Sheet Metal Guy Blog

13 Sep 2006   02:34:51 pm
But I am drawing in 3D!
“I want to be able to unfold my part in the CAD system.“ “Well, you have to draw a 3D model of your part to do that.” “I did! I have a front, top and side view. That is 3D, isn’t it?” I have heard this too many times over the years. Sheet metal fabricators want the benefit of 3D modeling, but many are still using their CAD software like a drafting board. “But drawing in 3D is too difficult to do.” Drawing 3D in today’s CAD software is even easier than drawing 2D. They even include features to magically create the paper drawing for you from the 3D model. And yes, in 3D, it is a model not a drawing. The tools available in today’s CAD software make 3D modeling so easy, and the benefits so great, you can’t afford not to take advantage. Even for sheet metal [arts, there are specific features and add-on programs to build flanges, hole patterns, and unfold the parts. SolidWorks, Solid edge, AutoDesk Inventor, Alibre, VX CAD, even KeyCreator brag about their sheet metal modeling features. If you really believe drawing in 3D is too difficult, perhaps you should investigate the training classes available from your local reseller. Or look into the many books available about your CAD software. A few steps in the right direction and you will be modeling all of your parts in 3D and loving it.
		Category : Sheet Metal | By : SheetMetalGuy | Comments [68] | Trackbacks [3001]
05 Sep 2006   12:53:44 pm
New bend relief capabilities in SolidWorks 2007
While SolidWorks indicates the Corner Trim feature was added to the Sheet Metal Toolbar, it really was not. Mine shows two Vent icons and no Corner Trim icon. But this is easy to correct. Just right click on the sheet metal toolbar and select ‘Customize…’ from the pop up menu. At the top of the Customize dialog box, pick the ‘Commands’ tab. And in the ‘Categories:’ list, select ‘Sheet Metal’. Find the ‘Corner Trim’ icon and using your mouse, drag it into the Sheet Metal toolbar. I put mine in between the two ‘Vent’ icons. Then place the cursor on one of the ‘Vent’ icons and drag it out of the toolbar. When you release the mouse button, the unwanted icon will disappear. Click the ‘OK’ button and you're done. But what is new with the Corner Trim command? Remember this feature was available in 2006, but only when the Flat Pattern was unsuppressed and through the Break Corner command. Well the Break Corner command is now only for the 3d model and the Corner Trim command is only available for the flat pattern. And yes, you can use it does include the Break Corners features for in the flat. What’s new is that both the Relief Options and the Break Corners Options have a nice new ‘Collect all corners’ button. This certainly speeds up the process since you no longer have to individually select each corner or relief area. The problem though is that on the Break Corners side, it found all of the inside corners of my cutouts and holes and ignored all of the outside corners. Even the outside corners of my cutouts. The old method of selecting the face gave me the corners around the part boundary and not the corners of my cutouts. And if I added corner reliefs to the bend areas the Break Corners command ignored the inside corners where the bend reliefs where place. A little consolation, but still a concern for corners I may not have wanted modified. The Relief Options has also added a few of new check boxes. Some greatly needed features. The first, “Centered on bend lines”, shifts the relief feature from the intersection of the flange edges to the intersection of the bend lines. Next is “Tangent to bend”, which quickly sizes the relief to the width of the bend area. No more guessing what size to make the relief. This check box is mutually exclusive to the Ratio to thickness check box. You can’t have it both ways. And a third check box to “Add filleted corners” to the relief. Terrific for those whom laser cut the notches and want to eliminate the rough corners. Too bad these features can’t be included in the 3d model. But at least it makes preparation for fabricating much easier.
		Category : Sheet Metal | By : SheetMetalGuy | Comments [79] | Trackbacks [5137]
24 Aug 2006   11:56:44 am
What k-factor should I use?
