Solid DNA blog

Blog about stuff on Solid Edge CAD software

Flash Fit

Flash fit

Introduction of Flash Fit (FF) around V17-18 has cause the same wave has ST but at a smaller scale.

Lately I was surprise to see that SE users did not adopt it has their default to assemble parts.

Would it be because, SE users are more traditional the other CAD users? May be users like the comfort of their old slippers?

Avoid integrating new function in you workflow, in many cases, is related to a lack of training.

I usually try to blog with an informative state of mind. My goal is to educate the market about the possibilities offer by Solid Edge.

However, for this one I will dive in more has a training article.

Flash Fit concept.

Flash Fit try to replicate the process of our brain when placing part.

When we hold an object, our brain process geometry and send informations to our hand to move/rotate so we can align two parts to make them fit together.

Like Keanu Reeve in the Matrix who see things in term of 0 and 1


SE needs to process part at the mathematical level. Faces of a part are describes by a bunch of 0 and 1 and each face get a normal.

Normal is a vector perpendicular to the surface pointing outside the part volume.

Ok I came from far but told you that i was writing more like a training session 🙂

How many of you had this normal concept in your head while working?

This is what Solid Edge sees:

Normale vector

How to read Assembly Icon?

I would bet 1 million dollars that many of you never ask them self what is the signification of the icons use when placing a part.

Relation_01 Relation_02Relation_03Relation_04Relation_05Relation_06Relation_08Relation_09Relation_10Relation_11

Ok Nice, but how can I link assembly icon to SE vision?

Take closer look at the first four icons.

From the picture showing how SE see parts, you will see that the normal look like an arrow.

From here you should be able to make the connection between assembly icon and normal!

Just a tip for those who are visual…


Therefore, when you ask for faces to be mating,SE place the normals so they point in opposite direction.

  • For Planar align normal point in the same direction
  • Axial normal are collinear
  • Insert is a combination of Mate/Planar align and Axial

If you find yourself fighting with SE when it comes time to place constrain, try to visualize the normal associtate to the faces you are selecting.

Be honest who should paid me that 1 million dollars…..

When  pick face how SE know what relationship to use?

Here a table showing the logic placement:


Note 1: To determine if a mate or planar align relationship is applied, the orientation of the two faces is compared, and if the faces are closer to a mate solution, a mate relationship is applied. If the two faces are closer to a planar align solution, a planar align relationship is applied. You can use the Flip button or TAB key to apply the other relationship.

Note 2: To determine if a mate or planar align relationship is applied, the orientation of the two faces is compared, and if the faces are closer to a mate solution, a mate relationship is applied. If the two faces are closer to a planar align solution, a planar align relationship is applied.

When using the Assemble command to position a part already in an assembly using FlashFit, the Flip option is available when you select circular edges. When placing a new part into an assembly with FlashFit using circular edges, the Flip option is not available. You can edit the relationship later.

Where are my assembly constraints?

Once you have place a constraint they are place at the bottom of the Pathfinder.


The separation bar can be move to accommodate the number of relations.

Relations display represent those who are relevant to the selection (Valvel01)

The line in the relations section represents your selection.

  • Relation above point to parts above the selection
  • Relations under point to parts under the selection

This gives valuable information when it comes time to heal our assembly.  You have the name of the part, the value and the name of the relation. Relation names appeared in the variable table.

If you RMB on any of the constraint contextual menu will give additional information.

Constraint RMB

When a constraint is click, Placement options are available for select constraint.



How to access the Flash Fit?

Flash fit is the default assembly relationship, no need to setup anything.

When a part is drop in the assembly:

  • Drag’n drop from Windows explorer
  • Drag’n drop from windows toolbar
  • Copy/paste from windows explorer/windows toolbar
  • Drag’n drop from the parts Library
  • Drag from assembly structure
  • etc….

The command is automatically start.

