10 replies to this topic

[Doom]

A few days ago I made a homemade turret that was intended for my Max Shot. My Max Shot needs some repairs, but this worked great. I do not have any detailed instructions because it was just a proof of concept. Making comprehensive instructions would have been difficult anyway because I made it up as I went along, and I changed my plans several times during the construction. I figure that posting something is better than not posting it.

This design features easy rotating barrels, indexing, and a good seal without lubrication or any sort of sealing material. I've found that the plastic on plastic seal is pretty good as is in this design. I can't say there is any loss in range because I did not test range. Blowing into the coupler seams to seal very well after I upgraded the spring to a fairly strong one. And as I said, that's without sealing material or lubrication.











There are only four barrels attached to this because I did not have enough material for more. The turret itself can have 8 barrels. Aluminum is good for this because it has an OD of 5/8 inches, is light, and has low friction. The holes I drilled in the acrylic sheet were 5/8 inch holes. The brass tube I stuck in with electrical tape, but it wouldn't be held in as solidly without the aluminum. Note that I didn't use any glue at all to keep the aluminum in. Glues simply were not necessary.

The acrylic that I used to make the parts that attach to the barrels is not the best material for that job. PVC would be best in my opinion because you can attach PVC fittings to it very easily and it is much easier to machine. The dark gray plastic used is PVC sheet. I only had about as much as I used, so the acrylic was used for the remainder. If you want to use PVC barrels, I would suggest PVC because it would be very easy to attach a coupler or half a coupler to a PVC sheet.

You don't get a very good view of the indexing mechanism with the barrels in the way, so below is a picture of it.



I used a circular screw head to index the turret. This works great. The head is smaller than 1/2 inches in diameter so I didn't have to be too precise in my measurements. The barrels can be moved a bit when locked in place, but not enough to affect flow.

I'd write more, but my brain's fried right now. Wednesday is my busy day at college. I attend University of Maryland and I made this because I wanted to attend a Nerf war or two in the spring by the Nerf club, but since my Max Shot doesn't seem reliable enough, I'll probably build a quick spring gun and attach this to it. Once I buy some more aluminum, this plus a good spring gun should be a dangerous combination.

Feel free to ask any questions you have about this or its construction. I might edit in some more later too.

Edited by Doom, 30 January 2008 - 09:39 PM.

[Dayko]

This is a pretty good idea. I'm gonna try this some time. How strong is that spring?

[CaptainSlug]

Almost makes me want to refine mine. Almost...

I too am using a plastic-on-plastic seal, which is okay.

Edited by CaptainSlug, 31 January 2008 - 12:45 AM.

[slowguitarman]

Almost makes me want to refine mine. Almost...

I too am using a plastic-on-plastic seal, which is okay.

That is one of the most beautiful turrets I have ever seen. Awesome job, to both of you guys.

[Doom]

This is a pretty good idea. I'm gonna try this some time. How strong is that spring?

I actually have no idea how strong the spring is. Again, this was just a proof of concept. The spring constant is probably 20 to 25 pounds of force per inch, but that's just a guess going by what my fingers tell me. The spring I used is very stiff.

Almost makes me want to refine mine. Almost...

Wow! I hadn't seen that before. That's very similar to mine, but I guess there isn't any better way to hold the barrels on.

What are you doing for your indexing mechanism? I just read some posts in your +bow thread and I couldn't figure it out completely.

I'd suggest a heavier spring because that made all the difference in improving seal. That's especially true in spring guns because the plunger stopping makes the gun buck forward. I didn't get anything reasonable from my Max Shot until I used the spring in the photos above.

Another thing I would suggest would be flipping the turret upside down. This might seem pointless at first, but you want the weight of the barrels to help the seal more than help break the seal. Putting the coupler on the bottom will reduce the area that is not in contact with whatever sealing face you are using due to the weight of the barrels. I tested mine with the coupler on bottom.

Though, that problem is not noticeable with the heavier spring. I only saw it on my lighter springs.

Edited by Doom, 31 January 2008 - 10:06 AM.

[CaptainSlug]

I had contemplated doing so, but didn't use a spring on mine in the prototype form. The seal was decent On average the 10-inch barrel turret shot only 10-15 feet shorter than the 12-inch barrel slide breech. I preferred the slide breech because it weighed less and was easier to reload.

And the indexing mechanism is a spring-loaded tooth on a ratchet track.

To refine it I would probably want to replace the ratchet tooth system with just a spring plunger (to reduce space, weight, and complexity), try to add an o-ring seal inbetween the turret and the muzzle piece, and resize the frame pieces and diameter to make back-loading of the darts easier.

