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At 8 pages a minute, an SX-based laser printer using 8-point type will print over 1300 characters per second. This is faster than any dot matrix printer and equivalent to a line printer rated at about 530 lines per minute. Given this level of performance, the inherent high quality of laser output, and the low cost of most SX-based printers, it's only natural that many people want to use the SX engine for high-volume jobs.

Unfortunately, Canon doesn't offer high-capacity feeders for their 4-, 8-, and 17-ppm machines. Canon builds the large 20-ppm LBP-20 and 50-ppm LBP-50 machines for high-volume application. These big printers are larger than most washing machines. Whether Canon is protecting its high end market or protecting its desktop printers from excessive use, the absence of a high capacity solution has created an opportunity for third party vendors.

Several third-party companies provide high capacity input and output mechanisms to replace the small 200-sheet input trays that are standard on all SX, RX, and TX printers. But before you attach a 1500 sheet paper feeder to your LaserJet III, you should understand some of the issues relating to duty cycle and machine life.

How Hard Can You Drive an SX Engine?

Canon printers have been found to be much more durable than Canon originally predicted. Original specifications from Canon rated the SX, RX, and TX engines for a duty cycle of 5,000 pages per month. HP knew that Canon's specification was conservative, and rated the SX-based LaserJet II at 12,000 page per month. Based on 5 years of experience with the LaserJet II, HP raised the recommended maximum duty-cycle of LaserJet III to 16,000 per month, over three times Canon's original recommendation. Although some minor improvements had been made since the introduction of the SX engine, for all intents and purposes the LaserJet II and the LaserJet III are mechanically identical.

Duty Cycle versus Engine Life

With laser printers, as with photocopiers, the lighter the duty cycle (pages printed per month), the longer the machine life (pages printed before mechanical failure). The 8-ppm rating should be considered the "burst" printing speed that is available for fast printing of short jobs (less than 200 pages). It does not indicate the duty-cycle of the printer. Running continuously, 24 hours a day, an 8-ppm SX engine is theoretically capable of printing 11,500 pages a day. At this rate, more than 300,000 pages would be printed in a month. The rated life of the engine mechanics is 300,000 pages, so running an SX continuously should wear it out in less than a month.

In fact, printing at such high rates is likely to overheat gears, motors, and the rubber parts near them. At an excessively high duty cycle, many mechanical parts of the machine will wear out prematurely. Warm operating environments can also shorten engine life. The Printer Works has found that SX-based printers, such as the LaserJet III, if subjected to extremely high duty cycles, are likely to suffer component failure after fewer than 100,000 pages.

Despite Canon's more conservative estimate, HP's published duty rating of 16000 pages per month is probably a safe bet. This means that in a month consisting of 20 business days, an average of 800 pages per day can be printed without exceeding the recommended duty cycle. To avoid overheating it is probably wise to print less than 1200 pages a day and not more than 300 pages in any one hour.

High Capacity Trays: Advantages and Cautions

At 16,000 pages per month, a standard 200 page paper input tray must be refilled 80 times, or about 4 times a day for the 20 business days in an average month. A 1500 sheet tray will only have to be refilled 11 times a month. But the time saved reloading paper is only part of the convenience. Most of the lost productivity associated with low capacity paper trays results from users waiting for a job to finish printing while the printer sits idle, because it ran out of paper in mid-job. Users tend to assume that because a print job has started, it will finish.

High-capacity trays increase productivity, but they also make it easy to exceed the rated duty cycle of the printer. The 200 sheet tray design ensures that there will be at least a small cool-down pause every 200 pages while the operator fetches and reloads the paper. A 1500 sheet tray allows users to exceed the prudent duty cycle limits of 300 pages per hour and 1200 pages per day. If you have a big print job and a high-capacity feeder, it's a good idea to split the job into smaller segments, either through software or by periodically taking the printer off line.

Do not try to cool the printer down by turning it off! Rapid cooling caused by turning the printer off after a long print job should be avoided because the fast temperature changes can stress the electronic and mechanical materials of the printer more than slow cooling. After a long period of printing, leave the printer on, but idle, so that it cools off gradually. This will maintain the fixing assembly, which is the most vulnerable part of the printer, at a comfortably warm temperature. The result should be a longer life for your printer.

