Glass Bore Grinding Machine BG-50
A glass bore grinding machine that grinds round holes and slot holes in small hard-brittle rings — glass, ceramic, sapphire. A 30,000 rpm electric spindle does the cut, and once a part is fixtured every set hole position is machined with no operator at the machine.
What this machine makes, and what it is not for
Most machines in the grinding stage cut the curved or flat faces of a lens. This one cuts the hole. A glass bore grinding machine grinds the round bore or the slot in a small ring or annular part, and it can grind the outer diameter and the flat too — bringing a bored part to size and finish rather than shaping an optical surface. It is the bore station, a branch of the grinding stage of its own.
The part arrives as a sawn ring and leaves with its bore ground to size. Where the job is a curved lens surface instead of a hole, the curve generators are the right machines; for a cylinder, the cylindrical grinder. The BG-50 is the one built for bores.
A glass bore grinding machine grinds internal holes — round and slot — and, on the same setup, the outer diameter and flat. It does not generate or polish a spherical or cylindrical optical surface; those are separate machines on the line, and this page links to them.
How does a glass bore grinding machine grind a hole?
With a very fast, very true tool and a fixture that holds every hole position — so the part is placed once and every bore is ground without it being touched again.
The cutting is done by an electric spindle turning up to 30,000 rpm with a small diamond tool in an ER32 collet, held true to ≤0.01 mm. A fixture clamps and locates the part; once it is set, the machine works through every hole position the job calls for, with no operator handling in between.
What that buys you:
- 30,000 rpm electric spindle — the surface speed a small diamond tool needs to grind a clean bore in hard, brittle glass
- Fixture-set positions — a quick-change fixture locates the part, and all the set holes are ground from that one placement
- Servo workpiece axis — its stroke and speed are set independently, which holds the bored thickness and the wall finish
- Also OD and flat — the same setup can grind the outer diameter and a flat, not only the bore
Because a glass bore grinding machine runs the whole set of holes from one fixturing, the operator’s job is loading and unloading, not guiding each cut — which is where the accuracy and the repeatability come from.
The fixture is made to your part and your hole pattern. Send us the part, the bore sizes and the material, and we specify the fixture and the tools with the quotation.
Four things the machine does while nobody is watching
Loading and unloading a fixture is by hand; the grinding of every set hole runs automatically. These are what a glass bore grinding machine gets right.
Runs every hole from one setup
Once the part is clamped in the fixture, the machine grinds all the set hole positions without further handling, which is what keeps hole-to-hole position true.
Feeds itself on X/Y/Z modules
Motorised X/Y/Z modules present the part and the tool, replacing the hand placement that a bench bore-grinder would need for every hole.
Holds thickness with a servo axis
The workpiece axis reciprocates under servo control, with stroke and speed set independently, so the bored thickness and the wall finish stay consistent part to part.
Enclosed, waterproof, washable
The working zone is fully 304 stainless behind an inner and outer guard, semi-sealed and easy to wash down between jobs.
Which materials and features can it grind?
| Item | Capability |
|---|---|
| Features ground | Round holes and slot holes; also outer diameter and flat |
| Part type | Small and medium rings and annular parts |
| Maximum machining range | 50 mm |
| Spindle speed | Electric spindle to 30,000 rpm |
| Spindle accuracy | ≤ 0.01 mm |
| Materials | Glass, ceramic, sapphire, quartz and crystal, among other hard-brittle materials — send yours for a free trial run |
| Fixture | Quick-change, made to the part |
A glass bore grinding machine is judged on bore size, roundness and wall finish, so those are the numbers to send. If you are choosing glass, the optical materials data helps, and drawings dimensioned to the ISO 10110 framework are ideal.
Technical specifications
The BG-50 grinds bores in rings; the curve generators and the cylindrical grinder shape optical faces, which is a different job.
| Features | Round holes, slot holes, outer diameter, flat |
| Maximum machining range | 50 mm |
| X-axis travel | 0 – 160 mm |
| Y-axis travel | ±75 mm |
| X / Y / Z module travel | 500 / 400 / 300 mm |
| Electric spindle speed | up to 30,000 rpm |
| Spindle accuracy | ≤ 0.01 mm |
| Spindle collet | ER32 |
| Workpiece speed | 0 – 35 cpm, servo, stroke and speed set independently |
| Enclosure | Inner and outer guard, 304 stainless work zone |
| Control | 7″ touchscreen |
| Total installed power | 12 kW |
| Overall dimensions (L × W × H) | 1500 × 1000 × 1800 mm |
| Total weight | approx. 650 kg |
| Base construction | Cast iron, hand-scraped mating surfaces |
The diamond bore tools and the part fixtures are process items chosen for the material and the hole pattern. They are quoted separately — tell us your parts and we will specify them.
Main assemblies and what each one is for
This is the vocabulary your operator and our service engineer will share on the shop floor.
| Assembly | Function |
|---|---|
| Electric spindle unit | High-speed spindle to 30,000 rpm with an ER32 collet; carries the diamond bore tool |
| Workpiece axis | Servo axis reciprocating the part, stroke and speed set independently |
| X / Y / Z module | Motorised modules that present the part and the tool to each hole position |
| Part fixture | Quick-change fixture holding the ring and every set hole position |
| Stainless waterproof set | Inner and outer guard, 304 stainless work zone, semi-sealed |
| Operation panel | 7″ touchscreen for parameters and status |
| Coolant system | Circulating supply to the cut |
Utilities, environment and safety
Electrical supply, compressed air, coolant, floor loading and the ambient conditions the machine is to run in are confirmed with us for each order, together with the safety and protective arrangement supplied with it. These figures depend on the voltage and frequency of your site, the material you are running and the destination market, so we do not publish a single set of them here.
Send us the site conditions with your enquiry and we will return the utility and environmental requirements in writing, before the order is placed.
The BG-50 grinds bores and edges in rings — it does not generate a spherical or cylindrical optical surface, and it is not a face polisher. A new part needs its fixture made and its bore tools proven on trial parts, the reason we ask for your parts before quoting.
What happens after the machine is installed?
The same terms apply to every machine we ship, wherever in the world it goes.
| Warranty period | 12 months from final acceptance |
| Response during warranty | Response within 8 hours · solution proposed within 24 hours · issue resolved within 48 hours, including procurement, installation and commissioning of parts |
| After the warranty period | Service and spare parts available for the life of the machine |
| Certification | CE |
Specifications are subject to change as a result of design upgrades. Minor differences may occur at certain parts. For a binding specification, refer to the order confirmation.
See the machine running
The BG-50 grinding the bore of a ring, and the X/Y/Z modules stepping through a set of hole positions.
01 — Bore grinding, one ring
02 — Stepping through set hole positions
Send one drawing and a few parts
A glass bore grinding machine is easy to specify badly from a datasheet. Send us the part, the bore sizes and pattern, the material and the tolerance you have to hold, with a few of your own parts. We run them, return them, and send the process sheet with the quotation.
If your job is an optical face rather than a bore, we will point you to the curve generator or the cylindrical grinder instead of quoting this one.
12-month warranty · free trial run on customer-supplied material
Optics customers include Edmund Optics and Coherent
Related equipment and reading:
- CNC optical curve generator Auto-SG-50 — the spherical generating stage
- Cylindrical lens grinding machine CG-140 — for cylindrical faces
- Spherical lens curve generator SG-80 — spheres up to Ø80 mm
- Optical lens fabrication line — how the stations connect