25 replies to this topic

[KaneTheMediocre]

All the images in this writeup are broken. See this updated HAMP thread for more useful instructions.


HAMP (High Airflow Manual Plunger)

This is my first writeup, so be nice.

This propulsion system uses two nested tubes (I usually use 1.5” and 2” PVC) of no particular size, duct tape, cardboard, and yarn to produce a large low pressure blast of air. With long ( 3’ ish) airgun-fit barrel material it vacuum loads and fires well, regardless of how many darts you put in the barrel. I've been making them for about a year and a half, found the internet nerf community about 6 months ago, and feel its about time I did a writeup. I did a dick-waving video earlier that features some HAMP guns here:



And I built/played with a ridiculously oversize HAMP with at Ryan McNumbers mod party, documented here:

http://www.youtube.com/watch?v=UDvJS4ECyjw

And here's a pic of most of my HAMPS in a pile:



And a writeup on a couple blasters that use the HAMP:

http://nerfhaven.com...31

Materials:
2” PVC (~18 in)
1.5” PVC (~18 in)
Yarn (fluffy is good)
Duct tape
Cardboard
Glue (optional)

1. Cut the 2” PVC to length X+2, where X = stroke. I use about 12” normally.
2. Cut the 1.5” PVC to length X+4”, or X + whatever amount of PVC you want to use as a handle, or attach a handle/linkage.



3. Cap the 2” PVC however you want, but a cardboard cover/duct tape cover (See #5) will be easier to work with later than the regular endcap if you want to maximize stroke/minimize deadspace.

4. Cap the 1.5” PVC with something that easily clears the entrance to the 2” PVC. Standard endcaps will not work, so I recommend the cardboard/duct tape cover (See #5).

5. Duct Tape / Cardboard End Caps:
a. Cut out a circle of cardboard for both the inner and outer diameter of the tube you want to seal. Go slightly undersize for the inner. (Exact size could work if you are perfect in 5b.

b. Attach the inner (small) circle close to the center of the outer (large) circle. Glue is good here, since you don’t want to affect the diameter of the circle by taping over it. But, you CAN just use a mini-loop of duct tape.

c. Put the cardboard on the end of the tube. If you have a voluminous glue, like elmers, wood glue, or gorilla glue, its very handy here--Put it on the inside corner between the small and large circle, and you won’t have to worry about seal in 5d and 5e. The glue isn’t for strength.

d. Put thin (<1/2”) strips of duct tape tightly over the cap. If you did not use glue in 5c, you need to get something close to a seal here—Do this by going in a spiral, with each strip overlapping the previous, until have covered the endcap (180 degrees).


e. To complete the seal, and keep the end cap from peeling off, place a final strip of duct tape around the perimeter of the endcap / PVC interface, on top of the existing strips of duct tape. Thicker strips of duct tape will make it stronger, but I’ve done fine with ½”. Make sure that this tape extends slightly past the end of the cylinder. More winds adds strength, but if this is a inner/plunger cylinder, you probably only have room for a couple turns.

f. Cut and remove the duct taps strip ends sticking out past the ring of duct tape. A steak knife works extremely well for this, and other cardboard/duct tape/mixed material cutting jobs. I recommend keeping one in your crafting arsenal, since you don’t want to switch between using the knife for duct tap and using the knife for steak.

Edited by KaneTheMediocre, 09 February 2015 - 11:58 PM.

[KaneTheMediocre]

6. Squishy Slippery Seal: There are a many ways to do this. I started by taping down a strip of foam around the end of the tube, where the tape would be on each side of the foam, tight enough to compress it to a smaller diameter than the foam between the tape. Later I used old socks by cutting rings out of the ankle, and using them like the foam strip. Later simply stretched a sock over the end of the plunger (high friction), and even used shamwow fabric at one point. My current kick is the yarn spiral, which I think is best because it is easy and adjustable.
a. Tape down one end of the yarn, at the end of the 1.5” PVC. Wind a few layers of duct tape to make a retaining ring for the yarn.


b. Wind the yarn around the tube in a spiral-More winds and more distance covered by the yarn will result in a better seal, but they reduce the available stroke, because you don’t want the plunger partly out of the tube (see 7).

c. Tape the other end down, and make a few winds of tape for a retaining ring.


