# $100 chinese 4" vise deflection + DIY force gauge



## spaceman_spiff (Oct 25, 2014)

So I got sick of my part coming out wrong in the Y axis  as far as not syncing surfaces up when flipped over in the vise and simply geometry being in the wrong place, so I decided to measure my vise deflection. Turns out its moving quite a bit, enough to explain what I'm seeing I believe. 

The tools I used in the test:

-harbor freight in. lbs. torque wrench
-harbor freight ft. lbs. torque wrench
-homemade drawbar force gauge being used to measure clamping force 
-Mitutoyo 0.0001" test indicator

I took the deflection from two spots, one right above the fixed jaw on the drawbar force gauge block which was in the vise, and the other, right on the top rear of the fixed jaw. Obviously the torque wrenches arent exactly NIST grade, but I'm pretty sure the force gauge is accurate. Regardless, everything is accurate enough to get a good enough idea what is going on. When I did the back-of-jaw data, I slid the force gauge over so its piston was centered in the vise. 

After I did all the tests, I closed my eyes and tightened the vise to what I usually tighten it to (damn tight until I'd need to do a push up on it to get it any tighter)..the PSI went OFF THE GAUGE. Meaning Probably 3000+ lbs of force. I'm pretty sure thats overkill for the work I've been doing.

I've seen two interesting web sites about tuning up the cheaper vises. Neither one seems to offer any before/after data on deflection though.

Enco Vise Tune-up

Fixing the 4 inch mill vise

Before I did these tests, I took the fixed jaw off to see whats up. Didn't find anything shocking. I just filed lightly to remove any burs and put it back together. I replaced the two 8.8 grade bolts with 12.9 bolts and torqued them to 29 ft lbs (apparently the max. recommended). I found that they could be a bit longer too. there is a good 0.3" of thread left in the fixed jaw once they are tight. So I'll get some longer ones and maybe it will help a little. I might also explore upgrading the bolt size to bigger, like one of those threads shows, but I dont have another vise so I might run into trouble using my mill to do the work.

I am not badmouthing this cheap-o vise. It was about $100 from some no name ebay seller about a year ago. Its been my workhorse and has taken me VERY far. And from what I read about kurt vises, deflection of this sort is still a reality even with those. I'm not sure what the kurt 4" deflection vs. force relationship is, but its not a horizontal line.

EPILOGUE:

I have now started using a $9 horrible freight torque wrench to tighten the vise during my setups, and only use the standard vise handle for loosening the vise or if I need to move the vise jaws a large distance and take advantage of its U joint. 

The torque wrench lets me create consistent and proper clamp loads, which reduce vise deflection and make the accuracy and repeatability of my setups go way up. Its a major improvement. Alot of my work involves multiple vise-aligned setups where the tilt of the part in the vise cant be easily compensated for by zeroing off a particular machined location.

I'm not sure how much these tests indicate the quality of the vise either way, or how much they would improve with a more expensive vise. All vises deflect. Kurt does make a 4" vise with a one-piece fixed jaw (no key or bolts), which would surely have better deflection, but its $1100. I think in this case, as usual, proper setup and planning can equal or exceed counting on superior specifications of better equipment. 

Now if you were doing a cut that needed 3000 lbs of clamping and had to be aligned within 1 thou when it was flipped over, blind, the vise accuracy may play a more important role. But for small machines with lower clamp load requirements, a more rubbery vise can probably get the job done if used properly.






















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## JimDawson (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*

Very cool setup, and good write up.  Would you provide some details on your force gauge?  That looks like a useful tool.


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## spaceman_spiff (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*



JimDawson said:


> Very cool setup, and good write up.  Would you provide some details on your force gauge?  That looks like a useful tool.



Thanks, the force gauge is indeed a useful tool to make, and its simple too.

Its exactly what it looks like, a piston with an o-ring that rides inside a blind hole (cylinder) in a block.

