Side bending with Fox bender

[Paul Mac]

It's been about 5 years since I last bent some sides in my Fox style bender which was heated by globes so now that I wanted to bend some more sides I upgraded my bender by taking out the globes and bought a Keenovo heat blanket which includes electronic temperature and time control with a digital display. I am bending Qld Maple sides of 2.5 mm thickness, so I watched Robbie O'brien demo the LMI bender and took his advice to set the temp at 320f, bend the waist first turning the press handle 1/2 turn every 30 secs, then upper then lower bouts slowly, then reduce heat to 260f for 15 minutes, then turn off and leave overnight. My sandwich consisted of stainless steel slat, craft paper, wood wetted by spray bottle, craft paper, heat blanket, stainless steel slat. It did smell like the wood was cooking although there wasn't any smoke. Checked my results today to find creases in the waist, creases and cracks around the upper bout and the wood looking a lot darker than before. Can somebody offer advice on where I went wrong please.
Cheers Paul.

[Steve.Toscano]

2.5 seems a bit thick. Also might have been too dry this would explain the burning. If you're willing to potentially sacrifice the other side, try soaking it for 15mins prior.
I freehand bend and find QLD maple (even the highly figured stuff) bends like butter at 2mm and after a short soaking.

I'll caveat my advice with the fact i've never used a fox style bender.

[Jeremy D]

I agree. I just bent some black walnut at 2.2mm. While thicknessing I noticed that there is a big difference between 2.5 and 2.2. Sides feel very stiff to me at 2.5.

[jeffhigh]

Yes Just under twice the stiffness 2.5 to 2.0.

I can't help you with temperatures I just know what works for me with my setup. I bend at 2.0, use veneer softer, Turn my blanket up full, start bending after 60 seconds and have the bending complete within the next 60 seconds. I turn it off, let it cool completely. then give it another 30 minutes on low temp.

I notice Robbie is wrapping his in foil, with the seam folded over. This is probably retaining the moisture and allowing higher temperatures and durations without drying out and scorching.
I think this detail and the thickness may be the issue

[56nortondomy]

I agree with the other guys, 2.5mm is a bit thick, around 2mm is what I aim for. I only soak the sides if I'm doing a cutaway otherwise it's just a squirt with the bottle. I also bend at a lower temp. than what you've used, I start pulling the waist down at around 250 f and then finish at about 300 f.
Wayne

[Paul Mac]

Thanks everyone for the input, it seems like I need to thickness down to 2mm for a start and maybe reduce heat for my next bend.
Cheers Paul.

[demonx]

I was having trouble when I first bought mine as I was using scrap pieces of flat sawn to test on (didn't want to waste good quartersawn) and they kept buckling and burning.

Advice I was given was as above, less heat, quartersawn.

Going quarter sawn fixed the buckling, dropping the heat fixed the burning.

1.8 - 2mm seems the standard for people using these benders and if you follow everyone's advice so far should solve all your problems.

Also, when you say you're spraying water, make sure it's demineralised water otherwise you could be introducing mineral colouring into the timber that becomes a chore to remove with acid. I learned that the hard way also.

One more piece of advice is to add aluminium foil into your sandwich. So either side of your timber you'll have wax proof paper (supermarket stuff), al foil, heat blanket on top and then steel.

Good luck!

[Paul Mac]

Thanks for your input Allan, sides are quartersawn so I've got that covered, do you have a recommended temperature setting and time of heat application?
Cheers Paul.

[Jeremy D]

Bob has a great tutorial that includes temps etc.

viewtopic.php?t=974

[jeffhigh]

[quote="demonxOne more piece of advice is to add aluminium foil into your sandwich. So either side of your timber you'll have wax proof paper (supermarket stuff), al foil, heat blanket on top and then steel.

Good luck![/quote]


Wax paper? why I would not want wax and hot timber together due to contamination.

[demonx]

Wax paper? why I would not want wax and hot timber together due to contamination.

Read it again, it says wax PROOF paper. You know, cooking paper that cooks use so stuff doesn't stick? Bought from the supermarket. It's a tip I was given from someone who bends a lot more sides than I ever do and it seems to be a good one.

[demonx]

Thanks for your input Allan, sides are quartersawn so I've got that covered, do you have a recommended temperature setting and time of heat application?
Cheers Paul.

Not off the top of my head, it's in my notes, I'll look tomorrow while I'm in the workshop.

