Eagnas Machines

[Gaines Hillix]

There are a lot of differing opinions on these machines among stringers in the U.S., particularly related to the support and service, or lack of, by their U.S. importer, Maxline. I understand that Lilly-Lee/Eagnas is the largest seller of stringing machines globally. I'd like to see experiences from stringers in other countries on these machines. Have you had problems with their quality? Has service been a problem? I'd like to see positive experiences too, of course. :)

[kenzo]

I am planning to buy a stringing machine, as you can see, I've posted to look for opinions about Maxline. Here's what I heard when I was in one of the local last Fri:

"There is one, arr.....can't remember the name, something eagle...e-gas, don't buy that, it's very cheap but the worst machine out there, the quality is the worst...don't even bother, very cheap price but....."

I ask the store owner is it "Eganas"? he said "Yes" right away.

I am looking at either a Alpha or Laserfibre.

Kind of an experience on Eaganas.

[squashstring]

I had a bad week in 1992 - I broke the strings on my main squash racket and my spare racket on the same day. The next day I borrowed my wife's racket and broke the strings on that as well. It cost over £50 to get them all restrung, so I started looking out for a stringing machine.

I eventually bought an Eagnas DEN-3200 in 1992 from Gefen Sports in the UK. The DEN-3200 was the cheapest drop-weight flying clamp machine available in the UK at that time. Originally it was just with the intention of stringing my own rackets, but soon I was stringing for my friends, and eventually most players at my club. I was very relieved when another player bought a stringing machine so we could share the load!

Anyway, the DEN-3200 cost £300 (equivalent to $535 !!!) and that included a couple of Eagnas plastic double clamps, a metal badminton spring clamp, three awls, a string setting tool etc. I also got a lesson in stringing.

I noticed something was wrong when I strung my first racket - the tension was FAR too high. I set the distance of the weight on the drop arm to the 30 lb mark, but I ended up with a racket that felt like 40 lb +. I took the machine apart, weighed all the components, measured all the distances, did some calculations, and came to the conclusion that either the weights were wrong, or the scale on the rod was wrong.

I brought the machine back to Gefen Sports, and Mr Gefen put his calibrator on it and confirmed that it was way out of calibration - I can't remember by how much, but I think it was something like 15 lbs too much tension. Mr Gefen peeled off the plastic strip on the rod and hunted around and gave me another strip.

When I got home I found that that one was also way out! I did some calculations using a spreadsheet and marked the rod with the numbers I use for stringing squash rackets, and being a drop weight machine, the calibration can't have changed since.

I was fairly happy with Mr Gefen's support, as I could see it wasn't his fault, and I knew I could calibrate it myself. Mr Gefen has provided me with excellent support over the years, helping me out with stringing patterns and grommet strips, etc.

I then strung a few hundred rackets over the next few years, and then the clamps broke - both of them. They were the yellow and purple double clamps that are fairly popular, but being made of plastic, the handle/tensioning mechanism cracks near the pivots, and then they keep springing open unless you wrap an elastic band round them - very inconvenient. About five years after I bought the machine, I returned to Gefen Sports with the broken clamps. He was amazed that they had lasted so long! He sold me a couple of metal handles (£5 each), and they've been fine ever since.

I've been pretty happy with my machine. One reviewer on this (or maybe it was another similar) web site complained about friction in the rotating mechanism that the drop arm attaches to. I did notice this, but it's non existent at squash tensions, and not that bad at tennis tensions.

[Gaines Hillix]

Paul,

It's good that you had someone with a real store location you could go back to for help. BTW, what formulas did you use to calculate the locations on the drop weight arm(the parallel axis theorem?)?

[squashstring]

I just found the old notes and spreadsheet I used to calibrate my drop weight machine all those years ago.

Here goes:

There is no need to use the parallel axis theorem here - this is nothing to do with swing weights! All you need is good old-fashioned torque!

There are two torques to consider here. The anticlockwise torque is caused by the tension in the pulled string acting on the outside of the drum. The clockwise torque is caused by the sliding weight at the marked distance and also, the weight of the rod at whatever distance its centre of gravity happens to be from the pivot.

T is the tension in the string (pounds force)

r is the radius of the drum (mm). To make the calculation as accurate as possible, you should take the groove in the drum and the string thickness into consideration - you need to work out what the distance is from the centre of the string to the pivot the drum rotates about.

