Counting the number of pumps of the jack handle WILL NOT relate to the force being applied to the bridges. The number of pumps of the jack handle will relate to the distance that the jack ram travels, or the deflection applied to the bridges. Stiffer bridges (typically stiffer is stronger) will deflect less than flexible bridges at any given load level. The strongest bridges may in fact break with fewer pumps of the jack handle than the weaker, more flexible bridges. Imagine a rubber bridge. It will deflect a great deal, but it won't carry much load. This property of elastic materials is the essence of Hooke's law.

If you could substitute a port-a-power piston and pump then yes you could.

From the release valve screw, the oil is behind one or more check valves and/or seals so you won't get any pressure readings there. consider that if the oil pressure could be measured there, you'd lose most of your oil every time you opened that valve.

@@GFlCh and in the security valve ? some bottle jack incluye a ''do not adjust'' screw beside the release screw, if i do a replace of that security screw with a manometer you think is gonna work? sorry bout my english im from chile im speak spanish

Can you take a picture/video of it and show me. Not following the description.

You can find us on facebook under NelsonStudios.

I assume there are, but one that would operate in this pressure range might be too expensive. The one he used would be much less expensive, and he might have had it on hand. Plus, a digital gauge would require power. Either by batteries that you have to occasionally replace or recharge, or by a power cord/power adapter and perhaps an outlet and power switch.

Sure, a little index card with the numbers written out taped to the back is a great idea.

You could copy/paste the text from the auto-generated transcript. It would need some proofreading and minor corrections, but it's very close: 00:00 I like this I draw it press fine but I'd 00:03 very much like to know just how much 00:05 force I'm applying so what I plan to do 00:08 is install this 5000 psi hydraulic gauge 00:13 onto the jack and then once I calculate 00:15 the actual inside diameter of the piston 00:18 I can get a really good approximation of 00:20 how many pounds of force is being 00:23 exerted first step is to drain the jack 00:28 each jack is different but as you can 00:32 see normally they will have a oil fill 00:35 level it's that red one up here very 00:37 similar thing so first off I got to pull 00:41 that and drain it into a clean container 00:43 so that I can reuse it once you've 00:47 drained the fluid it's now time to get 00:49 the jack apart now unless you have a 00:51 welded jack one of the reasons why I'm 00:53 not using this red one is it's actually 00:55 a welded jack unless you have a welder 00:58 jack it'll come apart in two places 01:00 it'll come apart right here and will 01:02 come apart right here but they both 01:04 could be really really hard to get out 01:07 starting with a newer jack obviously 01:09 it's going to make this considerably 01:11 easier with the base and the vice big 01:15 pipe wrench big channel locks big 01:17 something go ahead and unscrew this once 01:20 you get this out the piston assembly 01:21 should lift out of it this is the 01:24 hydraulic fluid reservoir and that comes 01:27 off next now it took a very large pipe 01:32 wrench and quite a bit of force break it 01:36 loose but it came 01:45 this is the next piece of pipe that has 01:48 to unscrew this is the actual barrel for 01:53 the piston when you get that apart 01:55 you're going to want to carefully 01:56 measure the inside diameter so that you 01:59 know just how big it is it'll let you 02:01 calculate the surface area and figure 02:03 out what sort of formula you're going to 02:06 need to get your gauge accurate so next 02:09 pull that inside pin now we're down to 02:14 our key jack components okay so this is 02:18 the actual pump right here and the oil 02:21 comes up out of that hole right down in 02:24 there and that activates the piston and 02:29 the piston rides inside of here so when 02:37 you take it apart it's alright to put 02:41 marks on this shaft you put marks on 02:44 this shaft and it's ruined absolutely 02:46 ruined but this shaft unscrewing it and 02:49 it took even more force then crack on 02:51 the top did this is the actual piston 02:54 shaft this is what it slides up and down 02:57 in the base you have the seals none of 03:01 this needs to come apart though it all 03:02 does need to go into your solvent tank 03:04 to be cleaned up this part of the jack 03:09 is nothing more than a hydraulic 03:11 reservoir this is where the fluid rises 03:14 when the piston is down and then as you 03:16 pump the piston up that fluid drops if 03:20 you want to make a Jack that is 03:23 reversible that is that you can pump 03:26 while upside down that can be done can 03:29 be done very simply you need to tap into 03:31 this line here which is the suction line 03:34 when you tap into that line there and 03:36 you're going to put a nipple and you're 03:39 going to go the appropriate distance 03:41 down with a little piece of hose so that 03:44 when the jack is upside down then it can 03:47 still suck fluid because that's your 03:48 main problem next step really I got to 03:52 clean this up we have to pull the ball 03:54 return we have 03:55 to pull the pump assembly out and get 03:59 ready to do some drilling down in there 04:02 so now I've got all the check and ball 04:05 return belts pulled out of it and these 04:08 are different for every jack and you 04:10 just got to be careful and try to catch 04:12 what can come flying out of the hole if 04:15 you're not careful a lot of modern jacks 04:17 will have them behind the bleed valve 04:18 this one had them in the pocket there so 04:21 it had a small valve which is basically 04:25 a steel ball in a seat in there on top 04:28 of that it had a spring on top of that 04:30 it had the large ball and then it had a 04:34 rubber Cup and they all go together 04:40 inside something like this you're going 04:42 to have something very similar and if 04:44 you shoot it across the shop and you hit 04:46 a little bits and pieces fall behind the 04:47 corners you're gonna have to buy a new 04:50 jack so be careful so now we're ready 04:55 for the milling process so what's got to 04:57 be done is we've got to tap into the 05:00 center of this part here but if you 05:02 touch with your drill bit that edge or 05:05 any of these threads again the jack is 05:08 ruined so there's not a whole lot of 05:09 wiggle room in there we're going to find 05:12 a way to go in through the side here 05:18 reach it in the center and then drill 05:21 and tap this out for your gauge 05:27 take some careful measurements do some 05:29 careful planning make sure you get this 05:31 right the other opportunity is to go 05:34 straight to the bottom which isn't an 05:37 option in this press all right so the 05:41 milling is complete I didn't have a lot 05:43 of base thickness to work with here so I 05:45 had to be very precise I came down just 05:48 below the edge of that lip I went inside 05:51 with a larger hole big enough that I can 05:54 then tap it out for a quarter inch pipe 05:57 and then using a tiny drill bit I 06:00 actually made my incision it you know it 06:03 doesn't have to be a big hole it can be 06:06 hardly larger than a pin hole and the 06:08 gauge will still read pressure at about 06:11 1/8 inch hole plenty that's bigger than 06:13 the hole it's in the bottom of the gauge 06:14 anyways so this should work perfectly 06:16 now I just need to tap this and give the 06:20 whole thing a very thorough cleaning 06:22 because you get those metal filings in 06:24 there and it will shorten your life your 06:26 jacket all right basically the operation 06:28 is complete I've got my threads in there 06:30 I've taken the time to very carefully 06:33 clean everything somehow already got dog 06:36 hair right very carefully clean 06:37 everything now I just need to put it all 06:41 back together it can't be too clean take 06:44 your time make sure everything is 06:46 spotless because any dirt in there and 06:49 it'll just cause you nothing but 06:50 troubles remember before you assemble it 06:54 to take the time to measure the bottom 06:56 of piston and it's not this diameter 06:59 here it's the diameter at the very base 07:03 the fatter diameter so I know that this 07:05 is one point two four five and that's 07:11 that's the number I'll enter in for my 07:13 calculations to figure out exactly how 07:16 many pounds of force is being exerted 07:18 one point two four five 07:27 you 07:29 again if you measure this you'll be off 07:32 and you'll be off fairly substantially 07:34 so it needs to be the base here 07:39 reassemble the jack the way you took it 07:41 apart it's a good idea before you 07:44 reattach the piston here to put a little 07:47 oil on that seal 08:08 well none of this footage is ever gonna 08:10 be used you know how tight it was when 08:15 you took it apart it's got to be pretty 08:17 tight when you put it back together and 08:21 there it is 08:22 all complete I just need to refill the 08:26 bottle it might take some time and 08:28 effort to get that to properly bleed 08:30 remember this is hydraulic stuff so you 08:33 know there can be quite a bit of 08:34 pressure on it and water pipe might not 08:37 hold so you should look into do using 08:41 the proper stuff I'm gonna go ahead and 08:44 bleed this and then test it out I hope 08:47 you have good luck with your own Jack 08:49 thanks for watching all right so here it 08:52 is all bled up I had some difficulty 08:56 bleeding it and there's still some air 08:57 in there somewhere 08:59 the handles a little spongy with luck 09:01 it'll work itself out on its own but now 09:05 when I add the pressure we bring her up 09:11 so the gauge it's just pressing on a bar 09:14 right now but the gauge is at 2,000 and 09:17 if I want to know how much weight that 09:19 is I have to multiply by one point two 09:23 three so that's actually putting 2,400 09:26 pounds of actual measurable force on 09:30 that I wish my piston would have been a 09:34 nice round number one would have been 09:36 nice one and a half would have been okay 09:38 one point two three at least it's easy 09:41 to remember so again good luck with your 09:44 project I hope it all works out for you

