Shell pasting

[NeighborJ]

I've been embarrassed to admit it but I've been using masking tape to paste my shells. I cut the fat rolls of tape into 5/8" wide rolls on the chop saw then paste away. I haven't noticed any issues in doing this but mabe someone else may know why others don't use this method.

[dagabu]

Nice looking shells!!!!!!

 

Nothing wrong at all, masking tape IS kraft paper with a gum (?) adhesive. It's expensive compared to kraft and paste but as long as they work, who am I to argue?

 

Again, fantastic pasting!

[Mumbles]

There are some places that do just this. I believe this is primarily in Spain on plastic shells, which I believe are burst with flashbags. It works fine for field expedient shells. The biggest issue I've heard of is that it doesn't stick to itself, which prevents a truly solid layer from being formed.

 

Otherwise what works works. The end over end pattern leads to more buildup at the poles than the equator, which can eventually disturb the symmetry of the breaks. Rotating poles will help negate this, but it's still not quite as symmetric.

[NeighborJ]

I've been playing around with different patterns. I've found that if I cut the tape width to 1/10th the shell circumference I can make three concentric rings and end up with a perfectly symmetric ball. It is also the most difficult pattern to make. On these small shells it isn't as important because they will be rocket headers and won't have the nicest breaks anyway. I've also put three or six bands of fiber tape underneath. They break hard for 1.75" shells, I get away with using mcrh only for burst.

[Seymour]

I am much more comfortable with masking tape being used on rocket headers than launched from mortars. Expense is the main downside.

 

I have tried pasting 4" shells with masking tape and lobbing them from a mortar. While I cannot guarantee that the problem was the tape and not my craftsmanship, the result was very exciting as 4" shells went off in the first meter out of the mortar. Flower pot.

 

Also, those are indeed very pretty looking shells

Edited September 16, 2016 by Seymour

[Pyrophury]

I've been playing around with different patterns. I've found that if I cut the tape width to 1/10th the shell circumference I can make three concentric rings and end up with a perfectly symmetric ball. It is also the most difficult pattern to make. On these small shells it isn't as important because they will be rocket headers and won't have the nicest breaks anyway. I've also put three or six bands of fiber tape underneath. They break hard for 1.75" shells, I get away with using mcrh only for burst.

 

They do look like very symmetrical even layers, nice job. I've also adopted this method of pasting, but I'm still getting a bit too much overlap at the poles - at what distance from center would you paste each layer for a 3" (2-3/4") shell, please?

[NeighborJ]

Phury, I usually fuse after it is pasted by poking an awl into the pasting and sealing it with hot melt glue. The method I use goes up and over the poles on center, this creates a raised ring of pasting from which I can start my next layer below. If I cut my tape to exactly 1/10 the total circumference of the unpasted shell it will be completed with just 3 concentric rings, each one applied below the previous ring and across the equator in a sign wave pattern. The tape will naturally conform to this wave shape.

So if I am to paste a 2.75" shell, the circumference can be calculated by multiplying 2pieR. Then divided by 10 and this will give you the proper width tape to use for three rings.

If I am pasting a fused shell, I simply measure from the edge of the fuse penetration to the equator and divide that measurement by three and the resulting answer is the width of tape I use to paste the three rings.

What is so confusing about this is I start pasting at the equator with a short sign wave and Finnish my last layer at the fuse penetration with the tallest wave. This gives it the illusion that it was all pasted as one layer because the first two layers are hidden underneath. The key to making the shell look so good is to take special care to ensure the pasting layers are evenly spaced as they cross the equator, everything else should fall in line.

To answer your original question, on a fused 2.75" shell, the proper pasting width is 9/16" and the unfused width is aprox 5/8". If you don't understand my description of the process, don't feel bad. I need illustrations or video to fill in for what I left out. I will try to take pics the next time I paste and post them here if you want.

Thanks everyone for all the kind words, I mostly blame this on my OCDs. I know they will just be blown to smithereens but I wouldn't even feel right sending it up if it didn't at least look good on the ground.

[NeighborJ]

OK Phury, I've included the pics of a 3" shell pasting, hopefully these pics answer any questions.

If this method has a name and someone knows what it's called, can you let us know? Thanks.

[CrossOut]

Those are beautifully wrapped shells!

 

That is the same the method i like to use when hand pasting. Way faster than three strip and gets just as nice of a break. The Chinese use the same method but done on a machine in about 30 seconds for a 3" shell lol. i looked into getting one out of curiosity, a machine that can wrap up to 8" shells thing costs about $6000...

 

Neighbor is right about the method. i found best results doing just that. i call it the the multi ring method. it produces perfectly round breaks every time. as you go up to larger sizes you will need more rings.. i still use 3 rings on 4" but ill step it up to 4 for 5"

 

 

As for the masking tape, there is nothing wrong with it. The adhesive will begin to melt and deteriorate in the heat so as long as you arent keeping them locked in a hot box during the summer there shouldn't be any issues. the first shells i ever built were just that. As a cheaper alternative, you can look into getting gummed craft tape. You will need to wet the sticky side of the tape prior to application but i do that using a moist rag in one hand and let the tape pass over it and immediately onto the shell.. takes a few minutes per shell and costs a lot less than masking.

 

Eventually you will find your self producing way too many shells than your cramped hands can handle. then maybe you will break and get a WASP like i did.. lol until then keep at it those are beautifully made! TBH this method makes a much prettier shell than a WASP does.

 

Post some vids of your shells in the air. id like to see the breaks!

Edited September 17, 2016 by CrossOut

[Pyrophury]

OK Phury, I've included the pics of a 3" shell pasting, hopefully these pics answer any questions.

