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http://www.lmii.com/CartTwo/DisplayLargePhoto.asp?largephoto=BENDINGMachineHeatControllerTCzoom.jpg
http://www.lmii.com/CartTwo/thirdproducts.asp?CategoryName=Bending%2FHeating&NameProdHeader=Side+Bending+Machines+and+Accessories

New to me, at least. Looks like a neat setup.
Nelson

http://www.lmii.com/CartTwo/DisplayVideo.asp

Nelson,

Here is a video I did on the subject recently. I am also testing the brand new flux capacitating LMI bending machine that is used with the heat controller. It is a pretty fancy set up. There was a prototype of it at the last Healdsburg show if you happened to be there.

Robbie, I didn't make it to Healdsburg.
Can you elaborate on the flux capacitating LMI bending machine?
Sounds interesting!
Nelson

Robbie,
Flux capacitors work ok in bending machine applications, but IMHO dilithium crystals are better.

RustySP

haha. It is like no design you have ever seen before. I will wait for the go ahead from LMI to talk more about it. Eventually I will probably be doing a video about it.

Not sure what Stew Mac charges for that unit but the whole thing can be purchased as seperate components and assembled yourself without too much trouble. It's considerably cheaper to put this together yourself and quite simple when you come to understand the system. I've made dozens of them in many different configurations to heat aluminum molds but the basic idea is the same.

The basic components are:

1. Microprocessor controller. Watlow is a good brand name - Watlow 935 is specifically one the could be used - there are controllers in the range of $80-$120 that have all necessary features.
2. Solid state relay....25 or 40 amp depending on the wattage of your heat blankets. 120-240 volt
3. Type J thermocouple....probably one with a little eyelet as a terminator is best.
4. Silicone heat blanket(s).
5. Some 14 awg wire - that's total overkill.
6. Utility plug.

The thermocouple is fixed to the heated surface and reads the temperature. The microprocessor recieves its signal and, depending the temperature, sends a low voltage pulse to the relay, which opens and closes the circuit carrying power to the heat blanket. The microprocessor maintains the set heat by extending or shortening the duration of these pulses. I would advise anyone who is interested in getting into one of these systems to make their own. It's pretty easy.

PM for help.

_________________
I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

Robbie, your pulling leg again.
That was next years Healdsburg where you saw the flux capacitor.
Nelson

This is almost the exact same thing I used at Bourgeois shop back in 2001 (and he had it long before then). For sure nothing new, but nifty.

I think Dana's was made by Watlow.

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John Mayes
http://www.mayesluthier.com

I built mine several years ago using a PID controller off of Ebay. It is amazing to watch it come up to the preset temperature, overshoot briefly by a few degrees, cut the power to the blanket and then repeat the cycle until it homes in on the preset quite accurately. The PID's internal contactor didn't have quite enough ampacity for the blankets so put a SSR (solid state relay) in between and also use a Variac to control the volts up to about 130VAC for quick warmup. Something like this except mines an antique. http://cgi.ebay.com/Metered-Variac-Variable-AC-Output-Transformer-20-Amp-/380215222078?pt=LH_DefaultDomain_0
I would buy a ready made controller like LMI's if had to do it over again. Building your own is interesting but cuts into build time. Guess it's the old make/buy decision. The LMI unit at $162.50 isn't such a bad price when you consider your time
Nelson

I wonder if the LMI controller can regulate 2 blankets using a 2>1 adapter for the plug. I would think so, but idk.

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John Mayes
http://www.mayesluthier.com

I suspect not John,

I made one of these a while back and I reckon the load would be too high for such a compact unit. The unit I put together could probably do the job OK because the SSR (Solid State Relay) and the heat sink is substantial enough to take the load. As you can see the unit had to be considerably larger than the LMI unit to accommodate those components but it also left room to add a digital timer into the package. This makes things a little safer as the unit will power off the blanket automatically once the preset timed cycle has been completed. The thermocouple in my unit was embedded into the blanket during manufacture so you simply plug it in, set the desired temperature and time cycle and push the start button. The rest button allows you to repeat the last set cycle or to simply shut off the blanket for a re-start.




