While the luthier supply landscape changed with the closing of Luthiers Mercantile International (LMI)—which was historically the primary shop offering modular custom prep services like custom jointing, joining, and precise thicknessing/sanding—a number of specialty tonewood vendors and luthier suppliers continue to offer these prep services:

 

1. Dedicated Processing & Custom Sanding Specialty Suppliers

• TCS Custom Woodworks (Franklin, Georgia):
  Offers dedicated, stand-alone Thickness Sanding Services. You can send or purchase tonewood sets (including Sitka and Engelmann spruce tops) and specify exact Target Thickness dimensions in decimal inches or millimeters prior to shipping.

   

• Colonial Tonewoods (Barhamsville, Virginia):
  Specializes in high-grade North American softwoods (Sitka, Engelmann, Lutz, and Adirondack red spruce). They frequently perform custom thickness-sanding and edge-jointing upon request for builders ordering raw sets, allowing you to receive two-piece tops pre-joined or brought down to preliminary thicknesses.

   

• RC Tonewoods (Buffalo, New York): Known for custom luthier processing. In addition to supplying raw billets and two-piece sets, they offer custom millwork, edge-jointing, and wide-belt calibration/finish-sanding for tops and backs based on customer-specified target dimensions.

   

2. Major Luthier Supply Houses (Pre-Joined / Thicknessed Tops)

• StewMac (Stewart-MacDonald): Offers Joined and Routed Spruce Soundboards (Sitka and European). While these are standard product options rather than a custom job-shop service, their pre-joined tops come factory-jointed, thickness-sanded to standard dimensions (~0.115"–0.125"), and ready for final graduation or bracing.

   

• Pacific Rim Tonewoods (Concrete, Washington): Primarily supply high-volume acoustic tonewood, but they provide precision thicknessing and wide-belt calibration sanding on their spruce soundboards for manufacturing luthiers and custom shops seeking consistent preliminary board metrics.

   

3. Specialty European & Alpine Spruce Harvesters

• Rivolta Snc / Wood for Guitars (Italy):
  Sourced directly from Val di Fiemme (resonance spruce). They offer pre-jointing (placcatura) and calibrated thickness-sanding on request for classical, acoustic, and violin family soundboards.

   

• EurotoneWood  (Ukraine) and Carpathian Tonewoods (Romania):
  Specialty harvesters of high-stiffness European/Carpathian spruce. They accommodate special ordering options for joinery prep and calibrated surface sanding for soundboard sets.

   

Key Considerations When Ordering

Target Dimensions vs. Seasonal Movement: When requesting custom thickness sanding, specify whether you want a rough calibration (e.g., .125" / 3.2mm) or near-final dimension. Many suppliers will leave .010"–.015" of extra thickness so you can perform final finish-sanding on your bench after the joint has fully cured and acclimated to your shop environment.

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