Then you add a small passage to the cylinder for the pressure gauge.

I just filled mine with water, perhaps hydraulic fluid would be more appropriate. You need to bleed the air out of it somehow so there is nearly no movement of the piston when compressed. 

I'm not completely sure but I believe you could use old welding gas pressure gauges for this..a cheap source most people might have laying around the shop.

In effect its just a hydraulic force gauge.

To make it specific to measuring your drawbar force you need to figure out a way where the drawbar ends up compressing the piston somehow.

The oring groove and cylinder size are all designed using standad oring gland tables found all over the internet.

Make sure to do a little pre-planning to make sure the forces you expect to measure will show up on the gauge you use, accounting for the cylinder diameter you select.


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## Andre (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*

What a cool force gauge, I just so happen to have a 3600 PSI pressure gauge lying around (no joke) and now I have a use for it! I will probably use a bore that measures one square inch. Looks like I'm going to have to find a .5641895835477563" reamer :rofl:


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## spaceman_spiff (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*



Andre said:


> What a cool force gauge, I just so happen to have a 3600 PSI pressure gauge lying around (no joke) and now I have a use for it! I will probably use a bore that measures one square inch. Looks like I'm going to have to find a .5641895835477563" reamer :rofl:



be sure to post pics when you do!! of the reamer and the force gauge you make lol


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## JimDawson (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*



Andre said:


> What a cool force gauge, I just so happen to have a 3600 PSI pressure gauge lying around (no joke) and now I have a use for it! I will probably use a bore that measures one square inch. Looks like I'm going to have to find a .5641895835477563" reamer :rofl:




You might want to use a 1.1283791670955125738961589031215 reamer, it's a bit closer to 1 in[SUP]2[/SUP]


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## Glenn_ca (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*

Why be concerned with the size of the hole since you are measuring total force not force per square inch.


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## spaceman_spiff (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*



Glenn_ca said:


> Why be concerned with the size of the hole since you are measuring total force not force per square inch.



itd be nice so your gauge reads directly in lbs force instead of requiring arithmetic ..otherwise doesnt matter really as long as the force and piston size will show up on the gauge psi for whatever force range you expect to encounter


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## Glenn_ca (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*



spaceman_spiff said:


> itd be nice so your gauge reads directly in lbs force instead of requiring arithmetic ..otherwise doesnt matter really as long as the force and piston size will show up on the gauge psi for whatever force range you expect to encounter


Regardless of the size of the hole the indicated pressure will be the same and is the pressure being exerted on the vise. To determine the psi you need to divide by the area within the jaws.


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## spaceman_spiff (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*



Glenn_ca said:


> Regardless of the size of the hole the indicated pressure will be the same and is the pressure being exerted on the vise. To determine the psi you need to divide by the area within the jaws.



not really..

say your piston is 1 square inch

and you put 1 lb on it

your gauge will read 1 pound per square inch (convenient)

now say the piston is 10 square inches

and you put 1 lb on it

now the gauge reads 0.1 psi (do some multiplication)

now just replace "you put x lb on it" with "the vice exerts x lbs clamp force on it"

the area within the jaws is irrelevant because it translates into the same force on the piston, regardless of how much of the piston is inside the jaws. If the entire piston isnt within the jaws thats not good for this simple design, because the piston will tilt to the side and probably not work right, but for discussions sake, it doesnt matter, because whatever force you are exerting on the piston does not depend on how much of the piston you put it on.

Kind of like how your bathroom scale doesnt care how big your feet are, or if you decided to balance yourself on a soda can on top of the bathroom scale..youd get the same weight (plus the soda can).

are you sure we're talking about the same thing?


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## Glenn_ca (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*



spaceman_spiff said:


> not really..
> 
> say your piston is 1 square inch
> 
> ...


If you read your own response through I think you will find that you have proved my point especially the second to last line. Take the top off your bathroom scale and replace it with one of a smaller or larger size of the same weight the reading on the scale will not change.


