Short answer: Both the GTT Kobuki and the Bethlehem Grand are three-stage, surface-mix bench torches built for large borosilicate and sculpture, and both sit in the pro price band. The real decision is how each one builds its fire and how much oxygen it wants. The Kobuki uses GTT’s layered Triple Mix: a nested center, middle, and outer fire that let it imitate the flames of several smaller GTT torches, with a catalog oxygen estimate of ~33 LPM. The Grand uses three fully independent rings of fire, each on its own pair of needle valves, and publishes a higher max-flame oxygen figure of ~60 LPM. If your shop already runs bulk or tanked oxygen and you want the widest possible flame for big tubing, the Grand’s independent-ring control and larger envelope are the draw. If you want one torch that behaves like a whole family of GTT flames for fast melt-ins in production, the Kobuki is the one to look at.
How each torch stages its fire
The two torches reach “three stages” by different routes, and that difference is the heart of the comparison.
The Kobuki is built around GTT’s Surface mix approach. Its three fires are nested and separately controlled: the center is the standard 7-jet Lynx fire, the middle is the 15-jet Phantom fire, and the outer is a single 27-jet ring, for 49 jets in total. Because those stages mirror GTT’s own smaller torches, GTT positions the Kobuki as a torch that can imitate the flame types of the Lynx, Phantom, Mirage, and Delta Elite, plus a wider Kobuki flame of its own. GTT frames it for artists who love the Phantom-size flame but need more heat for fast melt-ins and rapid heating in production work. If you want the background on how the layered mix works across the GTT line, see our GTT Triple Mix technology explainer.
The Grand reaches three stages a different way. Bethlehem describes it as a stainless-steel surface-mix bench burner with three separately controlled rings of fire: a center of 6 jets, a middle of 12, and an outer of 24, for 42 jets across a face of about 1 3/8 inches. Each of the three rings is governed by its own two needle valves, so gas and oxygen to each stage are dialed independently. Bethlehem describes the Grand as combining its Alpha, Bravo, and Champion torches into a single burner, producing soft enveloping flames from small detail-stringer work up to flames large enough to fully encompass 11-inch-and-larger diameter tubing.
Both are Surface mix designs, so neither premixes fuel and oxygen inside the head; the gases meet at or just past the face. For more on what that means for flame character, see surface mix vs premix torches.
Jets, stages, and flame range side by side
| Spec | GTT Kobuki | Bethlehem Grand |
|---|---|---|
| Stages | 3 (nested Triple Mix) | 3 (independent rings) |
| Jets | 49 (7 + 15 + 27) | 42 (6 + 12 + 24) |
| Mix type | Surface mix | Surface mix |
| Mount | Bench | Bench |
| Oxygen (estimate) | ~33 LPM | ~60 LPM |
| Price | $3,550 | $3,317 |
The jet counts are close, and both torches span a wide flame range. The functional distinction is what happens when you light more than one stage. On the Kobuki, the nested stages combine into layered GTT flame shapes, so lighting the center alone gives you a Lynx-like fire and adding stages walks you up toward the wider Kobuki flame. On the Grand, the three rings are independent, so you can run a small center detail flame or open all three rings into a large enveloping flame, tuning each ring on its own valves.
Oxygen appetite and what it means for your supply
This is the clearest measurable difference between the two, and it deserves care because the two figures are not measured the same way.
Bethlehem publishes the Grand’s max output on its technical page: gas at 5 psi feeding 12 LPM, oxygen at 20 psi feeding ~60 LPM, and 1,150 BTU per minute. That is Bethlehem’s own published number at full flame. The Kobuki’s catalog oxygen of ~33 LPM is an estimate we derived from GTT’s flow table at the largest usable flame. Both are ceilings at full flame, not the draw you will see during typical working, and because they rest on different bases you should not turn the gap between them into a fixed ratio. What is fair to say is that the Grand’s published max-flame appetite is higher, and both are pro-level torches that will pull hard when every stage is open.
Editor’s note: the Grand’s oxygen figure is Bethlehem’s own published 20 psi / 60 LPM max-flame number; the Kobuki’s is our estimate from GTT’s flow table at the largest usable flame. They are ceilings at full flame on different bases, not typical working draw, and were not measured the same way. Actual consumption depends on flame size and how many stages are lit. Confirm current specs with the maker before you buy.
