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Clemens,
The hardest part for me is trying to describe the filing effort. I file the bottom so it has a 19 or 20 mm wide flat area on the bottom. This leaves 2 mm or so of gently rounded edge on each side. I do not file the tip.
I use a coarse file for aluminum or steel. Be aware that aluminum galls, and it will be easier to smooth with sandpaper if you clean small chunks of aluminum out of the file. An alternative would be to use an aluminum wheel on your grinder – and go very carefully.
I smooth the filed area with 220 grit sandpaper, followed by 360 or 400 grit paper and fine steel wool. Then I rub in on wood or paper to see if it is still rough and leaves aluminum marks. I don’t want to leave marks on the yellow fabric!
When done I can use the tip with a raised handle position – and I do this very frequently! Then I slowly lower the handle to use the full length of the bottom. I get a fair way down a seam before the iron cools.
On seams I can tilt the iron to one side, rocking the rounded edge over the tame edge and squishing the TPU to the edge of the tape. Not always easy to see with black tape, it is more readily viewed with seam tape made from red fabric! IMO.
Hope this helps.
Bruce
Sean, Excellent question.
My experience with Aliexpress is limited, but excellent. My guess is that all of the 220 leather irons work the same, but the Chinese sellers can’t really test them and are incorrectly estimating the output based on current, when the thermostat which controls the temperature doesn’t rely on current. The resistance heating element just keeps on heating until the thermostat blinks and it cuts power.
I think that any of these tools with the 350 degree dial and thermostat will work with North America 120 volts – just at lower temps than indicated on the dial – and a lot slower to heat up. Fifteen to 20 minutes! Mine goes way past 250 degrees if I don’t have the dial taped down and accidentally bump it!
I really wanted to order one of the sets of 6 (red handles) for $140 thru Aliexpress, but couldn’t justify it for class use, yet.
I found a simple digital instant-read oven thermometer worked to measure temperature. (Instant is a relative term.) Besides you need one for roasts: see my Dutch Oven Campfire Cookbook at http://www.russia-alaska.com , Ha!
Please post your results!
Bruce
I have tried several irons and can now enthusiastically recommend the JingdaLeather Iron ordered thru Aliexpress, and initially suggested by Lyn, thanks Lyn. I have used the Leather Iron by Jingda Thermoelectronic Products to build both V2 and V3 rafts, one of my own and helping with several built by others. I can complete seams in roughly half the time compared to using a model aircraft iron – due to the better, narrower shape of the Jengda iron and especially the upswept tip that allows sealing at high angles.
I think the Jingda is three or more times faster than the Clover (I built my first raft with a Clover and helped with many others) because the Clover is slow to transmit heat to the foot of the iron and quickly drops below TPU welding temperatures as one moves along a seam.
I ordered mine from: https://www.aliexpress.com/item/220V-150W-50-350C-degree-adjustable-mini-electric-iron-for-leather-clothes-87mmX27mm/32705305023.html?spm=a2g0s.13010208.99999999.288.2C5OLO
Mine came with a US plug adaptor, which worked fine in standard 3-prong US 110 volt outlets. No transformer needed. Please don’t plug it into 220 volt circuit unless you have the electrical knowledge of the difference between one leg Chinese 220 volts and two-leg alternating US 220 volts.
I see others online with better cords (my plastic one melts if brushed with the hot foot) at
and
Some come with UK or EU plug adaptors.
All will need the aluminum foot filed flat so you can best heat seal a seam. Lyn also filed it narrower.
Hope this helps,
Bruce, Fairbanks, Alaska
P.S.: Yes, you need a tandem V# raft too! Fantastic raft!
First inflation of my V3 Tandem packraft! It is 11 feet or 3.5 meters long, interior is 182 cm long. I will have to search for a safe lead in winter’s ice to give it a try!The uplifted front of the Jingda Thermoelectric Products “leather” Iron, purchased through Aliexpress, makes it indispensible for tight spots and small corners especially when finishing the ends or reaching through bunched fabric.