Edit: And here's the new design. Will accept 8, 6, 4, or 3 barrel turrets.

Edited by CaptainSlug, 31 January 2008 - 03:06 PM.

[Carbon]

Another thing I would suggest would be flipping the turret upside down. This might seem pointless at first, but you want the weight of the barrels to help the seal more than help break the seal. Putting the coupler on the bottom will reduce the area that is not in contact with whatever sealing face you are using due to the weight of the barrels. I tested mine with the coupler on bottom.

I hadn’t thought about rotating the turret up from a leverage/seal standpoint…that’s a good idea. I’ll have to try that on my turret and see if it works any better.

Your indexing system is nice and simple. Do you have problems with it catching on the edge of the head and binding a little, or is it pretty smooth?

[ice]

nice job, must have taken a while
have u ever made a homemade? cause if not, i think you should try.
if you can build that, you could probobly make a sick homemade.

[Doom]

I had contemplated doing so, but didn't use a spring on mine in the prototype form. The seal was decent On average the 10-inch barrel turret shot only 10-15 feet shorter than the 12-inch barrel slide breech. I preferred the slide breech because it weighed less and was easier to reload.

And the indexing mechanism is a spring-loaded tooth on a ratchet track.

To refine it I would probably want to replace the ratchet tooth system with just a spring plunger (to reduce space, weight, and complexity), try to add an o-ring seal inbetween the turret and the muzzle piece, and resize the frame pieces and diameter to make back-loading of the darts easier.

Perhaps your design wasn't as similar as I initially thought. The spring helps the seal, so you should see some improvements by adding one.

Could you explain what you mean by a spring plunger? Is that like what I did? The terminology is confusing me.

I hadn’t thought about rotating the turret up from a leverage/seal standpoint…that’s a good idea. I’ll have to try that on my turret and see if it works any better.

Your indexing system is nice and simple. Do you have problems with it catching on the edge of the head and binding a little, or is it pretty smooth?

The only reason I noticed this was because the first spring I used was pathetic. I didn't know how strong was too strong, so I used a spring I took from a dollar store dart gun. Even with only one barrel, the angle was noticeable off. I realized if I changed the orientation it would fix a lot of the problem. And after changing the spring to a stronger one, the problem was completely solved.

Again, to reiterate, with a strong spring it's not much of a problem. I don't think there's any disadvantages to placing the coupler on the bottom though, so that is my suggestion.

For your turret, upgrading to a stronger sealing spring would help more than changing the orientation. That would be even better for your design because your indexing mechanism doesn't get any harder as the seal spring does.

As for the indexing system, the way I had the screw oriented in the picture did catch sometimes. Changing the angle fixed that. Right now it's smooth, but stiffer to turn than most other Nerf turrets because of the spring. Nonetheless, I can rotate the barrels rather quickly, which was all that I was hoping for.

One thing that is not obvious from the photo is that there is a small indentation for the screw head to fit into. The screw head itself had a flat portion on the side that interfered with turning, so I drilled in half a millimeter.

nice job, must have taken a while
have u ever made a homemade? cause if not, i think you should try.
if you can build that, you could probobly make a sick homemade.

From conception to fabrication was probably less than three days between packing for college and other things. It didn't take me long at all. What took the longest was drilling the two acrylic sheets in alignment. That probably took a half hour because I did it slow. My drill press is relatively weak.

I've built several homemades. Check out some of my earlier posts here and my website. I've built spudguns, Nerf guns, water guns, and water balloon launchers. In the Nerf world I've just gone relatively unnoticed despite how long I've been here.

If you like what I do I'll post when I complete my next gun. As I might have said earlier, I'm interested in making my own take on a spring gun. I also have another project at home that I stopped doing when I went to college. It's an air pressure gun with a semi-auto valve. Normally I'd post photos of it, but I seem to have lose the ones of the construction so far.

As a side note, is there any way to change your username on this board? I haven't used the Doom handle in a long time and I am not too fond of it any longe

Edited by Doom, 31 January 2008 - 02:45 PM.

[CaptainSlug]

A spring plunger is like a set screw but it has a spring loaded ball or rounded rod on the end. They're used for tensioning or indexing.

[Doom]

That's a useful part. I can see it's application here immediately. I'd like to upgrade my design with that, though, it might be really be worthwhile. Thanks for posting it.

Edit: Now that I think about it, the spring plungers with handles might make good catch mechanisms. I'll investigate that.

Edited by Doom, 31 January 2008 - 03:27 PM.