For either torch at these sizes, oxygen supply is the real constraint, not the torch price. Community discussion on Lampwork Etc. is consistent that a single standard medical concentrator generally cannot supply the pressure and volume a big boro torch wants, so workers link multiple concentrators with a holding tank or move to tanked or bulk oxygen. Treat that as community knowledge rather than a measured spec, and do not assume a fixed number of concentrators for either torch. Our guides on oxygen concentrators vs tanks walk through the trade-offs. Plan your oxygen system around the flame sizes you will actually run, and remember the Grand’s higher published ceiling points toward a more serious supply if you intend to open all three rings on large tubing.
Price, base hardware, and adjustment
The two torches are priced close together in the pro band: the Kobuki at $3,550 and the Grand at $3,317. Price alone will not decide this.
Their base hardware and positioning differ. The Kobuki ships with a purple manifold, colored valve caps, and rack-and-pinion adjustment on a powder-coated base with holes for securing it to the work table; it includes a short length of hose with adapters and filter screens, instructions, and a cleaning kit. A compressed-air configuration is offered separately at its own price; the catalog price and specs here are for the standard model.
The Grand mounts on Bethlehem’s scroll-base positioning arm, which Bethlehem describes as an upgrade from traditional rack-and-pinion that locks in place. If you have a preference for how a bench torch is positioned and locked at the bench, that hardware difference is worth handling in person if you can.
Which suits a production boro shop
Both torches are aimed squarely at large boro and sculpture, so the choice comes down to how your shop works.
The Kobuki leans toward shops that want one torch to cover the jobs several GTT torches would otherwise handle. Its Triple Mix stages imitate the Lynx, Phantom, Mirage, and Delta Elite flames, and GTT positions the wider Kobuki flame for fast melt-ins and rapid heating in production. If your team already knows the GTT flame family and wants that behavior scaled up with more heat on tap, the Kobuki fits the muscle memory. Our best torch for borosilicate guide gives more context on matching a boro torch to the work.
The Grand leans toward shops working the largest tubing and sculpture, where an enveloping flame big enough to wrap 11-inch-and-larger diameter tubing matters, and where independent control of three rings on their own valves is worth the learning curve. Its higher published oxygen ceiling is part of the same story: more envelope generally means more oxygen. If your shop’s signature work is big and you have the oxygen supply to feed it, the Grand’s independent rings and larger envelope are the argument. For thick solid work specifically, see our guide to the best bench burner for thick glass sculpture.
Neither choice is a downgrade. They are two well-regarded production burners that solve the three-stage problem differently: layered, family-imitating fire versus three independent rings.
Fuel, pressure, and safety notes
The published pressure figures here are Bethlehem’s own for the Grand (5 psi gas, 20 psi oxygen at max output). GTT’s flow table underlies the Kobuki oxygen estimate. For any torch at this size, the manufacturer’s manual governs the actual pressures, tip care, and the flashback protection your specific torch and gas supply call for; those instructions take precedence over anything here, and we do not prescribe universal arrestor placement or tape on gas fittings. Read flashback arrestors explained for how that protection is chosen. This article informs your decision; it does not replace the manufacturer’s instructions or advice from a qualified professional for your setup.
One naming note: the Bethlehem Grand and the Bethlehem Grand Sharp Flame are distinct models. This comparison is about the Grand.
Related guides
- GTT Triple Mix technology explained
- Surface mix vs premix torches
- Best bench burner for thick glass sculpture
- Oxygen concentrators vs tanks for lampworking
- Best torch for borosilicate
Sources
- Glass Torch Technologies, “Kobuki”: https://www.glasstorchtech.com/kobuki
- Glass Torch Technologies, “Triple Mix torches”: https://www.glasstorchtech.com/triple-mix-torches
- Bethlehem Burners, “The Grand”: https://www.bethlehemburners.com/torches/grand/
- Bethlehem Burners, “Technical information”: https://www.bethlehemburners.com/resources/technical-information/
- Lampwork Etc., “Oxygen for large boro torches” (community discussion): https://www.lampworketc.com/forums/archive/index.php/t-56942.html