I’m looking for information from anyone who has experience with making double layer vinyl bags. After getting a feel for Paddy Keenan’s pipes in November I’ve been planning to make a double layer vinyl bag. I’ve been playing on (and have a pretty good method for making) the single layer bags and I desire to get rid of some of the squishiness-which the double layer vinyl achieves well as I found with Paddy’s set. I inquired of Paddy about his bag and, though he gave some good pointers, his tie-ins are not traditional and therefore don’t help me much in that department.
I’ve scoured the internet and both forums for tips but I can’t find much on double layer stuff. My biggest concern is the tying in of the mainstock and blowpipe stock. An obvious method would be to just cut through both layers and tie in as you would any other bag. Another method I remember reading from somewhere (though I can’t seem to find it again) was to cut only a small inlet hole on the inner bag and tie stocks in to just the outer layer.
My concerns with both methods (which may or may not be an issue, which is why I seek experience) is air excaping from between the two layers of vinyl at any one of the tie-in locations. I didn’t think it would be practical to put glue around the tie-in locations as it would possibly make the bag stiff and difficult to store and/or set up ergonomically.
Any advice/experience is much appreciated.
I don’t want to start a discussion on leather vs. vinyl here. I can’t afford to buy a leather bag and prefer to experiment with vinyl for awhile anyways so that I can get the ergonomics (placement of stocks) down before I ruin a leather bag in the future. Please comment only if you have something practical to share regarding my inquiry
I’m at the exact same place, struggling with how best to tie in.
Paddy was using a custom mainstock cup that gave an airtight connection of cup to bag via an arrangement of nuts and washers on a threaded tube (if I remember) that sandwiched the bag material between the two washers. The concept was much like how a air valve is attached to an inflatable raft. I also noticed that the mainstock was mounted very low on the bag, and Paddy was not using a strap to hold up the stock. We had a conversation about this.
I tried something like this a few years back with a leather bag, and it worked quite well until the edges of the washers wore through the leather, which did not take long, perhaps a month or two. Maybe the vinyl is more durable in regards to edge abrasion? Paddy’s arrangement must hold up because he was on the road with it.
I did not get a great look at the blowstock connection, but did see that he was using a circle cut in the vinyl rather than a pie cut, and the blowstock valve was outside the bag rather than inside. At least that is what I remember.
Have you considered building an arrangement like this? It might be more suitable for the vinyl. I think all parts could be found at True Value Hardware, except the cup itself which could be made on a lathe.
Although I am a leather person myself, I have two suggestions to offer you.
If you look in a marine store (West Marine, etc.) they have plastic through hull fittings that will
sandwich the material between a nut and a flange.
they come in various sizes and could be used for the blow pipe and main stock.
Dinghy repair kits have replacement inflation ports that attach the same way.
I machine all my own stuff , but if you don’t mind using off the shelf sizes, there are lots of these types of fittings that could be adapted to experiment with.
Will the chanter stock be unchanged and just have 2 layers tied to it ?
A mate of mine got a tracing of paddy’s bag so we were able to make a fairly accurate replica on size. My mate used the washer/screw tie in method and I did the traditional tie in. There was honestly no difference in terms of air tightness if either method is performed correctly. I guess its a matter of preference. I couldnt be bothered with another trip to the hardware store and I’m proficient in the trad tie in method. Regarding leaking between layers, its a non-issue. After the two layers of vinyl are glued together there is no way in hell anything is passing between them! If you need some instrutions on making the double vinyl bag, I’ll happily post some instructions.
I tried something like this a few years back with a leather bag, and it worked quite well until the edges of the washers wore through the leather, which did not take long, perhaps a month or two.
I did something like this also, except in addition to using large fender washers inside and out, I used a thin wooden disk about the size of the cup on the inside, and built a disk with a shoulder facing out, on the outside. I then attached the cup-ring to the outer disk with small screws around the circumference. Everything was well sealed with Barge cement and has remained airtight for over twenty years. Clearly I stitched the bag myself to be able to place the inner disk. The same system might work for vinyl.
I’m playing two bags made out of double thickness vinyl. Avoid “Marine Vinyl” and stuff stamped “naughahide” - or at least the examples I tried, which refused to glue up well with DAP contact cement. Maybe some other crap would do the job. The Marine vinyl costs extra, btw. One bag I glued up with Barge cement, that worked well, but stunk even more than the DAP. Yes, you cut into both layers. I have a bit of scrap wood like a tongue depressor to make sure the razor blade doesn’t go all the way through. First inflate the bag, then make a cut with the razor blade, then make other cut with the shim of wood in place, ensuring you go through both layers. Doesn’t matter if the odd molecule slips between the layers.
These bags are huge - like airships. I need to make a smaller one for the concert pipes, since I’m bumping into walls/punters, the thing’s so big. Also needs to be deeper, I’m always having to pull the bag up to get my arm around it. You figure this stuff out ipso facto. Oh, I throw on a leather seam and sew that on, too. Keenan’s bags explode on a regular basis, I’m told. Paddy likes to tie the stock in low, to get his arm around as much of the bag as possible, to be able to power it more effectively.
