Understanding Rollerguns Part 1 | Unrolling the Roller Speargun
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- เผยแพร่เมื่อ 2 ก.ค. 2024
- Unrolling the Spearfishing Rollergun Series by Chris Coates.
This spearfishing workshop episode covers the basics on what is a roller speargun & how spearguns work.
The Tutorial covers the science behind how a roller gun is powered compared to conventional spearguns. If you are into rollerguns or spearfishing this series is a must see.
#spearfishing #rollergun
0:00 Introduction
1:25 History of Rollerguns
2:00 What is a Rollergun?
3:45 Recoil and Rollerguns
5:00 Speargun Power Formula Explained
10:05 Potential Energy Formula
Here is the newest version of the Coatesman Double Roller:
coatesmans.com/shop/
Here are the articles originally published in the Ultimate Spearfishing Magazine:
spearguns.blogspot.com/2016/02...
spearguns.blogspot.com/2016/02... - กีฬา
Incredible info, thank you! I’ve used your original CDR on my 110 RA for blue water and set up as a single on the reef. It’s provided me with only great success for multiple years. 🙏🏼
I can't tell you how glad I am to see a proper explanation of standard vs. roller recoil in such an approachable way. In almost every argument I've gotten into about recoil between the two, you have one guy who thinks it's all about impulse, and another who thinks it's all about energy. Here you have a unified treatment in an intuitive way (without even getting into the recoil reduction from roller band return). I'm a bit late to the party but had to check it out after recently getting a roller after hearing you on NSP. Thank you for your contribution to the community.
Coatesman making rollers great again! The world needs this info!
Needed this vid everyone to busy wanting power I want it explained better b4 I buy and I'm loving this.
Amazing - I´ve been waiting for this! I have set up my Rob Allen 90cm roller based on your original article - the speed on the shaft and the lack of recoil is amazing! Looking forward to the next videos.
Love the use of the spear shaft as a straight edge haha. Great job explaining the concept of energy into the spear. Great vid!
Excellent explanation Chris. Thanks for making the video. Looking forward to the next one
Great post! Thank you for doing the work to make available to us!👍👍
Stoked
Very excited about this video series. Thanks Chris
I read and watched seven years ago how you did a rollergun test. The best and clearest explanation on the net, how to understand the functioning of roller gun! Thank you very much!
thanks chris glad your posting again
Wow! I love seeing the energy equivalence. Great explanation.
Good video! The thing many people don't realise is how great the losses are due to the rubbers going around the rollers as they contract. They don't contract as fast. I've been down the roller road and had quite a few different set ups. Came to the conclusion I like to go diving and not worry about things failing like bridles popping out of rubbers cos they're stretched to 400% to get any benefit over conventional gun. Also the bridle lifts the tail of shaft on release as rubbers go around rollers causing shot to go low.
Fish Hunter Thanks.
You are correct there is some energy loss going around the rollers. And the calculations I am using could in many cases have a 10% difference. However no matter which way you put it, a well set up roller giving the same (actual) penetration as a conventional gun. Will be shorter and have less recoil.
Your other issues are all solvable with right equipment and setup. I will be covering all of these.
@@CoatesmansSpearfishingI'll keep my eye out for the next video, you might persuade me to give rollers another go! Do you find bridles get frayed quickly?
Badly designed rollers cause that lifting on the notch which causes the wear on the bridle.
@@CoatesmansSpearfishing I haven't tried the rob Allen roller head and I notice it has a little Ridge on the ramp/stopper. Is this to slow the bridle down and let the spear exit without lifting tail? Very interesting and well designed head which I need to try.
@@fishhunter348 Yes the cut out was made to do exactly that. If you have a good shaft with no sharp edges on the notch your bridle should outlast your rubbers.
Nice one Chris! Excellent explanation
Great info. Excellent explanation. Easy to follow. Thanks.
Many thanks for the informative and thought provoking video Chris, really enjoyed it, made me have a good think about what we are doing. I'm looking forward to watching the rest of the series. I gave rollers a go a while back, but went back to my 3x 16mm 1100 due to it's versatility, range, hitting power and penetration. Recently I was thinking about revisiting rollers to see if things have improved with the multi roller heads, and if the accuracy had improved. Looking forward to watching the rest of the series. Great work, cheers for sharing the video, Dive safe!
