Scaling problems, sheet metal objects.

Jim Canale

 I don't know much about changing units in BricsCAD or any other CAD program.  99.9% of my work is in inches.   When I need something in  millimeters, I just SELECT ALL and SCALE by 25.4.  If I ever have to take something from mm to inches, I just scale by .03937.   

That all blew up today when I tried to scale a sheet metal design from mm to inches.  (the model is still unfolded.)   The corners and reliefs were all screwed up.  (Apparently the scaling process didn't shrink the junction gaps, split gaps and junction gaps.   I confess I don't know anything about these things..  I select the material thickness, k-factor, and bend radius, but leave the default settings for the other stuff. I haven't even been able to find a good definition of these three things......  Can anyone here explain how to fix this?  Attached are screen shots of the mm model, the conversion, and the sheet metal settings.

Patrik Sparrman

 The thing is you dont do anything to your model. Just draw it in inch if you like then change the dim setting to mm. and put your  dims there.

VOILA ! The object is the same whether you dimension it in inch or mm.

d1.dwg

Jim Canale

@Patrik Sparrman:

... change the dim setting to mm. and put your dims there.

VOILA ! The object is the same whether you dimension it in inch or mm.

Patrik,
Thanks for taking the time to reply.   What "dim setting" are you referring to?  This is not just a dimensioning issue.  I have several objects which have to be combined into an assembly.  Some are scaled in mm, and others scaled in inches.  I need to put them all in inches, so the assembly goes together properly.

Patrik Sparrman

 Click one dimension change Primary units/dim units try Architectural and metric.

In settings search for linear unit type to change your display as you draw.

You are not supposed to scale your object just what dimensions you show.

Jason Bourhill

@Jim Canale:

I have several objects which have to be combined into an assembly.  Some are scaled in mm, and others scaled in inches.  I need to put them all in inches, so the assembly goes together properly.

In this situation you want to make sure that your source parts and target assembly are all declared in the correct units. When you insert the parts BricsCAD will pick up the different units, and scale accordingly. Under SETTINGS check the value of INSUNITS, and set it to the units you have used to model in. By doing this you can work in whatever units you like, and get BricsCAD to take care of the scaling.

Attach a simple example of a box and lid to illustrate. The box has been created in mm, and the lid in inches. The assembly of the two is in mm, here BricsCAD automatically scales the lid to suit.

As your using the sheetmetal module, I recommend that:

• In each model (part and assembly), first Initialise the mechanical structure using BMMECH. This will allow you to add additional details and properties to your part, such as description, and material type.
• In your assembly use BMINSERT to insert the components rather than INSERT. Doing this will recognise them as components rather than as simple blocks.

Regards,

Jason Bourhill

CAD Concepts

SM-Assembly-mm.zip

Jim Canale

Patrik,

Thank you, but I am not sure we are talking about the same thing.  It sounds to me that you are talking about changing the way the dimension tool reports the dimension   (fractional, decimal, etc. are options, but not mm)   To make the dimension tool read in mm or inches, the object either has to be scaled in the correct units  to begin with, or a scaling factor needs to be applied to the dimension.

My tasks are a bit different.   First of all, I have to create an assembly drawing.  Jason is correct in saying that my assembly drawing will automatically scale the components for insertion.   But I still have to generate drawings for each component..  I'd like them all to be done in the same measurement system (because most local shops prefer inches).   Unfortunately some of the components were originally drawing in metric units (mm). 

Now a solid model or a 2D model will scale just fine by applying the SCALE tool.  But these sheet metal models do not!   The corner and junction reliefs are not scaled properly.

I finally converted my sheet metal object to a block, and imported it.  That seemed to do the trick.  However I am not so sure about the unfolding operation.  I exploded the block and tried to unfold the sheet metal.  That did not work, so I applied SMCONVERT, and was able to unfold it.  However I believe the unfold was based on the parameters (K-Factor, etc.) that were resident in the mechanical browser when I unfolded, not when I originally designed the part.

Jim Canale

@Jason Bourhill:

In this situation you want to make sure that your source parts and target assembly are all declared in the correct units. When you insert the parts BricsCAD will pick up the different units, and scale accordingly. Under SETTINGS check the value of INSUNITS, and set it to the units you have used to model in. By doing this you can work in whatever units you like, and get BricsCAD to take care of the scaling.

Attach a simple example of a box and lid to illustrate. The box has been created in mm, and the lid in inches. The assembly of the two is in mm, here BricsCAD automatically scales the lid to suit.

As your using the sheetmetal module, I recommend that:

• In each model (part and assembly), first Initialise the mechanical structure using BMMECH. This will allow you to add additional details and properties to your part, such as description, and material type.
• In your assembly use BMINSERT to insert the components rather than INSERT. Doing this will recognise them as components rather than as simple blocks.

Regards,

Jason Bourhill

CAD Concepts

Jason,

Thank you very much for your reply.  As always, very thorough.   While you are absolutely correct that using the BMINSERT command to bring my components into an assembly drawing will automatically take care of scaling, I still have to create "inch" drawings to get the components quoted. (Most of the local shops prefer to deal in inches.)   As Patrik stated, I can apply a dimension scale factor to the dimensions I place on the 2D views.   But I prefer that the model itself is scaled in the correct units. 

That has never been a problem with solid models, or 2D models.  It IS a problem with sheet metal designs, because junctions and reliefs do not respond well to the SCALE command.   I ended up saving the model to a file with WBLOCK and then importing the block into a drawing which has ISOUNITS set to "inches".    The remaining issue is the unfolding of the scaled sheet metal model..  I am not certain it is correct.

Not to get off topic, but I am having a problem with V17, that the support group has yet to solve.  When I create a sheet metal design, I am not seeing any sheet metal parameters (k-factor, thickness, bend radius, etc.) in the mechanical browser window.   If I move the sheet metal design to my old V15 installation, the parameters are there.    Do you have any ideas on this?