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Main Boards => The Bowyer's Bench => Topic started by: dbeaver on December 15, 2023, 10:55:10 AM
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Alright lets weigh it out. I love the good old stability of a massive chunky form with fat steel straps and the hunky fasteners. Its what ive seen most and what ive used exclusively. Id love to hear from guys who have topless forms that have moved away from the standard hardware. How are you glue ups compared to when you were making a two sided form, what do you like better, whats to watch out for?
Im about to make at least one new form and am ready to try anything even if its my tried and true classic method. (Kirk im willing to build a stainless conduction bed form on hinges too, im just behind on my research for getting a consistent slow temp rise to peak and maintain peak temp through a dc regulator and the possibility of super easy temperature probes and cheap circuitry)
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definitely keep me in the loop on any new developments on heat strip power source. These battery chargers only last so long before needing to be replaced.
I’ve seen a lot of topless form ideas that should work fine with or without an air hose. Using a lot of air pressure is not really necessary, but …..getting an even pressure along the whole surface is important. For that reason I do like the fire hose method.
I’ve seen guys using pegs along the form, and bicycle inner tubing that came out with beautifully even lay ups. But they were very precise in their procedure working from the center outward in both directions. I’ve seen the same peg system used with 2500# heavy mule tape and an air hose…..
I think a vacuum system could work theoretically, but I have very little experience with the process, and doubt it would be a cost effective solution.
Kirk
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The form I made was early summer. It had a top. Either way works. With the price of good plywood maybe cheaper top less, but them you have to buy steel rod or wood dowell. And mule tape
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You can get 100 ft. of the mule from Amazon for 17 bucks.
1/2" steel rod, get the 20 ft from some steel supply, should be less than 20 bucks, I bought three 36" from tractor supply but should have bought the 20 ft. my bad.
I like the topless form for long bows , R/D and working recurves.
I have a short 50" static recurve that is hard to get good results but I worked out the bugs.
This short Korea bow is 50" (not the static I was talking about) has 14" of reflex so the 2 piece form would not work in my hot box, so the topless worked fine. This is the form, and the first time I did a topless form.
(https://i.imgur.com/qT6DX7c.jpg)
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I use topless Forms for Prototypes and Bows, that i don't build that often.
Saves space, but it's inconvenient. Takes a lot more Time, than using a Form with top.
For Heat, i use Silicone Heat Strips.
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all good information gentlemen, some ideas to chew on
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Max how thick of a pressure strip you using?
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.035
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The form I made was early summer. It had a top. Either way works. With the price of good plywood maybe cheaper top less, but them you have to buy steel rod or wood dowell. And mule tape
No need for mule tape. It's a "solution" that has become popular due to you tubers. I use a couple dollars worth of paranoid with completely satisfactory results. One of my forms has 7/16" oak dowels for pegs and has held up fine. 3/8" oak gave me one broken peg late enough in.the cure to not matter. That and other 3/8" pegs were converted to 3/8" steel.
I go to 65# on mine.
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I would expect that with snug holes wood dowells would be fine. Para cord also.
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The form I made was early summer. It had a top. Either way works. With the price of good plywood maybe cheaper top less, but them you have to buy steel rod or wood dowell. And mule tape
No need for mule tape. It's a "solution" that has become popular due to you tubers. I use a couple dollars worth of paranoid with completely satisfactory results. One of my forms has 7/16" oak dowels for pegs and has held up fine. 3/8" oak gave me one broken peg late enough in.the cure to not matter. That and other 3/8" pegs were converted to 3/8" steel.
I go to 65# on mine.
It's all good until you come in the next morning and find a broke wood dowel and screw up a good bow.
The mule tape is flat and wide (1/2" or so) and the steel rods don't break.