If the part is already in the working zone:

  • From the Home tab, group Assemble simply click:

Assemble command

Select area will change for Assemble

Path assemble

Then follow the prompt…


First click

Prompt 02

Second click

Mate overall

After part has taken is place.

Prompt 03

Most of the users screw up at the end because they try to win over the machine. At the speed of light they hit ESC.

This is one of many cases, where speed cause discomfort that lead to complain 🙂

After you click the destination face, if result is not what you expect, first thing to do GET OUR HANDS OF THE MOUSE AND KEYBOARD AND STOPE before doing any other move.

In case you did not know

S – Stop

T – Think

O – Observe

P – Plan our actions

E – Execute your actions.

In many cases simply use the TAB key will replace everything. In case you still prefer speed and redo you work CTRL-Z undo your last action.


Ok I use the tab Key but my part is position at a weird place what should I do?


What the prompt ask after the first click.« CLick…….or drag placement part»

  • E – Execute your action

Click one of the faces and drag. Make sure you will not click twice because second click is to select destination face.


What do I do if I click instead of drag?


  • T-Think…. What’s is the most important thing to do in SE?

You didn’t read the second prompt up to the end…….

«Click….or RMB to select other (cancel the face selection)»

Once cancel the first selection, click drag again on the correct face to move the part off its current location.

Ok I got one difficult question for you.


How can I predict behavior when placing constraint?

When choosing a cylindrical face only edges or other cylindrical faces will be allow for the second click, FF automatically, filter base on the first face you select.


Yeah right what kind of prediction is that?

If you read the table about the logic placement you will have understand that normal are compare and SE choose the relation that match the situation.



OK…OK…OK I’m coming to it….

Again READ second prompt

«Click…… or drag placement part (CTRL to rotate).»

You still need more control to predict behavior….

When using the Part library of the EdgeBard, preview should be available at the bottom.

ASM preview

If no preview is display, RMB in the background of the part library

RMB background

Then make sure you check Interactive.

Once you place the correct orientation in the preview, part will be place in that orientation. This will ensure that initial orientation get you near a predictable behavior.

Remember no need to be in the exact orientation, just something that look like correct.

This will be demo in the video at the bottom.


What other option i have when placing constraint?

When placing constraint this icon will be available


Giving you access to:

Option windows

I will not retype information’s already available simply click help for description. Options in gray will be available only when assembly are place in assembly and meet certain criteria.

I often use references to place part how can i use them?

Again it is only a matter of taking time to read available information, this include looking at the interface. When inserting a part, the top of the assembly bar has a icon to display references of the part being place.

Construction en

If you have taken time to read paragraph bout contextual menu for parts library, there is an option «Show part reference plane». When a part is insert, he’s references planes will becaome available. For smal assembly i will recommand for biger assembly this is too much informations.

Once you have select the reference plane click on a nother part using the «R» key. Other part plan’s will show click the one you need.

While we talk about too much informations ?

For those who complain about too much information when placing a assembly, go back and read the paragraph about the contextual menu of the part Library. You will see that you can use configuration when placing assembly.


From here, you should have a good portrait how FlashFit work. Base on those information’s, there is no justification not to use Flash Fit in 80 % of the case. That last 20% involve relation like angle, Connect, Gear etc…

I repeat myself get train if our unsure how a command work. Everything i show/write in this blog is simply because I take time to train myself and others users.

Avoid trainning for some obscur reason, it is like running out of gas but avoid gas station thinking you can make it to the next. Then….. you have to walk a mile or two, «Not too bad it could have been worst»….. and you continue the same pattern weeks after weeks. Then you discover that running a mile or two is faster than walking when you don’t make it to the next station…….

Training allows you to establish a dialogue with someone out of our job context, a different point of view. It will make you realize that instead of walking or running, you could have taken the forgotten roller blade or bicycle in the trunk 🙂

Go to for a series of video about Flash Fit

1 Comment »


    Comment by nulptroulsony | 10 April 2009 | Reply

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