Home Tournaments Calendar Weather Merchandise Sponsors

Go Back   Spearboard.com - The World's Largest Spearfishing Diving Boating Social Media Forum > Spearfishing Gear > All About Guns

All About Guns What's your weapon of choice, and why? Discuss the beloved speargun here!

Reply
 
Thread Tools Rate Thread Display Modes
Old 09-16-2019, 07:26 PM   #1
musubi
Registered User
 
Join Date: Jan 2017
Location: Big Island
Posts: 72
My Invert Roller

Hey Everyone,

I thought I'd share my invert roller gun that I put together almost a year ago.
It's been the most accurate gun I've had so far. The following are the specs on it:

- MVD Handle
- Invert Roller G3 Muzzle, with Inox bearings
- Ronstan Block Pulleys (the MVD pulleys didn't give me confidence in holding)
- Nautilus Carbon barrel (110 cm)
- 3 pairs of 9" 14mm (small I.D.) bands
- 7.5 mm, euro, wire fin, Rob Allen shaft

I'm all about accuracy with my guns and I'm very picky about its function over anything else. With that said, it can be a pain to load compared to my other classic style band setups. Things get tangled more easily and everything needs to wrap just so.

When I first built it I was encountering problems with my shooting line tangling with the 6 bottom bands. MVD's videos show the shoot line running between the pairs of bands and it was tangling with that configuration. Also, the shaft didn't slide into the mechanism nicely. The shaft butt was coming in too high to the mechanism and so I needed to raise the shaft front up a bit to get it in. Both of these issues were causing shot inconsistencies and it was frustrating me.

Discouraged, I gave up on the gun for months, but then decided to give it another try and resolve the issues. To resolve, I added a SS line wrap/anchor at the side of the barrel, near the muzzle. Second, the shimmed the handle higher to allow the shaft to slide right in with no fuss.

I target shot the gun at about 15' from the muzzle and I was able to hit center in a repeatable fashion.

I've been using this gun the past few months and I'm VERY happy with the accuracy. The gun also has extremely low recoil and an amazing line of sight, since no bands in the way. This has become my Mu gun.

With the 9" bands all loaded, the gun is powerful. If I recall correctly, I measured the pull of one band pair at 50 lbs. So for 3 bands, 150 lbs. My 110 KAP speargun, two bands, also measured at 150 lbs with two bands pulled back, except the invert has the longer throw (which we know).

The modifications I've had to make resolved two issues, but also created other minor ones in the process. If you scrutinize what I've done in the pictures below (at the muzzle), it's odd, and it makes loading a bit more difficult and, at times, causes my roller line to be pushed off the roller when first pulling back. So I have to be careful.

I'm planning to grind off the plastic line guide/wrap on the muzzle and replace with a more standard SS line guide/anchor. The plastic one is fraying my line and a little too far forward, near the muzzle.

Aside from this gun, I'm still planning on building a wooden gun, but this gun is really making me think about building an invert roller style wooden gun.

Question, why do some invert roller guns also have a single classic band on top? Does it give the shaft more initial velocity?











Last edited by musubi; 10-02-2019 at 02:51 PM.
musubi is online now   Reply With Quote
Old 09-16-2019, 08:24 PM   #2
popgun pete
Registered User
 
popgun pete's Avatar
 
Join Date: Mar 2006
Posts: 3,127
Re: My Invert Roller

The "helper" band on top seems to unstick the roller system, the rollers need to turn and cables can take a temporary set under tension from the cocked bands. The gun will shoot without it, but with a conventional band there is no delay and it just jerks forwards when you pull the trigger.
popgun pete is offline   Reply With Quote
Old 09-16-2019, 08:59 PM   #3
musubi
Registered User
 
Join Date: Jan 2017
Location: Big Island
Posts: 72
Re: My Invert Roller

Quote:
Originally Posted by popgun pete View Post
The "helper" band on top seems to unstick the roller system, the rollers need to turn and cables can take a temporary set under tension from the cocked bands. The gun will shoot without it, but with a conventional band there is no delay and it just jerks forwards when you pull the trigger.
Thanks popgun pete. I think I know what you mean, but let me give it go. The current setup with just the invert bands creates more of a push rather than a snap. The helper band is intended to help the roller system along to get going.
Did I describe that right?

