TheSamba.com :: View topic - What scale for balancing parts do you guys use?

Thu Dec 18, 2014 12:07 am

I am looking to get a triple beam scale for balancing rods and pistons and other things, I don't like digital scales so I will be looking at Ohaus scales mostly.
I have a Ohaus scale but it is for heavy things, it will up to 20KG in 1 gram increments, this thing is 3 feet long and weighs 20 pounds, I could weigh cranks with it! Its missing the weights for any thing over 1010 grams but I am watching Ebay for a set.

I don't have the 1 KG weight so I don't know what a Weber 44 IDF weighs.

Casey

Thu Dec 18, 2014 5:53 am

Why don't you trust a digital scale? They can be certified and just as accurate as anything else.

Thu Dec 18, 2014 6:51 am

earthquake wrote: I don't like digital scales so I will be looking at Ohaus scales mostly.
Casey

Suit yourself, but time is money. The digital scales read instantly, and there are no weights to lose. I have two pelouze brand digital scales, they never have let me down. One of them is a counting scale, that has a few memory settings, it comes in handy when you're matching sets, or want to remember what you started with.

Thu Dec 18, 2014 7:07 am

The Ohouse will work ...if you want to measure it in pounds! :lol:

The digital is about as fast and accurate you can get...depending on tolerance of course.

I have a Shadow Scale from Stewart Warner (1/2 gram tolerance) if you want to have your own. Let me know..I am very agreeable. I need money for my M14 projects. :lol:

Thu Dec 18, 2014 7:52 am

earthquake wrote:
I don't have the 1 KG weight so I don't know what a Weber 44 IDF weighs.

Casey

Seems like balancing the carbs is a little overboard... but to each his own. :lol:

I use digital scales from a local hippie shop. Works for me.

Thu Dec 18, 2014 8:09 am

I have an Ohaus Triple Beam and a 600 gram Ohaus digital. My triple beam measures in grams. The digital is much more convenient, smaller, and just as accurate. I got mine on Ebay for $60 new, out of the box.

Thu Dec 18, 2014 8:17 am

I just bought a cheap 2000 gram max 0.1 gram accuracy digital on ebay for $20.00.

I just tested it with some test gram weights I own from a powder scale and it tested right on, or + or _ 0.1 grams with various calibrated weights. Pretty good for $20.00

Thu Dec 18, 2014 8:42 am

Cheapo AWS brand digital scale for around 20$. 3000 gram x .0.1. Amazon. I bought the 4x 500 g calibration wieghts also. Able to get down to a 10th or two and thats good enough for any build.

Thu Dec 18, 2014 10:46 am

I have digitail scales.i dont like the shadow scales.and dont care for beam scales either. Ive found the digital to be better for repeatability no mater where the part is put on the scale.

Thu Dec 18, 2014 4:48 pm

I use a cheap digital scale I bought at Harbor Freight. I check it by weighing something on my powder scale and again with the digital. For being as inexpencive as it is, it is very accurate.

Fri Dec 19, 2014 4:56 am

Metric.

On a more serious note, balance scales are more accurate than most electronic scales in the right hands. Most lay people confuse accuracy with precision - a resolution of 0.1 gram is useless if it is not repeatable due to changes in temperature, scale and position on the scales (most electronic scales have a single load cell and can show wide variations in readings depending on where on the scale the center of gravity falls.) Laboratory scales can overcome most of these problems, but are expensive.

Fri Dec 19, 2014 7:16 am

Digital, before i start i have a couple penny stacksI stick on , if theycheck out i go ahead.

Fri Dec 19, 2014 11:01 am

O Haus beam. Works great for the infrequent need I have for it.

Fri Dec 19, 2014 1:50 pm

The thing I don't like about digital is they have to be plugged into a outlet or they have batteries, when they are plugged in they can fluctuate when there a load on the line and when batteries start to go flat,
You can plug them into a UPS and they will be pretty stable but
"A triple beam don't need no stinking power!"
I know a lot of guys that reload using digital scales made by "Denver Instruments" and they like them but the are not cheap.

Casey

Mon Dec 22, 2014 9:28 am

This is what I use...Stewart Warner.

Mon Dec 22, 2014 10:42 am

for most small time engine building don't be too concerned about absolute accuracy. repeatability is more important. ( ie You are most concerned in matching four rods, or four pistons in weight to each other, not so much concerned about their absolute weight, for engine building the difference in weight in a small number of samples is the main concern.)

1... repeatability issues can be overcome even on cheapo electronic scales by measuring all four pistons at the same temperature, since four pistons can be measured in less than a minute, temp variations of the scale should not be an issue. If you end up lightening a piston that is too heavy, and don't get to re-weighing it until a day later, it would be wise to re-measure all of them again (or at least one of the pistons you did not alter)) to see if any drift occurred in the weight measurement. Also you can do a repeat measure of each piston and compare values to check for drift of measurement

2... Also it is always wise on any scale when comparing samples, to set each sample (say pistons) that is measured in exactly the same position on the scale platform each time, this eliminates issues with repeatability due to placement on scale.

3. On ANY scale it is wise to have one or more proof weights to be used periodically to check accuracy if accuracy is required. The Proof weights should be close in size to what ever sample is being measured, and the location on the scale platform for setting the proof weights should be consistent (see item 2 above).

So digital or mechanical can both be used well. Digital has a great speed advantage for production uses. For an engine builder that does even an engine a week, the time savings of a digital scale is not great. Not needing batteries or needing an electric outlet may be a deciding factor for some. If your running a huge production facility with 1000's of parts to measure daily, semiskilled work force, then digital scales make a lot more sense.

Engineers have come up with procedures to address issues with accuracy and repeatability and understand how to do work with different types of measuring equipment, knowing the strong points and weak points of different methods of measure, and appropriate responses to meet various manufacturing and hobby needs.

Mon Dec 22, 2014 1:10 pm

I used a digital scale that read in grams and to get even more precise i added pieces of packing foam into the process for weighing. The foam I had just happened to weigh 1g for 10 pieces so I would add a piece on at a time until the scale when up to the next gram then the math gave me a rough 0.1g reading.

Mon Dec 22, 2014 2:46 pm

That is clever.

Wed Dec 24, 2014 5:42 pm

Boolean wrote: That is clever.

My Ohaus triple beam easily reads one tenth gram, no foam.

Problem is with the foam trick is that you are still depending on the scale having 1/10 th gram resolution, when it may not be able to resolve that well. It would make sense for a scale maker to have a display that resolves as well as the scale is able to resolve.

A resolution a full order of magnitude reported beyond the scale readout is suspect.

I wont claim my triple beam Ohaus can resolve 1/100th gram, just because I have ten pieces of 1/100th gram foam.

Wed Dec 24, 2014 6:23 pm

You don't have to have good resolution to get good results with the foam (or whatever) trick. The clever part is that you can use small, say 0, 1 gram weights to find the resolution clickover point exactly.