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I don't think you can ask for a tension number. They stretch them as much as they can, but aluminum frames will relax by the time you get them. I think you'd be lucky to get 20 newtons.
 

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Hi, No I would like to know a typical tension for aluminium frame (N/cm). Where I buy them, I can choose the tension. I already bought some from others dealers. When I checked the tension with the tension meter I read from 8N/cm to 15N/cm depending of the frame. I want to make a standard for my shop and have a constant tension from frame to frame. I would like to know what is your common tension in your shop with aluminium frame (not Newman Roller retensionable frames) ? When I gather some informations on internet I can only find any for people using retensionable frame. Thks
 

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I would like to know a typical tension for aluminium frame (N/cm).

Where I buy them, I can choose the tension. I already bought some from others dealers.

When I checked the tension with the tension meter I read from 8N/cm to 15N/cm depending of the frame.

I want to make a standard for my shop and have a constant tension from frame to frame.

I would like to know what is your common tension in your shop with aluminium frame (not Newman Roller retensionable frames) ?

When I gather some informations on internet I can only find any for people using retensionable frame.
I have been a screen printer since 1979, and I have no clue how you might "make a standard for my shop and have a constant tension from frame to frame". Without the ability to re-tension, each and every frame will be different.

With ANY static frames, you will continuously, progressively lose tension as the fibers elongate and relax - especially when you are printing. Your existing frames are a fine example of what is 'typical'.

14N/cm is considered a minimum tension, because it takes 14 newtons of tension for the mesh to resist being manipulated by the squeegee. Move the skin on the back of your hand with your finger. Now tighten up the skin by making a fist and see how it is harder to manipulate the skin.

14 newtons is twice the force that 7 newtons and 28N/cm is twice the force of 14N/cm. Alas, the resistance of the mesh against your 'flexible' squeegee blade is not equal. There is more resistance near the frame than in the middle.

This means that if you have high off-contact, your blade will print at a different angles at the edges - altering deposit. Lower off-contact (a benefit of higher tension), means less distortion and faster blade speed.

14N/cm is 100 pounds of force per linear foot. A 24" frame has 200 pounds of force loaded in the mesh at 14N/cm.

When you are able to print with an automatic press, each and ever screen with different tension will require custom blade pressure and speed to print equally.

If you sharpen your blades and make each one unique and different, you will really have problems setting up each head.
 
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Discussion Starter #7
HI,

I mesure with a newman tension meter.

I think it is hard to get high tension with aluminium frame.

With my frame and the actual tension I have, it is impossible for me to print wet on wet, the previous color just stick under the screen.


So for better quality I should consider buying roller frame or remesh my aluminium frame more often.

I don't have automatic, I use manual press.
 

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Why do you not prefer Newman Roller Frames? With roller frames, you have the ability to retension the frame after each print. After each print, the tension loosens, and you retension the frame. After time, you will max out your tension because you will have "worn in" the amount of tension you can give that specific frame. After one use of you stretching your mesh to an aluminum frame, you'll need to take it apart and restretch.

Has anyone used Melray? I was wondering how it works when you get a stretched screen from them (I currently stretch all myself). Is a good amount of tension lost when you get the frame? How many prints can you get off before having to send it back for retensioning?
 

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my aluminum frames barley loose tension..i think its how you handle the screens and what gauge alum u used to make them and who welded them...
Oh, they do lose tension. Most of it is lost between the time they're stretched to the time you get them. Has nothing to do with welding.
 

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i use a heavy duty large diameter filament mesh. i stretch the 166 mesh to 65 newton meters. sometimes this takes awhile as the mesh likes to stall at 50 newton meters. i use this 166 for almost every thing except process jobs. these screens are a dream to print with. i'm surprised richard didn't say how much nicer they coat emulsion when stretched to 40 plus newtons. stan
 

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i'm surprised richard didn't say how much nicer they coat emulsion when stretched to 40 plus newtons. stan
Indeed, coating is much nicer because the resistance is very even across the entire mesh surface - no dark stripe of emulsion in the middle because the coater doesn't bend.

You can never can never be too rich, or have too much tension.:)

I will say that printing can be much harder to become accustomed to using elevated tension. You have to start using much stiffer squeegee blades that don't bend as you overcome the mesh resistance, but all you have to do is bring the mesh in momentary contact with the garment.

There is so much energy focused on the mesh just to overcome the off-contact distance, that the ink transfers through the mesh like toothpaste from a tube. This is not a easy concept to understand because we all know from printing that if you press harder, (bending the blade), you deposit more ink.

A key principle to high tension printing is that you don't use the blade angle as a variable, but use screen thickness to determine ink deposit. Blade angle will actually drive ink into the garment - not leave the deposit on the surface where it counts, especially on dark garments.
 

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Indeed, coating is much nicer because the resistance is very even across the entire mesh surface - no dark stripe of emulsion in the middle because the coater doesn't bend.

You can never can never be too rich, or have too much tension.:)

I will say that printing can be much harder to become accustomed to using elevated tension. You have to start using much stiffer squeegee blades that don't bend as you overcome the mesh resistance, but all you have to do is bring the mesh in momentary contact with the garment.

There is so much energy focused on the mesh just to overcome the off-contact distance, that the ink transfers through the mesh like toothpaste from a tube. This is not a easy concept to understand because we all know from printing that if you press harder, (bending the blade), you deposit more ink.

A key principle to high tension printing is that you don't use the blade angle as a variable, but use screen thickness to determine ink deposit. Blade angle will actually drive ink into the garment - not leave the deposit on the surface where it counts, especially on dark garments.