So my original thoughts on a helper band is that it would create more recoil to the system and not provide that clean line of sight. Would that be true? Also, how powerful (% stretch) do people typically make this helper band? Similar to a single band setup?

I realize I'm not going to be able to add a single helper band to my carbon gun, but I'm just curious since a helper band may make more sense on a wooden gun with more mass. Plus, I'm reluctant to mess with a helper on this gun since it shoots well for me.
musubi is online now   Reply With Quote
Old 09-16-2019, 10:10 PM   #4
popgun pete
Registered User
 
popgun pete's Avatar
 
Join Date: Mar 2006
Posts: 3,127
Re: My Invert Roller

Quote:
Originally Posted by musubi View Post
Thanks popgun pete. I think I know what you mean, but let me give it go. The current setup with just the invert bands creates more of a push rather than a snap. The helper band is intended to help the roller system along to get going.
Did I describe that right?

So my original thoughts on a helper band is that it would create more recoil to the system and not provide that clean line of sight. Would that be true? Also, how powerful (% stretch) do people typically make this helper band? Similar to a single band setup?

I realize I'm not going to be able to add a single helper band to my carbon gun, but I'm just curious since a helper band may make more sense on a wooden gun with more mass. Plus, I'm reluctant to mess with a helper on this gun since it shoots well for me.
Yes, that is right. The helper bands are not that long, so their contribution to recoil would be very little. If you look at an Alemmani that is swarming with bands the helper band does not even reach to the muzzle. The helper band is band group 5 on the diagram.
Attached Thumbnails
Click image for larger version

Name:	Band groups.jpg
Views:	72
Size:	73.4 KB
ID:	244034  
popgun pete is offline   Reply With Quote
Old 09-17-2019, 12:26 AM   #5
Diving Gecko
Shooter & Shooter
 
Join Date: Nov 2014
Posts: 822
Re: My Invert Roller

Cool build and great to hear that the perseverance paid off.
No disrespect, but if you need a tad more power it seems you can gain an inch or more of band pull by shortening the connections at the Ronstan blocks. Might not be so easy to change bands after that though - I think you may have some loop now to easily get the bands on and off the blocks if needed?

As for the band on the top, perhaps drop Neven (gspearguns) a line in one of his posts or PM him as his Gladiator spearguns have had a booster band for a long time now. Would be good to hear his thoughts.
I think he tends to use 16-17.5mm on the bottom band and a 14mm (small ID?) on the top. Your MVD handle actually does what Neven does on some of his guns - moving the reel to the trigger guard to be able to put the attachment points for the bands a bit further back than if the reel was mounted on the stock in front of the trigger guard.

The Gladiator band setup seems to be what Carbonia has adopted, too though they have dropped the riser at the front and use a stopper knot system a la Roisub (or your muzzle) and their solution to increasing band stretch on the bottom is to put the reel on a bracket:
Attached Thumbnails
Click image for larger version

Name:	59622460_2065954476864203_1954590679552229376_n.jpg
Views:	67
Size:	60.7 KB
ID:	244039  

Last edited by Diving Gecko; 09-17-2019 at 01:46 AM.
Diving Gecko is offline   Reply With Quote
Old 09-17-2019, 12:41 PM   #6
musubi
Registered User
 
Join Date: Jan 2017
Location: Big Island
Posts: 72
Re: My Invert Roller

Quote:
Originally Posted by popgun pete View Post
Yes, that is right. The helper bands are not that long, so their contribution to recoil would be very little. If you look at an Alemmani that is swarming with bands the helper band does not even reach to the muzzle. The helper band is band group 5 on the diagram.
Thanks popgun pete for the confirmation and the picture diagram. You're right that the helper band isn't at the muzzle like I see traditionally.