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Kenny had a small build along for a simple American longbow he used mule tape and routed slots into the bottom of the formboard so the mule tape would wrap around fully not weave back and forth pin to pin. With enough routed slots and plenty of cheap paracord you could get as much or little coverage as you'd need. See any disadvantages with something like that? I think I may stick to the standard hardware for my next form. But it's good to hear everything play with ideas
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The form I made was early summer. It had a top. Either way works. With the price of good plywood maybe cheaper top less, but them you have to buy steel rod or wood dowell. And mule tape
No need for mule tape. It's a "solution" that has become popular due to you tubers. I use a couple dollars worth of paranoid with completely satisfactory results. One of my forms has 7/16" oak dowels for pegs and has held up fine. 3/8" oak gave me one broken peg late enough in.the cure to not matter. That and other 3/8" pegs were converted to 3/8" steel.
I go to 65# on mine.
It's all good until you come in the next morning and find a broke wood dowel and screw up a good bow.
The mule tape is flat and wide (1/2" or so) and the steel rods don't break.
Not promoting wood dowels. To the contrary, I stated that I've changed all but the 7/16" oak. Another reason for those oaks to hold up is I wrap very close to the form. Move your loops out and away and the leverage game is on. The other factor with that form is the pegs are closer together.
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For some, this wouldn't matter, but topless allows both major and minor changes in length shapes of risers. On one ASL form I've varied riser length from 13 to 17 inches. Only that changes is pressure strip(s).
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Kenny had a small build along for a simple American longbow he used mule tape and routed slots into the bottom of the formboard so the mule tape would wrap around fully not weave back and forth pin to pin. With enough routed slots and plenty of cheap paracord you could get as much or little coverage as you'd need. See any disadvantages with something like that? I think I may stick to the standard hardware for my next form. But it's good to hear everything play with ideas
I would put the pegs in it!! What a PITA getting the spool of tape around it without dropping it!! :biglaugh:
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Yeah Kenny I've done the round and round for overlays and a hose and it's a pain :thumbsup:
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When I use the topless method I try to eliminate the parts of the process which are a PITA. Managing the mule tape is the biggest challenge. I start with the air hose just slightly inflated. I have two lengths of the tape that have been repeatedly. Starting on the center pin I wrap the tape out to about the 4th or 5th one and anchor the tape there using a spring clamp. Then back to the center pin, on opposite end and using the other length of MT, wrap it out to 6 or 8 pins and clamp it there. Then back to the other side to complete wrapping the hose and finally wrap the other end. Now it’s the time to check that the hose is centered along the entire form - this is important. This form in the photo is only 1 1/8” wide which presents its own challenges regarding centering the hose. I keep thinking I need to find a smaller diameter hose … because the hose diameter is larger than the thickness of the form the tape wants to slip off the pins before the hose is pressurized. One wrap of friction tape around each pin now prevents the tape from slipping off.
I store each length of tape wrapped flat on separate HD cardboard tubes. When it is time to use the tape, I put both tubes over a section of 3/4” pipe which is loosely anchored on the bench parallel to the form. The weight of the pipe allows the tape to unroll only when pulled on, so this eliminates dropping rolls or coils. Also there are no unplanned stops to straighten tangles or knots. So to have this topless method go smoothly it helps to have a clearly practiced procedure in mind.
I thought I would give the topless approach a go but I find it is more time consuming than using a two piece form and I will go back to that method soon. The added hassles are not worth the lesser labor of not making an upper half to a form. The one exception I can think of is, if you just want to do a one-off bow. Then topless might make sense. Just my opinion based on my experience.
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Such good information, thanks everybody I heard from most of those who I expected would have experience to share and I appreciate the responses
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I tie a overhand loop knot in the center of the mule tape. it give's me a starting point that is anchored.
I start in the center too.
https://www.youtube.com/watch?v=mvm8yI8BRU4
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PFFT think I will stay with tops.
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For some, this wouldn't matter, but topless allows both major and minor changes in length shapes of risers. On one ASL form I've varied riser length from 13 to 17 inches. Only that changes is pressure strip(s).
