Official Luthiers Forum!
http://w-ww.luthiersforum.com/forum/

Controller for heating blanket
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10101&t=45666		 Page 1 of 1
Author:  PeterF [ Thu May 07, 2015 12:18 pm ]
Post subject:  Controller for heating blanket
I've just got the heating blanket for my ukulele side bending machine that I'm making and it just came with 2 wires sticking out the end. I know I need some sort of regulator and obviously a plug, but I'm not sure exactly what type. I've found this on ebay - would this be suitable as a regulator? The blanket is only 350w so should be well within its capabilities I think.
http://www.ebay.co.uk/itm/Adjustable-Vo ... 1115305541

I've got a digital kitchen thermometer and I plan on regulating the temperature manually to save complications.

Also, for the UK residents - I'm assuming the 2 wires coming out are simply live and neutral. Does it matter which is which? I guess there's no earth wire.

https://www.dropbox.com/sc/xlzr3lt1u0u8 ... L9qU8vS_wa
Author:  PeterF [ Thu May 07, 2015 12:37 pm ]
Post subject:  Re: Controller for heating blanket
Or would something like this be better? It has thermostatic control built in

http://www.ebay.co.uk/itm/Digital-PID-T ... =undefined

With a controller like this, where do you put the thermocouple? It says its 4.5mm in diameter. Wouldn't that get in the way of bending? Can it be built into the mould somehow?

Sorry for all the questions!
Author:  klooker [ Thu May 07, 2015 2:00 pm ]
Post subject:  Re: Controller for heating blanket
You need to check the power rating of your blanket - it's usually in watts/area but be sure it's listed at your voltage, then multiply that by the surface area of your blanket to see how many watts. The blanket is basically a big resistor.

Kevin Looker
Author:  PeterF [ Thu May 07, 2015 2:46 pm ]
Post subject:  Re: Controller for heating blanket
It's 5 watts per square inch which is I think is pretty standard from what I've heard. 350w in total. At 240V that's 1.5A.
So basically anything that reduces the input voltage will reduce the temperature?
Author:  Colin North [ Thu May 07, 2015 2:57 pm ]
Post subject:  Re: Controller for heating blanket
PeterF wrote:
I've just got the heating blanket for my ukulele side bending machine that I'm making and it just came with 2 wires sticking out the end. I know I need some sort of regulator and obviously a plug, but I'm not sure exactly what type. I've found this on ebay - would this be suitable as a regulator? The blanket is only 350w so should be well within its capabilities I think.
http://www.ebay.co.uk/itm/Adjustable-Vo ... 1115305541

I've got a digital kitchen thermometer and I plan on regulating the temperature manually to save complications.

Also, for the UK residents - I'm assuming the 2 wires coming out are simply live and neutral. Does it matter which is which? I guess there's no earth wire.

https://www.dropbox.com/sc/xlzr3lt1u0u8 ... L9qU8vS_wa

Yes that regulator should be suitable. I use something similar for manual control.
I use a digital kitchen thermometer, and just stand over it all the time.
The thermostatic controller is probably suitable, the temperature probe is too big really.
See Fred's post at the end of this thread - In fact the whole post may be of interest to you. http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=43928&p=581044&hilit=+heat+blanket#p581044- there were actually a few others by Fred that may be of use to you.
And yes, anything that reduces the input voltage will reduce the temperature.
And yes, I've just been researching this subject recently.
Author:  Colin North [ Thu May 07, 2015 3:02 pm ]
Post subject:  Re: Controller for heating blanket
P. S.
With any new set up for heat bending, best sit over it for all the time of course. And when heating the side initially, try "stepping up" the temperature to check how the temperature indicator is keeping up with the temperature change, kitchen thermometer or probe/controller.
In fact I would use the digital thermometer alongside the probe controller as a double check, at least the first couple of times.
EDIT
Just noticed your temp. controller is very inexpensive compared to Keenovo's latest offering which costs £63. I wonder why?
http://www.ebay.co.uk/itm/Digital-PID-C ... 417fc23b91
Author:  PeterF [ Thu May 07, 2015 3:48 pm ]
Post subject:  Re: Controller for heating blanket
Thanks Colin
Just been looking at all the old threads. I think I'm going to go with my first idea and do everything manually with the voltage regulator. I could probably get my head around the automatic system, but at the moment, I just want to get this thing done and working! (Plus its's cheaper)

Image

So with this regulator, I'm guessing the '110V-250V AC' port would be the live wire from the wall plug, 'Output' would be the neutral wire back to the wall plug, 'Motor' would be the output to the blanket and 'Input' would be the return from the blanket?
Is this all I need with this setup? No extra relays or controllers or anything?
Author:  Colin North [ Thu May 07, 2015 4:10 pm ]
Post subject:  Re: Controller for heating blanket
PeterF wrote:
Thanks Colin
Just been looking at all the old threads. I think I'm going to go with my first idea and do everything manually with the voltage regulator. I could probably get my head around the automatic system, but at the moment, I just want to get this thing done and working! (Plus its's cheaper)

Image

So with this regulator, I'm guessing the '110V-250V AC' port would be the live wire from the wall plug, 'Output' would be the neutral wire back to the wall plug, 'Motor' would be the output to the blanket and 'Input' would be the return from the blanket?
Is this all I need with this setup? No extra relays or controllers or anything?