Quote:
Originally Posted by Diving Gecko View Post
Cool build and great to hear that the perseverance paid off.
No disrespect, but if you need a tad more power it seems you can gain an inch or more of band pull by shortening the connections at the Ronstan blocks. Might not be so easy to change bands after that though - I think you may have some loop now to easily get the bands on and off the blocks if needed?

As for the band on the top, perhaps drop Neven (gspearguns) a line in one of his posts or PM him as his Gladiator spearguns have had a booster band for a long time now. Would be good to hear his thoughts.
I think he tends to use 16-17.5mm on the bottom band and a 14mm (small ID?) on the top. Your MVD handle actually does what Neven does on some of his guns - moving the reel to the trigger guard to be able to put the attachment points for the bands a bit further back than if the reel was mounted on the stock in front of the trigger guard.

The Gladiator band setup seems to be what Carbonia has adopted, too though they have dropped the riser at the front and use a stopper knot system a la Roisub (or your muzzle) and their solution to increasing band stretch on the bottom is to put the reel on a bracket:
Thanks Diving Gecko for your advice. I'm definitely open to critique and I know there's room for improvement all around. You're right though, I can shorten the connections at the ronstan blocks. I could actually shorten the green line all over. When I load the gun, the pulleys are still about 4 to 5 inches away from the muzzle, so I do have room to increase power. And I'm also learning what pain it is to remove bands (when I do need to) since my bands are typically under tension. They stretched a bit from my last dive.

I'm thinking I could actually add a helper band. I could just increase the hole size a bit at the muzzle where the green line runs through. I would have to see how cumbersome it would be to load it for me. If I didn't like it, it would be easily removable.

I'd love to add more power as long as I could control it and my accuracy remained. Sometimes I feel like the fish I shoot at have that split second more to react or turn away with my invert gun vs my classic 2 band setup. I end up hitting the fish, but not in the angle I shot them at. Happens sometimes. Ultimately, if I add a helper band, I'm going to want to target practice again. Wish I had access to a pool.

Thanks for the connection. I'll see if I can get Neven's thoughts as well.
musubi is online now   Reply With Quote
Old 09-17-2019, 01:25 PM   #7
Diving Gecko
Shooter & Shooter
 
Join Date: Nov 2014
Posts: 822
Re: My Invert Roller

I hear you on the pool access.. I tinker more than I dive, being landlocked and all but but would be great to have a pool.

I'd def start by shortening your connections where ever you can and then checking if you have enough power for your needs. I know you spent money on the Ronstans already and it's nice they are plastic so they wont scratch the barrel, but I was wondering if there's an easier way to shorten the connections by switching to Harken Micro blocks with the pin? Then you could just use a small loop in the rubber and put the pin through each loop "mini wishbone" of the rubber? I have probably seen pics of this somewhere as Harken Micros have def been used on rollers by others.

Last edited by Diving Gecko; 09-17-2019 at 01:44 PM.
Diving Gecko is offline   Reply With Quote
Old 09-17-2019, 02:16 PM   #8
popgun pete
Registered User
 
popgun pete's Avatar
 
Join Date: Mar 2006
Posts: 3,127
Re: My Invert Roller

You can have cords at either end of a helper band to shorten the band, the rear is the usual wishbone and the front ties to your muzzle as the band anchor. From memory the Alemanni had that extra band as optional on the Vela 135 Special which is the gun shown in the diagram. It may now be included as the diagram was done a year or so back for another thread.
https://www.alemanni-sub.com/en/prod...la-120-special
popgun pete is offline   Reply With Quote
Old 09-17-2019, 02:29 PM   #9
Behslayer
Registered User
 
Behslayer's Avatar
 
Join Date: Aug 2008
Location: Big Island
Posts: 4,970
Re: My Invert Roller

Musubi, maybe try 1-2 thicker bands on bottom. 14mm are pretty thin, even 14.5mm have more Schnapp to them. 15mm more. 16mm more..You should be able to get away without a kicker band with a 7.5mm Shaft.

Another thing I would fuddle around with is using a Roi type partial band on top. This will allow you to grab bad to load on top and maybe that band section is set to a certain elongation with a string inside or not, but I think that little section of band stretches and may function to give that little bit of a boost you are looking for.

