You just finished a complex CAD assembly. The client needs it today. You try to email the files and hit the 25MB limit before attaching the first part. Sound familiar?
CAD files present a unique challenge. A single SolidWorks assembly can balloon to 500MB. AutoCAD drawings with xrefs can exceed 1GB. And when you’re sharing with clients, subcontractors, or manufacturing partners, you need a method that’s both professional and reliable.
This guide covers proven methods for sending large CAD files, tested with real engineering workflows.
Why CAD Files Are So Large
Modern CAD files carry enormous amounts of data that non-engineers don’t realize:
Parametric history: Every design decision, sketch, and feature is stored for future editing. A simple bracket might have 50 features, each adding to file size.
Assemblies reference everything: An assembly doesn’t just link to parts, it stores mating relationships, configurations, and often copies of referenced geometry.
High-resolution surfaces: Complex curves and surfaces require dense mesh data. Organic shapes and imported scans are especially large.
Drawings reference models: A drawing file links to the model but also stores view-specific data, dimensions, and annotations.
Understanding this helps you choose the right sharing method and explains why “just compress it” doesn’t work.
Method 1: Email (With Limitations)
Best for: Small files only, quick reviews
Most email services cap attachments at 25MB. This works for simple 2D drawings but fails for anything complex.
When email works:
- Single-part simple geometry (under 20MB)
- Exported PDFs of drawings
- Screenshots or snapshots for review
How to check file size before emailing: Right-click file > Properties (Windows) or Get Info (Mac) to see exact size. If over 20MB, use a different method.
Email workarounds (not recommended):
- Splitting RAR archives across multiple emails (annoying for recipient)
- Removing history and features (destroys editability)
- Downsampling surfaces (loses precision)
These workarounds create more problems than they solve. If the file doesn’t fit in email, use a method designed for large files.
Method 2: FTP Server
Best for: Regular exchanges with same partners, IT-supported environments
FTP (File Transfer Protocol) is the old-school engineering standard.
How it works:
- Your company or client provides FTP credentials
- You use FTP client (FileZilla, WinSCP)
- Connect to server
- Upload CAD files
- Notify recipient files are ready
- They download from same server
FTP advantages:
- Unlimited file sizes
- Fast transfers
- Reliable for large files
- Common in enterprise environments
FTP disadvantages:
- Requires FTP server setup
- Client software needed
- Security concerns (use SFTP instead)
- Not user-friendly for non-technical clients
- Recipient needs credentials
When to use FTP: You’re working with enterprise clients who already have FTP infrastructure, or your company runs an FTP server for external sharing.
Method 3: Cloud Storage (Google Drive, Dropbox, OneDrive)
Best for: Personal cloud subscribers, occasional large transfers
If you already pay for cloud storage, this is a familiar option.
Google Drive process:
- Upload CAD files to Google Drive (drag and drop or Drive app)
- Right-click file/folder
- Select “Share” > “Get link”
- Set permissions to “Anyone with the link”
- Copy link
- Send link via email
Dropbox process:
- Upload files to Dropbox
- Right-click > Share
- Create link
- Copy and send
OneDrive process:
- Upload to OneDrive
- Right-click > Share
- Send link or set permissions
Storage comparison:
| Service | Free Storage | File Size Limit | Speed |
|---|---|---|---|
| Google Drive | 15GB | 5TB | Fast |
| Dropbox | 2GB | Unlimited (paid) | Very fast |
| OneDrive | 5GB | 250GB | Fast |
Pros:
- Familiar interface
- Version history (paid plans)
- Accessible from anywhere
- Collaboration features
Cons:
- Upload, then recipient downloads (double time)
- Counts against storage quota
- Free tiers too small for regular CAD work
- Monthly cost adds up
Engineering reality check: A single product design project might include 50 parts, 10 assemblies, and 20 drawings. Total: 2-5GB. You’ll burn through free storage in one project.
Method 4: WeTransfer
Best for: One-off transfers, professional appearance, clients who expect it
WeTransfer is popular in design industries for good reason.