No extra relays or controllers or anything - that's all I have, regulator and a blanket + themometer. (well, actually, I have a step down transformer in between, as the blanket is 110V)
And my best guess would be:-
Input - neutral from supply
110 - 250 - live supply
Output - neutral to blanket
Motor - live to blanket
You can ask the supplier to confirm if you are unsure.
Author:  PeterF [ Thu May 07, 2015 4:16 pm ]
Post subject:  Re: Controller for heating blanket
Thanks [:Y:]
Author:  Mike2E [ Fri May 08, 2015 8:07 am ]
Post subject:  Re: Controller for heating blanket
I use a motor speed controller similar to what you are looking at. Works great, I have a digital IR thermometer which I find much better than a contact probe, more accurate and easy to quickly check the temperature at any place. Just point and pull the trigger. It cost about $15 or so
Author:  ernie [ Fri May 08, 2015 9:39 am ]
Post subject:  Re: Controller for heating blanket
I use an omega heat blanket that is similiar, it heats slowly which is perfect for bending uke sides for me . I use an oven thermostat, and no controller works vy well
Author:  Colin North [ Fri May 08, 2015 12:20 pm ]
Post subject:  Re: Controller for heating blanket
Mike2E wrote:
I use a motor speed controller similar to what you are looking at. Works great, I have a digital IR thermometer which I find much better than a contact probe, more accurate and easy to quickly check the temperature at any place. Just point and pull the trigger. It cost about $15 or so

Are you talking about something like this below?
My experience when I use one on the top of the slat bundle was it shows substantially less than the digital kitchen (meat) type thermometer against the blanket itself, presumably due to the cooling effect of the air circulation (by convection)
I know it reads correctly, and I do use one, but I use it to measure the temperature on the bottom of the slat bundle, inside the form, because I am using light bulbs at the same time as the blanket.
Just thought that heating both sides of the wood might be constructive.
Attachment:
318MJR61+iL._SX425_.jpg

Good price (£8.25) in UK here http://www.amazon.co.uk/GM550-Non-Contact-IR-Infrared-Digital-Thermometer/dp/B007Q87J3U
Author:  Goat Rock Ukulele [ Fri May 08, 2015 5:49 pm ]
Post subject:  Re: Controller for heating blanket
Here in The States when you have 240 volts in a wall circuit it is two 120 volt hot wires out of phase. If you have a ground it is a safety equipment ground only. The only time you would have a neutral is if the equipment you were powering had a 120 circuit as well.

But you guys must do it differently if you have a one 220 volt lead and a neutral. My point is the advise of us Yanks may not fit your wiring.

By the way you drive on the wrong side of road as well.
Author:  Colin North [ Fri May 08, 2015 6:09 pm ]
Post subject:  Re: Controller for heating blanket
Quote:
By the way you drive on the wrong side of road as well.
idunno
No we don't. We drive on the correct side of the road.
If you drive on the wrong side of the road, it causes accidents...
Some people :shock:
Even calls the earth a ( wow7-eyes ) ground.
laughing6-hehe
Author:  bluescreek [ Mon Mar 29, 2021 2:58 pm ]
Post subject:  Re: Controller for heating blanket
before you do anything be sure your blanket is a 220 or 240 Vac unit
wattage is this
Width time length time your 5 watts pre sq in is total wattage
Not all blankets are 5 per sq in many are 2.5
now divide that by your voltage for the amps if it takes more than a few minutes to get hot something is wrong. I get full heat and am done bending in 4 min.
You can use a router speed control and a cooking thermometer and wire accordingly. I don't think you will have a neutral for 220 04 240 that is 2 hot legs
120 uses neutral
when in doubt talk to an electrician it beat burning a house down
Author:  Dave m2 [ Mon Mar 29, 2021 4:10 pm ]
Post subject:  Re: Controller for heating blanket
An easy way to control the output of a heating blanket is with a lighting dimmers switch. These go up to around 1 KW so with your fairly low wattage blanket you should be able to find a suitable one.

Measuring the temperature is a bit messy. As several people have said there are lots of different ways, all with their limitations. A good themocouple with a thin sensor is the ideal, that can sit at an appropriate place in the sandwich. I'll leave it at that.

However don't ignore your own senses. If the wood feels like it is bending freely then go for it. Is there lots of steam coming out of the sandwich - probably a good sign that it it is up to temperature.

As a final comment though, as everybody has said do NOT walk away from it. Catching fire is a serious possibility. You only ever walk away when everything is turned off and unplugged!

Good luck Dave
Page 1 of 1 All times are UTC - 5 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/