Any big Mus?
Behslayer is offline   Reply With Quote
Old 09-17-2019, 06:33 PM   #10
musubi
Registered User
 
Join Date: Jan 2017
Location: Big Island
Posts: 72
Re: My Invert Roller

Quote:
Originally Posted by Diving Gecko View Post
I hear you on the pool access.. I tinker more than I dive, being landlocked and all but but would be great to have a pool.

I'd def start by shortening your connections where ever you can and then checking if you have enough power for your needs. I know you spent money on the Ronstans already and it's nice they are plastic so they wont scratch the barrel, but I was wondering if there's an easier way to shorten the connections by switching to Harken Micro blocks with the pin? Then you could just use a small loop in the rubber and put the pin through each loop "mini wishbone" of the rubber? I have probably seen pics of this somewhere as Harken Micros have def been used on rollers by others.
That's a good idea on going to a block with a pin. I looked up the Harken Micro series and seems like they have good options there. I don't mind the scratching of the barrel. You think the mass difference between the plastic blocks vs the steel blocks make much of a difference in shooting?

Quote:
Originally Posted by popgun pete View Post
You can have cords at either end of a helper band to shorten the band, the rear is the usual wishbone and the front ties to your muzzle as the band anchor. From memory the Alemanni had that extra band as optional on the Vela 135 Special which is the gun shown in the diagram. It may now be included as the diagram was done a year or so back for another thread.
https://www.alemanni-sub.com/en/prod...la-120-special
Thanks for the Alemani example. I'll probably look into adding something like that should I decide to build the wooden invert. Is the reason the band anchor is further away from the muzzle because more band stretch would cause more recoil? Out of curiosity, on the Vela 135, what is that silver metal tube that the shaft is going through at the muzzle?

Quote:
Originally Posted by Behslayer View Post
Musubi, maybe try 1-2 thicker bands on bottom. 14mm are pretty thin, even 14.5mm have more Schnapp to them. 15mm more. 16mm more..You should be able to get away without a kicker band with a 7.5mm Shaft.

Another thing I would fuddle around with is using a Roi type partial band on top. This will allow you to grab bad to load on top and maybe that band section is set to a certain elongation with a string inside or not, but I think that little section of band stretches and may function to give that little bit of a boost you are looking for.

Any big Mus?
It's good to hear your thoughts on this since I'm otherwise not sure what the 7.5 mm can take. I'll try and give a larger band size a go and target shoot with that. Like you said, that may give more oomph by itself without a kicker.

I always thought the Roi type band setup was interesting. For use with rollers, am I thinking about it right that I would be losing some length of a power stroke with the connected bands on top?

I've been getting some Mu's. Nothing too huge. That's my fiance's favorite fish, so I make sure she has some available. Personally, I love eating the goats. Although, hunting Mu's is much more exciting.


musubi is online now   Reply With Quote
Old 09-18-2019, 01:26 AM   #11
popgun pete
Registered User
 
popgun pete's Avatar
 
Join Date: Mar 2006
Posts: 3,127
Re: My Invert Roller

Quote:
Originally Posted by musubi View Post
Thanks for the Alemani example. I'll probably look into adding something like that should I decide to build the wooden invert. Is the reason the band anchor is further away from the muzzle because more band stretch would cause more recoil? Out of curiosity, on the Vela 135, what is that silver metal tube that the shaft is going through at the muzzle?
The helper or kicker band does not need to apply power anywhere else but at the launch of the shaft, so it is short and does not need to pull for any distance along the gun. The Vela 135 already has more than enough bands to blast the shaft from the gun, but unlike muzzle rollers I doubt that there are roller bearings in the shackles to the band battery, so you get some stiction. (the friction which tends to prevent stationary surfaces from being set in motion.)
Actually there are no decent photos of the shackle pulleys or rollers besides this one now added.

Nice catch, always good having fresh fish to eat.

