Topic Options
#2537976 - 08/17/18 11:39 PM grain scale accuracy
RapidRobert Offline
Circle Track

Registered: 11/20/03
Posts: 33995
Loc: Lincoln Nebraska
do these things stay calibrated (with zero weights-"lever" is hovering loose) or can it be calibrated with the weights? Thank you for your time. I cant get it to load
https://lincoln.craiglist.org/for/d/grain-scale/6668409842.html EDIT I found one on utube described as a "platform scale". this one ($65 local) is an old steel or iron one on metal wheels that is real heavy.


Edited by RapidRobert (08/18/18 12:18 AM)
_________________________
live every 24 hour block of time like it's your last day on earth

Top
#2538002 - 08/18/18 01:45 AM Re: grain scale accuracy [Re: RapidRobert]
A12 Offline
I Live Here

Registered: 01/20/03
Posts: 17941
Loc: N.E. OHIO, USA
Are you talking about a grain/potato floor scale something like below? If so they are not real precise but they are for the most part pretty darn close to say a pound or even half a pound. We had several at work that were is some cases decades old but still great for getting shipping weights to within a pound or so and that's all we expected out of them. Shippers don't split hairs and if for instance you put a big block engine block on it and it's within five pounds accurate it more than good enough. Go get some lifting barbell weights and check it for accuracy when you find one, maybe even take them to the seller's site and check it before you buy it? Pretty sure they can be adjusted using known weights and even think there is an adjustment that is easy to get to externally. They have to be adjustable as no scale can stay accurate forever without a way to correct it.


I did a search for calibrating old mechanical platform scales and several pdf's and videos come up on how to calibrate platform scales.

Mike


Edited by A12 (08/18/18 01:59 AM)

Top
#2538007 - 08/18/18 03:01 AM Re: grain scale accuracy [Re: A12]
skicker Offline
Pro Stock

Registered: 06/09/05
Posts: 3958
Loc: Western Md.
Get 4 identical ones and they're great for that mud buggy... up
As Mike said they are easily calibrated...
_________________________
Loving all the tears... bawling

Sorry Doc...

We'll try again in 4 years...up

Edited...Looks like it will be 8 years...biggrin

Top
#2538026 - 08/18/18 07:24 AM Re: grain scale accuracy [Re: RapidRobert]
Challenger 1 Offline
Too Many Posts

Registered: 02/05/05
Posts: 28166
Loc: Cincinnati, Ohio
The scale above is called a platform scale. They have a 1000 pound capacity X 1/2 pound graduations. They are accurate to within a 1/2 pound at 1000 pounds.

I worked on them for 8 years when I was in the scale business. I still use them currently in my business now.
_________________________

Top
#2538030 - 08/18/18 07:32 AM Re: grain scale accuracy [Re: A12]
Challenger 1 Offline
Too Many Posts

Registered: 02/05/05
Posts: 28166
Loc: Cincinnati, Ohio
Originally Posted By A12
Are you talking about a grain/potato floor scale something like below? If so they are not real precise but they are for the most part pretty darn close to say a pound or even half a pound. We had several at work that were is some cases decades old but still great for getting shipping weights to within a pound or so and that's all we expected out of them. Shippers don't split hairs and if for instance you put a big block engine block on it and it's within five pounds accurate it more than good enough. Go get some lifting barbell weights and check it for accuracy when you find one, maybe even take them to the seller's site and check it before you buy it? Pretty sure they can be adjusted using known weights and even think there is an adjustment that is easy to get to externally. They have to be adjustable as no scale can stay accurate forever without a way to correct it.


I did a search for calibrating old mechanical platform scales and several pdf's and videos come up on how to calibrate platform scales.

Mike


Fairbanks Morse^^^^^

The adjustment your talking about is a zero adjustment to make sure you start at zero.

To calibrate them is not easy and is done from down under by shorting/slowing down or lengthening/speeding up the lever underneath. Need 500 lbs of test weights to calibrate them.

Just handling 500# of test weights in 50# blocks is not easy . Once calibrated they do not change calibration until the bearings and knife edges/pivots get worn or get dirty. Bearings and knife edges/pivots should always be dry and clean in these small scales for sensitivity reasons. Once they are worn you lose sensitivity and repeat ability. You can not fix it with calibration.

I have rebuilt a few dozen in my time. First you get all four corners the same after new bearings and knife edges/piviots. W&M guys would move the test weights around the platform. In some cases you have to hand file a knife edge/pivot one way or the other to get all 4 corners the same and then calibrate using the main lever underneath. Sometimes you have to file the main lever knife/pivot edge to calibrate if the main lever is not adjustable. Does that sound easy?

I used to do them in front of state and local weights and measure guys at all kinds of businesses in order to get them sealed for business that were using them to sell stuff.

I also worked on these. Lot's more complicated to get the quarters right. LINK
_________________________

Top
#2538253 - 08/18/18 07:48 PM Re: grain scale accuracy [Re: A12]
RapidRobert Offline
Circle Track

Registered: 11/20/03
Posts: 33995
Loc: Lincoln Nebraska
Quote:
Are you talking about a grain/potato floor scale something like below? Mike
Yes, $65
_________________________
live every 24 hour block of time like it's your last day on earth

Top
#2538368 - 08/18/18 11:04 PM Re: grain scale accuracy [Re: RapidRobert]
Dcuda69 Offline
master

Registered: 10/17/05
Posts: 3978
Loc: WI
Back in the 80s we scaled our dirt track car with four of those type scales! Worked great! Sorry I'm no help with the OPs question, just brought back some great memories of late nights in the shop before race day. Good times!!

