CNC Brand Profiles

Johnford: The Lathe Company That Learned to Build Bridges

Johnford started as a lathe company. In 1984 it was building conventional lathes in Taichung. By 2022 it was commissioning a portal machining center roughly 89 feet long. How it got from one to the other is worth knowing if you are buying one used, because it explains why the lathes and the bridge mills share a name but not a naming system.

The short version: the company learned to make lathes first, then spent the next four decades building bigger. The long version is below, followed by a decoder for the model numbers, what the machines are built from, which controls you will find on them, and what to check before you buy one.

Johnford at a Glance

1984: Conventional Lathes in Taichung

Roundtop Machinery Industries was established in 1984 to produce conventional lathes. Not CNC lathes. The manual kind, the engine lathe with handwheels and a change gear box that sits against the wall in a lot of shops that have been open long enough.

It moved into CNC almost immediately. According to the company's own history, it began producing CNC lathes and vertical machining centers the following year, in 1985. By 1989 it had expanded the factory and bought a Hewlett-Packard HP-3000 system to computerize its management, which is a detail that tells you something about a Taiwanese builder in the late 1980s: it was investing in process, not just capacity.

In 1990 the company received what its history describes as an "A" class registration for its CNC lathes, and an "A" factory rating, from the International Trade Institute of the Ministry of Economy. Six years after it opened, the lathe business was established enough to be graded.

1992: The Year It Learned to Build Bridges

1992 is the year the company changed shape. It became a public company, and it added a set of production lines all at once: vertical CNC lathes, horizontal machining centers, double-column portal machining centers, flat-bed CNC lathes, CNC forming machines and screw-cutting CNC lathes, the last two both patented, along with flexible manufacturing systems and automation.

The double-column portal machining center is the one that matters for this story. A bridge mill puts the spindle on a crossrail carried by two columns, so the workpiece sits underneath a frame rather than beside a column. That layout is how you machine parts too wide and too heavy for a conventional vertical machining center, and it is one of the categories Johnford is best known for today.

The rest of the 1990s filled in around it. ISO 9002 certification from DNV came in 1995. In 1996 the VMC series and the TC series received what the company's history records as the award "It's very well made in Taiwan." In 1997 the company introduced the SV series of small vertical machining centers and the ST series of large horizontal turning centers. In 1998 it developed 5-face and 5-axis double-column machining centers. In 1999 it joined the GreTai Securities Market of the Taipei Exchange.

Every one of those steps is a lathe company learning to think in larger frames. The ST lathes and the double-column machines came out of the same factory within a few years of each other, and the brand still builds both.

In 2000 the company invested US$24,000,000 to build a third factory specifically to manufacture larger machines. The medium DMC series of fixed-column bridge mills followed in 2001, along with ISO 9002 certification from Entela. In 2002 the company listed on the Taiwan Stock Exchange and developed the SDMC-11000x2500-2H sliding double-column portal machining center. ISO 9001 certification from TUV came in 2003, and in 2004 it developed the SDMC-28000-2H.

Patents, and a Spindle Worth Protecting

The company had patented products as early as 1992, but the run that began in 2009 covered the core of its larger machines. A patent titled "Direct-drive spindle, machining centers, and their manufacturing method" was granted in the United States and Taiwan in 2009, in China in 2010, and in Italy in 2012.

Two more followed on the big-machine side. In 2010 the company patented a newer version of its "Hydrostatic Bearing Safety System" in Taiwan, and in 2011 it patented a "Rail-type Double Column Multi-Axis Machining Center." Taken together, those patents are a fair map of what the company considered worth protecting: the spindle, the hydrostatics and the double-column frame.

Then the Machines Got Bigger

The company's recent milestones read like a list of machines built to prove a point.

Convert the 2022 machine and it is roughly 89 feet long, 30 feet high and 36 feet wide. That is a building with a spindle in it. It is also a clean summary of where a company that started on conventional lathes in 1984 ended up.

Notice what is still on that list, though. A 10-meter twin-turret lathe in 2014. A turn-mill in 2023. Johnford never stopped being a lathe company. It learned to build bridges without giving up the thing it started with.

Johnford is not the only Taiwanese builder whose catalog grew outward from a single machine type. Chevalier started as a grinder company and never stopped being one. Johnford started as a lathe company and kept building lathes while its machines grew into bridges.

Three Names to Search Under

The English corporate name is Roundtop Machinery Industries Co., Ltd. The brand on the machines is Johnford. The Chinese name, the one printed on the company's financial reports and its stock listing, is ????????????. The company's own English materials also spell the corporate name Rountop in several places, including its own history page.

That matters when you are hunting for a manual, a parts diagram or a serial number record for an older machine. Search under Johnford, Roundtop and Rountop, and if you are working with a dealer in Asia, give them the Chinese name. Documentation can turn up under any of them.

One observation, clearly labeled as such: read aloud in Mandarin, ?? is Qiáofú, and it is hard not to hear the English brand name in it. The company's own history never explains where the name Johnford came from, so treat that as a resemblance, not a fact.

The Lineup in Shop Language

Johnford's current catalog, translated from brochure categories into what each machine actually is.

How to Read a Johnford Bridge Mill Model Number

Johnford uses two different naming systems for its bridge mills, and knowing which one you are looking at is a quick way to understand a listing.

The small and medium DMC models are named by X travel, then a letter for Y width, then an H if the spindle is 50 taper.

There is one trap in that system. On the base medium frame, the DMC-2100 actually travels 2,050 mm in X and the DMC-3100 travels 3,050 mm. Every other number on the small, medium, S and P sheets we checked matches its X travel exactly. If a listing says DMC-3100, measure before you assume you have 3,100 mm.

