Radius Braking

[Bob La Londe]

I need to bend some .125 5052. It doesn't have to be a sharp bend, but I do
need a net of 90 degrees. If I tried to brake it to 90 on the brake with
the standard apx(0) radius it will tear. 45 is about as far as it will bend
easily. I have not been very happy in the past with two close 45 degree
bends. It seems to harden further back then you would expect.

I was thinking of trying about a 1/2" radius by:

Cutting a wide notch in some 1/2" black iron pipe (apx 1" OD give or take).
Slip the pipe over the ends of the fingers.
Adjust clamping force and distance.
Adjusting the fingers on my brake back so that the edge of the bending part
(table? apron?) + .125 is tangential with the leading face of the pipe when
all is clamped down.
Bend (with some help) to 90+ in one continuous motion.

I was figuring a light coat of oil on the bottom face of the aluminum sheet
to help it slide against the apron.

Has anybody tried it? Will my pipe finger caps just go flying?

[John B.]

On Tue, 3 May 2016 18:09:01 -0700, "Bob La Londe" <no...@none.com99>
wrote:

You might want to read
http://www.thefabricator.com/article/bending/bending-basics-the-fundamentals-of-heavy-bending
It has some information on for bending radius that might be of
interest.

Admittedly it has been a long time since I actually bent aluminum
plate but as I remember it for thick aluminum plate we usually tried
to anneal the bend line - smoke the area with an oxy-acet torch set
very rich then lean out torch and carefully burn the soot off the
plate.

The bend radius was set by adjusting the distance from the edge of the
Brake's clamping plate to the bending plate. I'm not sure for thick
plate but we certainly bent 1/8"sheets using a conventional sheetmetal
brake without any additional bits and pieces.
--

Cheers,

John B.

[Jon Elson]

Bob La Londe wrote:

> I need to bend some .125 5052.

I put a fairly sharp 90 degree bend in 1/8" aluminum. I used to try to
anneal either 6061 or 5052. There is a grade of 5052 that is bendable at
1/8" thickness, but even if it sits around too long, it hardens and then you
get tears when you try to bend it. So, I do all this bent stuff in 3003.
That is a lot softer, so may not be desirable, depending on how the part is
used. But, the 3003 bends VERY nicely, with essentially no inside radius,
at 1/8" thickness.

Jon

[Jon Anderson]

On 4/05/2016 11:09 AM, Bob La Londe wrote:
> I need to bend some .125 5052. It doesn't have to be a sharp bend, but I do
> need a net of 90 degrees. If I tried to brake it to 90 on the brake with
> the standard apx(0) radius it will tear. 45 is about as far as it will bend
> easily.

If you have some thinner material around less prone to cracking, make
some 'wrappers'. Cut strips maybe 2" wide, a bit longer than your bend.
Bend back tight against the upper fingers. You now have a larger radius.
May not take much extra radius to get a crack free bend. Also try to
avoid bending parallel to material grain.

Jon

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

[Bob La Londe]

"Jon Anderson" <jande...@janders.info> wrote in message
news:XruWy.32912$4s3....@fx43.iad...

> On 4/05/2016 11:09 AM, Bob La Londe wrote:
>> I need to bend some .125 5052. It doesn't have to be a sharp bend, but I
>> do
>> need a net of 90 degrees. If I tried to brake it to 90 on the brake with
>> the standard apx(0) radius it will tear. 45 is about as far as it will
>> bend
>> easily.
>
> If you have some thinner material around less prone to cracking, make some
> 'wrappers'. Cut strips maybe 2" wide, a bit longer than your bend. Bend
> back tight against the upper fingers. You now have a larger radius.
> May not take much extra radius to get a crack free bend. Also try to avoid
> bending parallel to material grain.

THAT is a clever idea.

[Lloyd E. Sponenburgh]

"Bob La Londe" <no...@none.com99> fired this volley in news:ngdscv$nip$1
@dont-email.me:

> THAT is a clever idea.
>

Yeah... that is, actually!

I have a finger brake, because I do a good deal of 'box' work. But I have
occasion to do radiused work. Hmmmm....

The idea of bending 'stuff' to a new radius works. But I think I can
machine "radius noses" for my brake fingers, also.

Lloyd

[Bob La Londe]

"Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote in message
news:XnsA5FEBD9287DFDll...@216.168.4.170...

I can certainly do that, but I want to keep all my fingers. I thought about
making a second set, but I am jealous of time spent on fiddley stuff and of
burning thru stock to do it. Pipe is cheap, which is where my original idea
came from. Still it would take a little time. Throwing a piece of smaller
stock on and using it to make a radius uses minimal stock and minimal time.
If a larger radius is need I can just back up the fingers a smidgeon and
wrap a second one around the first. There are usually plenty of pieces of
.0625 (which brakes nicely) in the drops at my local metal vendor.