Pedantry makes the world go round.

From 1.245 how do you get 1.22 seems to me that it's closer to 1.23 if you round down....curious more than anything

Csaba Farkas No because air would make it spring. You could however start with an inexpensive air powered bottle jack jack from a company like Harbor Freight which when I think of it now is a dang good idea.

NelsonStudios Thanks for the very detailed tutorial. As for air over hydraulic, you can tap the fill plug and and use low pressure air (10-15 PSI) to raise the jack faster than pumping with hand. It won't be like a air hydraulic jack but it will extend the piston very rapidly until it gets to a place for actual pressure and then you continue with hand pumping. I've setup mine with 3-way air solenoid and a foot pedal and it works great.

Actually, on the air/ hydraulic jacks units, the air only supplies the power to operates a small hydraulic pump in place of the manual pumping motion that you normally provide

Northern Hydraulics sells them already made.

ugh....or just measure the diameter of the ram, divide it by 2, square it, and multiply by Pi. (pi*radius^2)

You can pull it apart to do that, or just use oil displacement method and no need to take it apart.

He had to take the jack apart anyway but no need to measure the piston and no need to use the displacement method. No need to know the piston diameter at all. Just put a known weight on the jack and read the gauge to get the ratio of weight to PSI.

IMO not an accurate method unless you put a ton on it and that's not safe.

This is what he used, a 5000psi pressure gauge. What other type of pressure gauge are you thinking of? Where would you attach it? Keep in mind that the gauge you use, and the fittings, are under the full pressure of the jack. If they can't handle that kind of pressure, the gauge and fittings will eventually (perhaps immediately) leak, fail, and break apart, perhaps violently.

WOuldn't be half as cool as building it yourself tho

It is how to tell actual pounds the press is putting out. Pounds per square inch, you need to know how many square inches the piston is to figure total pounds unless your piston is exactly one square inch.

ha . why would you care? everything is measured in psi or bar (pressure) when it comes to hydraulics.

adam sorell You understand that this is in a press and it is often useful, sometimes required to know how many pounds of force you are exerting on an item?

when is it useful?

@@adamsorell4851 Any time you are pressing something it is useful. An arbitrary pressure reading doesn't tell you anything.