If this method has a name and someone knows what it's called, can you let us know? Thanks.

 

Yep, that's very helpful, thanks. I've been doing the same but starting 3/4" from the poles and then moving each layer just half a tape width (1/4") closer, so they overlap by half. But your way of leaving a full tape width looks to give a more even thickness - I'll try this next time.

Edited September 17, 2016 by Pyrophury

[dynomike1]

It sure would be nice to have a video in the tutorial. Some times pictures and words don't work for me. I have never really pasted plastic shells, but i am seeing that i may have to on larger shells.

[Pyrophury]

Gave the wider spacing a go this afternoon...

 

http://pyrobin.com/files/pasting%201.jpghttp://pyrobin.com/files/pasting%202.jpghttp://pyrobin.com/files/pasting%203.jpghttp://pyrobin.com/files/pasting%204.jpghttp://pyrobin.com/files/pasting%205.jpg

 

I used 1/2" (1 tape width) spacing, it does look more symmetrical than my usual 1/4" spacing.

[NeighborJ]

I don't normally paste plastic shells either, it just made a good contrast for photos.

Phury, if it fits too loose in your tube I just tighten up the pattern, instead of covering half of the underlying paste at the equator I cover 2/3 and it will fit better use less lift and break harder.

Your shells look awesome. I like the circles you drew to keep it all in line.

[NeighborJ]

Crossout, here's the video of my masking tape headers, you'll need to excuse the drunken jagoffs in the background and the poor video quality. This was at my neighbors birthday party tonight. My phone doesn't pick up the glitters very well and I changed the type of fuel in my motors so, without testing, I didn't want to risk a longer delay.

[NeighborJ]

 

I've had several more requests about a pasting video for this method so I made a demonstration video. Go easy on me, I'm not a good public speaker but I'll give it a go.

 

I left out some of the specifics to keep the video length short but it still ended up being 25 minutes long. If anyone still has questions I'll do my best to answer them.

 

Jason

[OldMarine]

Excellent tutorial!

[rogeryermaw]

Eventually you will find your self producing way too many shells than your cramped hands can handle. then maybe you will break and get a WASP like i did.. lol until then keep at it those are beautifully made! TBH this method makes a much prettier shell than a WASP does.

 

Post some vids of your shells in the air. id like to see the breaks!

+1 my wasp required a lot of setting tweaks to get half decent looking shells but they perform quite well. For good break symmetry i have noticed it is as important to have evenly sized stars. Any significantly heavier will travel past the edge of the peony ruining the sphere

[greenlight]

I was just reading a cylinder shell building chart page and it has a section on how many turns of kraft to paste can shells. I thought pasting was mainly for spherical ball shells.

I am about to contruct my first 3 inch cylinder after many 2 inch designs. From this size onward do I need to paste the extra layers of kraft suggested after spiking?

[chuckufarley]

I believe fulcanelli specs 1 turn of 30# kraft per inch of shell for a paste wrap over the spiking. This is essentially a fire proofing layer in my opinion, though Im sure it adds strength to the shell as well.

If you want to avoid the pasting on cylinder shells read up on the rinfasciature method. That uses multiple dry wraps and spiking layer to replace the pasted layers.

[NeighborJ]

Thanks all for the positive feedback.

 

I'm not sure how this pattern stacks up to a wasp wound shell but it does make good breaks. I did have some excess shrinkage with this recycled Kraft paper, the shells were a bit small in the gun. I correct this problem with another layer of paste or I can simply draw a third evenly spaced latitude circle and cut my paper thinner for three layers. The two circle method was sufficient with virgin Kraft but not for recycled.

 

This process is trial and error, any change in material or design will change the final product. Once a method is worked out, it is best to not change anything. I can't really give much advice for the latitude reference circles, the diameters and number of them will need to be worked out with the paper(type and width), glue and variation of gun size buy experimentation.

 

Roger, I plan to send up some of these shells this weekend, I'll provide video. You brought up a good point with the star diameter being critical. These shells were not made with that in mind, I used up some left over stars which were rejects (twins, chipped, or of a different size) from previous projects. I was focused on demonstrating the paste pattern.

 

Jason

[starxplor]

I believe fulcanelli specs 1 turn of 30# kraft per inch of shell for a paste wrap over the spiking. This is essentially a fire proofing layer in my opinion, though Im sure it adds strength to the shell as well.

If you want to avoid the pasting on cylinder shells read up on the rinfasciature method. That uses multiple dry wraps and spiking layer to replace the pasted layers.

 

Last I checked, the rinf.... method still required some pasted layers, in addition to the string and dry layers?

[chuckufarley]

Haven't watched it all in a while, but its a good video of the process.

 

[rogeryermaw]

J i actually watched your tutorial twice! good result from a fairly quick method and i'm sure it would be faster if you didn't have to give instruction while you do it. thanks for uploading this!

[OldMarine]

 

Last I checked, the rinf.... method still required some pasted layers, in addition to the string and dry layers?

No paste is needed. The paper is pleated well over the discs and pulled tight with the spiking. You only need a good fillet of glue around the spollette or time fuse to keep the fire from getting through and top fusing lessens that danger.

That said, I've got me some paper hemis and have tried the strip style and disc pasting methods and found the disc method easier but after watching NJ's video I may give his method a shot.

[starxplor]

No paste is needed. The paper is pleated well over the discs and pulled tight with the spiking. You only need a good fillet of glue around the spollette or time fuse to keep the fire from getting through and top fusing lessens that danger.

That said, I've got me some paper hemis and have tried the strip style and disc pasting methods and found the disc method easier but after watching NJ's video I may give his method a shot.

 

I will have to revisit the rinf... method again then for next year. Thanks.