The large DMCs and every SDMC switch to dimensions: X, then the distance between the columns, then Z, all in millimeters. An SDMC-6000x2800x800 has 6,000 mm of X, 2,800 mm between the columns and 800 mm of Z. The middle number is the gap between the columns, not always the Y travel. The DMC-4000x2800-R2-AC4, for example, has 2,800 mm between the columns but 3,600 mm of Y.

Suffixes after the dimensions describe the head. On the large DMC sheets, AC4 heads take No. 40 or HSK-A63 tooling and AC5 heads take No. 50 or HSK-A100, -5F marks a head that works both vertically and horizontally, and -2H means twin spindles with a dual-path control.

One more habit worth keeping: read the millimeter column, not the inch column. Johnford's own sheet prints 80.7 inches for the DMC-3100H's 3,050 mm of X, which is a conversion slip; 3,050 mm is 120 inches.

The Bridge Mill Ladder

Published figures across the Johnford DMC and SDMC families, in millimeters and kilograms as the company prints them.

Two readings from that table. First, the spindle choice is made by the letter H, not by the frame size. On the medium frame, the 40-taper machines carry a 70 mm spindle bearing and offer speeds from 8,000 rpm up to 20,000 rpm with built-in spindles, while the 50-taper machines carry a 90 mm bearing and run 6,000 to 10,000 rpm. Same frame, very different spindle.

Second, the SDMC's table load is published per square meter rather than as a total. Do not compare it directly to a DMC's total table load figure. It is a different measurement.

How the Machines Are Built

Johnford's U.S. representative says its castings are poured in Johnford's own foundry, and dealer specification copy for the ST lathes describes them as cast from Meehanite iron, a controlled process for producing iron with consistent grain structure. The case for heavy iron in a machine frame is laid out in why the next machine you buy will still be iron.

The ST lathes are where the construction is best documented. The same copy describes a one-piece 60-degree slant bed with a torque tube, a hole cast through the center of the bed to add rigidity and carry heat away, square box ways for heavy turning, hand-scraped sliding surfaces coated with Turcite B, and double-nut ballscrews that are pre-tensioned. The GT series, larger still, uses a 45-degree bed with the saddle inclined at 60 degrees, giving a 61-inch swing over the bed.

On the biggest machines the engineering shifts toward fluid. The 2014 SDMC-16000 used a hydrostatic sliding system on its X axis, and the company holds a patent on a hydrostatic bearing safety system. Hydrostatic ways float the moving axis on a pressurized film of oil instead of sliding metal on metal, which is one way builders keep a very long axis moving smoothly.

Controls

On current bridge mills, the basic configuration ships with a Fanuc 0i-MF Plus control with a 10.4-inch screen and Manual Guide i conversational programming. The medium ST lathes ship with a Fanuc 0i-TF Plus. If you already run Fanuc elsewhere on the floor, a Johnford with a Fanuc control will feel familiar to your programmers.

It is not the only option, and that matters on the used market. Johnford lists the Siemens SINUMERIK 828D, the Fanuc 31i-MB Plus or Siemens SINUMERIK ONE, and Fagor or Mitsubishi controls as alternatives. A used Johnford can arrive with any of them, and older machines will carry older generations. Identify the exact control before you quote a job on it.

Linear scales on X, Y or Z are offered as an option on the DMC line. On a machine with several meters of X, whether the scales are fitted is worth asking, because a big machine measuring itself is a different machine from one trusting its ballscrews across that distance.

U.S. Presence and Support

Absolute Machine Tools of Lorain, Ohio has represented Johnford since 1992, the same year the company started building double-column machines. Absolute says it has sold, serviced and installed more than 3,000 Johnford machines in the United States and in other countries including Mexico, Canada, Romania, Singapore and China. Phillips Corporation also offers Johnford machines in its engineered products lineup.

What to Check When Buying a Used Johnford

Decode the name first. The letter tells you the Y width, the H tells you the taper, and on the large machines the middle number is the column spacing. Know which frame you are looking at before you compare prices.

Measure the travel. The DMC-2100 and DMC-3100 base models travel 50 mm less than their names. Run each axis end to end and read the travel off the machine, not the listing.

Identify the spindle. The same DMC frame was offered with geared spindles and built-in spindles at very different speeds. Confirm which one you are buying, the taper, and the hours if the control records them.

Check the heads and what comes with them. On 5-face and twin-spindle machines, confirm every head, adapter and head-change component is included and working. A 5-face machine without its heads is a 3-axis machine.

On the lathes, check the ways. Box ways with Turcite B are durable but not permanent. Look for scoring, lifted material and signs that the lubrication system has not been doing its job. On any Johnford, current or old, confirm the lubrication system works; current DMCs list automatic centralized lubrication with alarms.

On the big machines, check the hydrostatics. Pump condition, pressure, oil condition and the safety system all matter when a column rides on oil.

Plan the move before you make an offer. The published DMC and SDMC-6000 sheets run from 10 to 68 metric tons, roughly 22,000 to 150,000 pounds, and the largest SDMCs weigh more. Rigging, the foundation, and in some cases the building itself are part of the purchase. Ask for foundation drawings.

Then the usual list: control generation and whether it is still supported, ballscrew backlash, way cover condition, tool changer function through every pocket, and whether linear scales are fitted.

Resell CNC Take

The bridge mills are the reason to know the name, and the lathes are the reason to trust it. Read the letter and the H before you read the price, measure the X instead of trusting the model number, and budget the rigging and foundation as part of the machine, because on a bridge mill that weighs 10 tons or more, they are. A company that started on conventional lathes in 1984 and was commissioning a portal machine roughly 89 feet long by 2022 built its reputation on iron.

Frequently Asked Questions