The tip allows one to reach and heat spots at high angles.
I have been using the Jingda Leather iron for a couple weeks now and I would not want to give it up. Thanks to Lyn for discovering it. With the relatively simple modification of filing the foot flatter it becomes an indispensible tool. I particularly like the uplifted tip that provides accurate work in tight corners, and allows one to approach the edge of a piece of fabric with good control.
I cannot measure the temperature with my infrared thermometer, due to the reflectivity, but using a digital oven thermometer, it appears to have very little temperature swing, probably due to the digital thermostat. It will get hot! And the thermostat dial has to be taped down. If you have a file, and are willing to rework a new tool, I can recommend it!
I am using it in standard US 110/120 volt current. (Mine came with a simple plug adaptor, which you can also buy one online for the Chinese “W” style plug.) It does not take a converter/transformer to use, just a simple plug adaptor.
Now, if I only had the courage to take a file and round the tip of my model aircraft iron so it isn’t totally flat . . . .
The new 420D and 1000D two sided fabrics make fantastic tie downs including web plates, and D-ring points. I also used a 1.5 cm strip inside a fold on my inside tube to floor reinforcement strip, so I can punch holes in it and tie a separate floor to the raft.
Simplest are webbing plates. I cut circles or ovals from either 420D or 1000D fabric, seal a small circle of one sided fabric on the inside (it prevents accidentally welding the center of the tab to the packraft) then I punch 2 oval holes (6mm x 25 mm) about 25 mm apart.
Round plates are easy to attach anywhere. Oval plates make great two-point seat back attachment points.
I also made long attachment strips for the top of my center tube.
Another picture of the finished webbing strip laid out with an oval seat point and a round D-ring for a thigh strap.
Sewing D-rings onto the 1000D fabric requires a solid sewing machine with steel internals. Better might be to take your patches to a local tent or shoe repair shop and have them sew polyester webbing on with plastic D-rings. I can recommend the sexy black and white Dyeema webbing from DutchGear.com.
I made heavier duty points to attach bow and stern grab loops a swimmer could hang onto in a rescue.
I also made one-piece grab lopps with 210D fabric cover to help a swimmer climb into a raft, of in my case provide a hold for a youngster in front of the tandem packraft.
I made a simple zipper pull loop from a 20mm strip of two sided 1000D fabric. This gives one a solid tab to pull against when opening the zipper.
Other packrafters complain about their floor pad floating and floundering about when paddling in whitewater. I added a 15 mm strip of 1000D fabric inside a fold of the fabric I’m using to seal the inside of the tube to the floor. The 1000d fabric is tough enough to punch holes and weave cord to tie in a pad or a separate inflatable floor. It is so tough I couldn’t rip through it by hand.
Mounting the inside tube to floor reinforcing strip to center tube 3.
Laying out attachment points with inflated raft to help determine placement.
Outfitting takes time. I spent weeks working out what I wanted. Of course, I’d have to spend almost as much time if I went downtown and bought a “finished” raft – judging from the time others spend adding and tuning their outfitting.
Now I have to start assembling the raft! Wish me luck!
Update and current recommendations
I tested the Valad HS-3T heat sealing iron. It is the one unit I could not recommend for use with TPU coated Nylon-66 fabric.
The Valad Electrical Company hand held Heat Sealing Iron, model HS-3T, is a 165 watt stainless steel iron that I purchased for $15, well used, on eBay. It can also be purchased new for $750 from the Valad Electrical Company in Tarrytown, New York. I was drawn to the iron because of its narrower foot. Unfortunately, It is the one iron that did not work for TPU coated nylon fabric.
The Valad failed my review for two reasons:
1) The thermostat has a 30 degree C temperature swing (50 degrees F.) causing it to swing from too cool to melt the TPU coating, to too hot and melting the nylon. There is no happy medium.
2) The nice Stainless steel foot was too thin, causing the foot to have two hot spots that were much hotter than the rest of the foot, and I was unable to prevent the hot spots from melting the nylon fabric.
