How to flatten a curved steel plate.

[JD Mather]

Not only that, but you can create flat states in autocad more accurate than pro-e or inventer can and I can explain why that is.

 

Anybody who knows what they are doing can often out-perform someone who doesn't know what they are doing.

 

... and I can produce these more accurately in AutoCAD than them in pro-e.

 

My guess is they don't know how to use the tool.

I don't know Pro/E sheet metal either, but I'll make a wager that I could figure out how to use it correctly to do the work you do much much much faster than you can do it in AutoCAD. If you do a lot of this type of work - (training) should pay for itself in short order.

 

In Inventor I can specify global k-factor or a different k-factor bend-by-bend. K-factor is a constant, an average value used within limits. In Inventor I can also use a Bend Table generated from actual machine data if I need precise accuracy. Can't get any more accurate than that.

 

Challenge - post one of your more challenging AutoCAD sheet metal parts.

It turns out that I am in a Creo class for the next week.

Post the Pro/E solution and your solution and I'll pose the problem to the instructor.

[JD Mather]

... So I would say that there is a high percentage of pro-e users out there doing drawings of metal parts that are not correct, and I can produce these more accurately in AutoCAD than them in pro-e....

 

Haven used a variety of CAD programs since '87 of the last century, and been exposed to a lot of users and a lot of files, my opinion is that only about 10% of users of any CAD program really know what they are doing. The problem is not the tools.

[tzframpton]

Stykface, I am doing this on a manual basis. I have done metal parts in pro-e (with the k-factor set correctly) made the flatstate and then imported the model into AutoCAD and made a separate flatstate in AutoCAD. The results are identical.

Oh okay... so from what I gather, it's use error, not software error?

[tonyj]

JD,

I'm on an android phone and its difficult to reply with quotes. Buy you are right in what in what you are saying, but the fact still remains that a high percentage of pro-e users are not familiar with sheet bending so why do PTC not have the k- factor set to .44 by default. I don't know of a material that requires a .31 k-factor, thats not to say that one does not exist. By doing this they are not helping themselves. Pro-e is a difficult program to learn, and the last thing on a studens mind when learning pro-e is k-factors.

The challenge. I can not send you a model of a complex part because, pro-e or inventor will not br able to make it into a flatstate, unless its a simple part. The reason this is, for example if I have two hoppers joining each other at 45 on the plan and they are splayed out. I will have to cut the part in a certain way so that when its in the flatstate it will be square, as the plasma cuts square.

Now there is no problem doing this, by changing the orientation on the fold ends etc. The problem is pro-e and I'm sure inventor also will not be able to convert it to a flatstate because it is not satisfying its criteria. So, I can't send you a complex part but I could send you a simple part, but who wants simple. So you post me a .sat file of a complex part done in inventor or pro-e and tell me what k- factor you used, to the highest degree of accuracy that you can set it to and I will send you back my flatstate with fold lines.

Also there is know doubt that inventor or pro-e can do this much quicker, your talking abouts seconds. I used pro-e for over 12 months and thought it was an absolute disaster for trying to design things. The positive thing was modifying the model and having the drawings change with it.

The text on my phone is hopping all over the place, I hope all the above makes sense.

[tonyj]

Oh okay... so from what I gather, it's use error, not software error?

 

Stykface,

I wouldn't call it user error I would call it software manufacturer error.

[JD Mather]

Stykface,

I wouldn't call it user error I would call it software manufacturer error.

 

I would call it user error. I don't know how a default setting not to your liking can be termed a software manufacturing error.

[JD Mather]

 

.... I can not send you a model of a complex part because, pro-e or inventor will not be able to make it into a flatstate, unless its a simple part. ...

 

...The problem is pro-e and I'm sure inventor also will not be able to convert it to a flatstate because it is not satisfying its criteria.

 

....I used pro-e for over 12 months and thought it was an absolute disaster for trying to design things. ....

 

I don't know how you can make these statements, show the evidence. I suspect you could benefit from training (in Inventor or Creo).

[tonyj]

JD,

Attached is a simple solid of a panel with its flat state. The flat state took 5 minutes to create. If I ask you to bring the solid model into inventor and make a flat state of it you will have no problem, as long as you use a k-factor of .44 it will be identical to my flat state. It is a simple panel with only two folds, but there are no limits to this only if I attach a complex part pro-e or inventor will fail to create the flat state. That said, you send me any part you like, however complicated, and I will create a flat state identical to what inventor creates.