How to use WeTransfer:
- Go to wetransfer.com
- Click “Add files”
- Select CAD files (assemblies, parts, drawings)
- Enter recipient email
- Enter your email
- Add message (project name, revision, notes)
- Click Transfer
- Recipient gets email with download link (expires in 7 days)
WeTransfer limits:
- Free: 2GB per transfer, 7-day expiry
- Pro: 200GB per transfer, 30-day expiry, password protection, custom branding
Pros:
- Clean, professional interface
- No account needed (free tier)
- Email notification to recipient
- Optional password protection (Pro)
- Widely recognized in creative industries
Cons:
- 2GB limit on free tier (tight for large assemblies)
- 7-day expiry (may need to resend)
- Upload can be slow for large files
- No version control
When to use WeTransfer: You’re sending to clients in architecture, product design, or creative industries where WeTransfer is expected and recognized.
Method 5: CAD-Specific Solutions
Best for: Collaborative design, version control, cloud workflows
Some tools are built specifically for CAD collaboration.
Autodesk A360 (now Autodesk Drive):
- Integrates with AutoCAD, Inventor, Fusion 360
- Cloud storage and viewing
- Revision tracking
- Shared projects
- Free tier available
GrabCAD Workbench:
- Built for engineers by engineers
- Version control
- Supports SolidWorks, STEP, IGES, etc.
- Free for small teams
- Project organization
Onshape (cloud CAD):
- Entire CAD environment in browser
- Built-in sharing (no file transfer needed)
- Real-time collaboration
- Version control integral
- Free for public projects
Pros:
- Designed for engineering workflows
- Version control built-in
- CAD file preview without opening
- Team collaboration features
Cons:
- Learning curve
- Requires recipient to have account
- Some are platform-specific (Autodesk tools for Autodesk files)
- Can be expensive for commercial use
When to use CAD-specific tools: You’re working on ongoing projects with the same team, need version control, or want integrated commenting and review features.
Method 6: Link-Based File Sharing
Best for: Large files, diverse recipients, clean workflow
Services built for file sharing (not storage) remove friction from the process.
How FileGrab works for CAD files:
- Go to filegrab.link
- Click “New Link”
- Get shareable link instantly: filegrab.link/abc123
- Upload CAD files (assembly, parts, drawings, PDFs)
- Share link via email, Slack, text
- Recipient opens link in browser
- Downloads files (no account needed)
Why this works for engineering:
Link-first model: Create link before uploading. You can put the link in your email signature, project documents, or RFQ responses, then upload files when ready.
Real-time updates: Send link to client, upload files over the next hour as you export them, client sees each file appear.
No recipient friction: Client doesn’t need account, app, or specific software. Just click link, download files.
Professional appearance: Clean interface, no ads (even free tier), looks legitimate for client work.
Real engineering scenario: You’re responding to an RFQ. Client needs STEP files of 3 assemblies by end of day.
- Create FileGrab link: filegrab.link/xyz789
- Include link in RFQ response email immediately
- Export assemblies to STEP (takes 30 minutes)
- Upload each STEP file as it’s ready
- Client opens link, sees files appearing
- They start review before you’ve finished exporting
- Async, efficient workflow
FileGrab for engineering files:
- Free: 100MB storage, 100MB max file (good for simple parts)
- Pro: 10GB storage, 2GB max file (handles large assemblies)
- Pro features: password protection (for NDA work), forever links (ongoing projects), delete files (update with revisions)
Pros:
- Purpose-built for sharing
- No account needed (free tier)
- Upload once, multiple people download
- Password protection (Pro)
- End-to-end encryption (Pro, for sensitive IP)
Cons:
- Requires internet
- Free tier limited for large assemblies
- Not a CAD collaboration tool (just file transfer)
Method 7: Physical Media (USB, External Drive)
Best for: Extremely large datasets, secure transfer, local handoff
Sometimes the old ways are still the best ways.
When physical media makes sense:
- Complete CAD libraries (50GB+)
- Transferring to on-site manufacturing partner
- Air-gapped secure environments
- Internet too slow for large uploads
How to do it right:
- Use USB 3.0 or faster drive (critical for speed)
- Format as exFAT (works on Windows and Mac)
- Organize files clearly (folders by assembly, revision notes)
- Include README.txt with file structure explanation
- Test files open correctly before sending
- Ship via FedEx/UPS with tracking
Pros:
- No file size limit
- No internet required
- Secure (physical possession)
- Fast for massive datasets (vs upload/download)
Cons:
- Requires physical shipping
- Delays of days
- Drive cost
- Can be lost in transit
Step-by-Step: Sending SolidWorks Assembly to Manufacturer
Real-world example: 350MB SolidWorks assembly with 47 parts, going to CNC shop.