[DoN. Nichols]

On 2016-05-04, Bob La Londe <no...@none.com99> wrote:
> I need to bend some .125 5052. It doesn't have to be a sharp bend, but I do
> need a net of 90 degrees. If I tried to brake it to 90 on the brake with
> the standard apx(0) radius it will tear.

Since you don't mention this, I'm not sure whether you already
know, but aluminum sheet has a "grain" resulting from the rolling which
formed it. If you bend in parallel with the grain it will tear a lot
sooner than if you bend at a 90 degree angle to the grain.

I don't know whether this will make enough difference for what
you are trying to do. You are working with thicker aluminum than my
brake can handle. :-)

There is also the trick of annealing it (you don't mention the
temper). You don't mention what temper you have, but if it is anything
other than the fully-annealed state, you can improve the bendability by
(assuming you have an oxy-acetylene torch) first putting a deposit of
soot along the intended bending line with just the acetylene flame, and
then bring up the oxygen and move along the seam heating it until the
soot goes away. At this point, it should be about as bendable as you
can get for that alloy. Bend it soon, because the aluminum re-hardens
(though not fully) with time. Again, I don't know whether this will
make enough difference or not.

> 45 is about as far as it will bend
> easily. I have not been very happy in the past with two close 45 degree
> bends. It seems to harden further back then you would expect.
>
> I was thinking of trying about a 1/2" radius by:
>
> Cutting a wide notch in some 1/2" black iron pipe (apx 1" OD give or take).
> Slip the pipe over the ends of the fingers.
> Adjust clamping force and distance.
> Adjusting the fingers on my brake back so that the edge of the bending part
> (table? apron?) + .125 is tangential with the leading face of the pipe when
> all is clamped down.
> Bend (with some help) to 90+ in one continuous motion.

Hmm ... I think that the pipe would crush on the part under the
fingers.

If you're going to do this more than once, I would suggest
making an alternate set of fingers with the radius machined into the
tips. (Likely with a radius end mill.)

> I was figuring a light coat of oil on the bottom face of the aluminum sheet
> to help it slide against the apron.

Oil -- or a wax, perhaps that which is used as a bandsaw lube.

> Has anybody tried it? Will my pipe finger caps just go flying?

I'm more worried about the radius being crushed out of them on
the first close

Just my thoughts above.

Good luck,
DoN.

--
Remove oil spill source from e-mail
Email: <BPdnic...@d-and-d.com> | (KV4PH) Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

[Lloyd E. Sponenburgh]

"Bob La Londe" <no...@none.com99> fired this volley in

news:ngdubv$tlm$1...@dont-email.me:

> "Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote in message
> news:XnsA5FEBD9287DFDll...@216.168.4.170...
>> "Bob La Londe" <no...@none.com99> fired this volley in
>> news:ngdscv$nip$1 @dont-email.me:
>>
>>> THAT is a clever idea.
>>>
>>
>> Yeah... that is, actually!
>>
>> I have a finger brake, because I do a good deal of 'box' work. But I
>> have occasion to do radiused work. Hmmmm....
>>
>> The idea of bending 'stuff' to a new radius works. But I think I can
>> machine "radius noses" for my brake fingers, also.
>>
>> Lloyd
>
> I can certainly do that, but I want to keep all my fingers. I thought
> about making a second set, but I am jealous of time spent on fiddley

Ahh... nah... I'm talking about little add-on tips to my existing fingers
that could be secured (at worst) with a set-screw into the TOP surface of
a finger.

I don't want to have to make all-new fingers for my brake, either! Too
much work for too little return.

Lloyd

[Jon Anderson]

On 5/05/2016 8:20 AM, Bob La Londe wrote:

> THAT is a clever idea.

Credit that one to my college work experience classes at NASA Ames.
Hardly anyone ever using the finger brakes, but we were taught how.
One class project was an aircraft sheetmetal style box. Press brakes
were constantly in use, so I did mine on the finger brake. Was a touch
out of tolerance in a few places, but got points for getting as close as
I did on the brake. About .015 out on a couple bends IIRC...

[Jon Elson]

Bob La Londe wrote:


> came from. Still it would take a little time. Throwing a piece of
> smaller stock on and using it to make a radius uses minimal stock and
> minimal time. If a larger radius is need I can just back up the fingers a
> smidgeon and
> wrap a second one around the first. There are usually plenty of pieces of
> .0625 (which brakes nicely) in the drops at my local metal vendor.

You can even do this with heavy card stock, like they make posters out of.

Jon