The Valad foot is about 32 mm wide, but the thermostat temperature swing is to great for use with TPU nylon fabric.
I also purchased an inexpensive 60 watt soldering iron and slid a tight fitting piece of copper refrigerator tubing over the tip. With the tubing off the iron, I flattened the tip and reinserted it to the iron.
The tubing heats slowly, and it feels much like a Clover Iron in use. I was able to get a temperature reading with the Coverite pocket thermometer. When I set the thermostat dial to 300 degrees C, the foot measured 200 degrees C. It is quite possible that it would continue to heat up if one set it aside while working on something else. Same as my Clover Iron. That is why I always have a piece of test fabric to pass the iron over before touching the packraft!
The simple homemade copper foot quickly transmits heat into the fabric. It cools quickly below the temperature needed for a full seal. Just like any iron of this size one has to move slowly down a seam and check for full adherence!
Updated conclusions:
I recommend either the Top Flight $20-30 or the Coverite $20-30 (TowerHobbies.com) heat sealing irons PLUS a Coverite pocket thermometer, digital infrared thermometer, or an oven thermometer. You need a thermometer to check the peak temperature, and to confirm the change when you adjust the peak setting of either iron. Out-of-the-box, I find them too cold by 20 to 30 degrees C.
A Clover Mini-Iron, $24, Amazon, needs reinforcement BEFORE you use it. A thin steel wire over the heating element and just barely tight under the red plastic guard. The narrow foot works seams, but it is very slow. Greatest problem using the iron is how slow one must go to prevent having a partial seal that doesn’t hold under pressure.
The Jengda 220 volt iron, purchased thru Aliexpress for $29 has potential. I have only used it on 110 volt US circuit. To use it I first filed the foot flatter. And I taped the thermostat in place because it is easy to bump. The high mass of the aluminum foot retains heat making it a faster option than the Clover.
I made a copper foot for a 60 watt soldering iron. The iron heats well above the temperature we need. A thicker piece of tubing might increase the thermal mass. One has to tape the thermostat dial in place or it too can be bumped out of whack. It is a low heat mass option and is slow to use.
Hope this helps,
Bruce
Fairbanks, Alaska
Lyn,
I wanted to extend my corner tube out several inches to provide more flexibility in the connection, but it required more fabric. It looks to me like Exped is using valves similar to the new red valves now available on DIY, but with an additional smaller connecting link. The 7/8 OD silicone tubing works great, but I don’t think it’s such a firm attachment that one could lay on it?
Here’s a photo of my fitted silicone tubing, with a cork that inserts on the inside to close the bag, similar to Exped’s idea. I’m using a homemade copper tip on a soldering iron to finish sealing in the corner around the tubing. It is also glued and I added heavy duty thread to tie it off. The thread keeps the glue from peeling back around the tube under air pressure when inflating the raft.
Update to Sealing Iron Review
I misspelled the name of the leather iron manufacturer: It is Jingda. Sorry for the typo.
Valad heat sealing irons are manufactured in Montgomery New York, made in the USA. Their website is: http://heaters.valadelectric.com/item/electric-heat-sealers/hs-3t-heat-sealers/item-1115
I have placed an inquiry to Valad Electric Co. to see if they sell direct. Otherwise there a couple new ones on ebay through: MyCyberOffice for $42 plus postage at: http://www.ebay.com/itm/Valad-HS3T-Heat-Electric-Sealing-Iron-150W-120V-with-Stand-/352077085678?hash=item51f96dfbee:g:j3sAAOSw1WJZMffb
Hope this is helpful,
Bruce
Using the new 40D ripstop is a fast and simple way to fashion an inflation bag. Took me about two hours. I used 1 meter of 40D fabric, less than 2 meters of 1/2″ thin nylon webbing, a plastic buckle, D ring, and I will insert a 7/8″ Silicon tubing into a bottom corner when it comes in the mail. I intend to plug the tubing with a cork, from the inside. Then I can roll down the top and use it as a fast access drybag, the roll-down handle/buckle will allow it to be quickly clipped in behind the seat.