The SSR and heat sink combo used in my unit are near as big as the entire LMI unit but compact size does have its draw backs and load capacity would be the first casualty IMHO.

Cheers

Kim

Hi Robbie,

The first time I saw a cantalever bending machine design was at the GAL convention in 2007 when Charles Fox presented his prototype....and very interesting it was too - I have lots of photos of it that I have refrained from publishing publicly at the GAL's request. It seems to me that the LMI version (which I saw at last year's Healdsburg Guitar Festival) is based heavily on Charles' design....different materials, yes, but basically the same principal. I hope y'all are planning to give due deference to Mr. Fox and his design idea?!

Cheers,
Dave F.

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Cambrian Guitars

"There goes Mister Tic-Tac out the back with some bric-brac from the knick-knack rack"

I´ve built a contoller setup myself using a industrial controller and a SSR but without a timer.
The SSR is cooled by a heatsink, the device contains a fuse at 10 Amps (230V).
I´m using it till now since 5 years with my blankets from John Dick with great results.

Harald

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http://www.hl-guitars.at

For a bit more $, another option is a ramp-soak controller,which gives a built-in timer limit.
If using PID, here's an easy way to set the parameters (see part D): http://www.newportus.com/Products/Techncal/techncal.htm
Also, an aluminum case makes a decent heatsink for the SSR.

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David Malicky

Yes Nelson it is interesting to watch the PID process. You probably know that PID is an acronym for Proportional, Integral, Derivative. For those not across this term it simply means that the controller works in 3 ways. The user sets the desired temperature and once switched on, the unit will detect the current temperature via a thermocouple. The thermocouple is simply two wires of dissimilar metals, such as one of iron and the other of nickle in the case of a "J" type thermocouple. Once these wires are joined together they create a thermal reactive current which can be measured in milliamps and it is the fluctuation of this current that the heat controller monitors in order to control output to source eg; the heat blanket.

So the 'Proportional' of the 3 part operation is the measurement of the existing 'error' between the current temperature, and the set temperature.

The 'Integral' part of the operation is the response to that error. IE: Turn power on to the blanket if too low, turn power off to the blanket if too higher.

The 'Derivative' part of the operation is the processor within the controller learning from each successive reading how long it should leave the power on to minimise the error and maintain the temperature as close to the the setting as possible.

This explains the change you see, a PID is a switch that learns quickly from its own mistakes....Sometimes I think we could all do with one of those wired into our own circuits.

Cheers

Kim

I think most of the Omron PID Controllers are self tuning these days David so its just a plug and play process and very user friendly. You are correct about the alloy case being a good heat sink in its own right, better still I am a Dr Who fan so shiny boxes with switches and different coloured neon lights are very important to the over all effect I think.

Cheers

Kim

Well of course it won't work without sufficient shinyness and enough various colors. Also I'm suprised no one has mentioned the the Heisenberg Compensators.



Seriously though, a PID PWM Bender Controller. Too Cool!

Peace,
Sanaka

_________________
...imagine there were no hypothetical situations...

Many of us have built such devices. I built a dual-channel version into the base of my bending machine, so I can do a large heating blanket and an additional small blanket for cutaways at the same time. I can report that having the second small heating blanket for the cutaway section makes bending them VERY much easier! Here's a picture of my version. I built it sometime in 2007 IIRC and it has provided excellent service ever since:



Cheers,
Dave F.

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Cambrian Guitars

"There goes Mister Tic-Tac out the back with some bric-brac from the knick-knack rack"

I'm just amazed at how lucky we must have been...those of us who have successfully bent sides for years without the benefit of such temperature control and feedback. Just the thought of not having to listen for steam hisses...or no need to have gloved hands feel the wood yielding just makes me want to go out and spend $162.00 for technology that will increase my success rate beyond its current 100%.

Sorry for becoming grumpy-like...but a simple thermocouple attached to a common multimeter could give the same information. To me, having the device control the temperature only encourages the user to walk away from the bender which we all know is a recipe for potential disaster, as Robbie mentions. But I really like Robbie's pocket timer idea. I happen to use my cell phone alarm each time I turn on a bending blanket.