 

BTW the default setting of pro-e, having the k-factor set to .31, is a mistake by PTC. They should at least have this set to .5 by default. Like I said, a lot of people (young engineers) using pro-e don't know the first thing about sheet bending.

 

I did have training in Wildfire 5.0 and from the very start I did not like it. Its fine if you know exactly what it is you want to create, ie. if you are copying something, but when you only have an idea of something that you are trying to create and you need to find ways to make it possible in reality pro-e is not the way to go.

I say , 'if you wanted to draw/design something, Autocad is like having a fine pen and a piece of fine paper, pro-e is like having a slab of stone and a hammer and chisel.'

SHEET PART TM 2000.dwg

[tzframpton]

Tony, while I respect the fact that you are highly experienced and skilled in your trade, I still disagree with you that the software manufacturer is at fault here. Software is a tool, not a handicap. An opinion of a preset value should never put the software at fault. Default k-factor settings of .31 may in fact be used by certain industries or trades. It is up to the user to properly configure the software to their needs. It is impossible for a software company to meet the default needs for every single user. In my mind, they should leave it blank so the value must be filled in.

 

If I ask you to bring the solid model into inventor and make a flat state of it you will have no problem, as long as you use a k-factor of .44 it will be identical to my flat state. It is a simple panel with only two folds, but there are no limits to this only if I attach a complex part pro-e or inventor will fail to create the flat state.

Isn't this contradicting? You say Inventor will make this correctly as long as a value is correctly set?

 

Like I said, a lot of people (young engineers) using pro-e don't know the first thing about sheet bending.

This statement falls into the "no kidding" category. Every young degree'd engineer barely knows anything about engineering in a real world environment. It's up to the company to train, mold and challenge these individuals in the mutual alliance we call employment. Whether you're teaching young engineers the correct bend tolerances in AutoCAD on a manual basis, or you're teaching young engineers the correct k-factor setting in Inventor... what's the difference? Either way they have to learn it. Why not use the better tool?

 

I say , 'if you wanted to draw/design something, Autocad is like having a fine pen and a piece of fine paper, pro-e is like having a slab of stone and a hammer and chisel.'

This statement is totally reversed. AutoCAD is now the hammer and chisel. I have to argue this same mindset with Revit all the time to the old-school AutoCAD guys. The parametric world (Inventor, Pro/E, Revit, etc) is a more efficient and more accurate world than the manual drafting world (AutoCAD, Microstation, etc).

 

Ever heard the term "Work smarter, not harder"? Why not use a parametric CAD software that mitigates a ton of possibilities of errors by doing things manually? You're advertising AutoCAD is more accurate, but in actuality the real truth in your statement is AutoCAD is only as accurate as the user who's using it. Parametric CAD applications make you "free". Free to set parameters, or values, and just "design" without always having to double check your work, or worry about calculations, etc.

 

But, it's hard to make people understand this concept who's been doing the same thing for 20 years. In my experiences, getting people to accept a new and better CAD application is VERY difficult and I cannot understand why, other than pure stubbornness.

 

Please be assured that my comments are not to be condescending to you personally at all, but mostly rants "in general".

 

[tonyj]

Yes Tanner, putting the default setting to '0' would be a good idea, because I don't know of any material that requires a k-factor of .31

(JD Mather replied before your last reply, but I can't see it on my computer now.)

I previously asked him to set his k-factor to .44 because that's what I was working to when I was doing the flat state in Autocad, ie for a particular steel, mild steel, so we would both have to be working to the same k-factor to get the same result.

Maybe you are both right and I do need to be educated more in pro-e or inventor. But all I am hearing at the minute is hype about pro-e etc. Some of the top guys at our company, who don't know the first thing about any Cad program, are swearing about how good pro-e is, if that's now swallowing hype what is?

I have been using auto cad since 2001 and before that I was a steel fabricator. I work for a company that uses pro-e and nobody at the company uses auto cad to any great extent except me. When I started there, about 2 years ago I was using auto cad and they sent me off for training in pro-e. When I got back I was using it, designing various products and I really tried to like it, but it was really painful. I just found it very restricting when trying to design something, it felt like having one hand tied behind my back. I am now back using auto cad.

There are many things in auto cad that I find much better for designing than in pro-e, and one of these for example is interference testing. Auto cad is just brilliant for this, with pro-e, I stopped using interference testing because I found it pretty much useless. I have also found it much quicker to model in auto cad, and the drawings I can produce in auto cad are much better than the ones I was producing in pro-e. That's not to say that somebody else couldn't do a better job of their drawings in pro-e than I do of mine in auto cad.

