Other 2D CAD

DoubleCAD XT vs. AutoCAD LT (Cadalyst Labs Review)

1 Jul, 2009 By: Bill Fane

IMSI/Design claims its new, free 2D drafting tool is a viable replacement for AutoCAD LT. Is it?

Once upon a time, back in the last millennium, CAD systems were very expensive and ran on very costly hardware. It was not uncommon to spend more than $200,000 for a single seat, and those were late-1970s dollars. Needless to say, not many CAD seats existed outside the aerospace and automotive market. Then along came PCs and AutoCAD, and everything changed. It is not quite true to say that AutoCAD took over the CAD market; rather, it basically created a whole new market.

DoubleCAD XT v1.1
2D Drafting and Detailing Software
Overall Grade: A (in its own right); C+ (as an AutoCAD LT "workalike"/compatible product)


Cons: Not as AutoCAD compatible as other products on the market.

Price: Free


Over the years, several things happened. Probably most importantly, AutoCAD and its DWG file format rapidly became the de facto standard. Over the years, AutoCAD continued to grow, adding new power and capabilities with each release, building its position as the market leader. A number of other CAD programs have come along to challenge that position, with varying degrees of success.

Some segments of the AutoCAD user base at one point began to lodge complaints along the lines of, “Why do I have to pay for a big, full-featured, customizable 3D-capable program when all I do is flat 2D schematics?” Thus was born AutoCAD LT. Autodesk discourages people from saying that LT stands for “lite,” but that is effectively what it is.

Surprise, Surprise
IMSI/Design is one company that markets a product that competes with AutoCAD. Its flagship product, TurboCAD, is well regarded and has a very loyal user base. But early this year, with much fanfare (and after some struggles with Autodesk over the product's original name, A/CAD LT Express), the company did something unusual. It introduced DoubleCAD XT, taking dead aim at AutoCAD LT.

Even more unusual is the price of DoubleCAD XT. It's free. Yes, that’s right -- free. The DoubleCAD XT download gets you a full-featured, unlimited commercial license. (This compares quite favorably with AutoCAD LT's retail price of $1,200 per seat.)

IMSI/Design claims that DoubleCAD XT is "an AutoCAD LT 2009 workalike." (A version 2010 workalike reportedly is on the way.) Is the claim true? I set out to test DoubleCAD XT v1.1 against AutoCAD LT 2009.

First Impressions: A Tale of Three UIs
Right off the bat, I had a quibble. When you double-click the desktop icon to launch DoubleCAD XT, a large splash screen appears immediately that takes up about two-thirds of your desktop. The problem is that the company has specified that this splash screen should always run on top of anything else you might be running, so most other applications are not available during the time it takes to launch DoubleCAD XT. This product is not the only one to commit this offense, but it still ticks me off. The splash screen must be closed manually when the program has finished loading.

Once running, DoubleCAD XT on first impression looks like AutoCAD LT 2008, with virtually identical toolbars. Unlike the 2009 (and 2010) versions of AutoCAD LT, DoubleCAD XT does not have a ribbon menu.

DoubleCAD XT (top) looks more like AutoCAD 2008 (bottom) than AutoCAD LT 2009 (center). (Click to view larger image.)

Closer inspection revealed some very significant differences, however.

For starters, it seems a command of some sort is nearly always active in DoubleCAD XT. Sometimes. Or maybe not. As you would expect if you were using AutoCAD LT, pressing the Esc key in DoubleCAD XT doesn’t exit from the Line command, but merely stops drawing at the end of the current segment. If you then move the cursor and pick a point, you have selected the start point for another line. Similarly, the Arc command seems to repeat until replaced, but Circle runs only once, sometimes. According to IMSI/Design, the Esc command as designed resets the command tool but does not cancel a command entirely (and you can use the space bar to cancel a command entirely). If you are accustomed to how the Esc key works in AutoCAD LT, as I am, you will likely find this functionality confusing.

