As some of you might know I build skis. Right now one of the the most important limiting factors is the pressing time. As I use a vacuum press at RT, the de molding time of the epoxy I use is 18h ish. The best solution to go faster would be a combination of hydraulic press and an epoxy curing at 80°C but the hydraulic press is too expensive and take up a lot of space. Therefore I am first trying o decreasing the curing time of my current setup by increasing the temperature from RT to °30 (the maximum allowed for teh epoxy I amusing which will still cut the de molding time in half.
The idea is to insert a blanket between the mold and the steel sheet which I use as the base for layering.
I have this blanket. The problem is the controller is crap and fluctuates too much. My understanding is that I could use a PID (and eventually thermocouple directly on the steel sheet). As my electronics knowledge is pretty basic, would this be an easy operation? Anything I should consider in advance? Suggestion an a relatively chap PID?
Maybe use a 120v 3d printer bed heater circuit (ssr) and a thermistor with a 3d printer control board. Maybe pick up an old ender off fb market for $40 and experiment with 24v bed or extruder heating. I know with both marlin and klipper you can run the pid tune and get very good precision and minimal overshoot. The critical part of your operation will be sensor placement to ensure accuracy of the temperature at the correct location.
I would always suggest something from ESPHome for basic electronics knowledge. All you would need is an ESP32, temperature sensor, and a relay. Here is a good breakdown:
Have you tried faster curing epoxy resins? I have experimented with different Part B activators to speed up the curing process with my paddle boards with some really good success. I can use the fast or slow harder depending on level of application and shop temperature. I use entropy resins and I know their compression molding epoxy (if you use that for skis) has slow and fast hardeners available.
Also, have you considered making a curing oven? Could get you to that curing temp easier.
Thanks for the video I will look at it. I like the idea.
For the epoxy I use Sicomin and in particular Greenpoxy 56 with the fastest hardener. I am going to reach out to them to seek advice. I see they have new Greenpoxy 80 but I cant find the documentation. As tehe philosophy of my ski is to use green materials I am somewhat limited on the epoxy I can use.
Oven could be an option but right now I am quite limited in space. I could potentially conceive a box that I put on top of the mold. Have you experience with this kind of setup?
For epoxy I have the same thoughts. The Entropy is something like 70% plant based and made locally in Michigan for me.
I use laminating epoxy for most of my paddle board projects, they are too big for a vacuum bag and fragile for compression. I have made an oven-type box once and it was pretty straight forward, back then I had a thermostat AC switch that would turn the chicken light on an off at temp. I also used the same silver bubble wrap insulation that is in the video and it is pretty magical to keep in the heat, I also used it for the inner insulation on my sauna.
In one year or so I am going to have more space and I will reconsider my options but most probably I will try to switch to a hydraulic or pneumatic press with the heat blanket.Therefore going already ahead with the blanket control makes probably more sense.
I reached out to Sicomin…let’s see what they suggest.