I have a one piece long bow form with a hinged top that i just over sized the center section on top for using different riser configurations on. I just strap everything down with heavy zip ties, put the hose over it, close the form and put two hinge pins in it. takes about 10 minutes tops. For different sized risers i just use wedges over the hose in the belly ramp areas. No muss, no fuss.
BTW....I do throw a pipe clamp in the center instead of adding more straps..... You guys can have your topless forms...
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I haven’t made as many bows as a lot of guys that are commenting here, and I guarantee some of them have forgotten more than I know about bow building. Having said that, I changed my forms to topless about 5 years ago and have never looked back. I use metal pins and mule tape. I’m pretty careful during a build, and there’s definitely a bit of a learning curve, but I’ve not had those gaps at the fade-outs that have ruined a few bows when using the 2 piece form. Yes, it takes a little longer but smooth-on gives me plenty of time. It works for me but your results may be different
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:shaka:
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I use topless Forms for Prototypes and Bows, that i don't build that often.
Saves space, but it's inconvenient. Takes a lot more Time, than using a Form with top.
For Heat, i use Silicone Heat Strips.
Hi B-JS,
you can publisch a link to thoses silicon heat stripes?
Thanks in advance
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Got them from China.
https://keenovo.store/collections/standard-keenovo-silicone-heaters
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Got them from China.
https://keenovo.store/collections/standard-keenovo-silicone-heaters
Thanks a lot, I have found before something similar but not the sizes i need. This supplier hits my needs!!!
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Got them from China.
https://keenovo.store/collections/standard-keenovo-silicone-heaters
I'm curious how many bows you get out of these heat strips, and if you use them top and bottom of the limb in the form?
I used these many years ago made in USA and the longevity and warranty on them sucked. I actually sold them on my website for awhile until the company quit honoring the warranty. I had a lot of failures with these type heaters. Some would last longer than others with no pattern for longevity. Kirk
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I have 2 Sets for Recurves and Longbow (45mm and 40mm)
The 45mm was allready used, when i got them.
The 40mm was bought there.
The 45mm Shows some wear, and a may replace IT in a couple of months.
I have them 3-4 years now.
But i don't build several bows a day/week.
So If used heavy duty, they may Not hold forever.
But they consume WAY less Energy than a heatbox.
I use one one both sides of the Form.
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When you say “both sides of the form” does that mean they are applied to the form after the top and bottom of the form have been bolted together? If that’s how you do it, how are they held in place?
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When you say “both sides of the form” does that mean they are applied to the form after the top and bottom of the form have been bolted together? If that’s how you do it, how are they held in place?
Next to the glass on both side.
German translation I guess did not come threw
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So top and bottom, in the form, silicone under bottom glass and silicone over the top glass? Just trying to make sure I have the right picture of the process.
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Well, on both Sides of the bow IN the Form.
No native english speaker, sorry. :biglaugh:
From bottom to top.
Bottom of Form/1mm Rubber/Heatstripe/bow(wrapped in stretch-foil)/Heatstripe/1mm Rubber/Hose/Top of Form.
Held in place with washers at both Sides If the Form an some Straps for Initial Fixation before Hose and Pressure are applied.
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So top and bottom, in the form, silicone under bottom glass and silicone over the top glass? Just trying to make sure I have the right picture of the process.
:thumbsup:
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When we were using those silicone heaters years ago, everyone was using aluminum pressure strips between the glass and the heaters above and below them. I also used a second Formica pressure strip between my air hose and heater to protect the silicone heater.
It’s actually not a bad way to go for a hobby builder. Sure beats cooking your forms to death in a hot box, and wrestling bow forms in and out of them. Kirk
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Bodnik uses the same for their Bows.
I think they are a bit above Hobby-Level in Numbers.
But i don't know, how much bows they get out of one Set of Heat Stripes.
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Thanks for the further explanation B-JS!
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How did you regulate them, Kirk?
On/Off or with a voltage/Power-Regulator?
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How did you regulate them, Kirk?
On/Off or with a voltage/Power-Regulator?