Wow wow you convinced me sir with roller guns
thats soo good mate helps heaps
Good stuff makes perfect sense
Thanks heaps mate 👍🏻
WOOOOW!!! Thats some serious mind blowing roller geekery going on. Thought I was the only person thinking this deep about roller guns. Superb vid Chris, looking forward to the next ones. Can you also do a video on inverted rollers. pros & cons.. Ive been playing around with them. Very interesting when it comes to power vs recoil but man it takes a long time to reload... very frustrating. Any tips on setting up a RA as a inverted roller? ??
Thanks 😊 Will definitely have to bring up inverted rollers. Many pro's and con's
Hi Chris, great video and so glad you are starting this series. I would like to hear your opinion on the Fusion Rollers that seem to be popular in certain areas these days. Maybe you will cover this in your series. Also, I still have your White Paper on roller guns that I believe you posted in your Ultimate Spearfishing magazine. I learned everything I know from that article and have built several roller guns using the set-ups in that article.
Roland, thanks. I have only seen the Fusion guns online, but have not actually used one. From what I have seen they looked well put together.
Nice video. I was thinking I'd have to do these calculations for my inverted roller
What kind of inverted roller do you use? The one with pulleys? If so, the calculations would be not as straight forward as in this videos
thx Coatesman , amazing video and very useful knowleges, i think the main reason why roller has less recoil is that the reverse force occurred both at muzzle and the anchor or the rubbers , and they are at different directions , the backward force which generated at the anchor point absorbed most of the recoil
Hey Noah, yes there is a certain amount of inertia traveling backwards. But by spreading the energy out over the length of the gun, is by far the greatest reducer of recoil.
@@CoatesmansSpearfishing thx for your great knowledges !
Amazing video as usual, and really interesting, so I'm now applying you calculs to my spearguns. But I was wondering, if I want to apply this to an invert roller gun, is it working the same way ??
Cheers 🤙🏼 Keep up the good work !
for inverted rollers you work out each rubber , from rest to full load x the drive length and add them together. This only gives you an idea of the kg/cm energy as there is loss around pulleys, just like rollers and that needs to be factored in. Will have to do a vid on this
Chris, this was very useful - thank you! What is your go-to way of measuring kg load at fully loaded? I'd be curious to do this with my own guns (as well as friend's guns) and also track how the rubbers perform over time with usage.
I use a test bench with a digital scale and pulleys. I guess you could somehow attach a scale to the handle and load onto scale hook?? Bit of a dodgy idea tho, safer on the bench.
We would like to see the different sizes of sharft
Great series. You see a lot of guys today swearing by the classic setups with 2x 14mm small id bands stretched to 360%. It seems the comparison 130 you used in this video was a bit of an overpowered setup. How would it all shakeout if the classic setup was put up against the rollers? I see some guys swearing the classic setup will hold its own but wondered what you thought.
Hey Blue Dog Gum
Have a look at @RobAllenSpearfishing video where they compare the two
th-cam.com/video/FfnyQBAMdNY/w-d-xo.html
Maybe not the exact same setup but similar
Great and informative video. What about a comparison to a 1100 tuna RA with twin 16mm? With 350% band stretch and using your 37Kg per band load with a 78.6cm band stretch distance for a 110cm barrel i got 2,907...ie Rob allen tuna vs Rob Allen roller 1100? What do you think?
1100 with 57cm 16mm (386%) x 2 using the same rubber metrics is: 4797 kg/cm
This gun will have greater penetration than both the guns discussed in this video. But if you have used a roller for any amount of time, and then try use a std double rubber gun. It won't matter how strong it is, it's just horrible to shoot.
Hey Chris, I am not sure about the power into shaft calculation for the roller gun. Should the rectangular section of the graph be added to the total power imparted to the shaft? The energy is still stored in the rubber at rest is it not?
Hey Paul. Yes you add the total area below the line.