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## Andre (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*



JimDawson said:


> You might want to use a 1.1283791670955125738961589031215 reamer, it's a bit closer to 1 in[SUP]2[/SUP]




For a piston to cover an area of one square inch, remember the area of a circle is radius squared times pi. .5641895835477563 squared is .31830988618. Multiply that my PI equals 1. So to create a piston/bore that will displace one psi with one pound on it I need a bore that measures .5641895835477563. Please correct me if my math is wrong.


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## Glenn_ca (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*



Andre said:


> For a piston to cover an area of one square inch, remember the area of a circle is radius squared times pi. .5641895835477563 squared is .31830988618. Multiply that my PI equals 1. So to create a piston/bore that will displace one psi with one pound on it I need a bore that measures .5641895835477563. Please correct me if my math is wrong.


You need to calculate the diameter not the radius.


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## JimDawson (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*



Andre said:


> For a piston to cover an area of one square inch, remember the area of a circle is radius squared times pi. .5641895835477563 squared is .31830988618. Multiply that my PI equals 1. So to create a piston/bore that will displace one psi with one pound on it I need a bore that measures .5641895835477563. Please correct me if my math is wrong.



You are correct, if you are using a .5641895835477563 _RADIUS_ reamer.  Reamers are normally measured in diameter thus _1.12837.... DIAMETER _:whistle:


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## spaceman_spiff (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*



Glenn_ca said:


> If you read your own response through I think you will find that you have proved my point especially the second to last line. Take the top off your bathroom scale and replace it with one of a smaller or larger size of the same weight the reading on the scale will not change.



Yeah but the bathroom scale reads in lbs force not lbs force per square inch like the gauge.

So just to be clear, you are saying that a given force on a piston does not pressurize the fluid behind the piston differently as piston diameter changes? That would basically mean all hydraulic circuits which generate mechanical advantage through different piston sizes wouldn't work.


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## Andre (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*



Glenn_ca said:


> If you read your own response through I think you will find that you have proved my point especially the second to last line. Take the top off your bathroom scale and replace it with one of a smaller or larger size of the same weight the reading on the scale will not change.



Were not talking about weight, were talking about pressure. 

Piston size DOES matter. Imagine a hydraulic cylinder, with a piston face that measures one square inch. Pump 100 psi of hydraulic fluid into it, it can lift 100 pounds. Try that same 100 psi into a cylinder with a piston face of 10 square inches, and it can lift 1000 pounds.


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## Andre (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*



JimDawson said:


> You are correct, if you are using a .5641895835477563 _RADIUS_ reamer.  Reamers are normally measured in diameter thus _1.12837.... DIAMETER _:whistle:



Oh, I feel stupid now. 

Thank you for pointing that out! My bad.


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## Glenn_ca (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*



Andre said:


> Were not talking about weight, were talking about pressure.
> 
> Piston size DOES matter. Imagine a hydraulic cylinder, with a piston face that measures one square inch. Pump 100 psi of hydraulic fluid into it, it can lift 100 pounds. Try that same 100 psi into a cylinder with a piston face of 10 square inches, and it can lift 1000 pounds.


Certainly piston size in that instance is of importance when we are talking about work capacity but what we are talking about here is gauge pressure. Apply the same force to a 4" piston as a 1" piston and the hydraulic pressure within the cylinders will be the same. The work they can do is different but the pressure within the cylinder is the same and that is what we are looking at with this force gauge.


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## JimDawson (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*

The pressure can be calculated with the formula p = F/A. where:


p = pressure (psi)
F = force (pound)
A = area (square inch)


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## spaceman_spiff (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*



Glenn_ca said:


> Apply the same force to a 4" piston as a 1" piston and the hydraulic pressure within the cylinders will be the same.



This is incorrect.

