[pgandy]

Many thanks Henry. I had been considering a Dankung. The primary reason for quick change thinking it ideal for the tube bands I’ve been planning on. I had suspicions about the comfort of that frame with high draw forces and you proved me correct. I now plan to order the bands and pouches in within the next couple of weeks and use on my PSs. I even have a new PS1 on order as they fit my hand to a T distributing draw forces well.

 

[pgandy]

Thanks for the information Henry. You have taken much work out of me finding a good starting point. My 1842 is out there somewhere and hopefully will arrive in a few more weeks. My goal is to increase band life while equalling, if not to exceed present power, which while acceptable is not all that great. Your findings make me optimistic. Hopefully this will save money as it costs much to import the Theraband. Advise when your new video is out.

 

[pgandy]

@Henry the tutorial was what I was referring to.

 

[pgandy]

say guy's can you give me some info on what you use to aquire you weight of ammo, and your weight in draw. I've been ask to do some of these and can't, also maybe I can also bother you in how to put in photos .... I've got some real uglys to show ya

This is what I use for draw weight.
http://www.amazon.co...s00_i00_details
Check here for something to weigh your ammo.
http://www.amazon.co...Scale&x=15&y=15

 

[pgandy]

Thanks again Henry. I appreciate your efforts and time in this project and I am sure it will be helpful to many. Approximately how much force are you applying when stretching the bands during fabrication?

 

[pgandy]

[sub]I got my first 1745 rubber yesterday. I still haven't completely explored the 1842 putting it on hold until I could get more 1842. Being satisfied with the results of the 1842 I decided to save what I had left until I could replace what I had used before more experimentation. I have more enroute out there somewhere. [/sub]
[sub]As for the 1745 I like it and find it more powerful than the 1842. I found one 1745 band set that gave the same energy as the 1842 that I use for general purpose. As a comparison; the difference was that I was stretching the 1745 388% vs the 1842's 517%, leaving me to believe longer band life and less expense. The trade off is 21# pull vs 15.5#. I consider the 21# pull good PT. When stepping it up to about 25# I zipped hex nuts through tin cans with no problem. One can is pictured below.[/sub]
[sub]That is about max for me and I don't care to shoot it many times. I can pull more but the fool frame of that Dankung bites into my hand. Also I began having trouble holding on to the pouch and needed large balls or double hex nuts. Perhaps in time I can build those finger muscles up. [/sub]
[sub]The Dankung is now my most used slingshot, but only because of the way it carries. And I like the quick band change ability. Having said that I feel that I should say: My PS slingshots will out shoot it and are more of a pleasure t shoot. They certainly shoot smoother. I get the same accuracy at 40' with my PSs as I do at 30' with the Dankung. I get the same power with the PSs as I do using the Dankung with several band sets requiring 18-19# pull compared to Dankung at 25#. I think that I haven't found the right Dankung formula yet. Band life is shorter with the PS in the upper ranges though. After wearing the second hole in my pocket with a PS I started leaving them home in favour of the Dankung that I can easily conceal under my shirt. For an afternoon of shooting fun the PS has it beat, hands down in my book. [/sub]
[sub]

[/sub]

 

[pgandy]

Here's a photo of a coconut made after the above post with the 1745. One shot nearly halved it. And I haven't reached its maximum potential yet.

 

[pgandy]

Henry those results closely approximate what I recorded with a 31" draw. The 2040 was on my want list, but after reviewing your results I'll save the money. Thanks.
Henry's
.30 Pb-3.62 fpe
.375 steel-4.89
.36 Pb-5.81
.429 Pb-6.53
Mine
.31 Pb-3.72 fpe
.375 steel-4.97 fpe
.375 Pb-5.83 fpe
.429 Pb-6.43 fpe

I had the comparison in side by side columns but the forum skewed them badly.

 

[pgandy]

Henry this is where we differ. Also I would, for clarity's sake, like to make it clear that I am using one strand per side of 1842 with both ends tied to pouch. There seems to be little difference with lighter ammo. The real difference occurred with .50 cal. lead, as no doubt my larger double hex nuts that weigh 8.2 gm and .50 steel at 8.4 gm will measure also. I am getting 7.47 fpe with .50 cal. steel, about what you are getting with the lead. Those large double hex nuts w/star washer gave 7.51 fpe. With .50 cal. lead I get 8.53 fpe. Draw is 31".

