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  #21  
Old 03-18-2018, 10:19 PM
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Originally Posted by Lew Hartswick View Post
One of the "benefits" of that old "squared" in the Pi * R squared. :-)
...lew...
Yup, math is a wonderful thing...if you understand it...
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  #22  
Old 03-19-2018, 08:29 AM
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Yup, math is a wonderful thing...if you understand it...
I have some of my son Karl's old high school notebooks. One has a little doodle/sketch in the margin that says "AP Calculus hurts". There's a little face with a pained expression.
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  #23  
Old 03-19-2018, 09:11 AM
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Originally Posted by RED caddy View Post
Well, we already know the correct bore size (1.128") and stroke does not seem to be a big deal in this case. I was just concerned that 2 "O" rings might not stand up to 24-2500 PSI and a better seal setup might need to be brought to bear.
What do you think?

I have a pancake cylinder lying around, might have to open it up and check the bore size.


Thanks, RED
you could use one of these from HF to make a scale
Click image for larger version

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  #24  
Old 03-19-2018, 09:29 AM
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Originally Posted by Ironman View Post

I have one of these Cam. It says Sensator 3AH0205 on it. Off a drill rig I think, the gauge was destroyed so have no ratings on it.

Gerry, generally drilling rig indicators are much higher range than these ( units of thousands of pounds or decanewtons). That indicator style is used for wireline ( .92 -0.188 " wire) used to run service tools into wells that have had tubing run into them during the completion and production phases of a well's life. Think a giant roll of MIG wire 10,000 - 15,000' long mounted on a truck.

Drilling rig weight indicators tend to be 8" - 12" pancake diaphragm sensors hooked via 1/4" or 1/8" high pressure hose to 10 - 14" face pressure Gage's with interchangeable faces for different cable sizes and reeveing ( number of lines carrying the load).

To put this in perspective, rig hoisting loads range from a few thousand pounds to several hundred thousand pounds depending on well depth and drill string size. Wireline loads are on the order of a couple thousand pounds max.
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Design to 0.001", measure to 1/32", cut with an axe, grind to fit..

Last edited by camdigger; 03-19-2018 at 09:35 AM.
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  #25  
Old 03-19-2018, 09:34 AM
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Originally Posted by MetalWolf View Post
you could use one of these from HF to make a scale
Attachment 144011
That should work,k drill another port and put a gauge in it.
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  #26  
Old 03-19-2018, 09:40 AM
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That should work,k drill another port and put a gauge in it.

No need to drill another hole. Just add a tee on the quick coupler and make sure all fluid channels are full of oil on assembly.

I have a sucker rod iload cell built like that. I also have a pancake load cell I built for my hydraulics press I made.
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Design to 0.001", measure to 1/32", cut with an axe, grind to fit..
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  #27  
Old 03-19-2018, 09:51 AM
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Metalwolf, any idea what the bore size is, or how to find out without buying one and measuring?

If it is not 1 1/8th, it won't direct read and will require me to break out the ol' Texas instrument calculator every time I use it. That's not gonna happen.

The existing design is spot on and easy, why build in complications. Practical applications of the KISS principal...

Thanks, RED
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What I really need to know is, WHEN DOES THE SHOOTING START?
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  #28  
Old 03-19-2018, 10:10 AM
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Default Some general thoughts re hydraulic load cells.....

In my experience, I have seen 4 types of hydrauliic load cells....

1. Direct indicating piston/ cylinder type as being contemplated here. The theory is the load is supported by the indicator because the pressure gage is connected directly to some kind of chamber with a piston of a known diameter. The pressure in the chamber is related to the load applied by the mathematical formula F=PxA.. The reality is the force applied does not actually directly relate to the load due to friction losses. It takes a certain amount of force to make the piston slide through the seals. ( ever tried to pull a hydraulic cylinder apart? Even with the ports open, it takes some force to extend or retract the cylinder even with the lines disconnected. This is sliding friction between the piston and cylinder AND the rod and rod seal.)

2. Bladder style as per the link IM provided and as applied in air ride truck suspension. The cross sectional area of the bladder(s) supporting the load is still related to the F=PxA formula, but the friction force is much less, as it is related to the friction.required to flex the bladder. There are truckers who can judge how heavy their loads are by how much air pressure it takes to support it ( carry the load at a certain suspension position - my air bags are at 70 psi, so my truck weighs xx,000#).

3. The indirect style used on drilling rigs where a large diameter bladder or diaphragm is loaded up by applying side force to the line with the load applied. The load applied to the line is related to the force to make the loaded line deflect a certain amount by some rather complicated math. The advantage is that relatively small forces on the diaphragm are related to very large loads on the load carrying line. Add in multiple lines, and the math gets very hairy.....

4, The bladder style IM posted is rigged such that the loaded run through pulleys at 90 or 180 degrees and measure the side force make the wire bend through the pulley/sheave system. The bladder style indicator has the benefit of lower friction loss because the bladder only changes shape rather than a piston having to slide in a cylinder

All this to say there are multiple ways to skin this particular cat.
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Design to 0.001", measure to 1/32", cut with an axe, grind to fit..

Last edited by camdigger; 03-19-2018 at 10:19 AM.
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  #29  
Old 03-19-2018, 11:04 AM
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Originally Posted by RED caddy View Post
Metalwolf, any idea what the bore size is, or how to find out without buying one and measuring?

If it is not 1 1/8th, it won't direct read and will require me to break out the ol' Texas instrument calculator every time I use it. That's not gonna happen.

The existing design is spot on and easy, why build in complications. Practical applications of the KISS principal...

Thanks, RED
Just by looking at mine it 2" bore so wont work was just an idea thinking it would save time and work on the machining
but ill measure mine and be sure
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  #30  
Old 03-19-2018, 11:11 AM
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Once you know the diameter, do the math and make a chart. Depending on the gauge you might even be able to add your own labels for scale.


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