7. When you wind the yarn, you can make tighter winds for a more rigid, smaller OD, and lower stiction seal—But, with tighter winds, there is less “squishiness”, and thus less room for error on the outer diameter. For a larger OD, you can make a few winds of tape beneath the whole yarn assembly,

or you can wind more loosely. Neither good seal nor particularly low friction are required for this to work, but improving these will be beneficial. Using duct tape beneath the yarn becomes absolutely necessary when you have a wide gap to fill between the inner and outer tubes of the HAMP, as illustrated here:



You can't see it in these pics, but there are actually 2 yarn/duct tape seals, spaced about 3" apart, to help keep inner and outer tubes of the MegaHamp coaxial. In order to get the seal/slip that you want, you may have to tighten/loosen the yarn after you've put it together--fortunately, this only requires undoing the last strip of duct tape on the plunger. However, if you decide you want more duct tape beneath the yarn, you pretty much have to start over.

8. HAMP systems work well with long, loose fitting barrels. With tagger darts, which have been my primary ammo for these, I have had the best luck with ½” EMT steel electrical conduit, which was $1.35 / 10 feet at home depot. ½” PVC will also work, and in fact gets slightly better range, but it occasionally jams. In general, any material used as an “air gun” fit will work well--the EMT, despite a 5/8" OD, will fire streamlines from a HAMP, albeit poorly. So yeah, loose dart fit is good.


Questions are welcome, even stupid questions. Which is not to say I won't mock you if you ask a stupid question, but I welcome the opportunity nonetheless. Any details you feel are missing may help me improve this writeup.

[Ryan201821]

Good lawd, It's Kane, yo. I'm guessing you remembered your password?

Anyway, these things are seriously awesome.



We (mostly Kane) built this HAMP a few weeks ago in the cancer shack. It's incredible how much air this system puts out. Most of the modifications and stuff I do involve, relatively low volume, high pressure. This is way cooler. With mad airflow you don't need perfect seal by any means. Plus they don't need a trigger to fire.

But seriously, you need to post a picture of the dual action mega-super HAMP. Now that is a scary weapon.

Edited by Ryan201821, 25 February 2010 - 02:32 AM.

[durka durka]

I like this a lot. It's something simple that can be built with a few lenghs of pvc and duct tape.

The last gun in the video was simply awesome. Is there any chance of a writeup for that?

[bourbon]

Wow, now what I would like to know is if it's possible to make one for a ball gun. Homemade Reactor anyone?

And Ryan if you think this is cool, you need to get your hands on an Expand A Blast.

[Ryan201821]

Wow, now what I would like to know is if it's possible to make one for a ball gun. Homemade Reactor anyone?

And Ryan if you think this is cool, you need to get your hands on an Expand A Blast.

This is definitely capable of launching a ball pretty far, or at least better than most ball guns. I'm going to build my version tomorrow and I'll test it out with a ball barrel attachment on it.

EaBs have maybe 1/10th of the volume as the Mega HAMP we built. Look at the picture I posted. There is at least three feet of 1/2" PVC that is just dead space. And it still penetrates cardboard. Fuck EaBs. They are insignificant compared to the volume this puts out.

The last gun in the video was simply awesome. Is there any chance of a writeup for that?

Yo, this is the write-up.

[Draconis]

Wow, now what I would like to know is if it's possible to make one for a ball gun. Homemade Reactor anyone?

Yeah, except that the reactor is pretty much the WORST design of ballgun. It's only advantage is small size, due to the reverse plunger design.

[rork]

Duct tape? PVC? YARN? Well done.

[AgentMoe64]

If one would not have the materials to do this, would you be willing to sell one of your one? And for how much?Please answer.

[Zorns Lemma]

If one would not have the materials to do this, would you be willing to sell one of your one? And for how much?Please answer.

It's fucking duct tape, PVC, cardboard, and yarn. The cuts are made with a combination of hacksaw, scissors, and steak knife. We're not milling military grade aluminum on a CNC machine here.

[3DBBQ]

Simple and Practical?Cool! I like it!

[Chadpuff]

Very interesting. Definitly liking the last gun in the video.

[BustaNinja]

I got to see these at Chano 3, and they stand proudly against the diddle guns and +bows. It makes for a different style of play, but damn, I got hit by that thing alot..

Nice Kane, I was always curious as to what the seal was made out of. Using yarn means that you don't need lubricant, and thus, there is practically no maintenance unless you get something in the plunger. Thats an incredible idea.

I really hope these take off. They are awesome.

[Ryan201821]

My new favorite propulsion system, yo. I built a MEGAHAMP this weekend with outstanding results. My hamp accepts any kind of attachment. The best is definitely hopper clip on a hose. It's the perfect Nerf machine gun.

I know people also wanted to see it shoot with balls. I did experiment. I used a 2" PVC wye for the hopper. There is no actual barrel. The balls are pushed out of the lip on the front of the wye. I added a 2" x 1.5" reducer to create the lip for the balls. Then I added a seat for the balls so they don't get stuck behind the lip. The only problem is that one balls sometimes goes into the back of the hopper clip, and never fires.



