A bridal brand in Toronto came to us with a CAD file they loved. We printed the wax, cast the first ring, and on the first article the buyer said the head sat 1 mm too high. Adjusting that after casting meant re-CAD, re-print, re-cast and re-set. It added nine days to the order and ate the margin on the whole run. The mistake was not the design; it was that revisions happened after tooling. We run a staged CAD revision window specifically so changes happen when they are cheap. Here is the process.
When a revision is cheap versus expensive
A change in CAD software costs a draughtsman 20 minutes. A change after wax printing costs a re-print, about 4 hours of machine time and a day of queue. A change after casting is a new tree, new metal, new setting. The ratio is roughly 1 to 10 to 100. Our job is to push every decision into the 1x window. We give customers two free revision rounds in CAD and then charge for any change after the wax is approved, so the incentive lines up.
Read the background on how revision cycles usually run, our approval rounds for ring models and the tolerances our factory expects out of CAD. Buyers can also reference grading standards through IGI's certification pages when specifying stone sizes in the model.
Our staged revision process
Round 1: volume and proportions
The first model arrives as three renders: front, side, top. We ask the buyer to check only proportions, shank width and head height at this stage. Detail changes come later, because moving a head 1 mm in round 1 is trivial; in round 3 it means re-tooling the seat.
Round 2: detail and stones
Once proportions are locked, we add stone sizes, prong count and gallery detail. The buyer overlays their actual stone measurements from the supplier. We check that the seat depth matches the stone's pavilion angle; a 0.2 mm mismatch here is the reason stones sit high after casting.
Round 3: wax print approval
We print a physical wax and mail it to the buyer. The customer holds it in hand, checks the weight feel and the profile against a prototype. This is the last free revision. After wax approval, any change becomes a paid engineering change order (ECO) logged with a new lead time.
| Stage | Turnaround | Cost to revise | Approval needed |
|---|---|---|---|
| CAD render | 24 h | Free (2 rounds) | Email sign-off |
| Wax print | 3 days | Free (1 round) | Physical sign-off |
| First casting | 5 days | Paid ECO | Written change order |
We also require the buyer to confirm the production timeline at each gate so a revision does not silently push a launch date. Our CAD export settings are published in our STL export guide so outside designers can hand off clean files.
How we track change orders
Every revision gets a numbered ECO in our project log: who requested it, what changed, which round it landed in, and the new delivery date. The buyer receives the log with every weekly update. If a revision lands after wax approval, we quote the ECO cost and the new lead time before starting, so there are no surprises on the invoice. This discipline is what lets us hold a 20-piece custom run to a 21-day clock even when the buyer asks for tweaks.
Frequently Asked Questions
How many free CAD revisions do you allow?
Two in the render stage and one after the wax print. After that we charge a flat ECO fee and re-queue the job.
Can I revise after you start casting?
You can, but we quote it as a paid ECO with a new lead time. Most buyers choose to run the revision on the next SKU instead of re-tooling a finished batch.
What file format do you accept?
STL or 3DM exported to our published tolerance. We also accept rendered images and will rebuild from scratch if the file is not printable.
How long does the whole approval cycle take?
Typically 5 to 7 business days for render rounds plus 3 days for wax mailing. We schedule casting to start the day after your written approval.
Do you keep my CAD file on hand for reorders?
Yes. Reorders pull the locked approved file, and we will not ship a new run without the old approval on record unless you issue a new ECO.
Key takeaways
- Revisions cost 1x in CAD, 10x after wax, 100x after casting.
- Lock proportions first, then details, then wax. Do not mix the rounds.
- Every change after approval is a logged ECO with a quoted cost and date.
Next step: send us your sketch, reference images or existing CAD file. We return the first render within 48 hours and walk you through the three approval gates before any metal melts. Custom manufacturing opens at 20 pieces per SKU, with the ECO log shared weekly so your launch date never moves by surprise.
Gemstone grading terminology used here follows the Gemological Institute of America’s gem encyclopedia.
