Wexmar is a custom dowel pin manufacturer for OEMs, tool builders and fixture makers that need dowels outside catalog sizes, in special materials, or with features a standard pin does not have. Our Canastota, New York shop produces CNC machined dowel pins on Swiss-type lathes and finishes precision diameters on an in-house centerless grinder.
What dowel pins do and who buys them
A dowel pin locates two parts relative to each other with high repeatability. It is pressed into a reamed hole in one part and slip-fits into the other, so the assembly can be taken apart and put back in the same position. Standard dowels to ASME B18.8.2 and ISO 8734 cover common sizes. Custom dowels are needed for odd diameters or lengths, stepped or relieved shanks, pull-out threads, vent flats, special materials, or tighter diameter bands. Buyers include tool and die shops, fixture and gauge builders, mold makers, machinery OEMs, fluid power and gearbox manufacturers, and aerospace and defense hardware programs.
Custom dowel pin machining process
Dowels up to 32 mm diameter are turned on our four Maier MLK-32 Swiss-type machines with FMB bar feeders. The Swiss process supports the bar at the tool, holding diameter and straightness on long, small-diameter dowels. It also cuts end radii, chamfers, relief grooves, tapped pull-out holes and vent flats in one cycle. Larger dowels run on our Mazak and Doosan CNC lathes. See Swiss machining.
For hardened dowels, the sequence is: turn with grind stock left on the diameter, send for heat treat through a qualified outside processor, then centerless grind to final size in-house. Grinding after hardening removes heat treat distortion and produces the tight diameter band and fine finish that press-fit locating requires. Soft dowels in stainless, brass or plastic are turned or ground to size directly.
Dowel pin materials
- Alloy and bearing steels: 4140, 8620 case-hardened and 52100 through-hardened.
- Tool steels: A2, D2, O1 and S7 for high-wear locating.
- Stainless: 416 and 440C (hardenable), 303 and 316 (non-hardened), 17-4 PH.
- Others: brass, bronze, titanium and engineered plastics for non-marring or non-conductive locating.
Critical dowel features and how we hold them
- Diameter band: ground to a total tolerance as narrow as 0.0002 in, often specified as oversize for press fit or undersize for slip fit.
- Roundness and straightness: controlled by centerless grinding, which generates a true round OD along the length.
- End geometry: chamfered or radiused ends to guide the pin into its hole without shearing material.
- Pull-out threads: tapped holes in the end for extraction from blind holes, to UN 2B or metric 6H.
- Vent flats or grooves: relieve trapped air when pressing into blind holes.
- Hardness: specified by Rockwell range, verified by the heat treater's certification.
Typical tolerances and finishes
| Feature | Typical tolerance | Tighter on request |
|---|---|---|
| Ground diameter | ±0.0002 in | ±0.0001 in |
| Turned diameter (soft) | ±0.0005 in | ±0.0003 in |
| Overall length | ±0.005 in | ±0.002 in |
| Roundness | 0.0001 in | 0.00005 in |
| End chamfer or radius | ±0.005 in | ±0.002 in |
| OD surface finish | 16 Ra | 8 Ra or finer |
These are typical values for hardened, ground dowels. Final capability depends on diameter, length and hardness, and we confirm it at quote stage.
Secondary operations
Heat treat, black oxide, passivation and plating are performed through qualified outside processors. When plating is specified on a ground dowel, we account for plating thickness when we grind so the finished diameter meets the drawing.
Quantity patterns
Custom dowel orders often come as sets for a single fixture or mold, 10 to 50 pieces, or as production lots of 500 to 10,000 for OEM assemblies. Swiss lights-out running and batch grinding keep per-piece cost down on larger runs. For catalog sizes available off the shelf, we will tell you when a standard pin is the more economical choice.
Inspection
Ground diameters are measured with calibrated micrometers and gage blocks, with gage calibration aligned to ISO/IEC 17025. End geometry is checked on our Mitsubishi optical comparator. Heat treat certifications, material certs, lot traceability and AS9102-format first articles are available. See inspection and quality.
Getting a quote
Send a drawing or sketch with diameter band, length, material, hardness and quantity. You can upload a drawing for an instant estimate, and an estimator will confirm pricing. Or call (315) 400-2654. Related: custom pins and fixtures and jigs.