JD, I did have a positive attitude to learning pro-e, that's why I went to learn it, but like I said, 'it was really painful'.

[JD Mather]

...

There are many things in auto cad that I find much better for designing than in pro-e, and one of these for example is interference testing. Auto cad is just brilliant for this, ...

 

I have seen this happen frequently. Your lack of adequate training is costing your company money.

There is good reason why companies are willing to pay a premium over AutoCAD to get advanced tools. But they must be willing to pay for the training and the user must be willing to stick with the learning curve till they have learned the advanced tools.

 

Hmmm, what do you have to do to get correct flat pattern in AutoCAD. Should be a one-button solution. Autodesk is a sorry company by making you learn the work-around you have developed because of the lack of functionality they put for sheet metal into AutoCAD. Do you see the problem of your logic?

 

I know when I have hit a rock wall - I'll bow out now.

Edited June 4, 2013 by JD Mather

[tonyj]

JD,

Unless somebody actually shows me how good inventor or pro-e is at achieving what it is I want to achieve in designing, why should I just take their word for it and invest a heap of time in learning it? I can do what I need to do in auto cad, I can't in pro-e! Somebody educate me.

This horse is dead.

[tzframpton]

I have been using auto cad since 2001 and before that I was a steel fabricator.

When I started there, about 2 years ago I was using auto cad and they sent me off for training in pro-e. When I got back I was using it, designing various products and I really tried to like it, but it was really painful.

This is exactly my point from my previous post. You've been using a program that hasn't changed much in principle. You've been using it for 12 years, so you're used to it. Plus, you come from the field, which gives you a great advantage.

 

Old school hand drafters in the 80s and 90s would cuss AutoCAD and say it'll never catch on. How many hand drafting positions are there now? Old school AutoCAD designers in today's market say the parametric CAD programs are inadequate and useless. I wonder how many vanilla AutoCAD designers will be left in 10 years, for trade-specific CAD employment positions? It happens quicker than one might think. My company just announced "Revit only" last year, and scared a few of the AUtoCAD old-schoolers because in a single day they were on top, then on bottom, all because of a company decision and announcement. Good thing my company is loyal enough to not lay-off these very intelligent individuals and is providing tons of in-house training for all to benefit.

 

Not trying to put you on the spot or insult you at all, but I am trying to make you aware of the common historical transition of manual drafting to computer aided design software, and nowadays the transition of outdated CAD software to new parametric CAD software. It's all the same argument and it simply is a false perspective.

 

Simply put, you don't know how to use the software effectively. Not faulting you personally on this, it could have been the training. But it shouldn't take much for someone to see the writing on the wall and use a small amount of intuition to think "Hmmm, if all I have to do is preset this k-factor value and save it, it'll do all my flat patterns in the click of a button, instead of manually calculating these values by hand in AutoCAD?"

 

$0.02

[tonyj]

Thanks lads, I will take on board what you both have said.

[Bill Tillman]

Bend allowance is dependent on 4 variables, material, thickness, bend radius, and bend angle (and perhaps a fifth - grain direction).

 

You forgot the 6th variable in this one...the guy running the brake press.

[tzframpton]

You forgot the 6th variable in this one...the guy running the brake press.

Nice!!!

[SuperCAD]

I just went through this with SolidWorks. I completely redid the steel gauge tables as well as the K-Factor and bend radius tables. The problem is that unless you're using the same bending method, and the same machine, and the same operator, the K-Factors will be all over the board (not by much, but enough to matter). I spent some time talking this over with the shop that we outsource our bending to and I was able to get his K-Factor chart, all of his possible bend radii, and the thicknesses of material that he can work with. With all of that information, I was able to get SolidWorks to make a flat pattern that was 100% accurate to the way they were figuring their flat patterns (and they also use AutoCAD and do everything as a flat 2D drawing).

 

There is another shop that we occasionally outsource to, only because they have a machine with more tonnage so they can bend sheets that are thicker than 1/4". No matter how much I try, they will not give me any bending information, so I have to send them the 3D parts and let them figure it out. The K-Factors that our main vendor uses are completely useless to this one. They'll be close, but not close enough.

 

My point being that it is possible to have a parametric modeling program figure out sheet metal flat patterns that are accurate and more efficient than doing them the "old way".