Maybe I'm a wee bit cynical because it's 4:18 AM and I just need to get back to sleep...later!

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JJ
Napa, CA
http://www.DonohueGuitars.com

Yeah!! Does your cell phone have dilithium crystals?

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Billy Dean Thomas
Covina, CA

"Multi famam, conscientiam, pauci verentur."
(Many fear their reputation, few their conscience)

Hmm JJ maybe you do need a sleep...I seem to recall much the same sentiment directed toward those who turned to light bulbs and bending forms from the hot pipe and water bath...and the same again toward those who went from bulbs to blanket, and again when folks started to experimented with veneer softeners like super soft etc. The one constant is that these sort of comments offer no beneficial input to the topic at hand because regardless of what some may think, the technology is here, the technology is cheap and readily available and the technology is safer, both for the wood and the user if a simple timer is included in the loop. Also the technology allows greater control over the process. I know that many will argue this point but the fact remains that a PID allows the user to record to a high degree exactly what has worked for them with what wood and can also allow experimentation with bending at one temperature and then holding the wood for an extended period at a much lower temperature very accurately to set the bend to eliminate all spring back. So regardless of what some may say, the benefits are there or the product would simply not exist so it remains a simple matter of choice whether or not one considers them useful and if you do not, then that is 'your' choice.

Cheers

Kim

OK...I'm awake, properly caffeinated and ready to respond to my friend on the opposite side of the planet!

Kim...I am not rejecting the purchase of this product per se. I am only stating that the same info can be obtained far less expensively. Your shop made device is as impressive as hell and I applaud you for your skill and choice in incorporating it into your practices. We happen to be in violent agreement, however, about the need for collecting data and controlling a process. I have collected the same data over the years with readily available equipment far less expensively than what the product does for $162.00. The fact that I have never broken or cracked a side in 8 years of bending has a way of making one confident in one's current process. Dammit...I may soon regret stating that I have never cracked nor broken a side. The bending gods are sure to be angry now!

Just to set the record straight, I went from light bulbs to blanket to SS2 and will incorporate whatever it takes to improve a process in a flash. I'm an early adapter of technology where it makes sense. Its just that I have an honest disagreement as to the cost/benefit of this particular device in light of my experience.

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JJ
Napa, CA
http://www.DonohueGuitars.com

All is cool with me JJ and I completely understand your point considering your 100% strike rate in 8 years. You have made your investment and it is still paying you dividend so good for you. My point remains that this technology does not need to cost $162.00 and that it offers an even greater level of accuracy and control than the router speed controller used to limit voltage and an analogue thermometer that so many currently use.

The truth of the matter is that 'today' one can have a PID set up for much the same cost as those older tech components, and because of their greater control and accuracy, a PID system offers a greater buffer against failure than anything else currently available and we all know what just one set of good wood costs and that ain't going down. Just one more consideration, I am by no means an electrical engineer, but as I understand, limiting voltage is not the best option to control out put of anything electrical. I seem to recall reading that the lack of current 'causes' burnout. A PID controls heat by switching output fully on and fully off so it eliminates that danger. I do not know if this is applicable to a heat blanket situation but if it does, this point my extend its life expectancy of a blanket used in a PID system over that of one controlled via a router controller. Can someone with electrical knowledge clarify this for the sake of discussion please.

Cheers all

Kim

Dave,

I am not familiar with Charles' design and have never seen it. I also had nothing to do with the LMI design and development of their new bender. All I am doing is testing it by bending 40 plus sides in the next week or two just to make sure it does what it is designed to do. I also don't have the go ahead yet from LMI to show any pictures of it or elaborate on it. So, until I get that, mums the word.

I'm curious! If you ever watched John Hall bend a set of sides, why would you even consider one of these. The whole process only takes something like 5 minutes from turn on to turn off the blanket. I suppose if you cook sides for a while, but a router controller($12.00 at HF) and a thermometer($5.00) will tell you everything you have to know. A timer is a good safety feature, in case your short term memory is bad!

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Waddy

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