This is wrong. Pressing harder doesnt neccesarily deposit more ink. bending the blade will result in smearing. And more blande angle makes more deposit as long as u dont bend (smear) it too much. Sharper angles ( as in more perpindicular to the mesh) will result in less deposit and finner printing(halftones & outlines). Too leave a heavy deposit requires less pressure, and more angle ( off contact will take me too long to explain, just play with it) But its also critical..

George
 

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This is wrong. Pressing harder doesnt neccesarily deposit more ink. bending the blade will result in smearing. And more blande angle makes more deposit as long as u dont bend (smear) it too much. Sharper angles ( as in more perpindicular to the mesh) will result in less deposit and finner printing(halftones & outlines). Too leave a heavy deposit requires less pressure, and more angle ( off contact will take me too long to explain, just play with it) But its also critical..

George
I beg to differ. If you are pressing too hard and bending the blade, then you are losing your off contact distance and driving the ink directly into the garment, not laying the ink on top of the shirt. That is the whole point of having off-contact distance.

I believe that the point that was being made, is that while you can get more and less ink out of the blade angle, you should not be pressing so hard into the screen that you are bending the blade. Once you have achieved the point where you can produce the right amount of ink without bending the blade, you will be able to get the right amount of ink from the thickness of the emulsion, not from the angle.
 

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This is wrong.

Pressing harder doesnt neccesarily deposit more ink. bending the blade will result in smearing.

And more blande angle makes more deposit as long as u dont bend (smear) it too much.

Sharper angles ( as in more perpindicular to the mesh) will result in less deposit and finner printing(halftones & outlines).

Too leave a heavy deposit requires less pressure, and more angle ( off contact will take me too long to explain, just play with it) But its also critical..

George
Wrong? Perhaps. If you only use low tension mesh. With elevated tension (my point), blade angle and pressure have very little effect on deposit.

I specifically wrote that many people will have a hard time understanding how variables change at higher tensions.
http://www.t-shirtforums.com/screen-printing/t56840.html#post339258

Smearing
One of the most important reasons to elevate tension is to prevent smearing. That is why I wrote that you should take a finger and move the skin on the back of your other hand. That is how a blade can manipulate the stencil while you are printing. Now, make a fist and tighten the skin on the back of your hand. It will be much harder to manipulate.
http://www.t-shirtforums.com/screen-printing/t56840.html#post338131

Screen printing by definition is an off-contact medium, BUT you can't transfer ink through the mesh until the stencil comes in contact with the substrate.

Yes, the job of the blade is to push ink around the screen, but the blade never touches the shirt. The primary role of the blade is to bring the stencil in momentary contact with the substrate.

Once your mesh comes in contact with the platen, more blade pressure will bend the blade, no matter how stiff it is, changing the angle of the blade lip - increasing deposit. If the stencil is in contact withe the garment, the ink has to go into the shirt.

If you are using elevated tension, every millimeter of off-contact has to be overcome by the blade pressing down. More resistance by the mesh tension will bend the blade, (especially a soft blade), even before the stencil comes in contact with the garment. A stiffer blade will not be effected as much as a lower durometer blade.

Off-Contact
Minimum off-contact is enough distance for the mesh to pull itself out of the ink film.

If you don't have enough tension for the mesh to pull itself out of the ink film, you have to raise the off-contact distance so you can use the squeegee, as a mesh tensioning device. More off-contact will distort the length of any image you are printing. You will also have to slow the blade speed down. In extreme cases, you might have to pull the mesh out of the ink deposit, because the mesh didn't do it's job.

High tension and low off-contact is the most efficient printing setup.

Deposit
Low tension - having to push and smash ink through the mesh is not as elegant as building up pressure and when the ink comes in contact with the substrate, it moves through the mesh easily.

Smashing ink usually means some of the ink splits like a Oreo cookie, leaving some of the ink in the the stencil.

The thickness of the mesh and stencil decide how much deposit there will be. Textiles are very forgiving because they are usually 60% air and excess ink can be absorbed. This is not the case when you print on non-absorbent metal or plastic.

In this picture, blade angle will have very little effect on the deposit.
 

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OK well if the variable is my tension, then ill get you the specs from my guy on the tension and post back tomorrow. From my experience on mhms all my life, deposit depends on your emulsion(layers) or capiliary film + off contact. Or not pushing it into the fibers of the material( less pressure ) ,more angle + off contact + less flooding.

I print 10c jobs 1500+pcs every day. Maybe its just a matter of the machine and its capabilities?

George
 

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I was writing about tension, but it is not the only variable. The important variable to deposit is blade angle. Tension and off-contact will modify the angle at the lip. Soft blades will not stand up to mesh tension and will bend more. Pressure is not a good way to control blade angle. You can minimize the effect of many variables by increasing blade durometer and mesh tension and lowering off-contact.

Mesh and stencil thickness + shirt knit characteristics + ink viscosity + blade angle will determine your ink deposit, like a meat slicer or the picture I posted.

Off-contact distance will effect blade angle because mesh tension will increase as you bring the stencil in momentary contact with the garment. You are using the blade as a mesh tensioning device and blade angle will change as you overcome off-contact. Most printers use off-contact to compensate for low tension. If every screen is a different tension, it is common to modify off-contact on every screen. Very tedious at setup time.

If you sharpen your blades and they are all a different length, you add another tedious variable to setup because every pressure will have to be tuned to match the off-contact and mesh tension on all 10 heads of your press.

Less pressure, should mean, you don't bring the stencil in contact with the garment - and no ink will print. Too much pressure, (typically from bending the blade once it touches the platen), usually drives ink through the shirt and prints the platen - a waste.

These are all variables to be controlled and modified. They are screen printing principles. The ink doesn't know if it is being printed on a 10 color MHM or a hinge clamp on an ironing board.
 
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