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So my temp controller system has bit the dust. I've been limping along without it by plugging and unplugging the blanket as needed in a fun little ballet timed with the bends. Usually I plug the blanket into an extension cord and yank th extension from the wall as needed. Last night I plugged the cord in first, and then the blanket, and was treated to a dazzling light show as the blanket's plug arced with the extension and sent sparks flying everywhere. Quite...exciting.

Taking the side out of the mold, I noticed it had burned the paper, no real surprise.

What did surprise me was that apparently it burned a few hole right through the slats as well. I didn't think it could do a thing like that.



Zot!

No particular point, just an amusing anecdote:)

YIKES, Hope you got a clean set of drawers!

I just thought it interesting that it punched through steel like it was nothing...

That should be very replaceable.
Bet the light show was fun too.

I had a 600 amp 540V circuit box that was invaded by ants. They seemed to like the current home and invited all their friends and family and before long it turned in a giant arc welder frying not only the ants but melting the aluminum bus bar sending sputtered aluminum throughout the power box and shutting down my service. I'm sure yours felt just as bad but mine cost $8000 and shut down 4 businesses for the better part of a week.

Always good to check your stuff every so often

Tim

Well, mine is rather anticlimatic in comparison...

That sort of damage to slat-thickness stainless would seem to me to be more than just the damage done by a shower of sparks from the arcing of a plug contact. Have you checked your blanket for any wear-throughs/burned/crumbled silicone? Given that the damage appears to be at the end of the blanket (where the connections to the heating elements reside), a short from blanket hot to neutral/ground or blanket hot to an earth ground on the bender would do a nice job of arc welding on your slats.

Blanket digital programmable temperature controllers sound very handy, but could you get by with a $16 router speed control from Harbor Freight for controlling at least the 'off/on' function? Our bending is done knowing the temperature rise of a wide-open (speed control rocker switch 'ON') 5 watt/square inch blanket is just about perfect for starting the waist down as steam becomes evident in both upper and lower bout areas, and - once the bend is briskly completed - going to the 'Variable' position on the switch and a 2/3'd setting on the rheostat of the controller for drying.

If nothing else, perhaps an appropriately rated switch in a grounded enclosure in line to do the switching duties?

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When I was using my blanket (I'm moving back to a hot pipe for a while), I just used a dimmer switch with the right specifications for this load. It worked great; nothing exciting ever happened.

I was thinking the same thing. Mine did that too. Take a close look at your blanket. Or, this will happen again.

We have the benders wired with a timer (mechanical 0-60 minute) and separate outlet box - adding a dimmer switch would be easy with that set-up. If not interested in a hard-wired solution on the bender, maybe either the router speed controller (which is just a 15A rated rheostat ad on-off-variable switch) or an in-line switch and 1200 watt rheostat packaged in an appropriate project box or two-gang box would work.

On another topic, we've been successful in repairing damaged blanket facings and even one crumbling area with high temperature RTV silicone - the orange Ultra Copper material from Permatex (# 81878) can be applied to a blanket in worn areas, and even in very thin films, adheres well. For those using silicone heating blankets without an upper slat to reduce wear, the material can be applied to the upper surface wear areas for what appears to be a long-term anti-wear fix. Our oldest blanket is over 12 years old and has two repairs that are well over 8 years old (based on the in service and repair dates on the control tag) - no delamination or bubbling of the repaired area.

_________________
For the times they are a changin'

- Bob Dylan

For some of my tools where I want the on off switch to be closer at hand I buy a little on/off switch that plugs into the end of an extension cord and allows the plug end of the tool to be plugged into it.

www.lifeandhome.com/products/leviton-c2 ... ggQAvD_BwE

"Pulling the plug" while it is under load burns out the plug and the receptacle, causing a little arc each time, that creates a layer of resistance on the surface of the contacts (black stuff). I try to avoid doing that (still do sometimes).

That’s great information, Woodie. Indeed my main blanket is looking a bit dodgy at this point and this sounds like the perfect fix. Just placed my order online for a tube of this stuff


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Methinks I need a brand new setup. It's been ~100 bends since it was new so it's about time.

Also, maybe adding a third slat on top might be a good idea...

Reminds me of the time in the electric circuits part of my high school physics class that my lab partner and I put on a nice display of sparks from our circuit board (110 V) and tripped the circuit breakers for a whole wing of the school. Famous last words "Are you sure it's ok to close that switch?".

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

Definitely anecdotal.

Andy

Thank u Woodie for that great tip. Tired of sticking electrical tape to my blanket. And I will not be adding the third slat. So this is perfect for me!

Edited

Do you mean Woodie perhaps?

I’ve always been a 3-slat guy, but I’ve wondered if that 3rd slat is killing my ability to feel what’s going on, especially with the difficult-to-bend ebonies. So, if the mold itself is solid (most of mine aren’t, but that could change) does it make any sense to lose the bottom slat? I’m wondering what Michael Greenwood does in that video he produced last year — something tells me that he eliminated the bottom slat, but I’ve got to view it again — I could be in the potato. I know for sure that Kent Carlos Everett bends without a top slat, despite the wear and tear on the blanket.


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Yes. Sorry

Tim, I’m in that camp. Extra slat is more to deal with, less visibility. Extra force for bending. I decided it was worth trading wear on blanket for this. I’m stoked that there is a way to repair the blanket.

looks like the wire on the blanket got exposed and shorted out on the blanket

happened to me once

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I went back to review the video carefully and came away with a partial answer. He is bending thin pieces for a 3-ply lamination. He uses a solid MDF mold, without aluminum tape or other protection. His sandwich appears to use only one spring-steel slat — on top! He then puts the wood between 2 blankets — I’ve never seen/heard anyone else doing that. He uses PIDs for temperature control. The video bypasses the lamination process itself entirely.



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Good tips!

I have a very thin protective top slat, like .007, works well and does not seem to make bending any more difficult.

I’ve always used two blankets since seeing John Mayes doing it years ago. I am a believer as I have not damaged a side since I started doing that. I did answer the phone once during a bend and started jabbering only to be interrupted by lots of smoke and a burning smell. Not much left of that side and my scorched bending mold serves as a monument to my ineptitude.

Still have the controllers I got from LMI 14 years ago.

Go Vikings!

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[quote="Terence Kennedy"
I have a very thin protective top slat, like .007, works well and does not seem to make bending any more difficult.
I’ve always used two blankets since seeing John Mayes doing it years ago.
Still have the controllers I got from LMI 14 years ago. ![/quote]
Interesting. Do you run the blankets independently through separate PID controllers



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Interesting. Do you run the blankets independently through separate PID controllers



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Yes, I have a meat thermometer between the blanket top slat and crank them both to high, bend when there is a lot of steam (around 260 for me), usually finish the bend around 330 or so and then just sit there and turn the power strip on and off to keep the temp around 300 for 12-15”. Controllers stay on high the whole time.

Just one of a million ways that work just fine but theoretically two blankets could give more even heating.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

Power strip! Short term solution, thanks:)

Wish I was surprised I didn't think of it