Bending Blanket Question

Hippety Hop · Post by **Hippety Hop** » Thu Sep 18, 2008 10:20 pm

Need some advice please fellas.

Omega silicone flexible heat blankets come in 2.5, 5 or 10watts/sq.inch.

Which do you think would be most suitable?

Cheers Hip.

SteveF · Post by **SteveF** » Thu Sep 18, 2008 11:50 pm

G'day Hip,

I went with the 10 watt 6"x36"model no SRFG-636/5.I haven't bent any sides with it yet but I can tell you that it heats up really quick..Steve

Kim · Post by **Kim** » Fri Sep 19, 2008 12:23 am

Hip,

You need to consider the total wattage eg; 6" x 36" = 216sq"@ 10 wpi = 2160 watts total. If you had the same sized blanket at 5 wpi you would of course halve the draw down to a total of 1080 watts. If your circuitry can handle > 2000 watt then there should not be an issue but you would nee to watch you don't burn the wood.

My own blanket is 5 wpi and it works fine, but I also had to consider the limitations of a PDI I have that I will eventually wire into the loop to control template digitally, so this dictated that I keep the total wattage down below 1500 watt.

You may also want to consider getting a quote from Jim Foote at MEI, you will find his contact details in the preferred vendors section. Feel no obligation to buy from Jim but he has looked after a few of us pretty well in the past.

cheers

Kim

Allen · Post by **Allen** » Fri Sep 19, 2008 6:12 am

My blanket came from MEI and is the 1100 watt model. It gets very hot very quickly. It's really easy to scorch wood if your having a little snooze while bending.

Hippety Hop · Post by **Hippety Hop** » Fri Sep 19, 2008 10:15 am

Thanks for your help lads.

I tried contacting MEI, but didn't get an answer. He could have missed my email, or perhaps it's because of the unusual size I asked for.

You see I want to make a concert uke with one-piece sides. My first attempt with a pipe ended up as scrap, with a half melted heat gun. I tried again with some honduras mahogany - that was reasonably successful, but still painfully difficult, and resulting in a remarkably silly looking piece of pop sculpture.

Now I've made a plywood bending jig (concert uke size), but it needs a blanket 80mm x 800mm (3" x 32") to go around it.

Of course I can resort to 2-piece sides and make a light globe jig, but I won't give up on the one-piece idea just yet.

John @ Blues Creek told me he has a 3" x 24" blanket that isn't listed on his site, so that's another option, but could be a bit awkward.

Hotco in Cheltenham said they had several enquiries from instrument makers recently, then apologetically quoted me $600 for a one-off job.

Anyway I'll see how I go with Omega.

Cheers

Allen · Post by **Allen** » Fri Sep 19, 2008 4:22 pm

I had trouble getting through to MEI the first time I contacted them as well. He told me their mail server gives them trouble often enough that he wants to kick it out the window. You might try again. I really don't think size is an issue at all with them as they make to order.

Also, mine with the thermocouple installed was $100 AU landed on my door.

Richard · Post by **Richard** » Fri Sep 19, 2008 5:19 pm

Hippety Hop wrote: Now I've made a plywood bending jig (concert uke size), but it needs a blanket 80mm x 800mm (3" x 32") to go around it.

Of course I can resort to 2-piece sides and make a light globe jig, but I won't give up on the one-piece idea just yet.

Let us know how you go with that -- I've got a couple of ukuleles with one-piece sides on the go at the moment. I'd be interested in seeing some photos your bending jig... I've got an idea in my head for the sort of jig needed but ended up just doing it on the bending iron for my first two. For my next few I'll probably get a blanket so I'm keen to hear how you go with it.

One possibility might be doubling the width of your jig and bending sides for two ukes at once with a normal 6x32" blanket?

joel Thompson · Post by **joel Thompson** » Wed Sep 24, 2008 11:21 am

try watlow,
they are bound to have a australian/new zealand branch.

i get mine from watlow uk and there prices are very good,

Joel.

Kim · Post by **Kim** » Wed Sep 24, 2008 1:12 pm

joel Thompson wrote:try watlow,
they are bound to have a australian/new zealand branch.

i get mine from watlow uk and there prices are very good,

Joel.

As I recall I had a quote from the AU distributor of watlow around 2 or 3 years ago, I think they wanted >$800

MEI are fine, you just need to use the online order tool and place the order it really is not that bigger deal.

Lillian · Post by **Lillian** » Wed Sep 24, 2008 1:56 pm

Hip, there is a discussion buried in the MIMF's library, or it should be by now, its been 4-6 years ago. Anyway the gist of it was that the 2 watt would top out temperature wise close to the top end of what we need. So it will work, but no extra heat. So saw this as an asset. I went with the 5 watt from Omega because I like the idea of having more than I need. I might never need it all, but its there.