This is the finished inflation bag, with a piece of grey tubing to illustrate where the silicone tubing will go.
Heat sealing the 1/2″ webbing requires fashioning a small slot and feeding the webbing out, through a buckle, then back into the tube. Easier if done first, provided you are careful and don’t melt the webbing. I placed a small strip of wood under the fabric for better edge accuracy.
Finishing the webbing loop included cutting a small rectangle out of the fabric, turning it inside out and inserting it into the webbing tube. You can see the webbing pulled back into the tube prior to applying heat. I fished the webbing out after completing the side seam.
I will place the silicone tubing into the corner, which seemed simpler to me. The grey tubing is a rigid placeholder that prevents me from going too far with the iron.
I made a smaller inflation bag from Sil nylon, but prefer the larger one fashioned from one meter or fabric, full width. It is folded down one side. I sealed the top edge with webbing, one side, and the bottom, leaving a hole through the corner seal where I will glue in the 7/8″ tubing.
Thanks for stocking such great material!
Bruce
Comparing Heat Sealing Irons: Clover Mini-Iron, Coverite, Top Flight, and Jandga Electrothermal Products
By: Bruce Campbell
Date: September 4, 2017
Background: I built my first DIY packraft using a Clover Mini-Iron and an old household Iron. They worked, but the Clover is slow and fragile. The old household iron was a challenge to keep hot enough.
Coverite and Top Flight irons are 165 Watt tools developed for heat-sealing and shrinking thin plastic film (fabric) onto model aircraft.
The Jindga Thermoproducts leather clothing iron is a 220 volt 150 amp Chinese appliance. It feels solid and heavy duty, and it worked with it’s 110 adaptor in a US 110 volt outlet.
In this comparison I will try to detail what I’ve learned about each iron, its dimensions, temperatures attainable, and various features.
Coverite and Top Flight irons are 165 Watt tools developed for heat-sealing and shrinking thin plastic film (fabric) onto model aircraft wings and fuselage to create a smooth lightweight surface. In the world of boat building I know of one “Skin-on-Frame” ultralight kayak and canoe designers suggests one can use the film as a lighter, smoother alternative to paint or varnish on heavy nylon fabric covering a kayak or canoe frame, though at significant cost. I have never used Aircraft film.
Model Aircraft fabric requires less heat than I use for TPU coated nylon-66 fabric. I find the TPU coated fabric seals best with an iron in the 205 to 225 degree Centigrade (C) temperature range. The Nylon 66 melts at temperatures over 240 degrees. The hottest of the model aircraft fabrics, Monokote, requires temperatures from 100 to 175 degrees C. Low temperature model aircraft fabrics may only need 65 to 80 degrees C.
Given the price range, one would expect significant temperature variation, perhaps 20 to 40 degree C from one iron to the next. But I found much better accuracy, all three Coverite were set for a maximum heat at 199 to 201 degrees C, identical to the Top Flight iron. The thermostats in these irons provide about a ten degree cycle. From the factory this means they hit a peak temperature of 199 to 200 degrees, then cool to 189 to 190 degrees before the thermostat kicks back on and heats back up to 200 degrees.
In use, the heat transferring to the fabric and its underlying base, cools the iron down much further, often under 175 degrees. At the lower temperature the fabric may appear to have “wetted” and sealed, but it is only lightly stuck together and will readily peal apart. To avoid this I prefer a hotter iron, one that doesn’t cool below 205 degrees in the thermostat cycle, as measured with my infrared thermometer or the Coverite thermometer.