The silver tube is slotted on top and is the wishbone arrestor that lifts the wishbone off the shaft tab as otherwise it might hang onto the tab and pull up the shot slightly.
Attached Thumbnails
Click image for larger version

Name:	Travel Pro Vela 120 muzzle.jpg
Views:	31
Size:	31.4 KB
ID:	244042   Click image for larger version

Name:	Vela 135 Special band  battery.jpg
Views:	38
Size:	17.5 KB
ID:	244043  

Last edited by popgun pete; 09-18-2019 at 01:44 AM.
popgun pete is offline   Reply With Quote
Old 09-18-2019, 03:35 AM   #12
Diving Gecko
Shooter & Shooter
 
Join Date: Nov 2014
Posts: 822
Re: My Invert Roller

Hey Musubi,
Sorry, I was mistaken - if you wanna try the Harken option with a pin, you don't want the Micro series, you want the even smaller '16mm' series.
(I used to race sailboats and just looking at Neven's pics I always thought it was a Micro block, but nope).

This is the smallest Harken with a pin:
https://www.harken.com/productdetail...4395&taxid=410
The specs say it weighs in at 11g.
If I am not mistaken, you now have the RF25019 block, which Ronstan says weighs in at 9g, so a 2g difference. Probably nothing to sweat over.

I downloaded tech drawings for both and dropped them into a CAD program to give you a bit of a size comparison. The measurement is in mm:




I hope Neven doesn't mind I share a few of his pic of how sleek it can be done with these blocks (If one was to make his own block you could eek out a few mms more, haha). I think the reason, he and others use a spacer bar is to have no friction between the bands. But for your use, leave out the plate and just imagine your dyneema loops going around the pin:


Last edited by Diving Gecko; 09-18-2019 at 03:44 AM.
Diving Gecko is offline   Reply With Quote
Old 09-18-2019, 05:37 AM   #13
spearq8
Registered User
 
spearq8's Avatar
 
Join Date: May 2009
Posts: 3,096
Re: My Invert Roller

Someone needs to design a pulley specifically made for invert roller spearguns.
spearq8 is offline   Reply With Quote
Old 09-18-2019, 06:11 AM   #14
Diving Gecko
Shooter & Shooter
 
Join Date: Nov 2014
Posts: 822
Re: My Invert Roller

Quote:
Originally Posted by spearq8 View Post
Someone needs to design a pulley specifically made for invert roller spearguns.


Yep. I agree;-). Been thinking about a spacer with built-in pulleys and wishbone inserts. There’s about an inch more band stretch to be found on the pulley and connection over the Harken solution.
That said, someone already has done the plate with pulley wheels but not the inserts (again, it is one of Neven's beautiful Gladiator guns, but not sure where the hardware is from):


Having inserts - as you have pointed out before - would stop water getting into the bands which none of the pulley setups are doing yet.
The inserts could be pinned in place on the plate or screwed in. So, changing bands would still be easy if the replacement bands had the insert already in them. Even if the inserts are permanently attached to the plate, changing a band would still be as easy as just tying one constrictor knot.

Ah, that plate is an Ermessub product but Neven customized it with some centering plates in CF and larger pulleys.


Sent from my iPhone using Tapatalk

Last edited by Diving Gecko; 09-18-2019 at 09:04 AM.
Diving Gecko is offline   Reply With Quote
Old 09-18-2019, 07:22 AM   #15
Diving Gecko
Shooter & Shooter
 
Join Date: Nov 2014
Posts: 822
Re: My Invert Roller

Musubi,
Finally found a pic of what it was I was trying to describe all along, haha. No surprise, but Neven did it ages ago


Notice the lack of spacer plate - I think he started doing that later on. I suspect to not have the bands touch each other at all. But on a pipe gun you may just have to live with that. And then if you build a woodie, you can take it into consideration.

No disrespect to Neven at all, as he is one of the most amazing builders, but in case he is dropping by on this thread, I am just wondering how come the pulleys don't go all the way to the front in the loaded position?
Diving Gecko is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 02:02 PM.


The World's Largest Spearfishing Diving Social Media Forum Powered by vBulletin® Version 3.8.1
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Copyright ©2002 - 2014 Spearboard.com