First I want to say this site rules and is a wealth of info. Thanks to everyone who contributes and shares their experiences. I am also glad to see materials are available for sale here and will continue to buy what I need from here to show my support.
Anyone an expert on getting heat blankets all hooked up? I got a quote from MEI and they were by far the best deal going but they don't include controllers. I plan on using two blankets for top and bottom and here are the specs.
Qty. 2 6 1/2" x 82" Silicone Rubber Heater
120 Volt 1350 Watts 11.10 Amps.
Type J Thermocouple
Even after reading the heated press article and all the posts on the subject I realize that this is above my head.(business student turned carpenter) I don't want to buy the wrong stuff and/or get shocked. I don't know if two controllers are necessary. If someone could help me out with buying the right parts and hooking everything up I would gladly pay you for your time and knowledge. I am in Truckee, North Lake Tahoe. I have everything else ready to go and am anxious to build!
Thanks everyone
Hooking Up Heat Blankets
Moderators: Head Monkey, kelvin, bigKam, skidesmond, chrismp
Edit: Mike is selling a heating blanket in the yard sale forum, check that out too.
Ill try and take a pic of my heater and show what each component is, will take me a few days tho.
As for your blanket specs I'd say it looks good, just make sure the thermocouples are positioned so they are not under the ski, that will make an indent in your ski, so make the blanket wider than the ski and make sure the T/C is in the cnter of the long dimension so its outside of the sidecut radius of the ski.
Also, as for heating top and bottom, I only heat from the bottom and it seems to work fine. So if you wanna save money go for only one, also if you running two 11 amp blankets (11+11=22A) on a household circuit, make sure it can handle the current. A lot of outlets are 15amp so make sure your on a 25A breaker, atleast.
good luck!
Ill try and take a pic of my heater and show what each component is, will take me a few days tho.
As for your blanket specs I'd say it looks good, just make sure the thermocouples are positioned so they are not under the ski, that will make an indent in your ski, so make the blanket wider than the ski and make sure the T/C is in the cnter of the long dimension so its outside of the sidecut radius of the ski.
Also, as for heating top and bottom, I only heat from the bottom and it seems to work fine. So if you wanna save money go for only one, also if you running two 11 amp blankets (11+11=22A) on a household circuit, make sure it can handle the current. A lot of outlets are 15amp so make sure your on a 25A breaker, atleast.
good luck!
Thanks for the tips. I saw the blanket that Mike was selling but it is too short. Also, my setup is for single ski pressing. I didn't realize that the thermocouple could get in the way but I see from Mike's pics that it would definitely be a problem with a single ski setup running down the middle. I guess I'll need a wider blanket then and maybe have it run down the side? I have heard of mixed results with using one blanket so I think in the long run I want two. Maybe I'll try one to start and see how it goes. My mold designs have untraditional camber so I want to make sure I preserve it. One has zero camber from tail to toe piece with a rockered tip and the other has traditional camber throughout most of the ski and then slightly rockered tip and tail.
Pics of your setup would be great.
Pics of your setup would be great.
Hooking up heat blankets
does anyone put a piece of PE over the aluminium and under the ski. I have been spoiled with the hot melt glue as a locater and shift preventer, and the easy cleanup of epoxy on the plastic. Is temperature an issue with the plastic? Any tips on preventing shift with just alum. and cleanup would be welcomed.
Careful using embedded TCs
MEI makes a great product. Our blanket arrived within the quoted delivery date and functions exactly as expected. We had a type K thermocouple embedded within the blanket near one end. Had to carve out a groove in the wooded ski form to accommodate the bump where the TC is. Fortunately the TC bump protrudes on only one side of the heater blanket.
We placed a sheet of aluminum on top of the blanket to create our hot pressing surface. 5052-H32 aluminum alloy sheet stock is very common and 1/16" thick stock is easily shaped to conform to the curves of the ski press. The aluminum is one inch wider than our blanket so a few wood screws can be used to secure everything in place.
We attached a thermocouple directly to the surface of the aluminum and compared its measured temp with that of the embedded TC. Up to 140F the two readings match. However at higher temps the embedded TC measures significantly less! At 175F on the aluminum the embedded TC only reads 155F or there about. We do not use the embedded thermocouple for control feedback or else we will over heat our bases! Wish we did not purchase it and may remove it using an Exacto knife.
The thermocouples we use are “ready made” type K units from Omega intended for fast response surface temperature measurement applications. A bit of Kapton tape holds them in place, right next to the edge of the ski. Additional TCs are attached to the top sheet on skis being pressed to enable temperature measurements during the process. Its nice to have a dual channel Fluke thermometer.
So far we’ve had no issues with heating from the bottom only. The top surface of the ski receives plenty of heat transfered through the ski. At the thickest part of the ski we measure only 20F temperature delta top to bottom. We post cure bake at 170F for nine hours or so. Absolutely zero spring back in our skis. (using QCM epoxy)
I urge everyone to measure the actual surface temp on their base forms and see how accurate your temperature controller is, especially if using embedded thermocouples for process control.
-S
We placed a sheet of aluminum on top of the blanket to create our hot pressing surface. 5052-H32 aluminum alloy sheet stock is very common and 1/16" thick stock is easily shaped to conform to the curves of the ski press. The aluminum is one inch wider than our blanket so a few wood screws can be used to secure everything in place.
We attached a thermocouple directly to the surface of the aluminum and compared its measured temp with that of the embedded TC. Up to 140F the two readings match. However at higher temps the embedded TC measures significantly less! At 175F on the aluminum the embedded TC only reads 155F or there about. We do not use the embedded thermocouple for control feedback or else we will over heat our bases! Wish we did not purchase it and may remove it using an Exacto knife.
The thermocouples we use are “ready made” type K units from Omega intended for fast response surface temperature measurement applications. A bit of Kapton tape holds them in place, right next to the edge of the ski. Additional TCs are attached to the top sheet on skis being pressed to enable temperature measurements during the process. Its nice to have a dual channel Fluke thermometer.
So far we’ve had no issues with heating from the bottom only. The top surface of the ski receives plenty of heat transfered through the ski. At the thickest part of the ski we measure only 20F temperature delta top to bottom. We post cure bake at 170F for nine hours or so. Absolutely zero spring back in our skis. (using QCM epoxy)
I urge everyone to measure the actual surface temp on their base forms and see how accurate your temperature controller is, especially if using embedded thermocouples for process control.
-S
So I finally got a chance to put together some info on how our heater blanket is hooked up, if anyone is interested. It should be straight forward but if anyone has any questions lmk. This is for a 120V 15AMP blanket so as your power increases so will the specs on some of your parts. keep that in mind.
WARNING: Theres def enough power here to kill you, so be careful, this works for me but in case i made a mistake doing the diagram, verify everything before you power it up and maybe ask someone who knows about this stuff to look it over. BOTH BLACK AND WHITE AC LINES ARE HOT!
fyi one of the switches is double throw but doesnt need to be so ignore that, , jsut assume they are all single throw switches.
WARNING: Theres def enough power here to kill you, so be careful, this works for me but in case i made a mistake doing the diagram, verify everything before you power it up and maybe ask someone who knows about this stuff to look it over. BOTH BLACK AND WHITE AC LINES ARE HOT!
fyi one of the switches is double throw but doesnt need to be so ignore that, , jsut assume they are all single throw switches.