While this is just barely hot enough to melt the TPU coating, I preferred to increase the temperature range on all of the irons by adjusting the thermostats in each from 1/8 to ¼ turn. The hotter iron cycled
While it is possible to test the iron’s temperature on scrap TPU coated fabric, I recommend using a thermometer so you be sure the peak temperature is not going to melt your nylon and so you can check it over time. Coveright sells a fine, inexpensive thermometer. I use an inexpensive infrared thermometer. One could easily use an oven meat thermometer. A thermometer lets you know the high and low temperature at your desired setting. It gives you confidence in your iron’s performance.
Dimensions: Coverite is 48mm wide while the Top Flight is 42mm wide. The Coverite is wider because it has rounded “wings” on each side for smoothing around aircraft wings and in tight places. They are both 120 mm long.
The Coverite handle, left, is a single piece that should prove to be stronger and less prone to failure.The handle on the Top Flight, right, is spot welded to the metal cover for the iron.
The rounded ‘wings’ of the Coverite on left, square Top Flight on right.
Similarities:
Both have similar ceramic heating elements, the same ceramic tip on the thermostat, and both are adjustable with a fine screwdriver inserted into the brass stem under the knob.
The Coverite internal components are firmly attached to the base of the iron with two black screws. The wiring has glass fiber or other high temp insulation. While the core heating element and thermostat appears identical from my visual inspection. In my opinion, the wiring and solid attachment of the Coverite is superior.
The internal parts for the Top Flight are not screwed to the bottom of the iron foot.
Both irons use what appears to be the same thermostat with superior ceramic tip. The white ceramic tip on the bimetallic thermostat is visible in the center of the photo above. The ceramic tip raises as the iron heats to break the circuit. The irons all rise about 10 degrees C before the ceramic tip breaks the circuit. They then cool 10 degrees for the circuit to be reenergized and begin to heat the foot of iron. The hottest part of all the irons is obviously in the center of the foot.
The temperature range of the thermostat is adjusted with a fine screwdriver inserted into the brass stem under the black plastic knob. A counterclockwise turn increases the heat range. It does not take much. If you need to adjust the peak temperature of your iron start with 1/8 turns and measure the temperature again. If the iron gets too hot, the thermostat may fail, ruining the iron.
The Jindga Electrothermal Products 220v 150 watt heating iron is designed for ironing leather goods. It is a very solid feeling iron with a narrow but massive aluminum foot. The thermostat dial reads from 50 degrees to 350 degrees Centigrade. It has a very nice red light indicating when the current is on and the iron is still heating, blinking when it is at temperature, and off when the thermostat has cut the current off.
It is a three wire, grounded, Chinese 220 volt appliance, which as I understand it is similar to a European 220 volt wiring. As such, one leg is 220 volts and the other neutral, the third wire is a ground. Some internet advice indicated one could use US 220 volt, which is composed of two 110 legs, each out of phase with the other. If you can figure this out, you might be able to use the iron on 220, I found I didn’t have to because it came with a simple converter plug for US 110 volt outlets and it worked. I can only recommend using it on 110 volt current, because that’s all I’ve tried. Lyn St. George, the original discoverer, used it with 220, and the aluminum blistered. I don’t know why.
I’m sure it isn’t as hot as it would be in a 220 volt circuit, but it got plenty hot, measuring up to 225 degrees, and probably hotter, but I simply turned the thermostat down to find my preferred 220 degrees C. It is easy to bump the thermostat dial and inadvertently change the setting, so I put a piece of masking tape over it.
The Jindga iron is 27mm wide and 85mm long. The bottom is rounded in the narrow dimension, and it has an upswept nose. It comes with a heavy three wire cord that ends in an “I” style three prong plug. A US adaptor was included.
Using the irons
Clover Mini-Iron: I built my first raft with a Clover Mini-Iron and an old household iron. The Clover is precise, but slow. The tiny foot cools very quickly as it moves across TPU coated fabric, and it takes a long time for heat to transfer from the element down the thin stem to the wide foot. As I got more experienced with the iron I found myself setting it aside to build heat. The iron would get too hot, hot enough to melt nylon, so I always rubbed it on my smooth wooden surface, and across a small piece of test fabric before touching my raft assembly. And I always kept the iron moving on the raft fabric. To pause or hesitate risked melting the fabric when first touching the iron to the fabric. Unfortunately, the Clover is fragile and one cannot push it solidly against the fabric or it will break. I fashioned a wooden handle to fit over the foot and could press down on the handle while lightly gliding the iron along a seam.
