What sort of underbend are you all seeing?
I double checked all the calibration and die sizes before hand.
4in x 4in 1/8" square using standard 30 degree punch and 26mm 30degree die using A36 1/8". Using straight 90 degree setting with 0 over/under bend setting. Punch one and getting about a 98 degree bend. Is an almost 8 degree underbend to be expected?
That’s a little high, but keep in mind that all of the presets are meant to yield a slight underbend by default (around 5*) so that you can trim it into whatever your desired bend angle is. There’s lots of factors that can affect the pre-compensated bend angle.
I’d start by verifying that your ram-to-table height is correct in the presets. The method to measure it is detailed in the quick start guide on the website.
If that is good, then measure your punches and dies to make sure they exactly match what’s in the tables.
Also make sure you are mic’ing your material thickness. Material thickness can have a large effect on bend angle, especially with narrow die opening.
Hey Daniel,
quick response! I did actually check the ram to table height. It was still spot on and only off by .001". Mic’ed the material as well and it measured .123" in a few spots.
Haven’t done much bending yet since I don’t have a backgauge, but the few sample materials I ran through were all around 1° of underbend, give or take 1°.
That matches my experience from the press brake world. Generally springback corrections on accurate machines are in the neighborhood of 0-3°.
Nothing like the degree of springback compensation that’s required in the world of tube bending, where 2-10° is the common range depending on the tube and style of bend dies.
In my experience a second hit will often times give you the one degree more that you are looking for.
Mostly because it doesn’t hit in eeeeexxxactly the same spot. I can tell you from experience that if you hit it accurately enough (in the same spot), tube or sheet, it doesn’t bend any more than it did the first time. I’ve done it enough times on CNC tube benders with the tube held in a collet so that it can’t move to be positive.
This thread was helpful, as I’m seeing similar underbend and was concerned I had setup incorrect. Did you manually adjust your test bends?
I am guessing this might be obvious when I get the machine running, but to do a second hit, do you just repeat the bend program? or is there a way to keep the punch down and re-hit?
Heat lot #'s can have an effect as well. Say you got one heat lot of sheet and the same stuff alloy-temper but different heat lot can/will result is subtle differences.
Oh god yes. I’ve sorted enormous piles of laser and saw cut tubes back when I worked as a supervisor because a laser or saw guy forgot to keep things organized when we had material come in from multiple heat lots. It’s way worse in tube bending than sheet metal, but either one will screw up your day.