It also seems that keyboard shortcuts don’t work if the current command has an option the same as the shortcut. For example, C starts the Circle command and A switches to Arc, but then another C doesn’t switch back to Circle but instead invokes the Center option of Arc, which is still active. The current command remains active even when you open a drawing within the current editing session. In short, the basic command functionalities of  DoubleCAD XT are not entirely consistent with those of AutoCAD LT.

File Compatibility
DoubleCAD XT has its own proprietary file format, but it also claims to support AutoCAD DWG files from R14 to version 2009. A few quick tests revealed some anomalies, however. For example, AutoCAD 2008 added self-scaling annotative objects such as text and dimensions. AutoCAD LT supports them fully, but DoubleCAD XT only displays the first size created and does not display the alternates for other scales that may be attached. Similarly, it does not have any provision for setting the annotation scale, so all annotative objects appear all the time in all viewports regardless of viewport scales. When I saved a drawing from DoubleCAD XT and reopened it in AutoCAD LT, the annotative objects had lost their annotations; alternate scale representations had disappeared.

Annotative objects created in AutoCAD LT (top) lost their annotations when the file was opened in DoubleCAD XT (bottom).

Another significant omission is support for xrefs (external references). Xrefs are maintained when opened in a DoubleCAD XT file, but you cannot attach or create new xrefs. If you update an xref in the source, it will display in the host once reloaded or the host drawing is reopened. Xref connections survive the round trip if you open an xref'd AutoCAD LT drawing in DoubleCAD XT and save it back to AutoCAD LT.

DoubleCAD XT also does not recognize AutoCAD LT file locking on a simple Microsoft Windows peer-to-peer network, so two people could potentially be editing the same file at the same time. The last one to save wins. File locking does work if your CAD department is using a network file server to share files.

Here’s Looking at Yours
Another big issue is interface compatibility -- that is, potential users are bound to ask about the ease of switching back and forth from one program to the other. This issue is tough to call because AutoCAD LT itself went through a major user interface change with the introduction of the ribbon menu in the AutoCAD 2009 product series. If your experience is mainly with AutoCAD LT's classic interface, the switch would not be too difficult. If you are accustomed to using the newer ribbon interface, the switch will be more onerous.

In any case, the adjustment is similar to driving a car that's not your own. You know the car has headlights and you know you have to turn them on at night. All you need to do is to find the correct knob or button. CAD programs are the same; you know you need to draw a circle, and you know the program can draw circles. All you need to do is locate the command.

On the Plus Side
DoubleCAD XT offers many features you won't find in AutoCAD LT -- several of which are on the AutoCAD User Group International (AUGI) Wish List for AutoCAD LT. Highlights include:

  • transparent fills
  • osnap prioritization
  • embed/bind images in a drawing
  • draw order by layer
  • self-healing walls
  • self-aligning block insertions
  • ability to input mixed units on the fly
  • true Bezier curves
  • parametric constraint variable palette
  • smart dimensions
  • advanced polyline editing
  • hide objects regardless of layer
  • retaining true units between drawings with different unit settings
  • one-step object splitting

DoubleCAD XT also supports Google SketchUp and SketchUp Pro v7. Note that these features are supported in DoubleCAD’s native file format, but may get lost or modified if you Save As to AutoCAD DWG format.

A full list of features and other details about DoubleCAD XT is available on the product web site.
The Bottom Line Could Be the Bottom Line
So why would IMSI/Design give away DoubleCAD XT? Because the company hopes you will upgrade to DoubleCAD XT Pro for a mere $695, which is said to offer most of the features of AutoCAD LT plus a few tricks of its own. One of those extras is 2D parametric design, which is now available in AutoCAD 2010, but not AutoCAD LT.

I would describe DoubleCAD XT as “works very similar to” and “mostly file compatible with” AutoCAD LT 2009. It is a competent, viable CAD product in its own right -- especially considering the price -- and would work very well in most standalone environments. Evaluate the product fully before introducing it in a mixed environment, either in-house or with clients, because in those types of applications the free version of DoubleCAD XT can have limitations.

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