Increase tension on crank machines because of lock-out on tension?

[coach]

I just upgraded from a drop arm machine to a crank model-- Eagnas Flex 940. What I liked about the drop arm (though it took 20+ minutes longer) was the string s t r e t c h e d as the arm came to a rest (sometimes for 10+ seconds).

I was reading about crank machines at Silent Partner and this is what they had to say:

What is a " lockout" spring and brake stringing machine?

A machine with a spring and brake tensioner relies on a hand operated crank to pull the string. A spring deflects against the tension being applied to the string. When the pre-selected tension is reached, a lever is tripped stopping the tensioning operation, and a brake is engaged to hold the tension in the string for this reason, these tensioners are known as "lockout" or "instant off" machines. When properly calibrated, spring and brake tensioners are very accurate and allow fast stringing, which is why they are extremely popular in pro shops. Because these machines "lockout" as soon as they reach the reference tension, professional stringers usually set the tension about 10% higher than they do with "constant pull" machines (see FAQ 11 for an explanation of the difference between instant off and constant pull machines).

So is this more or less correct? Do I have to go maybe 10% higher on my new machine to off-set this fast and basically incomplete stretch? thanks.

 

[topknocker]

constant pull lockout
50 52.5-55.0
51 53.6-56.1
52 54.6-57.2
53 55.7-58.3
54 56.7-59.4
55 57.8-60.5
56 58.8-61.6
57 59.9-62.7
58 60.9-63.8
59 62.0-64.9
60 63.0-66.0
61 64.1-67.1
62 65.1-68.2
63 66.2-69.3
64 67.2-70.4
65 68.3-71.5

copy these for reference(need to space them out)

 

[coach]

thanks, very helpful

 

[1012007]

So if you want 50lb you should string between 52.5-55? Correct?

 

[topknocker]

yes, the highest number being 10% of the original. that's what i used before 2086. i think it's a good reference chart.

 

[YULitle]

Only if you are switching like coach. If you start off stringing with a crank, you need not be concerned with any of it (unless you string someone else's racquet who is switching from CP to your LO.)

 

[1012007]

lol i realised that

Just checking the figures were ok

 

[ryohazuki222]

Only if you are switching like coach. If you start off stringing with a crank, you need not be concerned with any of it (unless you string someone else's racquet who is switching from CP to your LO.)

I string for a friend of mine who's had bad luck with his wilson frames cracking. Currently he's hitting with a K 6.1 95 (received from wilson as a replacement for his broken ncode version.) He usually strings over the recommended tension for the rackets... but he didn't want to do so with the K factor for fear itll break like his previous two rackets.

According to this chart... does that mean it should be safe to string up for 63-66llbs on my revo 4000?

 

[YULitle]

I string for a friend of mine who's had bad luck with his wilson frames cracking. Currently he's hitting with a K 6.1 95 (received from wilson as a replacement for his broken ncode version.) He usually strings over the recommended tension for the rackets... but he didn't want to do so with the K factor for fear itll break like his previous two rackets.

According to this chart... does that mean it should be safe to string up for 63-66llbs on my revo 4000?

That's really tricky. It's easy in my mind. I would just string it at the max of 60lbs. But, if he is used to getting his racquets done on a constant pull machine, wants to go to 60lbs. AND is switching to having it strung on a crank, then yes I would say that 63-66 lbs. is appropriate.

 

[Nellie]

constant pull lockout
50 52.5-55.0
51 53.6-56.1
52 54.6-57.2
53 55.7-58.3
54 56.7-59.4
55 57.8-60.5
56 58.8-61.6
57 59.9-62.7
58 60.9-63.8
59 62.0-64.9
60 63.0-66.0
61 64.1-67.1
62 65.1-68.2
63 66.2-69.3
64 67.2-70.4
65 68.3-71.5

copy these for reference(need to space them out)

So if I string, for example, at 55 lbs on a crank, it may stretch to somewhere between 50-52 pounds?

 

[YULitle]

So if I string, for example, at 55 lbs on a crank, it may stretch to somewhere between 50-52 pounds?

Excellent deduction.

 

[topknocker]

this chart is what it is, nothing but a chart. use your own judgement.

 

[theace21]

I would start at the same tension. You have change many variables. Crank vs Drop Weight, new clamps, new mounting system, etc.

The chart is a great reference in the perfect world of everything else being the same. But your clamping system is probably different, you might have been using floating clamps - and this will also make a difference.

When I went to the Wise from a crank, this is what I told all my customers. The string job might seem tighter, would you like me to drop the reference tension a couple of pounds. Most preferred to stay the same and make any adjustment later.

Just my opinion -

 

[fastdunn]

It could depend on strings, natural gut, nylon or poly.

Get a digital scale and see it for yourself.

 

[TravelinMan]

May also depend on how quickly you clamp. When I made the switch to a crank (my own) from the shops electric I upped the tension by 2 lbs. My racquets from 58 to 60 and my sons 60 to 62. We thought that worked best. I have strung for a couple of friends who had been getting their's done on a drop weight and used the same 2lb method. They said that my string job was much tighter than the previous drop weight job. As reference I usually clamp at about 3-5 seconds from lockout.

 

[000KFACTOR90000]

constant pull lockout
50 52.5-55.0
51 53.6-56.1
52 54.6-57.2
53 55.7-58.3
54 56.7-59.4
55 57.8-60.5
56 58.8-61.6
57 59.9-62.7
58 60.9-63.8
59 62.0-64.9
60 63.0-66.0
61 64.1-67.1
62 65.1-68.2
63 66.2-69.3
64 67.2-70.4
65 68.3-71.5

copy these for reference(need to space them out)

That's 5-10% rounded up