The simplest way to regulate them was a Rheostat. I used a simple dimmer switch wired in tandem with an AC outlet. But......Having an accurate probe thermometer was a must. Different length heat strips required different settings.....
The issue i had with them was durability. Using these under pressure requires a perfectly smooth surface and smooth pressure strips. I believe they use a small gage nichrome wire system embedded it the silicone.
Your mileage will vary a lot
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I was hearing the heat strips were not lasting long enough.
Never used them myself
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I don’t use them either.
The idea of having something spongy under and over the bow for the glue up makes me nervous.
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Actually those silicone heaters were made with pretty dense material used to cover the heat elements. there wasn't anything spongy about them.... But... i used aluminum pressure strips against the plastic wrapped glass.
I built my first couple 100 bows using them, before i went to the battery charger system with stainless steel strips. I haven't used a hot box system since 2007-2008.
I think there should be someway to use a flexible nichrome material for heat strips with a different type adjustable voltage regulator to regulate the temp. i'm only getting about 200 bows out of a battery charger before it pukes on me... Its quite safe using this system, but it's definitely battery charger abuse... But the stainless steel is very durable and you can sand the glue boogers off them when needed. :biglaugh:
:Kirk
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This is one reason I like a topless form.
The top of the form when the air hose is full could warp/bend the form while it cures.
(https://i.imgur.com/u2YUToK.jpg)
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Actually those silicone heaters were made with pretty dense material used to cover the heat elements. there wasn't anything spongy about them.... But... i used aluminum pressure strips against the plastic wrapped glass.
I built my first couple 100 bows using them, before i went to the battery charger system with stainless steel strips. I haven't used a hot box system since 2007-2008.
I think there should be someway to use a flexible nichrome material for heat strips with a different type adjustable voltage regulator to regulate the temp. i'm only getting about 200 bows out of a battery charger before it pukes on me... Its quite safe using this system, but it's definitely battery charger abuse... But the stainless steel is very durable and you can sand the glue boogers off them when needed. :biglaugh:
:Kirk
Kirk. Could you explain this battery charger system you are talking about.
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Actually those silicone heaters were made with pretty dense material used to cover the heat elements. there wasn't anything spongy about them.... But... i used aluminum pressure strips against the plastic wrapped glass.
I built my first couple 100 bows using them, before i went to the battery charger system with stainless steel strips. I haven't used a hot box system since 2007-2008.
I think there should be someway to use a flexible nichrome material for heat strips with a different type adjustable voltage regulator to regulate the temp. i'm only getting about 200 bows out of a battery charger before it pukes on me... Its quite safe using this system, but it's definitely battery charger abuse... But the stainless steel is very durable and you can sand the glue boogers off them when needed. :biglaugh:
:Kirk
Kirk. Could you explain this battery charger system you are talking about.
When I get back out to my shop pc I’ll post an attachment explains how I built the system and links to suppliers for stainless steel strips. I don’t have access on my iPad. Kirk
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Bow Press Heat Strips
This system for building laminated fiberglass bows is the best I’ve come up with in 15 years. But…. There are a few details in getting set up and operation that needs to be documented here.
First of all you will need 22 gage 304 stainless steel strips that are used both top and bottom in your form. I had mine cut to 1.5” and 1.75” widths and 72” lengths prior to shipping. You want these “Cut” not sheared too. You want enough length on these strips to have about 3” sticking out of each end of your form. I purchased enough strip material to have a pair for each bow form I use. I put the bottom strip in the form and attach it permanently and leave it there. Here is the link to my supplier:
https://www.stainlesssupply.com/order-metal-online/docs/g1c1045s1ss0p0/304-stainless-steel-sheet-4-finish.htm
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Next you will need a fairly large battery charger that has manual settings. These are difficult to find now with all the electronic safety over ride models they have available now. The automatic ones with circuit boards will not work for what we are using this for. Look at the photo of the charger I use.
