Grizzly T28959 Chain Grinder

[Philbert]

Summary

Grizzly is known for their stationary wood and metal working machines. I was surprised to see them selling a saw chain grinder (model T28959 - Electric Chainsaw Sharpener) while looking for something else on line, and was interested in trying one.



I was generally impressed with the unit I received, until I noted excessive run-out (described further below). I contacted Grizzly and they sent a replacement unit right away. The second unit had the same problem. Grizzly described this as 'an outlier experience' and referred me to the 'numerous 5-star reviews' on their website.

I was not able to use the product for sharpening, due to the run-out. If you are able to get one without this problem, you may find it satisfactory to use. Please take the time to read the reviews, posted on their website, for additional comments and perspectives.

Philbert

 

[Philbert]

General

Many of these 4-1/4 inch diameter, 'mini-grinders' have a lot in common: most feature a fixed grinding head angle, lots of plastic, and light duty components. This Grizzly model has a cast aluminum base, some beefier components, including a pretty nice chain vise, an LED light, and a handle for lowering the grinding head. It comes with one, 3/16-inch wheel installed, and requires only minor assembly.

The unit appeared to be well finished. This grinder also has a magnetic safety switch, which prevents unintended start up after a power disruption.



Philbert

 

[Philbert]

Capabilities

The manufacturer says that this grinder is suitable for sharpening 1/4" - 0.404" pitch chains, using 1/8" and 3/16" wheels, although, only the latter is supplied. The manual states that it is not suitable for grinding depth gauges, which is typically done with a 1/4" wheel.

It is described as capable of grinding 0° - 30° top plate angles, right and left, although, the vise is graduated up to 35° in both directions and can travel farther. The grinder head angle is fixed at approximately 55°, which creates a more acute top plate cutting edge than most mini-grinders, which are closer to 60°, but matches up with Oregon's recommended grinding angles for most chains.

Replacing the wheels on these mini-grinders first requires removing the side cover / guard, held in place by several small screws, which thread into the plastic housing. On the Grizzly, the 3 screws are retained by the cover, if not fully retracted, which reduces the chance of losing them; a nice feature. Replacing the cover, however, takes a little patience, as it has to fit around a clear, plastic shield and the top handle. Not an issue if you only use the one, supplied, grinding wheel.

Philbert

 

[Philbert]

Fussy stuff

A plastic cord clip on the side of the grinder snapped right off; might be due to the larger diameter (but still 18 gauge) cord insulation. Not sure that this clip is necessary anyways.



The base is cast aluminum, as opposed to the molded plastic on many of the less expensive grinders, but it is fairly thin. Not an issue if mounted in place, but I would be concerned about cracking it if dropped or carelessly handled.

The nut in the vise rotation handle kept falling out - thought I might lose it, so I fixed it in place with hot melt glue. None of these grinders have a washer between this plastic knob and the grinder base, which I think is important, so I added one.

I have never been able to remember the 'universal' 'ON' / 'OFF' symbols on the switches, so I marked these with a label maker to be sure.

The fine grit, red/brown, grinding wheel supplied has no paper blotters, which strikes me as odd, especially for an industrial machine company. They do not seem to offer a 1/8" wheel, so you have to source it elsewhere. I prefer coarser wheels on these grinders anyway.

With the supplied, 3/16" wheel in place, the outer flange nut is not fully threaded on, which makes me wonder if the arbor was only designed to accept 1/8' wheels, such as on other mini-grinders.



Philbert

 

[Philbert]

'The Problem'

I immediately noticed a vibration when turned on, and measured a 0.012 to 0.015 inch run-out across the inside wheel flange (part of the arbor) with a dial indicator. The rim of the wheel visibly wobbled approximately 3/32-inch when sighted through the clear shield. This makes accurate set up difficult, and could lead to uneven wheel wear, even if it is still possible to grind the cutters.

With the wheel removed, it is easy to feel deep dishes in the wheel flange. Someone with more machining experience might know how to remove this (pressed on?) part and resurface it. Or, perhaps, Grizzly could provide replacement parts and instructions; or exchange these for machines without this defect.

Philbert

 

[Philbert]

Manual

As a purveyor of industrial machines, Grizzly is very experienced with supplying user manuals and documentation. The manual for this simple tool is 33 pages long, including several pages dedicated to the general, cautionary warnings, disclaimers, and liability statements that we are used to.

It also includes very detailed electrical information on the motor, and a good illustrated parts list ('IPL' / 'exploded' parts diagram), although, I was told that parts are not available for this machine from Grizzly.

It was clearly not written by someone familiar with sharpening chains or experienced in the use of this machine. Some grinder and saw chain descriptions sound translated from another language. A procedure for adjusting the chain vise for different gauge chains makes no sense.

The description of the sharpening process is awkward. This is a weakness with most chain grinders. But the illustrations in this manual show the chains mounted backwards in the chain vise, and users are instructed to remove the chains and rotate them 180° in the vise to sharpen cutters on the opposite side. This just does not work with this grinder.

Chain grinding requires some knowledge and fineness, including a light touch and well-dressed wheels, to constantly expose fresh abrasive. But this manual specifically instructs users to not dress these grinding wheels, and to replace them as the edge profile changes. I should note that no dressing brick was provided with this grinder.

I know that a lot of guys ignore the manuals that come with tools and equipment, especially basic machines like this. An experienced user of this type of grinder might not have a problem using it, but a novice user could be really confused, leading to frustration and dissatisfaction.

Grizzly asks for feedback on their manuals, so I spoke to some of their technical guys about these issues and provided specific, detailed information.

Philbert