[jeffhigh]

Wax paper? why I would not want wax and hot timber together due to contamination.

Read it again, it says wax PROOF paper. You know, cooking paper that cooks use so stuff doesn't stick? Bought from the supermarket. It's a tip I was given from someone who bends a lot more sides than I ever do and it seems to be a good one.

I think you mean baking paper AKA Parchment paper (no wax)

Wax paper or wax proofed paper is proofed against moisture by being impregnated with wax. It is not paper that is proof against wax

[demonx]

Wax paper? why I would not want wax and hot timber together due to contamination.

Read it again, it says wax PROOF paper. You know, cooking paper that cooks use so stuff doesn't stick? Bought from the supermarket. It's a tip I was given from someone who bends a lot more sides than I ever do and it seems to be a good one.

I think you mean baking paper AKA Parchment paper (no wax)

Wax paper or wax proofed paper is proofed against moisture by being impregnated with wax. It is not paper that is proof against wax

You are correct, however it is commonly miscalled wax proof paper.

[jeffhigh]

Not Being Pedantic about it
I have a roll of Wax proofed paper that I use to prevent glue sticking, I would hate to see that used in a bending sandwich through lack of clarity.

[routout]

Taylor vid all bending done with a Brown paper shall we say.

[kiwigeo]

You are correct, however it is commonly miscalled wax proof paper.

Only in Victoria

[demonx]

Taylor vid all bending done with a Brown paper shall we say.

That'd work too, although I'd be cautious not to use anything with print or colouring incase it printed onto the timber. Mind you that could be a cool effect if wantin a "barn build"!

[56nortondomy]

I don't use any paper of any sorts, just an aluminium slat either side of the side with the blanket on top, no stains so far and no problems, seems to work for me ok.
Wayne

[Steve.Toscano]

You guys and your fancy fang dangle expensive bending machines and complicated sandwiches, with precise temperatures....

Below is my setup.
Ready to start bending in 2minutes flat at the precise temperature of "when a spray of water immediately steams off". Perfectly bend a side to any plantilla shape i wish in about 10minutes. I'm yet to crack or burn a single one.
Total cost = <$60.
From go to 2 sides and 4 bindings bent = around 30minutes, 45 if doing a cutaway.

Plus i get to freak out the neighbours if i leave the workshop door open, who probably think im bomb making or drug cooking.

Bending iron

[kiwigeo]

You guys and your fancy fang dangle expensive bending machines and complicated sandwiches, with precise temperatures....

Horses for courses. Working a bending iron requires a bit of skill and for some the blanket is easier. I have blankets and forms but I rarely use them preferring to use an electric iron. I feel I have more control over the bending process and well I'm just anal and old fashioned. That said it's taken many hours and a few failures to get skilled up on the iron.

[Paul Mac]

Update for side bending with Fox style bender after destroying a set of Queensland Mahogany sides earlies this week.
Some of you guys felt that 2.5mm with too thick so when thicknessing the next sacrficial set I took them both down to 2.5 then continued on to 2mm with one side only to compare the flexibility and yes the difference of .5 thickness is way more flexible, thanks guys.
Next my mate Adrian came around and loaned me his spring steel slats to use in place of my stainless steel slats that I felt were too thick and stiff anyway which will be replaced with my own set of spring steel shortly.
I checked out Bob Connor's tutorial and wished I had of seen that earlier, so spritzed my sides with rain water, craft paper either side, then wrapt in alfoil and sandwiched between slat blanket and slat. Placed the whole lot in the bender with blanket turned on and set to 240f, wound down the waist press to put on some tension, by this time I'm starting to get some steam, slowly(not too slowly this time) bent the bouts followed by winding the waist in which pulled everything up firmly, then increased temp to 300f for 5 mins, switched off then waited for cooling off.
When I removed the sides from the foil and paper the shape was bent smoothly without any cracks, creases or burnt wood, the wood was slightly damp in places and had some water marks that hopefully will sand out OK.
Thanks to everybody who replied to my post.
Cheers Paul.

20161027_081627_resized.jpg (64.3 KiB) Viewed 29807 times

[Paul Mac]

Don't know what happened with the attached pics but you get what's going on.
Paul.

[kiwigeo]

Don't know what happened with the attached pics but you get what's going on.
Paul.

Not sure what was going on there with the last pic......I've edited the post.

[Bob Connor]

Good to see it coming together.

Regards