Quote from: mmattockx on October 12, 2025, 07:03:45 PM

Quote from: Watsonjay on October 11, 2025, 09:11:05 PMAs I already stated IM not an electrician. So using and adjustable voltage regulator plugged straight into wall then connected to heat strips wouldn't work? Assuming you need it on a big 40-60 amp breaker based off of what you guys are saying .Just trying to figure out a way to eliminate the battery charger/power supply that will burn out.

You need to convert from the AC of the wall outlet to DC out to the strips. The battery charger/power supply does this for you and insulates you from the mains power to prevent the electrocution Kirk mentions.

If you size the power supply correctly it will not burn out and will provide years of service.


Mark

IC thanks for the explanation. Now how to figure out what size power supply I need.

When I get back to the shop tomorrow I'll attach a link with my set up. I figure I get 200-300 bows out of a battery charger before it pukes..... So the cost per bow is about $1.50. I can live with that....  Kirk

Quote from: Kirkll on October 13, 2025, 01:24:49 AMWhen I get back to the shop tomorrow I'll attach a link with my set up. I figure I get 200-300 bows out of a battery charger before it pukes..... So the cost per bow is about $1.50. I can live with that....  Kirk

Seems like a good deal as long as you can keep finding the battery chargers.

Quote from: Kirkll on October 13, 2025, 01:24:49 AMWhen I get back to the shop tomorrow I'll attach a link with my set up. I figure I get 200-300 bows out of a battery charger before it pukes..... So the cost per bow is about $1.50. I can live with that....  Kirk

Have you ever measured the voltage and amps going out to the strips? If we know that then it would make shopping for a power supply much easier.


Mark

Nope.... The battery charger plugs into the 120 volt voltage regulator and has a 10 amp fuse. The voltage regulator has that fuse. I tried a smaller regulator with a 5 am fuse and it kept popping. So I know the battery charger is drawing over 5 amps.

The power going to the stainless steel strips changes with the amount of voltage the charger is getting. The AC voltage varies between 35-55 volts to keep the heat temp between 160-180. I have a heat probe thermometer with a high temp alarm that goes off at 185 degrees. I'll often crank the voltage up to 55 volts to bring the temp up quicker, then dial it back down a bit once the alarm goes off. Winter time and colder temps require a bit higher voltage too.  When I'm doing a set of limbs I get the voltage setting dialed in on the first limb, and just leave it there for the second limb so they both cure at the same temp. The battery charger has a timer on it. I typically set the timer for an hour. The temp slowly comes up to 160 in the first 20-30 minutes and then cooks for 30 minutes. 

I could get my volt meter out next lay up and check the DC voltage input if you like.

Kirk

Im liking that welder idea as you can usually set the voltage.

Quote from: Kirkll on October 13, 2025, 11:43:06 AMI could get my volt meter out next lay up and check the DC voltage input if you like.

Kirk

That would be very helpful. We can extrapolate the approximate amperage to the strips from the power the battery charger is drawing from there.


Mark

Quote from: mmattockx on October 14, 2025, 10:35:02 AM

Quote from: Kirkll on October 13, 2025, 11:43:06 AMI could get my volt meter out next lay up and check the DC voltage input if you like.

Kirk

That would be very helpful. We can extrapolate the approximate amperage to the strips from the power the battery charger is drawing from there.


Mark

The battery charger is drawing power from an AC voltage regulator between 35-55 volts. I can measure the battery chargers DC output to the strips though.

I'm afraid using a small welder isn't going to work unless it's an inverter design with a built in voltage regulator. Even then, those welders are such high voltage designed for welding, I'm uncertain whether a std voltage regulator would handle it without blowing fuses. But.... My knowledge of AC/DC electricity is limited.

Kirk

Quote from: Kirkll on October 14, 2025, 11:55:25 AM

Quote from: mmattockx on October 14, 2025, 10:35:02 AM

Quote from: Kirkll on October 13, 2025, 11:43:06 AMI could get my volt meter out next lay up and check the DC voltage input if you like.

Kirk

That would be very helpful. We can extrapolate the approximate amperage to the strips from the power the battery charger is drawing from there.


Mark

The battery charger is drawing power from an AC voltage regulator between 35-55 volts. I can measure the battery chargers DC output to the strips though.

I'm afraid using a small welder isn't going to work unless it's an inverter design with a built in voltage regulator. Even then, those welders are such high voltage designed for welding, I'm uncertain whether a std voltage regulator would handle it without blowing fuses. But.... My knowledge of AC/DC electricity is limited.

Kirk

Sounds like I may have to buy a couple of those battery chargers and save a couple as backup. Although as few of bows as I make one would probably last me a decade or two.

Here is a pretty detailed instruction write up i did some time ago.

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

........

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
............
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

Quote from: Watsonjay on October 14, 2025, 12:07:43 PM

Quote from: Kirkll on October 14, 2025, 11:55:25 AM

Quote from: mmattockx on October 14, 2025, 10:35:02 AM

Quote from: Kirkll on October 13, 2025, 11:43:06 AMI could get my volt meter out next lay up and check the DC voltage input if you like.

Kirk

That would be very helpful. We can extrapolate the approximate amperage to the strips from the power the battery charger is drawing from there.


Mark

The battery charger is drawing power from an AC voltage regulator between 35-55 volts. I can measure the battery chargers DC output to the strips though.

I'm afraid using a small welder isn't going to work unless it's an inverter design with a built in voltage regulator. Even then, those welders are such high voltage designed for welding, I'm uncertain whether a std voltage regulator would handle it without blowing fuses. But.... My knowledge of AC/DC electricity is limited.

Kirk

Sounds like I may have to buy a couple of those battery chargers and save a couple as backup. Although as few of bows as I make one would probably last me a decade or two.

Even cranking out 50 bows a year or more, these chargers last 4-5 years. i'm on my 3rd charger now. That's why i never pursued it further. This is a pretty user friendly system that is safe, and the stainless steel strips are bullet proof. They sand easily if you get epoxy on them without distorting the surface....

The only thing i didn't mention with my build instructions is to purchase enough stainless steel to cover all your forms. I leave the bottom one in the form and screw my limb stop on top of it and leave 3" hanging out of the form on each end to attach the battery charger clamps on one end, and easily clamp the other end together with needle nose vise grips.      Kirk

Quote from: mmattockx on October 14, 2025, 10:35:02 AM

Quote from: Kirkll on October 13, 2025, 11:43:06 AMI could get my volt meter out next lay up and check the DC voltage input if you like.

Kirk

That would be very helpful. We can extrapolate the approximate amperage to the strips from the power the battery charger is drawing from there.


Mark

OK... i just laid up a couple sets of limbs and took some voltage readings with my multi meter. The settings on the charger has 3 settings 12V - 10amp, 12 volt-40 amp, and a 12 volt- 200amp used for starting vehicles. i run my heat strips on the low setting 12 volt-10 amp. Then i turn the AC voltage regulator knob powering the charger up to about 45 volts and the amperes gage on the carger hits 50 amps.

Using the voltage meter at the heat strips, it is only showing 2.43 DC volts. It takes about 20 minutes to hit 160-170 degrees.    kirk