Of course, if your SX-based printer does wear out, give The Printers Works a call. We can repair it or, if you are a service person, we can sell you the parts you need to repair it yourself.

Sheet and Envelope Feeder Models

General Information | High-Capacity Stacker | Generic Paper Trays |
Ordering Information | Text Only

Genesis JetTray 1500

[Genesis JetTray 1500 large capacity sheet feeder (holds 1,500 sheets of paper]

The JetTray 1500 provides a reliable source for up to 1500 sheets of 20 pound paper. The feeder mechanism is based on a mechanical elevator that continuously keeps the stack of paper up at the top of the tray. Motorized rollers slide the top sheet into the printer. The tall stack of paper requires that the printer be elevated to the height at which the paper input slot matches the output chute of the JetTray. Rails are provided to raise the printer to the correct height. A manual bypass slot is also provided, so that a single envelope, or a single sheet of a different stock, can be fed without separating the JetTray from the printer. No special software is required. The feeder is powered from an AC outlet and makes only a mechanical interface to the printer. No modification to the printer is required.

JetTray 250E

[Genesis JetTray 250E Large Capacity Envelope Tray]

For greater envelope capacity we recommend the Genesis JetTray 250E. On RX and TX printers, this large capacity feeder replaces the lower paper tray chute rather than piggybacking above the upper tray. The JetTray 250E leaves RX and TX printers two-tray machines instead of making them triple tray systems.

The JetTray 250E's mechanism works in basically the same manner as the JetTray 1500 but the tray area is sized for number 10 envelopes. Up to 250 envelopes can be loaded at a time. For mass mailings, the increase from 15 to 250 envelopes is a real time saver.

JetTray EX

The JetTray EX is designed for feeding heavy media such card stock and label sheets. As a paper feeder it can be used to feed up to 1250 sheets. The stock must be 8.5" x 11" and you can use up to about 50-pound stock. The JetTray EX is not shown here, but it looks exactly like the JetTray 1500.

High-Capacity Stacker

General Information | Sheet and Envelope Feeder Models | Generic Paper Trays | Ordering Information | Text Only
[Gradco Systems high capacity output stacker]

Simply increasing the input is only half the solution. In order to leave the printer unattended, you also need a high-capacity output mechanism. The Gradco "High-Capacity Stacker" increases the output capacity from 100 to 500 sheets. It can handle any size paper, including envelopes.

The stacker is essentially an extension of the printer's paper delivery mechanism. The mechanism nests in the output hopper of standard shaped SX, TX, and RX printers. It feeds the media to a higher level before releasing it into a deeper stack. Mechanical power for the internal rollers is derived from the printer by gears that mesh into the gears of the printer's paper delivery mechanism. An extension of the output tray is also provided for easy lifting of the stacked output.

Generic Paper Trays

General Information | Feeder Models | High-Capacity Stacker |
Ordering Information | Text Only
[Generic Paper Trays for SX, RX, TX]

The paper trays pictured here are functionally identical to the ones manufactured by Canon. The shape and color follow the original standard, as made for the Canon LBP-8II and the HP LaserJet series II.

See parts table below for part numbers, to check prices & availability.

See also Diagram 300

Ordering Information

General Information | Feeder Models | High-Capacity Stacker |
Generic Paper Trays | Text Only
For price and ordering information or to place the item in your shopping cart,
select a Part Number in the table.

Part Number Description
click on camera icons to see pictures
92295B Paper Tray, Letter (8.5"x11") for SX, TX, RX
R63-0051-700  Paper Tray, Legal. This tray is compatible with virtually all SX printers, including the HP II, IID, III, IIID.
92295C Paper Tray, Legal (8.5"x14") for SX, TX, RX
92295R Paper Tray, Envelope (various size) for SX, TX, RX
LCS-SX-USP Feeder, Sheet, Genesis JetTray 1500 for SX
LCS-RX-USP Feeder, Sheet, Genesis JetTray 1500 for RX and TX
LCSEF25-SX Feeder, Envelope, Genesis JetTray 250E for SX
LPPS-15 Printer Stand, Genesis LaserRails
310-001-05 Stacker, Gradco High Capacity for SX, TX, and RX

General Information | Feeder Models | High-Capacity Stacker |

Generic Paper Trays | Ordering Information | Text Only

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