Thinking back on it I tested the pseudo-taper and was disappointed with the results using the 1842 tube as I got more energy with the present, conventional set up. The only ammo that I tried was the .50 lead as I generally shoot heavier ammo. After the initial tests using .50 ammo I decided on the present set up, which measures 6" from pouch, and when time permitted I went back and tested with the lighter ammo. It appears the difference between the two configurations is more pronounced with heavier ammo. From what I've seen the 1745 tubes have about parallel results. With the pseudo-taper and .50. cal. lead I get 9.13 fpe vs 9.88 with a full loop using 1745. The trade off is the tapered band pulls about 6# less and has a slightly softer release, obviously more enjoyable to shoot. The 1842 also has an easier pull, softer release, with less energy in the upper regions. I have more 1745 coming, and the new 1842 is waiting to be cleared by customs. After which I hope to do more testing. From what I've observed and reading between the lines the thin tubes are better adapted to lighter ammo. There is a thread originating in China stating that in China they use 8mm ball with 1745 tubes. My Chinese slingshots all came with about ½ dozen steel 8mm balls.

 

[pgandy]

Thanks Henry. What were your band lengths?

 

[pgandy]

Thanks again Henry. It seems like I am always thanking you, this time for the coming tutorial on optimizing and lengths. I like 1842 and will be using it for sometime to come, but in the full loop fashion. It looks like 1745 will edge it out for me in the long run and perhaps your tutorial will give a clue and save some hard to come by rubber. With the 1745 I definitely will be using your pseudo-taper. I get slightly more energy (it seems like I am an odd ball here as I look at energy and not velocity) with the full loop but not enough to add 5 ¾ pounds to the pull. I really thank you for that. And finally, several times I tried posting a table to this forum only to have the forum skew the columns in *.xlsx or *.docx. I will attempt *.png the next time. You have contributed a valuable tool to this community and I am sure this thread will be referred to many times in the years to come.

 

[pgandy]

I had a most delightful morning thanks to you Henry. I've pretty much shelved my PS and flat bands due to the way a Dankung carries and the longer band life of those small tubes, not to mention the bands are faster to make. I had settled for a full loop of 1842 for practice and general purpose. And a more powerful 1745 pseudo tapered band for carry while looking for something better, both using one tube per side. I have a factory 2040 band w/4 loops (aka 8 strands). It was the most powerful band I have but at 25+# of pull it caused the Dankung to bite uncomfortably into my hand. It took a while but I finally latched on to some 2040 rubber and using from your posts and my experienced I correctly reasoned that I could up the power of that 2040 commercial band while lowering the draw weight and using less rubber by using 4 loops (2 per side) of pseudo tapered 2040. Now that's got to be a winning combination in anybody's book, upping the power with less.

The first band set didn't quite hack it. I used the same dimensions that I had on the 1745 sets forgetting that I'd made them slightly longer ratio than 4/4/3 to increase the life when rubber was in short supply and never changed back. The second set I shortened to that ratio and the band set is all that I had hoped for.

It pulls at 19.5# at 31". With a 33" draw I am getting 12.0 fpe with .50 cal. lead. The ball averages 177.0 fps. I know by the standards of some out there this is not exceptional, but it's significantly better than I've been doing which is 10.2 fpe using the pseudo tapered 1745 at a pound less pull. I'm now pushing .38 lead at 233 fps. This is up from 212 fps. The fpe went from 7.6 to 9.1. The factory 2040 gave me 10.5 fpe with .50 cal. lead. However, at the time I was drawing 31" and am now up to 33". I'm having a ball watching the effects of the extra power. It's too soon to know about band life.