I'm finishing up me bending form, in between house projects and have it at a point where I could take it for a test run, sort of. I wanted to see what bending was like and what I needed to do to the form, so why not. Uncle Bob had sent me three different mahogany practice sides, all thinned to 0.09. I don't have the means to nudge them down to .085 or less, so I went for it. I have my blanket routed through a mechanical timer and a 1000 watt dimmer, which I will be replacing. I put the sandwich together, slat, wood, blanket. slat, nope, no paper, no water. I turned it on full for about 30 sec and started cranking the lower bout down and the waist. I got the waist within a half an inch and had to stop, I forgot we were going somewhere. Turned it off and walked away after about a total time of maybe 1.5 minutes. When we got back, I basically repeated what I did above, but got the waist all the way down. If I had something to hold the lower bout against the form, It would have been a roaring success. I'm changing out the springs for a different system or stronger springs.

sebastiaan56 · Post by **sebastiaan56** » Wed Sep 24, 2008 3:02 pm

Ive got an unused one to liquidate, PM me if any one is interested,

Sebastiaan

joel · Post by **joel** » Thu Sep 25, 2008 10:34 am

I've got an Omega SRFG-636/5/240V. It's great . I use mine with a Thermostat I bought off ebay, so I can set it to any temperature between 0 and 200 degrees C. I've found around 150 degrees bent my Alpine Ash sides very well.

If I was going to buy all over again I'd seriously look at getting one of the MEI ones with the built in thermocouple. It would have made my setup a little simpler. And the price is comparable.

Hippety Hop · Post by **Hippety Hop** » Thu Sep 25, 2008 12:47 pm

Thanks. I've emailed MEI again asking for a quote.

Cheers Hip.

Hippety Hop · Post by **Hippety Hop** » Mon Sep 29, 2008 1:44 pm

... and this time I got a reply with quote, so I'm a happy fella.

3" x 32"
240 Volt 480 Watts 2 Amps.
6 Ft. Silicone Leads no/Tab
Type J Thermocouple Wire
$58.87USD each + shipping
estimated shipping $35.00.

And the pipe can get out and walk.

Cheers & thanks
Hippus Dippus

Lillian · Post by **Lillian** » Mon Sep 29, 2008 2:27 pm

Well Hippy, that's about what I paid from Omega five years ago. You should be a happy camper.

kiwigeo · Post by **kiwigeo** » Mon Sep 29, 2008 3:36 pm

480 watts dosent sound too high. Im sure my Bloues Creek 110volt blanket is at least 1000 watts. I know I had to get a stepdown transformer rated to at least 1500watts to be on the safe side.

Just curious

Hippety Hop wrote:... and this time I got a reply with quote, so I'm a happy fella.

3" x 32"
240 Volt 480 Watts 2 Amps.
6 Ft. Silicone Leads no/Tab
Type J Thermocouple Wire
$58.87USD each + shipping
estimated shipping $35.00.

And the pipe can get out and walk.

Cheers & thanks
Hippus Dippus

joel · Post by **joel** » Wed Oct 01, 2008 7:46 am

Surely you want a 6" wide blanket for guitar sides?

6" x 36" is the standard guitar bending blanket size.

Allen · Post by **Allen** » Wed Oct 01, 2008 5:06 pm

I'm pretty sure that it's for Uke sides that he's wanting to bend. Good idea too, because using the 6" wide one has been a bit of a pain on the one I'm building.

joel · Post by **joel** » Wed Oct 01, 2008 5:59 pm

3" makes sense then... If you wanted to build Ukes.

Hippety Hop · Post by **Hippety Hop** » Wed Oct 01, 2008 9:59 pm

That's right. Ukes.

I'd like to try building and learning to play a tenor guitar at some stage, and perhaps a mandolin.

But I'm more keen on ukes, and hope to make at least one. Preferably heaps. I've been playing uke for almost 5 years, and love having a sing-song.

I'd especially like to make a myself a koa soprano reso uke, but don't seem to be able to find a source for a cover plate. I therefore envisage having to drill or punch all those little holes myself.

At 63 I probably haven't got many new tricks left in me.

Cheers
Hip.

James Mc · Post by **James Mc** » Thu Oct 02, 2008 6:20 pm

63â€¦ should have a good forty odd good years left in ya, plenty of time to learn a new trick or few.

Cheers
James

Hippety Hop · Post by **Hippety Hop** » Sun Oct 05, 2008 8:48 pm

Well I've ordered the heat blanket from MEI, and my bending jig is just about complete.

Today I cut the slats from shim stock. Boy, when I went to unravel it from it's wrapper it jumped right out of my hand. Lucky it missed me and the cat who was sleeping on the floor.

That was the last I saw of her.

Anyway here's the jig with one of it's 4 cauls clamped in place.

There will also be 2 waist cauls, which I'll just hold in with a long clamp.

Problem is I have just a small bench at my mate's place to work on, and I'm only there on weekend afternoons.

If I use the drill, I have to clean up my mess and put the drill away before I can do anything else. It drives me dippy.

Cheers
Hip.

Hippety Hop · Post by **Hippety Hop** » Tue Nov 11, 2008 11:12 pm

They arrived - the two blankets I purchased, that is.

Now can someone with more intelligence than me please explain how I get the electricity out of my wall socket and into these little buggers - without shockin myself.

They have a printed blue wire, an unprinted blue wire and a brown wire.

I know that brown is active, blue is neutral, and presumably the unprinted blue is either a temperature sensor or an earth wire?

Cheers Hip?

matthew · Post by **matthew** » Wed Nov 12, 2008 6:51 am

You had best email MEI about that. If anyone here gives you advice and you end up cooking your blanket, or worse, you'll be right mad.

What *I* did on mine though - which only had two easy wires - was run the wires to an inline switch about 1 metre away, then run the switch off to the powerpoint. So you have control close by. It doesn't hurt to run your own earth wire to an alligator clip and earth your shim stock as well.

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