W is the sliding weight (pounds force)

d is the distance from the pivot to the centre of the sliding weight (mm)

R is the weight of the rod (pounds force)

x is the distance from the pivot to the centre of gravity of the rod (mm)

As the two torques are balanced, you get:

Tr = Wd + Rx

Solving for d:

d = (Tr - Rx)/W

You need to subtract half the width of the sliding weight, and half the diameter of the drum from this to get the distance from the perimeter of the drum to the left-hand end of the weight - this is where you put the mark on the rod.

For my machine, W = 2.67 pounds force, R = 0.89 pounds force, r = 31mm, x = 236mm.

So, for a desired tension of 30 pounds force, it gives a distance for the sliding weight of 269mm from the pivot point.

Subtracting the radius of the drum and half the width of the weight gives 219mm. So, I need to mark a point on the rod exactly 219mm from the drum. I then align the left-hand (inner end) of the squash weight with the mark.

Sorry for the nerdy post, but you can't get away from the maths. Assuming you can weigh the weights with a reasonably accurate digital kitchen weighing scales, you should end up with a machine who's calibration I would trust more than the cheapo calibrating scales sold by the likes of Eagnas, which appear to be accurate to within a couple of pounds!

There is one thing I didn't/couldn't take into consideration, and that is the torque effect of the string gripper. Sometimes this is adding to the clockwise torque (when it is horizontal on the RHS); sometimes it has no effect (when it is vertical pointing downwards); sometimes it adds to the anticlockwise torque (when it is horizontal on the LHS). I usually aim to get it to end up pointing downwards when the drop-weight arm is horizontal. From memory, it weights about 1 lb, and its Centre of Gravity is about 50mm from the pivot. This means that it can add or remove about 1.5 lbs to/from the strung tension.

This is probably one of the biggest inaccuracies/inconsistencies of drop weight machines (quite significant in the case of badminton rackets), and it wasn't mentioned in the two manuals I've looked through for these types of machines! People go on about how inaccurate drop weight machines are when the drop-weight arm is not absolutely horizontal, but providing you can get it to within 10 degrees of horizontal your tension will be within 0.5 lb (for a squash tension of 30 lbs). 10 degrees is the same as a vertical error of about 3" at the end of an 18" bar. This error is always negative, whereas the torque effect of the string gripper can be 1.5 lbs positive or negative. A newcomer to stringing could easily string two adjacent strings at 28 lbs and 31.5 lbs. That's -7% to +5%.

For a badminton racket with a desired tension of 18 lbs, you could end up pulling anywhere between 16 and 19.5 lbs depending on in what orientation the string puller ended up. That's -11% to +8%.
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[Gaines Hillix]

Paul, thanks for taking the time to do that very detailed post. :-)
I only finished first year college calculus and that was many years ago, but it still made sense to me. Also, very interesting on the effect of the weight and angle of the string gripper on drop weights with a rotating drum string gripper. Could this same effect exist on electric machines with this kind of tension head/string gripper?

[squashstring]

Hello Gaines,

The problem with the tension variation due to the gripper only happens when the gripper rotates about the pivot - see http://www.eagnas.com/lilygen/linear.html

All the electric machine that I've seen either have a linear puller - see
http://www.eagnas.com/lilylee/crystal2.html

... or a rotational puller - see
http://www.eagnas.com/maxgen/hygrip.html

Have you come across electric machines where the gripper is ouside the drum and rotates? A picture would be useful.

Paul

p.s. I'm not endorsing Eagnas products - I just find their web site useful for displaying all the different types of machines. Having said that, I'm quite happy with my two Eagnas machines (DEN-3200 and EAG-610S).

[Gaines Hillix]

Paul, my bad. I misunderstood your post thinking it also applied to drop weights with the rotating drum string grippers where the gripper is integrated into the drum, not the external linear type gripper.

[skarkboy]

I think that Eagnas has suckie drop weight stringers. But the manual one i got is awesome. The clamps dont slip and it is very easy to use. My hawk 10 was horible though.

[Gaines Hillix]

I think that Eagnas has suckie drop weight stringers. But the manual one i got is awesome. The clamps dont slip and it is very easy to use. My hawk 10 was horible though.

sharky, which Eagnas machine do you have now(Flex 940, perhaps)?