Sewing a seam on is quite easy, a couple hours work tops. Just watch what you’re doing. Punch the holes in first - I use a needle mounted in a block of scrap wood, and use a block of waste wood underneath. Some use a drill press instead of a needle. Make sure at all times the needle’s actually going through the bag and the seam. A talented bagmaker can crank one of the things out in less than an hour.
If you just have to use glue for the seam I remember Dave Daye decided that “Marine Adhesive” was the strongest stuff on Earth, after trying everything. I just use the glue to keep the seam in place as I sew, no doubt it adds a bit of airtightness too. Have been using waxed vinyl thread from Tandy Leather - lots of that wax goes into the hole and I haven’t had to season these one bit. Nice thing about the double thickness is it holds up the chanter all on its own, letting you focus on actually playing the notes.
I am experimenting with bag making, so this is a timely thread for me. Where do you get your vinyl? I got mine at Jo-Ann Fabrics, and I have found it is hard to keep glued together. (It has some sort of fabric on one side.) I am using a 90 minute epoxy for glue.
I have had great success with the marine grade vinyl sold at JoAnn Fabrics and made by Spradling. It has a polyester backing, not nylon, and is treated to resist mildew/stains/UV. I have been using the 3M 5200 fast cure marine adhesive/sealant caulk to seam them. Since I have been very experimental in my tie-in placement I’ve made a new bag every 3-6 months so I can’t rightly say how long they last, though I’ve yet to see any sign of wearing out/cracking/adhesive failure with very regular playing. I’ve got the tying in method of the single layer vinyl bag down to an art from doing it a half-dozen times over the last few years. My process has been to use circular cuts instead of the star pattern cut. I’ve found it to be a more snug fit as it is less prone to ripping when stretched tightly over the stocks. Pictures of this tidy method can be seen here:
I’m not really interested in using plumbing/hardware to replace the traditional tie-in as I feel this limits the options for angle of tie-in and is more bulky/heavy than I’d like.
Based on some comments above it sounds like the tie-in methods I’ve been using should work equally well for the double-layer bag. I’m a little nervous because I’ll now be wasting two pieces of vinyl if something goes wrong but I think I’ll go for it with my standard method.
Am I misunderstanding your post or did you actually glue the layers together face-to-face before seaming? I have only been gluing a 1" seam and Paddy said that was all he did as well. My concern was that when tying in I’d be making two holes and I was worried that it would be another way for air to escape between the two layers since it is that slick polyester backing that is face-to-face and not the vinyl (hope that makes sense).
I have found that epoxy is very stiff. I have not tried the marine stuff, but will with this next project. I have never had Barge work for me-- it blows apart. Maybe I am doing something wrong… but I also found it smells bad for some time after (at least to me). Thanks for the info in this thread----
I actually DID glue the two layers together with contact cement first. After that dried I then glued the 1 inch seam. Paddy Keenan told us that was what he did, so we just followed instructions!
Interesting point of note re gluing the two layers together. I think the type of vinyl you buy must be a factor with the resulting bag stiffness. My bag ended up much more rigid than my mates yet we both followed the same process. I can only put it down to differing vinyl products.
Having been a ships carpenter for over 20 years I am familiar with 5200 by 3M. I can smell it before I can see it. Do you find the stink subsides over time? I never put it on anything that was so close to my mouth or nose. It’s also messy to use. Most times it ends up all over you and all over everything near you but that’s a sure way you know you have used enough. As for it sticking, I doubt you could ever get it apart.
I do take care not to get it on anything - the first time I used it I had it on my fingers and a bit on my shirt and it was a huge pain to get off. My process is to put a flat board on the ground in my spare room, cover it with wax paper and lay the bag on the wax paper. I do a bead of the 5200 around 1/2 of the bag and then fold it into it’s final position so that the two sides meet. I use the edge of a DVD case as a sort of squeegie to encourage the sealant to contact well on both halves and also to push it away from the center of the bag so that it will spread out instead of in when pressed. I lay another layer of wax paper on top of the bag and then another board on top of that with weight on it. It sits there for 5-7 days to cure (I know the 5200 is fast cure but I give it the extra time just to be sure the bond is strong and won’t pull apart from the inside). With this method as long as care is taken with the caulking gun, there’s no reason to come into contact with the sealant. The smell is not noticable to me at all after it has cured. Obviously the edges of the seam are a bit messy when all this is done from the glue that spreads out when pressed but I do a final cut of about 1/8" along the seam to get a nice clean finish. Any excess sealant that gets on the vinyl surface will peel off without any residue.
Also, another side note on the vinyl: when you purchase it, don’t let the cutting clerk fold it. This creates unsightly kinks in the vinyl that take forever to come out (if they do at all). See the picture of my first bag in the thread I linked to above. It is especially bad if the fold ends up in the neck because it makes it more prone to pinching your air supply. Transport it in roll form and keep it from bending as much as possible for best results with the fabric.