Recently I have received a number of comments from our article about bend allowance. They all have one thing in common. “What is the correct k-factor to use?” And the answer is, I can’t tell you. It really starts with all of the variables involved in the manufacturing process. Number one is the material being bent. How hard or soft is the material? Then there is the process, are you air bending or bottom bending? Next is the radius of the tooling in your press brake. That’s right, don’t just sit in your office and say I want a .06 radius on this bend. Get out in the shop and ask what radius punch will be used when the bend is formed. Can you start to see why this isn’t an easy subject? Well how about some answers. Referring to “Tool and Manufacturing Engineers Handbook, Volume 2”, I found a chart on page 10-4 which shows some data for air bending and it includes a bend allowance based on the other data included in the chart. Using the Bend Calculator, I found the k-factor for 90 degree bends to be as follows: Gauge - Thickness - Inside Radius - k-factor - - 20 - - - - 0.036 - - - - - - 0.039 - - - - - 0.3314 - - 18 - - - - 0.050 - - - - - - 0.059 - - - - - 0.3224 - - 16 - - - - 0.060 - - - - - - 0.078 - - - - - 0.3340 - - 14 - - - - 0.074 - - - - - - 0.098 - - - - - 0.3963 - - 12 - - - - 0.104 - - - - - - 0.137 - - - - - 0.3967 - - 10 - - - - 0.134 - - - - - - 0.176 - - - - - 0.4016 So how about a rule of thumb and from there we will discuss this further in the Manufacturing Forum. Thickness > Inside Radius - - - - k-factor = 0.25 Thickness = Inside Radius - - - - k-factor = 0.33 Thickness < 2 * Inside Radius - - - - k-factor = 0.42 Any questions? I’ll see you in the forum.
		Category : Sheet Metal | By : SheetMetalGuy | Comments [66] | Trackbacks [2625]
21 Aug 2006   10:31:38 am
Still plotting your jobs and keeping paper files?
CNC programmers don’t like to change their habits. Back in the dark ages, just being able to plot your program was an exciting feature. As verification that our program was good, we plotted every job, then printed and duplicated the paper tape and setup sheet. This and any other paperwork we could generate was then stored in a file folder in our cabinet for safe keeping. When graphics based programming came to town we continued these habits. Still generating all of the paper print outs and storing them away. But wait. Now if a problem was to arise, you no longer went to the paper file to look at the plot. Rather you called the job up on the screen and checked it out. No more need to make and save the plots. And as for the paper tape, well now they are DNC files. But, why save a print out? If the file is lost or corrupted, you simply call up the job and run the post processor to recreate the DNC file. And the same with the setup sheet. If you are still printing and plotting everything you do, how about taking a few moments to consider whether these items are still needed. It’s time to empty those file cabinets and save the time needed to create all of that paper backup. After all, when is the last time you pulled a plot out of the file cabinet to find an error in your program?
		Category : Sheet Metal | By : SheetMetalGuy | Comments [49] | Trackbacks [3400]
17 Aug 2006   03:26:50 pm
Bend Allowance or Bend Deduction
During the past 20 years, I have worked with people around the world, helping them to unfold their parts. One of the first things I learned is that everyone uses the terms Bend Allowance and Bend Deduction interchangeably. I have visited many shops which have a chart tacked to the wall and labeled Bend Allowance only to be showing Bend Compensation values. On top of this, the chart was created back in the 1960’s or 70’s for 90 degree bends only. But these are two distinctly different things and you must learn their proper definitions if you are going to unfold your parts in your CAD system. Bend Allowance is the length of the arc through the bend area measured at the neutral axis. Meaning somewhere in the material thickness, where the material is neither stretching, nor compressing due to the bend. This is normally represented in the bend formula as the k-factor. By adding up the length of the flat portion of each flange surface and adding one Bend Allowance for each bend area, you then have the flat length. Bend Compensation is a calculated value (the bend allowance minus two times the setback) which you then subtract from the total of the dimensions of the part to get the flat length. Please review the formulas on our web page http://www.sheetmetalguy.com/bending-formulas.htm.
		Category : Sheet Metal | By : SheetMetalGuy | Comments [214] | Trackbacks [3844]
Prev 1 2 3 ...6 7 8