Re: Bender question

John, I have seen a similar project on Home Shop Machinist board:

http://www.homeshopmachinist.net

I want to say it was a tubing bender done by David Coffer (sp?).
It's worth your doing a bit of searching over there. I seem to
recall it worked more as a tab stop arrangement with an encoder, but
that could be completely off base. An encoder would certainly help
with the repeatability on different sizes of stock, or at least I
think it would. Not sure ELS is set up to deal with one though.

I've also seen a setup that didn't use a fancy controller at all.
It just had a moveable limit switch. You'd make one by hand, set
the limit switch when you got it right, and then pushing a button
made it repeat over and over again.

Best,

BW

--- In CAD_CAM_EDM_DRO@yahoogroups.com, John Dammeyer <johnd@...>
wrote:

>
> Hi everyone,
>
> On Thursday one of those 3 in 1 30" sheet metal tools followed me

home. I

> didn't have the heart to shoo it away so it now resides in my

shop. The

> original plan was to put a stepper motor on the back gauge and

dial in the

> lengths to cut or bend.
>
> Turns out that the back gauge is moved to either the bender or the

sheer

> when used. On the sheer, it sits attached to the bottom knife

assembly

> which doesn't move. On the bender the die part moves up against

the fixed

> anvil to bend the metal so the back gauge has to move with it.
>
> This means the stepper controlled back gauge will have to be easily
> transported between the two mounting positions and some sort of

repeatable

> calibration approach used.
>
> My plan was to use the ELS (Electronic Leadscrew) electronics to

drive the

> stepper motor since it's not a really heavy or co-ordinated

operation.

> Taking into account metal thickness and whether it should be an

inside or

> outside bend should allow the back gauge to be positioned without

problems

> and prepunched or drilled holes in the sheet metal should end up

in the

> correct spot relative to the bent edge. Just key in the bend

length, press

> start and when it's finished moving the back gauge, it would beep

and tell

> you to insert metal and bend or cut.
>
> OK. So that's the plan. But like most far east products, this

tool is also

> slightly wanting. Adjusting it for 90 degree bends on small 1"

wide 22g

> coupons at the ends results in an under bend of a 30" wide piece

of 22g.

>
> So here's the question. How do the large commercial CNC based

benders set

> up the depth for metal thickness? Do they have a leadscrew with

an encoder?

> Do they use a chain or belt drive between the two ends much like

my surface

> planer has leadscrews on all four corners connected by a chain?
>
> Or do they have a setup for thickness at all. Instead do they just

have a

> zero reference when the anvil touches the die and then back off

from that

> for metal thickness?
>
> Thanks.
>
> John Dammeyer
>