 

[pgandy]

Thanks for all of your work Henry. You certainly opened doors for me. For me, considering my strength, single full looped 1842 is the most enjoyable to shoot with the longest band life. I can get more shots in before fatigue sets in and I am happy with it. My favourite general carry band is 1745 tapered single band although I am beginning to use double 2040. I get more power than with the 1842, carries best in my pocket. And I consider it good for PT. At the moment it is my most used band, probably because I am trying to condition myself for 2040. I get the most power out of 2040 double bands, tapered. It carries well enough in my pocket and is what I carry away from the house these days. I was considering that combination with 1842 rubber although I have reservations. I think I’ve toped out with the 2040 double bands tapered but will have a go with the double 1842 when my new shipment arrives.

 

[pgandy]

I don't know your chrony nor type of lighting. However, the instructions that came with mine warned about fluorescent lighting.

When it comes to tapered tubes I also am getting better results with 1745 than 1842 with single bands. I can't go a double 1745, but double 2040 and double 1842 will exceed the single 1745 for those interested in more power. My best tubes equal about my best flats and have a longer life. I am now sold on tubes.

 

[pgandy]

Theroy is theory, which is good within limits. However in real life with my slingshot I find that I am probably the biggest variable, either with my shooting or in making a band set as has been proven with my chrony. Including the variables in shot to shot or band set to band set my chrony tells me that I obtain higher velocity with a pseudo taper than a full loop and my fish scale tells me, as does my arm, that the draw weight is less. I am more inclined to believe my instruments than what should or should not be happening.

 

[pgandy]

@Boby that explains why my pseudo tapered 2050 gave less performance than a full loop. I figured that I was on the back side of the curve and gave up testing early. 2050 is double the price of 1842 and 1745, and about 4x the 2040 and I wasn’t getting the expected results. I should point out that the factory full 2050 loop and the pseudo taper were from different manufacturers. The tests would have been more meaningful using the same lot. I have enough 2050 left to make a full loop and will go back and retest.

 

[pgandy]

Yeah, those tubes are quite cheap, from where I buy them, 10 metres are around 4USD.

Wow! can you share that site with us?
[/quote]
http://www.dankung.com/emart/index.php?main_page=advanced_search_result&search_in_description=1&keyword=20*40

 

[pgandy]

Wow! Did not know that. High shipping has always kept me from ordering. thanks for the info.

If you don't mind the longer delivery time, Dankung is, I believe the cheapest place to buy tubes. Truly Texas has great service and I have had good experience with them, but Dankung's delivered price is a lot cheaper and TT doesn't carry 2040.
[/quote]

The longer delivery time doesn't bother me either. I just move up the reorder point. The problem I found with Truly Texas two fold. One he misrepresents his policy saying that he will ship anywhere in the world. A quote "We ship anywhere in the world via USPS Priority Mail ". He refuses to ship to me directly saying he doesn't ship to Costa Rica. I have to have it sent to my US address and then forwarded, more time and money. Also he was posting a photo of the hemmed pouch but I kept receiving the unhemmed, cheaper pouches. So I switched to his supplier at a cheaper price, although since Dankung has increased their prices but it is still cheaper from me. My experiences with Dankung have always been polite, helpful, and courteous. I just move up my order point, no problem.

 

[pgandy]

I did some quick calculations. I couldn’t find the density of lead off hand so I used the fact there are 8 #00 buck/oz which is about 54.69 gr/ball. Using 325 fps as average that works out to be 12.8 fpe. The one shot at 350.9 fps had 14.9 fpe. I recently got serious with 1745 by using a double loop. I’ve used a single loop for some time and is my favourite for general shooting. The one double 1745 band that I’ve tested gave an average of 13.6 and 12.8 fpe during the two tests at different times. My pull length is 34”. I am still on that band set with 250 shoots testing for life before checking out variations with that tubing. I think the 1745 rubber will be the one that I’ll stick with as I can reduce my rubber inventory while obtaining good performance, and I am hoping for longer life. The double 1842 gives almost as much energy at a slightly less pull weight making it more comfortable. Since doing my PT I am pulling the double 1745 with no problem now and is becoming my favourite.

 

[pgandy]

As I said on the previous page theories are fine within limits. Bumble bees will testify to this, otherwise they would be grounded because theoretically they cannot. Your work would have more credibility if you published your test results, I am eager to see those results, rather than what theoretically should be happening, which is not in accordance with field findings of those reporting on such bands. As you Americans say, the proof is in the pudding.