https://photos.app.goo.gl/SxemPLaXwT66Ad6B6
This one below will NOT work
https://www.amazon.com/Schumacher-SC1353-Wheeled-Battery-Charger/dp/B07BVFGVQ1/ref=sr_1_21?crid=2O3KDCXISAPSA&keywords=battery+charger+automotive&qid=1642610980&sprefix=battery+charger%2Caps%2C399&sr=8-21
This manual wheel type below is what you want.
https://www.amazon.com/Schumacher-Manual-Wheel-Charger-Engine/dp/B08PQ28NPB/ref=sr_1_27?crid=3G7TN835WBGWC&keywords=large+battery+charger&qid=1642611374&sprefix=large+battery+chargers%2Caps%2C195&sr=8-27
OK….. once you have your brand new battery charger, you need to tear it apart and rewire the cooling fan. There is a small fan that runs on 110 volts that needs its own power source. Why? Because the battery charger is going to run off of the voltage regulator at a reduced voltage….. That reduces the voltage to the cooling fan too, and slows it way down if it doesn’t have its own power source, and….. it WILL over heat the fan and the charger, and eventually burn up…. Trust me on this one….. The only other option is to attach another fan to the battery charger body that blows cool air into it while its running. This is real important.
See the extra lamp cord I have plugged in to 110 and notice the battery charger plugs into the voltage regulator.
https://photos.app.goo.gl/T5qa6trSMqEaEx7J8
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Next you need a voltage regulator. This will adjust the temperature of your heat strips. Get the “10 amp” version…. The 5 amp model will be popping fuses all the time. This is what you want.
https://www.amazon.com/LVYUAN-Variable-Transformer-Regulator-110V-120V/dp/B082KYKP9P/ref=sr_1_6?crid=3PF7ACKQJN850&keywords=voltage%2Bregulator%2B120v&qid=1642611136&sprefix=voltage%2Bregulator%2Caps%2C141&sr=8-6&th=1
https://photos.app.goo.gl/sKNmmsB6kfPizvtP9
The last item needed is an accurate thermometer. There are many different types of probe thermometers out there, but I like this one the best because it has a high temp alert built into it…. I can set the alarm for 180 degrees and if the strips get too hot it alerts me and I can turn down the voltage a bit.
Here is what I use. https://photos.app.goo.gl/ZyzWkz1hz3vHBVfs5
OK….. so now you have all your parts and pieces and equipment, and have a set of heat strips ready to go….You install one in the bottom of your form, wrap your bow laminations in a thin painters plastic , and put them directly on the heat strip. Then put the other heat strip directly on top of the limb and use zip ties to hold everything tight to the form. Take care to align the heat strips so they are the same length coming out of the form, and use a small clamp, or needle nose vise grips to clamp the two heat strips together on one end, and the battery charger clamps red on one strip, and black on the other. Be sure these two do not touch each other. I separate them with a scrap piece of wood lam.
Next is your air hose and button up your form. Then slip your temp probe in between the air hose and the top of the heat strip and give that hose about 20-25# of pressure. Check your lamination alignment and let it set 60 seconds before going up to 50-60#s of pressure…. No more than that is needed. I’ve laid up limbs completely using 25# before and they came out fine…. That was an ooops though… Recurve limbs need that extra pressure.
Now turn on the voltage regulator and adjust the voltage to about 40-45 volts. That is a good place to start for 2 -36” heat strips…. One piece bows with long heat strips will need more voltage, and going from 1.5” width to 1.75” width needs adjustment too. You will have to do some dry trials to establish the right settings. But what you want is the temp to slowly rise to 160 degrees in about 30 minutes and stay between 160-180 for another 20-30 minutes. I set my timer on the battery charger for one hour and its perfect every time once I have my voltage setting established. Btw…. Hot or cold temp in the shop can effect the setting a bit too.
The only other thing of note is to wait until the temp cools to 90 degrees before removing them from the form. You could easily lay up 3 sets of limbs per day with this set up.
Here are some of my bow forms I have set up.
https://photos.app.goo.gl/1ihdPa5SExkyBCma7
Kirk