Press form straightening

[Kirkll]

I can take a few photos of my form if you like…

 but going back to your tests… after applying the angle iron brace. Did you cook it for 3 hours in a hot box and check it when it’s hot?   Steel expands and moves when it gets hot. If not… I would do that test…..

When I used angle iron on my bent form,  It was setting in my form vise and I was using heat strips and the angle iron never saw any heat. I haven’t used a hot box for cooking bows since 2008, and I don’t miss man handling the forms in and out, and cooking them to death.    I like my heat strips.    Kirk

[Kirkll]

Here are a few pictures of my 1.75" thick form using 1.5" heat strips and glass.  you can see how i used a router to bring ti down an 1/8"  and the holes are for heavy duty zip ties. The heavy ones hold really well.

https://photos.app.goo.gl/eXA2TqNLg2kvPHan8


https://www.amazon.com/XINGO-Strong-Plastic-Outdoor-Resistant/dp/B09WY1GVB6/ref=sr_1_1_sspa?crid=3IDTAR8D30GCP&dib=eyJ2IjoiMSJ9.PmrNJT-Q4naNYSvuFUe-1v0vhrhOCvpr_pvDHvNwGB984MDiepn8_T1SGHjSTD9ORa5_7giXG1l8wo8IyqDAFuzVPS5S6o65dMEGjwubxXPuRGbC-ZHA0grfW7UvvfRqrN8_JBXgQRAlLS8-0ehTKaWI8AZG3MBHutMMZKRZosB4RfPb950DP8JmrFJDr6fWjG7T-q587IQy7cuUJraW1PzmVJtxT6f1DZj40Jtobkk.XhqgdF2okhpCfbPIn9lgE4VQl2XpLsyR0KIb360u_m8&dib_tag=se&keywords=heavy%2Bduty%2Bzip%2Bties&qid=1740709187&sprefix=heavy%2Bduty%2Bzip%2Bties%2Caps%2C179&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&th=1

[TrenchFoot]

I can take a few photos of my form if you like…

 but going back to your tests… after applying the angle iron brace. Did you cook it for 3 hours in a hot box and check it when it’s hot?   Steel expands and moves when it gets hot. If not… I would do that test…..

When I used angle iron on my bent form,  It was setting in my form vise and I was using heat strips and the angle iron never saw any heat. I haven’t used a hot box for cooking bows since 2008, and I don’t miss man handling the forms in and out, and cooking them to death.    I like my heat strips.    Kirk

Havnt tested anything yet, not gonna be ready to even dry run for at least 2 weeks
You got a link to these heat strips you use by chance?

[Kirkll]

here ya go...

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 75” 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

[TrenchFoot]

That’s awesome, thanks for that definitely wasn’t expecting the full Monty. ever seen someone use a bench top tester instead of a battery charger though? Might not have enough voltage on mine, 60v 10a for a one piece form

[Kirkll]

I've talked with a few guys that recommended using a buzz box welder rather than the battery charger. But i'm not sure how i would set that up.

My system has worked well for many years and i have got between 200-300 bows out of a battery charger and i'm on my 3rd one now.  So for a buck a bow investment, i can live with it.

I played with a few home made heat strips using low voltage @ nichrome wire that worked for awhile but that was years ago. and.... they didn't hold up well.

The stainless steel strips are bullet proof. You can easily sand epoxy off them without deforming the steel when you get a leak in your plastic wrap. I've got to the point where i prefer a 3 mill painters plastic over that thin stuff. But i'm using the thin stuff right  now because that's what i got. I quit using masking tape on my limbs 15 years ago.  Just wipe the glass down with lacquer thinner before wrapping them in plastic, and it works excellent without cooking masking tape to your glass. The plastic comes right off easily.

Kirk

[TrenchFoot]

well I think I'll  give a shout out to just about everyone in this thread and say, everyone was right about something. I went and got some lvl over the weekend and took the lessons learned off of my first attempt and have a full form ready but for mounting the hardware. the old form came in handy for patterns and the whole thing that took me a couple weekends of sanding and tweaking to get to a place i was happy with condensed down to 4 hours start to finish. thanks everyone

[Kirkll]