Think about the term PSI. Pounds PER square inch. Pounds per SURFACE AREA. Think about it. A 4" circle has alot more surface area than a 1" circle. How could the PSI of the fluid behind it be the same? Pressure is not measured in lbs, its measured in lbs per surface area.

Think about the brake circuit in your car. A small master cylinder at the pedal pressurizes the fluid to say 1000 psi. At the caliper, the piston is much larger, magnifying the force 100 times (for instance).

The tradeoff is distance. Just like a mechanical lever. The larger cylinder will move much less than the smaller cylinder, so the power stays the same.

Or a bottle jack. You pump it up with a teeny cylinder and have to move the lever up and down a dozen times just to get the big piston to move 1 inch. Where does the mechanical advantage come from? It comes from you moving a little cylinder a very long distance (through a valve), pressurizing the fluid to maybe 50psi. But the jack output piston is MUCH larger, but moves much less, magnifying the force 100 times or more, just like a mechanical lever would.


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## Andre (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*

.....yes. We ARE talking about pressure. This is a hydraulic cylinder in reverse. 

A 1" piston with 100 pounds on it....will produce 100 psi.

A 4" piston with 100 pounds on it will create 25 psi.

A 4" piston with 400 pounds on it, will create 100 psi.


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## Glenn_ca (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*

Take your example of the hydraulic brake system if the pedal produces 1000 psi of force there will be 1000 psi of pressure in the hydraulic line, less minor loss, going to the caliper. Reducing the size of the caliper will not change the pressure in the line but it will reduce the total force that the brake can apply to the wheel. When you are talking about a clamping pressure of 3000 pound in you original post are you not talking about total clamping force rather than psi.


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## spaceman_spiff (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*



Glenn_ca said:


> Take your example of the hydraulic brake system if the pedal produces 1000 psi of force



Just to be clear, force is not measured in psi, and, the pedal produces a psi in the hydraulic fluid based on the piston size attached to the pedal. 



> There will be 1000 psi of pressure in the hydraulic line, less minor loss, going to the caliper.


Ok.



> Reducing the size of the caliper will not change the pressure in the line but it will reduce the total force that the brake can apply to the wheel.



Correct.



> When you are talking about a clamping pressure of 3000 pound in you original post are you not talking about total clamping force rather than psi.



"Total clamping force" doesn't have a definition besides one we make up for it. 

If you turned the vice on its head, you could use it as a jack to lift something, and say "the vice can lift 3000 lbs" with a certain torque on the handle. It doesnt matter if that 3000 lbs is all in one spot on the jaw or evenly distributed on the jaw. It just matters that its touching the jaw. The 3000 lbs remains the same. And by that same logic, the same amount of force is exerted on our force gauge piston regardless of how much of that piston is between the jaws. 

Now on the other side of the piston, in the fluid, the diameter of that piston comes into play, and the force in LBS gets distributed over a certain area, and we have LBS PER square inch, which is dependent on piston size, and represents the pressure of the hydraulic fluid.

"Clamping pressure" would not be measured in pounds, it would be measured in PSI.


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## spaceman_spiff (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*



Andre said:


> Were not talking about weight, were talking about pressure.
> 
> Piston size DOES matter. Imagine a hydraulic cylinder, with a piston face that measures one square inch. Pump 100 psi of hydraulic fluid into it, it can lift 100 pounds. Try that same 100 psi into a cylinder with a piston face of 10 square inches, and it can lift 1000 pounds.



BTW Andre, to make your experience a little more enjoyable, make sure you figure out what oring you want (and where you're going to get it) before you pick out a reamer. Standard oring gland dimensions may or may not permit a cylinder area of 1 square inch. And given that this is a fairly high pressure gland you may want to stick to conservatively designed oring glands.


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## Glenn_ca (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*

Maybe I need to rethink this. I will be back.


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## Andre (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*

The Oring actually acts as a piston too. So as long as it fits airtight and the bore is of the correct diameter I should be set, right?

I'll bore the hole to 1.1xx diameter than fit a piston, the bore is really the critical part.


