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Bosch Colt Variable Speed Palm Router Kit
Multiple bases, multiple functions = expanded utility
Text & photos by Tom Hintz
Posted – 12-13-2006
With the introduction of the Colt Palm Router, Bosch blurred the line separating full-on routers from laminate trimmers. When I first reviewed the Bosch Colt Palm Router (May 2005), interest from the home woodworking community was surprisingly intense. Since then, specialized bases and accessories have been developed that put the Bosch Colt Palm Grip Router in a class of its own.
The kit featured in this review (Bosch #PR20EVSNK) includes the Bosch Palm Grip router, three bases (fixed, tilt and offset), roller guides, straight edge guide, underscribe assembly, carry case and wrenches. This grouping of accessories may have been originally intended for the contractor/installer market but also brings a range of interesting capabilities for woodworking shops as well.
Though physically smaller, Bosch applied the same design and manufacturing prowess that has made their line of power tools a favorite of woodworkers for decades. The clean fit and finish of the assembled units are typical Bosch, as is the full dose of their industry-leading electronic motor controls that substantially extend the usefulness of this already unique tool. Ergonomic design and other user-friendly features make the Bosch Colt comfortable to the hand and easy to use.
Power and Electronics
With a remarkable 1 hp (peak) and a speed range of 16,000 to 35,000 rpm, controlling the beast is mandatory for both performance and safety. Bosch has a long-standing reputation for building powerful, reliable and ultra-smooth electric motors equipped with innovative circuitry that manages them.
The infinitely adjustable speed control dial has six numerical markings that make balancing rpm with bit diameter and the task at hand easy. The instruction manual contains a chart showing the rpm each dial position generates, along with general suggestions for the routing tasks each setting may be used for.
Just starting a 1 hp motor in a 7.5”-tall router weighing only 3.3 lbs could be dangerous if left unchecked. Bosch Softstart circuitry tames that torque response so the rpm builds gradually rather than trying to jerk the Bosch Colt from your hand. Somehow Bosch developed the Softstart circuit so it brings the motor up at a safe rate without creating a substantial startup delay.
Another bit of Bosch electronic trickery is their Constant Response™ Circuitry. This circuit samples and makes corrections almost instantly, often giving the operator little indication it is working. Simply put, when the Constant Response™ Circuitry detects a load being applied that tries to slow the bit, it increases power to maintain the selected rpm. Stabilizing the rpm lets the operator concentrate on controlling the router and making the cleanest, burn-free cut.
The motor housing, with its palm-shaped, rubber overmolded grip area is both comfortable and very easy to control. The guarded On/Off switch and top-mounted speed control dial are both easily accessible and function as expected.
Bits and Changing
The overall size of the Bosch Colt Palm Router limits it to ¼”-diameter bit shanks. A self-releasing collet and push-button shaft lock make changing bits an easy, one-wrench (included) job.
The Bosch Colt Palm Router is capable of using a surprisingly large range of bit diameters despite the ¼”-shank restriction. When installed in the Fixed Base, the maximum bit diameter that can be used is 1 5/16”. Safety and common sense restrict larger diameter bits to table mounted routers anyway.
All three bases included in Bosch #PR20EVSNK kit use the flip-lever, adjustable buckle-style closure to secure the motor. Moving the motor from one base to another is tool-free and quick. The Fixed and Tilt bases have an easy to use fine bit height adjustment feature. The Offset base bit height is fixed because of the belt drive system.
All three bases are based on high-end castings and show very good fit and finish. All three have no-mar plastic subbases.
Standard Base (PR001)
For many routing tasks, the Fixed Base has the capabilities and adjustment range to make those jobs easy and precise. The 3 ¾”-wide by 3 7/16”-deep, square-sided subbase surface makes following a fence or straight edge easy. When using a bearing-guided bit, there is plenty of subbase surface to keep the Bosch Colt Palm Router stable during operations.
The motor is “keyed” in the Fixed Base to make use of the “Locked” and “Unlocked” positions that enable coarse or fine bit height changes. When unlocked, the motor can be lifted manually to whatever height is desired. Give the motor a small turn into the Locked position and the fine height adjustment thumbscrew is engaged. This thumbscrew system makes tiny bit height adjustments very easy to accomplish accurately. An engraved scale on the front of the motor housing lets you quantify fine adjustments visually.
The palm-shaped grip continues from the motor housing onto the Fixed Base. This ergonomic fit between operator and tool makes the Bosch Colt Palm Router easy to control and remarkably non-tiring. Textured depressions on the base fit two fingers that add another level of control.
The Fixed Base has a thumbscrew that is used to mount the Straight Edge and Roller guides. Mounting or removing either guide is fast and tool-free. Round, accessory subbase plates are available for using the Bosch RA-Series Templet Guides (#PR009) or the Porter Cable-style threaded guides. (PR010)
Tilt Base (PR005)
While the Tilt Base is popular with contractors and the home improvement set because of it’s ability to trim laminates flush in corners or on angled surfaces, its unique capabilities are of interest to woodworkers as well. Being able to make cuts at other than 90-degrees to the surface allows creating interesting decorative grooves and edges with common bit shapes. Tilting the base also allows cutting angled grooves very close to vertical obstructions that can add another point of interest that is not possible with common routers.
The Tilt Base has a total range of 75-degrees, 45-degrees forward to 30-degrees backwards. Detents are provided every 7.5-degrees to make repeating more common cuts easier.
