resolved to .1 lbs and the other had a capacity of 600 lbs and resolved to .01 lbs, which one would you buy?

A 660 lbs scale would be more robust. The cells are usable to 120% overload and damaged at 150% overload. One problem the USDA has had with their scales is damage during shipping or being dropped on a concrete floor. At 150% overload, this scale could take 990 lbs before it is damaged.

Comments anyone?

Emil's picture
Load cell

I see the point in 300kg load cell, but this will probably give more unstable weighing result than 200kg?.
I think there should be possibilities to use both versions if this is not to expensive.
Look at this SMS scale which is normal for 120Kg and options for 240 and 360kg.
I also like the metal construction for this scale

The other thing I have seens is that the CZL642-x00 cells are running on 9-12V, is this tested on 5V USB power? or do we then always need 12V power input?

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