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Discussion Starter · #1 ·
To anyone who has tried the GZK 1636 tubes how does it compare to Dankung 1632 tubes? I will be buying some to try myself but I thought it would not hurt to ask if anyone on the forum has blazed this trail before me. I'm not sure what to expect from them but my guess is the 1636 may offer a little more speed with less draw weight than 2040s. If you have tried them already your opinion is most appreciated.
 

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Discussion Starter · #2 ·
Anyone??
 
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I don't have anything to contribute either, except to say I am also looking forward to your results. I do really enjoy shooting 1632s though.
 

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I've been curious about GZK's 1636 size tubing as well ... is it only available thru him? I haven't seen it offered anywhere else. I wonder why he offers this - is he onto something or is it a gimmick.

Does the OD really measure 3.6mm versus 3.2mm? According to my 1:2:1 ratio theory, that might produce a tiny bit more power and an equally small reduction in snap. I'm guessing it might perform more like a 'Premium' 1632 (that never materialized) rather than 2040 but the differences still wouldn't be huge.

I can easily feel differences in snap between Kent .125 (less) and 1632 ... some claim to perceive a difference between red and amber 1632 but DK claims there's no performance difference, only added color.

I'm anxious to hear what you think of 1636. Meanwhile, I'll order some orange 1632 from Aliexpress that you've mentioned, partly bc DK has been disappointing me lately.
 
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Discussion Starter · #7 ·
I've been curious about GZK's 1636 size tubing as well ... is it only available thru him? I haven't seen it offered anywhere else. I wonder why he offers this - is he onto something or is it a gimmick.

Does the OD really measure 3.6mm versus 3.2mm? According to my 1:2:1 ratio theory, that might produce a tiny bit more power and an equally small reduction in snap. I'm guessing it might perform more like a 'Premium' 1632 (that never materialized) rather than 2040 but the differences still wouldn't be huge.

I can easily feel differences in snap between Kent .125 (less) and 1632 ... some claim to perceive a difference between red and amber 1632 but DK claims there's no performance difference, only added color.

I'm anxious to hear what you think of 1636. Meanwhile, I'll order some orange 1632 from Aliexpress that you've mentioned, partly bc DK has been disappointing me lately.
I have yet to try the DK 1632 but I'm loaded up on both DK natural and red. Since I have already got over 1,800 shots from my first set on the "no-name" orange 1632 from Aliexpress I can't see how the DK 1632 could be any better. In all fairness I will be trying it. Since I have so much of it now, it's in all fairness to me not DK :)
 
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Discussion Starter · #8 ·
Okay guys,

I'll be the guinea pig on this and report my findings. Hopefully they are favorable. I needed to get at or over $59 for free expedited shipping so I sort of stocked up on some tube.

After the order went though I noticed the 1636 is listed as green or black so I emailed him the order number and asked if he could do an even mix of the two. If not I asked for at least some of each color if possible. I think the green would look good on some slings while the black would look fantastic on some others.

This is what I ordered:

1636 / 10 meters (6 Rolls) Green and/or Black

2040 / 10 meters (4 Rolls) Orange Only

2050 / 10 Meters (2 Rolls) Green Only

50/80 / 1 Meter (1 Roll) Black Only

If you are wondering what I would be using the 50/80 for, I want to try out using cuffs to attach bands to Feihu forks and similar forks rather than wrap & tuck.

This may work fine and it may not work at all but I'll find some use for a single meter of it regardless. Possibly fork protectors on stainless slings if nothing else.
 
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Discussion Starter · #9 ·
When I first started shooting the 1636 looped tubes my perception was they were considerably harder to pull than the 1632s I've been using.

Apparently what I perceived as a big difference in pull weight between 1632s and 1636s was just my perception and does not bear out to be true in an actual weight measured pull test.

I made new sets for each size tube so no wear issue would affect the pull weight tests.

All tubes sets were tied to 5-1/2" from the folded loop to the tie point and pull weight was measured at a 27-1/2" pull to measure at very close to 500% stretch. All measurements were taken with a digital scale.

Weight measurements were taken from the center of the pouch hooked by the scale and measured to the back side of the band on the slingshot. All were taken on the same slingshot. (Dankung Stainless PIXIU)

This is what we got.

1632s - 8.90 pounds at 500% stretch (Orange tube is an unknown maker from Aliexpress)

1636s - 9.84 pounds at 500% stretch (Green tube from GZK)

2040s - 13.5 pounds at 500% stretch (Black from Dankung)

I do feel I'm getting a slightly higher speed from the 1636s than even the 2040s and a considerable amount faster than the 1632s.

Until I pick up my screens for my chronograph from my storage facility and actually test the speed from each I will have no accurate speed data. I'm simply judging by the sound each tube size makes when the ball smacks my spinner and I'm getting a much harder smack sound from the 1636s than either the 1632s or even the 2040s.