Using a router bit in the tilted position makes it wise to make several light cuts to get the best finish and reduce stress on the bit. The Tilt Base has the same fine bit height adjustment found on the Fixed Base, making it easy to change bit depth a small, known amount between passes. The flat, square-sided subbase allows following clamped-on guide fences to make straight cuts accurately.
Offset Base with Roller Guide (PR004)
The design of the Offset Base enables trimming laminate very close to a vertical obstruction, as close as ½” with a 3/4"-diameter bit. It also makes scribing a counter top or similar piece to fit against a wall or other surface a simple, fast and precise operation. The triangular shape of the Offset Base lets the operator to keep the largest possible amount of the subbase in contact with the work piece for maximum stability in surprisingly small areas.
To accomplish the offset, Bosch developed a cogged belt drive system to transfer the motor power to the spindle/collet assembly that is set out near the edge of the Offset Base. A special, cogged collet nut replaces the standard hex-shaped one used with the other bases. A circular slot in the subbase plate provides access for a small screwdriver that is used to loop the drive belt over the special collet nut.
While this drive system works very well, it has limitations.
The drive belt generates some heat because of the friction and speed at which it is driven. That forces a limitation in the amount of time the Offset Base is used. The good news is that the instruction manual says to limit continuous use to 10 minutes or less. I can’t remember ever using a router for 10 continuous minutes and expect that this time-based limitation will be of little consequence to all but the hyperactive power users.
The motor installs in the Offset Base with the same buckle clamp used on the other base styles. The major difference is that a large red button on top of the offset spindle is depressed to tighten the collet rather than the spindle lock on the motor. This eliminates stress on the belt. Incidentally, the collet on the Offset Base spindle is identical to the one used on the motor, including the self-extracting design.
The other limitation of the Offset Base is that there is no bit height adjustment other than how much of the shank is inserted in the collet. In most cases, bearing-guided bits are used, making this a moot point.
The Bosch Colt Palm Router Kit includes a special Roller Guide for the Offset Base that attaches to the subbase plate. This attachment enables using templates to cut or trim openings in confined areas.
Straight Edge and Roller Guides
The Bosch Colt Palm Router comes with traditionally designed Straight Edge (PR002) and Roller Guides, #PR003 for the Fixed Base and #PR004 for the Offset Base. The PR003 Roller Guide attaches to the Fixed Base with a thumbscrew to an indexed boss that holds it square to the subbase plate. The PR004 screws to the Offset Base subbase plate with included screws. Both guides are fully adjustable, simple to use and feature tool-free adjustments thanks to thumbscrews being used at all locking points.
Underscribe Plate (PR006)
Cutting perfectly aligned seams in laminates can be a tough job to get right. The Underscribe Plate (PR006, included in the Bosch # PR20EVSNK Colt Palm Router Kit) attaches to the Fixed Base and makes creating a perfect seam a near no-brainer. The overall size of the Bosch Colt Palm Router means you can create these seams in surprisingly small areas.
The Underscribe Plate has a small lip on the underside that follows the straight edge on one sheet of laminate to cut a matching edge on the adjoining piece. When adjusted correctly, the resulting seam fits perfectly. To help get the setting just right, Bosch added an eccentric to the mounting that is adjusted with a special wrench (included) that makes fine-tuning easy.
In the Shop
After using the Bosch Colt Palm Router Kit in the shop for a little while I realized that accepting the prescribed uses seriously underestimates its capabilities in a woodworking shop. The physical size and available power make the Bosch Colt Palm Router a great tool for many lighter routing tasks and being able to work in confined areas extends its utility even more. As I gained familiarity with the included bases, it became clear that their capabilities were limited more by my imagination than by their design. Even the lack of bit height adjustment on the Offset Base can be easily overcome by securing a shim to the subbase with double-sided tape. Between this shim and fine-tuning the bit in the collet, the Offset Base can be used as a “go anywhere” grooving tool capable of making decorative cuts very close to vertical obstructions.
While assembling the Offset Base the first time, I had some concerns about how smoothly it would run. That proved to be a non-issue. While there is slightly more noise and a very faint “buzz” sensation from the cogged belt, both are minor and have no impact on use, operator comfort or the quality of the cut produced. I also did not notice excessive heat build-up despite intentionally pushing the 10-minute continuous use limit. My biggest realization during this extended run time test was that using a router for 8 or 9 minutes continuously seems like forever and is not something woodworkers are likely to do in non evaluation situations.
Throughout an extended evaluation process, the Bosch Colt Palm Router performed flawlessly. The motor is smooth-running and delivers plenty of power throughout the rpm range. I never felt even a hint of lacking for power. Somewhere between its size and shape, the Bosch Colt Palm Router feels very comfortable to the hand and is easily controllable.
The bit height adjustments in the Fixed and Tilt Bases work well and make tiny cutting depth changes easy. Swapping the motor from one base to another is also easy. I did have to make a slight adjustment to the buckle-style clamp on the Tilt Base, as it was a little too tight as it came from the factory. Backing the adjusting nut out on the buckle ½ turn or so cured that problem.
The Bosch Colt Palm Router Kit is a well-made tool that when combined with the selection of bases included has far-reaching capabilities for both installation contractors and pure woodworkers. Apply a little of the ingenuity woodworkers are known for and the limitations of the Bosch Colt Palm Router Kit become insignificant.
In addition to ever-expanding capabilities, the quality and long-term durability of Bosch manufacturing make the street price of $186.95 (12-12-2006) a surprisingly small price to pay. If you are considering a laminate trimmer or just like the idea of a small router, the Bosch Colt Palm Router Kit is a must-see.
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