I used an old household iron for larger areas, including sealing in the double bottom and sealing the inside of the tubes to the bottom over a wooden form. The household iron was faster, provided it was set hot enough. It was very easy to move it too fast and get only a very light “stick” between the two layers. At other times it got so hot the TPU coating bubbled and frothed. While the household iron felt like a lot of heat was being transmitted to the fabric, I found I often had to slow down and let it fully melt the TPU coating, going back over and over to work out air bubbles. Yes, I could get plenty of pressure to form the seal.
My current favorite iron is the Top Flight because I have it set to a heat cycle of 215 to 225 degrees C. This is hot, and requires keeping the iron moving when first touching fabric, but it also retains enough heat that one can keep moving over larger areas of wider seams, like the 4 cm tube to bottom seams of a raft. I also prefer the Top Flight because it is 8 mm narrower than the Coverite irons, and because I prefer the flat sides of the Top Flight.
The Coverite irons are better built, and as I get them adjusted to my preferred temperature range I’m sure they will meet or exceed the Top Flight when width is not a problem. This would be true when using a wooden form to determine the seam width.
The Jindga Iron’s narrower 27 mm wide foot is desirable. However, I found it to be slightly too rounded. It required moving it back and forth to melt even a 2 cm width of fabric. It needs a flatter foot to heat more fabric at a time. The rounded foot makes sealing a larger area, even a 20mm wide seam, difficult to seal without trapping air bubbles and it goes much slower. Modification needed: I simply filed the foot flat.
Update: After I filed a 15mm flat on the bottom of the Jindga iron, its performance is greatly enhanced. The iron stays hot, it doesn’t lose heat like the other irons, due to its massive aluminum foot and the nature of the heating element. Using 110 poser, it heats slowly, perhaps 10 minutes of more. The blinking light lets one know when it is at temperature. Measuring with the Coverite thermometer, I do not see a temperature swing, nor does it appear to loose heat from short heat sealing efforts, like the other irons. I will definitely give this iron a hard workout in my tandem build, and will report back.
Conclusion: The Model Aircraft irons have great attraction for wider seams, such as joining tube to floor. The narrower Jindga Thermoproducts iron has a lot of potential to improve speed and quality of the heat seal in seams. I always have my Clover to fall back on!
Further research: I hope to test one of the military surplus 110 volt, 150 watt heat sealing irons next. Cheapest alternative yet. But I sure wish they could be purchased new!
Thank you for wading through this long review!
Bruce Campbell
I also recommend putting a piece of teflon, parchment paper, or tape between the wire and the red guard. It helps ensure the wire doesn’t melt through the guard. Here is a picture of a teflon guard over the top screw. Yes, if it gets too close the masking tape scorches.
It is easy to adjust the temperature on a Top Flight model aircraft heat sealing iron. I suspect the other brand irons can be adjusted too, if needed.
When I got mine, it heated to about 198 degrees C (according to my innexpensive infrared thermometer – an oven meat thermometer works just as well). It was not hot hot enough to seal TPU fabric, a light stick, but not a full seal.
To adjust the thermostat, loosen the screw and remove the black plastic knob. Reaching down into the hollow brass stem with a fine jewelers screwdriver, turn the little screw counter clockwise to increase the heat. Try it in 1/8 turn increments, it doesn’t take much. My guess is that many of these will heat up just fine, and mine was just set too low at the factory. But it is easy to change. I really like the 165 watt heat source, and the added thermal mass these irons have. It greatly speeds up heat sealing larger seams!