I know that's no accurate way to judge actual speed but until I pick up my screens and actually test speed it's all I have to go by.

I will note that I've owned a high quality chronograph for several years I used extensively to test handgun ammunition reload speeds. I have never been curious enough about slingshot speeds to ever bother to set it up and test anything until now. The real speed to the 1636s versus 1632s and 2040s has finally peaked my curiosity enough to want real speed measurements so I'll get by my storage facility in the next couple of weeks and pick up the screens to test.

Until then, I'm setting the new matched 5-1/2" loop tube sets aside so none will have any wear when I do check real speed.

What the weight tests have proven to me is the 1636s are not that much harder to pull than 1632s in realty.

If I am correct about my speed assumptions it's probably quite a bit faster than 1632s and possibly a bit faster than 2040s as well.

Short story, The GZK 1636 tube is indeed a good middle of the road size between 1632 and 2040 and well worth trying out.

I'm not saying I would stop using 1632 but I'm certainly adding the 1636 size to my preferred looped tube sizes.
 

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Thank you very much for the info. This is what makes this forum such a great resource.

I have really been enjoying shooting 1632s lately, your tests and insights are definitely leading me to try the 1636 next
 

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Discussion Starter · #12 ·
Thank you very much for the info. This is what makes this forum such a great resource.

I have really been enjoying shooting 1632s lately, your tests and insights are definitely leading me to try the 1636 next
If you like 1632s you will also like 1636s. Just a bit more pull force and a bit more speed. How much more speed I won't know until I actually measure speeds with a chronograph but I'll get to that as soon as I can pick my screens up. The speed difference my be less than I perceive it to be but I'm quite sure they are faster.

I was most definitely way off on my perceived pull weight differences as the are not near as hard to pull compared to 1632s as I thought they were by feel alone.
 

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Everyone to there own opinion but for me 1632 is king over 1636. 1636 may have a very slightly faster but a heavier draw weight of about 11%, which is very noticeable when you shoot them side by side. I try 1636 a month ago and didn't like and try it again side by side to 1632 this weekend and still don't like it. Long live 1632,,,,
 

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The Dankung tubes chart I have follows closely the cross sectional area of each tube to it's pull tension at various elongation. For simplicity I just use the square of the OD minus the square of the ID to get a reference cross section. I do realize I should be factoring it as a circle. But, adjusting for Pi or to any degree of accuracy or inaccuracy is a complete waste of time as the variable is used as a constant that can be discarded to render equally accurate results.

Based on my model 1632 has a cross section of 1024 (32x32) minus 256 (16x16) or 768 Dankung calculates a ring area of 6.03mm.

My chart does not have a 1636 reference but my model suggests 1040 or 35% greater resistance with all else being equal.

Dankung's chart for 5090 indicates a ring area of 43.98mm.

Based on my model it should be 8100 - 2500 or 5600. If my model is viable 5090 is 729% of 1632s 768. 6.03x7.29 is 43.96 I accept the difference between 43.96 and 43.98 as a rounding error.

My interpretation is just look at the ring area increase or decrease to conclude likely performance based on that alone. This does mean 1636 is 35% (not 11%) more than 1632.

BTW the Dankung shows tension at 600% elongation to be 2.9kg for two strands and for 5090 to be 21.5kg for 2 strands 2.9x7.3 = 21.17 or accurate considering the ring area ratio allowing for rounding errors.

Just look at ring area. Then, select for your desired draw weight and feel comfortable with larger ID tubes that are easier to assemble into useful configurations.

All other differences are related to imperfect measurements and to manufacturing quality differences in batches of tube.

Pull weight in Kg of 2 strands at 600% elongation. My recommendations in bold. I pass on tubes where the ID is less than half the OD as they are more difficult set up. Why work that hard?

1632 = 2.9

1636 = 4

2040 = 4.6

1842 = 5.5

3050 = 6.1

1745 = 6.7

2050 = 8.1

2055 = 10.1

3060 = 10.4

4070 = 12.7

5080 = 15

3070 = 15.3

6090 = 17.3

5090 = 21.5
 

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From what I read so far is better to have 2-3 weaker tubes rather than one strong tube ... is this correct?
Multiple sets can get twisted and take longer to reload.

When they do break, individual heavy single tubes can cause more trouble than one tube in a set of tubes is likely to cause.

Power and performance should be similar if relaxed length, draw length and total cross sectional or ring area are similar.

You should figure out the ammo you will be shooting and the pull tension you will be comfortable with and the draw length you will be developing then select tubes that provide your design performance.

Another part of the equation is using tubes on less than full performance will allow much longer service life than getting maximum efficiency will allow.

I think you will find advice from both sides of the issue.
 
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