January 2, 20242 yr 1 hour ago, 4DThinker said: Yep. Without a vent you've got a pressure cooker. I don't think it could get to the level of pressure cooker But the steam does need to circulate through to get to the high temps it needs and for good moisture to flow as well.
January 3, 20242 yr Author Popular Post I watched Engals coach building videos a lot and he uses pressure and vinegar when bending coach parts. It's the temperature that makes the lignen more flexible as far as I can figure out. I don't plan on having pressure but might try the ammonia we'll see. I think I'm just going to test it without trying to make it water proof. JT
January 3, 20242 yr Author On 1/1/2024 at 4:48 PM, John Morris said: Great looking set up there JT, never thought of that design. I am sure ya know, but not to sealed, the steam needs to escape. Do you need a thermometer? I did, I had to wait for the temp to rise to a point before I inserted my pieces into the box. I remember it had to be at least 180degrees but I think around 220 was more preferable, again, you know all this already since you been building yours, just thought I'd throw it out there though. Thanks for the photos. I don't think you can get the steam temperature above 212 unless you have pressure. JT
January 3, 20242 yr 3 minutes ago, jthornton said: I don't think you can get the steam temperature above 212 unless you have pressure. Ya you right JT, just checked the instructions on my steamer and it states 212 max.
January 17, 20242 yr Author Did a test of the steam box today and it worked well. I just kept flipping the piece of plywood over as it took up. The first bending test without any strap ended like I expected and split out. The 1 3/16" radius is real small for steam bending wood so I used some 1/8" test strips. The second attempt almost worked with a bit of plumbers strap and two 1/4-20 hex bolts as stops. One side did pop out and I somewhat expected that to be an issue without any handles on the strap. You can see the left side popped out from the bolt head. My next test is to make some handles for the plumbers strap that overlap the ends of the piece to bend so it can't pop out as easy. Over all I'm happy with the steam box and the progress I'm making. JT Edited January 17, 20242 yr by jthornton
January 18, 20242 yr Author I took some scrap purpleheart and made the material stops and used scrap red oak to make the handles. The plumbers strap allows me to change the length within reason. I did figure out the spring back is approximately 15° so I'm making a new form to test that out as well.
January 18, 20242 yr Will this help? https://www.woodweb.com/knowledge_base/Calculating_Springback.html
January 18, 20242 yr Author I had a bit of a failure on my steam box just as I finished steaming the last piece... looks like the inside must be sealed to stop the wood from taking up and expanding. That was Titebond III glue that I used... JT
January 18, 20242 yr Author 15 minutes ago, lew said: Will this help? https://www.woodweb.com/knowledge_base/Calculating_Springback.html That's for gluing up strips but it's handy to have for sure when I do that. JT
January 18, 20242 yr Popular Post 11 minutes ago, jthornton said: I had a bit of a failure on my steam box just as I finished steaming the last piece... looks like the inside must be sealed to stop the wood from taking up and expanding. That was Titebond III glue that I used.. Mine did the same thing JT. I just screwed the heck out of it back together.
January 18, 20242 yr 18 minutes ago, jthornton said: That's for gluing up strips but it's handy to have for sure when I do that. JT More than you ever wanted to know- http://www.woodbodger.com/wp-content/uploads/2012/05/Bending-Solid-Wood-To-Form.pdf
January 18, 20242 yr Author Thanks Lew that's a lot of info. Here is another test piece this time 3/16" thick... I was amazed how much more pressure was needed to bend 3/16" compared to 1/8". JT
January 20, 20242 yr 40 minutes ago, DAB said: i think i'd just redesign that part to avoid bending..... Before we had CNCs to play with the students that presented designs that we knew would be more challenge than fun we always told them to go back and redesign. Simplify, re-think, but don't drop your aesthetic goals in the process. Usually the students came back with much better ideas. It was "easier" after the initial critique where the impossible aspects of their design were pointed out. Once I had a CNC that had the potential of jigging up for angled and compound angled cuts I more often encouraged the previously impossible to keep me interested in how their technical challenges might be done. 4D
January 22, 20242 yr Popular Post There used to be a guy who did a lot of steam bending and laminate work. He would cut the wood down thinner and put it into clamps and then let it dry but he would use a lot of thinner pieces to get the curves he needed. Then laminated up clamp it together let it set and then shape it.
January 26, 20242 yr On 1/22/2024 at 11:49 AM, DRAGON1 said: There used to be a guy who did a lot of steam bending and laminate work. He would cut the wood down thinner and put it into clamps and then let it dry but he would use a lot of thinner pieces to get the curves he needed. Then laminated up clamp it together let it set and then shape it. That'd be me. I'm still here. 😊
January 26, 20242 yr Author Popular Post @lew that's crazy insane bending. steam box has relaxed back into shape so another test tomorrow I think. JT
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