Top
#2538590 - 08/19/18 03:06 PM Re: grain scale accuracy [Re: Dcuda69]
Challenger 1 Offline
Too Many Posts

Registered: 02/05/05
Posts: 28166
Loc: Cincinnati, Ohio
Originally Posted By Dcuda69
Back in the 80s we scaled our dirt track car with four of those type scales! Worked great! Sorry I'm no help with the OPs question, just brought back some great memories of late nights in the shop before race day. Good times!!


I remember my boss selling those scales 4 at a time to race car teams. I think they were like 500 each new back around 1980. They were the sheet metal version and not cast iron like the old ones. No one wanted cast iron anyway.

65 bucks could be good price if the scale is in good condition and not missing any pieces.

Best way to check it is to put the slide weight at zero and slide your finger off to the right gently off the weigh beam while holding it down and see what it does.

Once balanced at zero,
It should oscillate 2-3 times up and down smoothly from zero before it comes to a rest at zero every time you do it.

It it's dirty which most times means worn out it will only oscillate once or so and not give repeatable readings.
_________________________

Top
#2538597 - 08/19/18 03:31 PM Re: grain scale accuracy [Re: Challenger 1]
pittsburghracer Offline
Slowride

Registered: 02/02/05
Posts: 13298
Loc: PA.
I worked on every thing from that type of scale to out heavy duty truck and railroad beem and lever scales. Then we started converting everything over to load cells. As a Millwright in a steel mill that work was the best of the best as that was usually cleaner and easier work.
_________________________
1970 Duster
Edelbrock headed 408
6.143@110.89 mph
9.73@135.05 mph shifting at 6700 RPM
422 Indy headed small block
6.001@113.27mph
9.44@138.23

Untitled by John Cadamore, on Flickr





Top
#2538618 - 08/19/18 04:25 PM Re: grain scale accuracy [Re: pittsburghracer]
Challenger 1 Offline
Too Many Posts

Registered: 02/05/05
Posts: 28166
Loc: Cincinnati, Ohio
Originally Posted By pittsburghracer
I worked on every thing from that type of scale to out heavy duty truck and railroad beem and lever scales. Then we started converting everything over to load cells. As a Millwright in a steel mill that work was the best of the best as that was usually cleaner and easier work.


Cool deal heck yea there are a ton of scales in a steel mill. LOL!! get it??!!

I was a helper and then later a mechanic. I worked inside AK Steel in Middletown Ohio on scales. We also worked on and I helped install new heavy truck/rail scales both the conventional lever system and full electronics load cell truck scales which were very suspect able to lighting strikes at the time. This was from 1978 to 86.

Our company specialized in trouble shooting old style walk in hoffman boxes in batching plants that controlled bagging scales that would bag all kinds of stuff by weight. Conveyor belts and discharge gates and more was part of the scale system. My boss built most of them when he worked at Howe Richerson scale company. He was a expert about them and traveled all over to trouble shoot them. The whole plant would go down and they would fly him out sometimes the same day.
They were used in everything from seed corn to salt to fertilizer to dog food and more. Monsanto had 2 bag lines and a 1000 pound box line we used to work at 2-3 days a week sometimes. They made plastic pellets that they made telephones and more out of.

We were busy back in those days converting truck scales and more to electronic read out with a single load cell attached to the balance beam with it locked down and the load cell senses the load and got displayed digital. Lightning storms always created service work as the electronic scales/read outs were easily damaged by stray currents in those days.
Full electronic load cell truck scale was even worse. So then they came out with a low profile hydraulic load cell full size 60' long truck scale that was closer to lighting proof. But nothing was for sure if you wanted a digital read out.
_________________________

Top
#2538620 - 08/19/18 04:30 PM Re: grain scale accuracy [Re: Challenger 1]
Challenger 1 Offline
Too Many Posts

Registered: 02/05/05
Posts: 28166
Loc: Cincinnati, Ohio
But with a single load cell setup the lever system that supports the platform still uses pivots and bearings. If they wear out then you still get erroneous/erratic output to the load cell and then on the display.
_________________________

Top
#2538674 - 08/19/18 06:51 PM Re: grain scale accuracy [Re: Challenger 1]
pittsburghracer Offline
Slowride

Registered: 02/02/05
Posts: 13298
Loc: PA.
We scraped so much of that stuff it would bring tears to your eyes. Old school but the dog gone stuff flat out worked.
_________________________
1970 Duster
Edelbrock headed 408
6.143@110.89 mph
9.73@135.05 mph shifting at 6700 RPM
422 Indy headed small block
6.001@113.27mph
9.44@138.23

Untitled by John Cadamore, on Flickr





Top

Advertisement
Forum Stats
25,485 Registered Members
32 Forums
192,911 Topics
2,251,780 Posts

Most users ever online: 1,424 @ 06/20/18 07:18 PM
Moparts Newest Topics
A body Door Jamb switches - what size is yours?
by Sixpak
09/18/18 06:44 PM
68 dodge coronet r/t for sale
by Gregboy
09/18/18 06:44 PM
Valve spring ideas
by dogdays
09/18/18 06:30 PM
New Oddball Hurst Challenger?
by -Cuda
09/18/18 06:27 PM