@@CoatesmansSpearfishing Hey Chris would you mind explaining why that is the case? What you have explained is the Potential Energy which I am understanding. I'm confused Like Paul on how much of the PE is converted to KE? With a standard set up you release all the PE and convert it to KE. With the roller that is not the case as you only release some of the PE which partly is why the recoil is much less than the standard set up. I'm thinking to understand fully what is happening here is you want to see the rate of acceleration the shaft is under and how even that is over the distance and what the velocity of the shaft is as it leaves the gun. By this I mean the shaft is being accelerated more evenly aka more force over the assigned distance of acceleration in the roller than the standard set up. Simply put, when the shaft leaves a roller muzzle it is still under force from the band and being accelerated. When the shaft leaves the muzzle of a standard set up it is not under force and acceleration. There are cameras that can capture this for you for fun and games :) Hope this helps
For larger fish at range, the extra mass of the longer spears help penetration though. Also, I believe there's a point where the shaft approaches the maximum speed that the rubber can recoil at, so that the extra pull length does not equate to much additional force.
Absolutely, mass is key. So with rollers go thicker and shorter so you can put more power.
@@CoatesmansSpearfishing I would love to see some side by side tests of rollers in a pool like madjq8 does.
Maybe we can set up a gofundme to send you to test guns with him when the COVID situation has normalised. th-cam.com/users/majdq8
This is something I have in the pipeline. Even contemplating building a long pool :-D
There’ seems to be a lot of emphasis on getting the most or optimum energy translated into launching the spear, but almost nothing on the hydrodynamic drag of the spear through the water. Has there been any research on the relationship of spear launch muzzle velocity and range for a given launch energy for different lengths, diameters and maybe materials of spear shaft? Maybe some refinements in shaft cross section profiles?
Hey Alan,
I have pool tested most different variations. The thickness definitely increases the drag. But this is sum what balanced out with the additional weight / inertia of the shaft. Shaft flexibility is also very important, especially with more powerful guns using 16mm etc. This why it is important to use high grade carbon steel shafts.
I talk a little about this in the 110 & 120 videos.
Penetration is something guys also miss. Like sliptips, they have a lot of drag going through a fish and require massive shafts with big guns to penetrate through the fish.
@@CoatesmansSpearfishing Thanks very much for this reply. It gives great insight into what works and what doesn’t, from your many years of experience. It brings back great memories of swimming in Durban, Natal way back my younger days! Has Rob Allen got an inverted roller conversion in the works to reduce drag of the bands squeezing around the rollers (through the holes) by using dyneema vs bands with eg 3 x 14mm short inverted bands underneath? This would improve the launch force, make more efficient use of the potential energy and make it much easier to load. 3 x 20kg vs 1x 60kg for 16mm bands?
I am going to love this and thank you for putting this out to us. I would like to see the different triangle of force (?) as compared to one short 20 mm band compared to two very short 14mm bands. They would stretch the length of the bottom vector (duration of shot or band pull?) further and also give maybe a large effective force of loading at end when added together. Just curious and with much respect. No one can doubt the results you get from the rollers and I love the rollergun I won for sure.
Not won- should say I own
2 x 14mm (3183 kg/cm) 73cm the same length provide more power with less recoil as the 1 x 20 x 73cm (3132 kg/cm)
And is easier to load. This was my go to before I found rollerguns.
Most tests I have used this gun as a yardstick to compare against.
could i rig a 120 RA roller with full pretension with 14 mm bands so i dont have to use a load assist? 7 mm shaft?what length of bands should i use?
You could go with a 70cm 14mm which will have 17kg on the muzzle. It will drive a 7mm shaft real smooth, but this is not a great setup as far as power goes.
Still confused. When comparing the two guns they are both compared with only one band. but the 140 conventional would be commonly used with two bands and would have substantial more load and more drive than the roller which would only have the capacity of the one band? Is this wrong ?
Jedidiah, you are right a 140 with 2 x 16mm bands would have way more power than a 110 single roller with a 14mm band.
I was not comparing power or the performance of the two guns. But rather illustrating the length of drive a roller has compared to a conventional gun.
A 120 single roller with 16mm bands and 7.5mm shaft would be a good gun to compare to the 140 conventional band gun.
@@CoatesmansSpearfishing ahhh I see thanks for the response !
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