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## JimDawson (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*



Andre said:


> The Oring actually acts as a piston too. So as long as it fits airtight and the bore is of the correct diameter I should be set, right?
> 
> I'll bore the hole to 1.1xx diameter than fit a piston, the bore is really the critical part.



Yup.  If you made the bore 1.125 it would be within the error in the gauge, and there are standard O-rings available for that bore.


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## spaceman_spiff (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*

heres parkers calculator showing the 1.125" bore oring..looks like a 2-314

parker is only rating it to 1150 psi unless you use backup rings..I'm not sure how conservative that is. I certainly do not use backup rings on the one I made.

this application is pretty mild: no movement, no temperature swings, no chemical attack. it does have a few thousand psi to deal with but mine seems to have worked with just an oring. But I would try and stick to the gland geometries within a few thou at most or you might get the oring popping out or impossible to press into the cylinder

note: there are other standard orings that would fit the same bore, with a different piston groove and diameter..and you may get lucky and find these at a hardware store near you


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## awander (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*



Glenn_ca said:


> Maybe I need to rethink this. I will be back.



Wow-I'm impressed, Glenn. Most people will not admit that they might be incorrect on web forums.


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## spaceman_spiff (Oct 25, 2014)

*Re: $100 chinese 4" vise deflection data*



awander said:


> Wow-I'm impressed, Glenn. Most people will not admit that they might be incorrect on web forums.



this place transcends all


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## middle.road (Oct 26, 2014)

*Re: $100 chinese 4" vise deflection data*

I can only imagine what the deflection is on my 1998 India vise I bought when Enco still had a store in the Chicago area....  :thinking:


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## drs23 (Oct 26, 2014)

*Re: $100 chinese 4" vise deflection data*

OT here but from what I can see awander that's a nice looking Pan in your avatar. Is that Linkert an M74B?

Back to your regularly scheduled programming. :biggrin:


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## Glenn_ca (Oct 26, 2014)

*Re: $100 chinese 4" vise deflection data*



awander said:


> Wow-I'm impressed, Glenn. Most people will not admit that they might be incorrect on web forums.


When you are wrong you need to admit it and I was obviously wrong on this one although it seemed clear to me yesterday. 
Thank you Spaceman_Spiff for your patience.

Note to self: Do not post on the internet while you are taking powerful pain medication for kidney stones.


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## spaceman_spiff (Oct 26, 2014)

*Re: $100 chinese 4" vise deflection data*



Glenn_ca said:


> When you are wrong you need to admit it and I was obviously wrong on this one although it seemed clear to me yesterday.
> Thank you Spaceman_Spiff for your patience.
> 
> Note to self: Do not post on the internet while you are taking powerful pain medication for kidney stones.



sometimes I wonder how many not quite correct things I have in my own head, and would I trade being publicly corrected in order to suddenly know the truth...hmm a faustian dilemma for sure..sort of...

Andre be sure to keep us posted in this thread or somewhere about whatever force gauge you make!!!


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## Andre (Oct 26, 2014)

*Re: $100 chinese 4" vise deflection data*



spaceman_spiff said:


> sometimes I wonder how many not quite correct things I have in my own head, and would I trade being publicly corrected in order to suddenly know the truth...hmm a faustian dilemma for sure..sort of...
> 
> Andre be sure to keep us posted in this thread or somewhere about whatever force gauge you make!!!




Will do! Should be an interesting project.


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## The Liberal Arts Garage (May 23, 2015)

Just think of piston areas as you would gear diameters..........BLJHB


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## awander (May 27, 2015)

drs23 said:


> *Re: $100 chinese 4" vise deflection data*
> 
> OT here but from what I can see awander that's a nice looking Pan in your avatar. Is that Linkert an M74B?
> 
> Back to your regularly scheduled programming. :biggrin:



Good eye, drs23. That's a 1952 FL (Pan) with an M-74B.


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