Maybe I should put on an actual barrel. The only problem is PVC pipe doesn't have an ideal fit with the balls. 1.5" is too tight, and 2" is too loose. I'll have to experiment with some pipes that actually have nominal sizing and see if I can create the fit I need.

Right now, it shoots roughly 50' with the ball hopper clip. I believe it should be able to shoot a bit further. I'm open to ideas.

EDIT: Grammatical error.

Edited by Ryan201821, 27 February 2010 - 05:43 PM.

[HOTH]

That is fucking nice. Fully auto penetrating cardboard? Hot damn

[KaneTheMediocre]

I like this a lot. It's something simple that can be built with a few lenghs of pvc and duct tape.

The last gun in the video was simply awesome. Is there any chance of a writeup for that?

Kind of. I'm not going to build another one, so I'm not going to make the kind of detailed, step-by-step instructions with disassembled photos that I have for the HAMP, BATS and VLTS. But I do intend to make a post explaining everything I can about how it works. The autoloader is, by far, the best possible combination of range and ROF that has been made for tagger darts, but that's kind of like being the coolest kid on the short bus. If you're not using tagger darts, there are better ways to achieve high ROF with HAMP systems, a couple of which I'll be writing up shortly.

If one would not have the materials to do this, would you be willing to sell one of your one? And for how much?Please answer.

I'm not sure if you're talking about the HAMP propulsion system, or one of the guns in the video. I'd be amazed if you couldn't get the resources to build the HAMP, as it IS pvc, duct tape, cardboard, and yarn. And making the simple shotgun (the VLTS) isn't terribly difficult either, but the others do take some machining. In any case, yes I'll probably sell guns and parts to interested parties in the near future. Right now I have at least 3 more writeups to do, and I feel I should get those done first.

Right now, it shoots roughly 50' with the ball hopper clip. I believe it should be able to shoot a bit further. I'm open to ideas.

EDIT: Grammatical error.

Having been the one holding the hopper on a hose, I think you're being optimistic with that 50' range. I'd guess 30 ish, which is still more than any stock ball gun. Add the barrel and I'm confident you can get 60+. Also, note that the Target foamy golf balls are cheaper than streamlines.

[durka durka]

My new favorite propulsion system, yo. I built a MEGAHAMP this weekend with outstanding results.

What size pvc does the megahamp use?


I'm building one of these things right now and I'm loving it. The parts cost me under 10 bucks and the performance is awesome. One thing I'm adding is a grip to make pulling the plunger a bit easier.

The HAMP is so simple and effective. It seemed like homemades on this site were trending toward more complex designs, until now. You don't need to order $50 in parts and use templates for this gun. Hell, I haven't seen a mod that uses cardboard in a long time.

[Broderick]

I see this being effective for camping during campture the flag.
Seriously though, I'm completely speechless; I really don't know what to say... in a good way of course. Just because I'd spend very little cash on parts, I'm gonna have to make a mini-HAMP in the near future. That's just too fucking awesome.

Edited by Broderick, 28 February 2010 - 10:15 PM.

[Fome]

Just for fun:

How NOT to make a HAMP:





I didn't have the proper stuff (2" pvc, elbow joints, yarn) so I tried it with a much smaller "plunger tube" (1.25") and a craft foam seal. Shoots taggers about 10 feet. This is a good example of an excellent concept and a terrible execution.

But fuck it. It took very little time and except for the drilled end caps, is completely salvageable

[CA13]

They are pretty cool, but could you somehow avoid the abuse of duct tape in the system?

[KaneTheMediocre]

They are pretty cool, but could you somehow avoid the abuse of duct tape in the system?

As soon as you can figure out how to put screws into 2" PVC without affecting the inner wall, and increase the OD of various tubes of various materials in specific places, I'll stop using duct tape. Oh, and I don't like glue fumes either.

[stuper bunny]

So all the VLTS is is a 1.5" PVC pipe rammed down a 2" PVC pipe with a hose connecting the pipe to the barrel?

EDIT: Sorry about this being a potential necro...

Edited by stuper bunny, 24 March 2010 - 09:41 PM.

[KaneTheMediocre]

hamp are awsem

I'm trying to imagine what the original message was which was so bad that this was deemed an improvement.

[mak-2012]

I don't think you realize how great the contribution is that you just made. This is a homemade that will go down in the books at the same level as the SNAP. It is cheap, easy to build, and effective. Plus, as you've proven with your own modding, it can be adapted with almost any type of clip, breech, or attachment.

You've made a very notable addition to the NERF community.

Kudos

mak-2012

Edited by mak-2012, 06 May 2010 - 10:09 PM.