Bending small dia pipe

[joe]

Hey guys,

As the title says how do you bend small diameter pipe and keep the shape or cross section of the pipe intact?

When I say small what I want to bend is about 3mm internal dia.

[LSP_Paul]

Hey Joe, as long as you're not trying to do a 90 degree bend, you can put a smaller piece of solid rod that matches the internal diameter, bend the piece and pull the rod out when you're done. I have done this with aluminum tube with a piece of brass rod inside, made the bend, then pulled out the brass part. The harder inside rod is still bendable, and doesn't allow the external tube to 'pinch" as its bent.  For projects where you don't have to have a hollow "inside", just use solid rod.

Hope this helps,

 Paul 

[LSP_Kevin]

Paul, how do you pull the internal rod out when it's bent?

 

Oh, and just to clarify: Joe, are you referring to metal pipe (brass/aluminium) or plastic tubing? I think we're all assuming the former.

 

Kev

[ssculptor]

There are tube bending devices which are just closely woven coils into which you insert the tube before trying to bend. Micro-Mark has some for about $6. They also have a tube bender machine for a C note ($100 for youse younger guys who dunt no no better)

http://www.micromark.com/benders.html

I've bought small scale tools from Micro-Mark and am now on their mailing list for life. They have fun stuff.

 

Also here are a few tips on bending small tubes

http://www.practicalmachinist.com/vb/fabrication-cnc-laser-waterjet-plasma-welding-fab/bending-small-dis-ss-tube-262780/

Clever techniques, kinda makes me want to try them out.

Better than trying to buy benders for $200 and up.

 

Go have fun,

Stephen

[joe]

Brass, aluminium or copper at this stage Kev.

[TonyT]

could you not fill with it solder then heat it to remove it afterwards?

[D Bellis]

Fill the tube with fine sand, bend it, then dump out the sand. Old school, but it works great.

 

HTH,

D

[Out2gtcha]

Fill the tube with fine sand, bend it, then dump out the sand. Old school, but it works great.

 

HTH,

D

 

 

Wow, that is something I would have never thought of. Great Idea!!

 

Is there any kind of special fine sand one should be using, or is the normal buy-some-@-the-store kind of sand fine enough?

[Kagemusha]

Albion Alloys make a tube bender http://scaleplasticandrail.com/kaboom/index.php/all-other-subjects/all-things-tools/75-all-other-tools/634-albion-alloys-ltd-tube-bender

[Out2gtcha]

I'm wondering if any of the previous would work for 3mm ID though

[D Bellis]

Is there any kind of special fine sand one should be using, or is the normal buy-some-@-the-store kind of sand fine enough?

Sand grains fine enough to avoid dimpling the tube from the inside, and small enough to fit within the tube are the only initial requirements. Regular silica 'sandbox sand' is more than small enough for 3mm ID tube. And, as long as the wall thickness isn't paper-thin, it shouldn't dimple it from the inside, either.

 

This method of bending tube has been around for as long as there have been tubes to bend. Just Google "sand bending tube" for a whole bunch more info.

 

D

[Guest Peterpools]

For bending small diameter tubing, nothing works as well as their Kadee Trip Pin Bender -  works like a charm.

http://www.activepowersports.com/kadee-237-trip-pin-pliers-model-train-train-parts/?gclid=CPK7q9yF2r8CFZJr7AodJkIATg

Just hold the cursor over the photo for a close up view.

I've had mine for nearly 25 plus years and it's super easy to use.

Peter

Edited July 22, 2014 by Peterpools

[joe]

Thanks for the discussion and options here gents.

This is off topic and not relative to LSP in the case but 1/35 exhaust pipes for a number of king tiger kits I have on the go.

The kit supplied exhaust in the Dragon kits are pretty terrible IMO so I was going to have a go at doing my own out of brass or aluminium tubing hence the question.

 

I could drill out the kit parts but they are undersized as they are anyway and metal pipes would look much more convincing.

I know Moskit made these but I haven't been able to track any down for years.

[D Bellis]

I'd like to see someone pound sand and bend a 3mm tube without kinking.

Here ya go:

 

It is standard K&S 1/8" brass tube (actually smaller than the 3mm Joe wants to bend). Probably not as tight a radius as Joe needs for his tank model, although I bent this with just my fingers. A simple pair of wooden dowels in a vice would yield a much tighter and more uniform curve. The sand used was regular beach sand (it is everywhere here), however it was not pounded - just loosely fillied the tube.

 

HTH,

D

[joe]

That is very cool and not far off what I'm aiming for. I think with some trial,and error I'll get close.