I recommend everyone reinforce their Clover Iron before first use! I loved Chris Christy’s solution, above, but couldn’t find a 1/2″x 13 “Tee” nut. I bought some aluminum round stock to toss onto the lathe to make a supply for our classes, but after thinking about how much work was involved, I “discovered” 4 inches of thin steel wire proved to be much simpler, stronger, and anyone can do it!
Use thin steel wire (I used galvanized picture hanging wire, do not use copper because I think it’s too conductive) to form a loop up through the red heat guard, over the heating element, and back to the red handle. Gently snug the wire taught, but only finger tight – don’t over stress the tiny dimple spot welds at the base of the handle.
I also recommend taping a piece of teflon over the heating element to cover the large top screw. This screw gets hot and can melt through nylon if you lose track of it amidst your partially assembled raft!
Of the 25 or so rafts we’ve started at The Folk School Fairbanks, we’ve suffered 5 or 6 iron failures. If they were expensive, this would be a complaint. But frankly, they do the job fine for such an affordable (inexpensive) tool. Compared to household irons, Aircraft heat sealing irons, Dritz Petite, various soldering irons, and everything else we’ve tried, we always go back to our Clover Mini-Irons for the fine detail and precise application of heat that they provide.
Of course, I’m absolutely thrilled to hear Matt is bringing out new plans to allow the wider model aircraft irons to work!
Bruce Campbell
As I close my first packraft, I find I “Need” two new styles. Highest priority for my daughter, is a kids size raft with smaller 10″ or 9″ tubes. These would allow her shorter arms to better navigate the craft. Not reaching so far out past the centerline of the craft means less side to side swing and better tracking. The complexity of the tube designs, however, mean this has to be initially designed digitally. I am willing to buy fabric and make the first prototype. I’ll mail it to you and you cna test it too!
The second “need” is a tandem with a rowing frame. I don’t think I need any new plans. I can simply “stretch” a large plan set making tube section 3 longer and the floor longer. Plus I’ll make it symmetric by using two stern sections. The only real test work is implementing some of my ideas for stiffening the craft so it doesn’t fold or flop in section 3, and in the design of my rowing rig.
Waiting for your fabric to get thru customs! Then I’ll schedule more DIY Workshops. They are incredibly popular!
Bruce
I will try stitching loops to fabric next, like Olympic Mtn Boy above. In the image below are four flat tie down patches with simple slots cut for webbing. I tested a two layer version, with the center “tab” doubled by heat sealing a piece of TPU coated fabric to the bottom. This served to prevent it from being unevenly sealed to the raft creating a stress point, and it tested to failure at 120 lbs (50 kg). I added a third layer of two-sided TPU coated 70D ripstop I purchased from Rockywoods Fabrics (12.99/yd) and the third layer increased strength to over 150 lbs (70kg).
In the photo there are four test assemblies, the one with a flat brown webbing was too weak to bother testing.
I have been using two-sided 70D Ripstop nylon from Rockywoods Fabrics as a middle layer in accessory patches for tie points. It serves to increase the strength of the patch over a two layer patch.
I would not suggest it for a raft because the TPU coating peels off the nylon. The coating does not appear to be as well bonded to the fabric. I seem to recall the manufacturing of top-of-the-line TPU coated fabrics like DIY sells as requiring multiple rollings to impress the coating into the weave of the cloth. None of the samples I have received from Rockywoods, Seattle Fabrics came close to the much higher quality fabric DIY provides. Extrim Textil had interesting double coated and one sided fabric, but cost was European in scale and shipping unimaginable.
Any suggestions regarding heavier material or more abrasion resistant material for Skin on Frame (SOF) kayaks, canoes, or in my case a row boat? The heat sealing is most attractive and I could try ironing on a double bottom, but the bottom is the one the area least needing heat shrinkage. Most SOF builders use 8 oz. nylon or dacron, which is then painted. But the paint cracks and is contra-indicated if one is planning on folding up the boat and tossing it in an aircraft, for example. And while pack rafts are fantastic, they aren’t what I’m looking for. Thanks.