Best method: Link-based sharing with password protection
-
Prepare files
- Save Assembly with external references
- File > Pack and Go (SolidWorks feature)
- Creates folder with all parts/assemblies
- Export key views as STEP or Parasolid (for non-SW shops)
-
Create share link
- Go to filegrab.link, sign in (Pro for 2GB files)
- Click “New Link”
- Enable password protection
- Get link: filegrab.link/mfg2024
-
Upload files
- Drag entire Pack and Go folder
- Include STEP files
- Include PDF drawings
- Add README.txt with revision notes
-
Send to manufacturer
- Email: “Files ready at filegrab.link/mfg2024”
- Include password in separate communication (phone, text)
- Include revision number and notes
-
Manufacturer downloads
- Opens link
- Enters password
- Sees all files organized
- Downloads what they need (might only need STEP files)
File Formats and Sharing Strategy
Different recipients need different formats:
For SolidWorks users: Share native .SLDPRT and .SLDASM files plus drawings. Use Pack and Go to ensure references.
For non-SolidWorks users: Export to STEP (AP214 or AP203) for best compatibility. Include PDF drawings for reference.
For manufacturers: STEP files for geometry, PDF drawings for specs, dimensions, and notes.
For clients (review only): eDrawings files (.EASM, .EPRT) or exported 3D PDFs. Much smaller than native files.
For archival: Native files plus STEP. STEP ensures you can open files in 20 years regardless of software.
Compression: Does It Work for CAD Files?
Short answer: Not really.
CAD files are already efficiently stored. They’re not like text documents or images that compress well.
Test results:
- SolidWorks assembly: 147MB native, 143MB zipped (3% reduction)
- AutoCAD drawing: 89MB native, 87MB zipped (2% reduction)
- STEP file: 215MB native, 178MB zipped (17% reduction)
STEP files compress better because they’re text-based, but native CAD files barely shrink.
When to compress:
- Sending multiple files (zip organizes them)
- Recipient expects zip files
- STEP or IGES files (text-based formats)
When not to compress:
- Single SolidWorks or AutoCAD file (no benefit)
- If it makes file harder to preview/access
Security Considerations for Engineering Files
CAD files are intellectual property. Protect them appropriately.
For internal sharing: Standard methods fine.
For NDA-protected work:
- Use password protection
- End-to-end encryption (FileGrab Pro, Tresorit)
- Secure FTP (SFTP, not FTP)
- Avoid public cloud without encryption
For ITAR/EAR controlled:
- Verify recipient authorization
- Use US-based servers only
- Maintain transfer logs
- Consider encrypted physical media
For competitive bids:
- Password protect
- Use expiring links
- Track who downloads
- Watermark drawings if possible
CAD File Sharing Checklist
Before sending large CAD files:
- Confirm file size (right-click > Properties)
- Pack references if assembly (SolidWorks Pack and Go, etc.)
- Include PDF drawings for reference
- Export to neutral format if recipient uses different CAD software
- Check revision numbers are correct
- Test files open correctly
- Choose appropriate sharing method for size
- Add password if sensitive
- Include README with notes
- Notify recipient link is ready
Which Method Should Engineers Use?
For quick review with another engineer: Cloud storage (if you have it) or link-based sharing.
For sending to manufacturer: Link-based sharing with password, include STEP + PDF drawings.
For ongoing project collaboration: CAD-specific solution with version control (GrabCAD, Onshape, A360).
For massive datasets (50GB+): FTP if available, physical drive if not.
For client deliverables: WeTransfer (recognized brand) or link-based sharing (cleaner).
For ITAR/sensitive: Encrypted link sharing or physical media.
Make CAD File Sharing Reliable
Engineering work is precise. Your file sharing method should be too.
You need a solution that handles large files, doesn’t require recipients to create accounts, and looks professional when sending to clients or manufacturers.
FileGrab was built for exactly this workflow. Create a link, upload your CAD files, share the link. Recipients download with zero friction.
Try it with your next project. Free tier handles simple parts. Pro tier ($10/month) handles large assemblies up to 2GB with password protection and forever links.
Get started: Visit filegrab.link and create your first link. Upload CAD files up to 100MB free, or upgrade to Pro for 2GB file support, 10GB storage, password protection, and end-to-end encryption for sensitive engineering files. No ads, no compromises, just reliable file sharing for technical professionals.