Keep in mind that I own and operate a short run machine and fabrication shop and I have the machines at my disposal to repair and upgrade various components of any device (in this case the chain grinder) that I deem necessary to improve the actuation and throughput of a device.
I would strongly suggest taking apart the clamping jaws of the chain vise and finishing it better than how it comes from Blount (who owns Oregon btw). I removed the shear lines on mine as well as improved the surfaces (inside) on the clamp rails using a surface grinder but you can achieve the same result using a sheet of abrasive paper on a flat surface and smoothing the inside surfaces. All the parts of the grinder are mass produced and as such can be improved by some attention to them.
Also, keep in mind that the clamp force on the chain vise jaws is concentrated in the middle of it and not on the ends and that is exactly where you want the most clamp force to be exerted. I did shorten the end screws a bit to increase the clamping force exerted on the ends of the 'jaws; simply because I like 'tinkering' with stuff, not that it in reality changes the clamping force exerted in the middle of the jaws because the impact is minimal at best.
Far as Blount (Oregon) is concerned, their replacement parts are expensive but that is how it works with most companies and replacement parts today.
I will also say that the cheapo Vevor grinder has a much more robust clamping vise and I have both the Oregon as well as the Vevor units to compare to.
The only difference between them is you cannot clamp the Vevor unit to anything vertical, it has to be secured to a horizontal surface. What I did, is I fastened both units to a length of 2x4 and I clamp the 2x4 to my welding table when I want to grind chains.
Like I stated earlier, the Vevor grinder has a much better depth stop than the Oregon unit has. The Oregon unit's depth stop is hard to set and is tucked away on the machine, kind of hidden and hard to adjust, whereas the Vevor unit has an easily accessible depth stop adjustment that locks securely and don't need to be constantly adjusted to set the depth of grind.
I read in the reviews that some of the Vevor units had wheel arbors that wobbled, mine didn't, mine ran true within 0.0025 and I checked it with a dial indicator.
Both units have a clunky wheel shield that makes it difficult to change wheels but again, not an issue with me because I don't use the conventional bonded stone wheels, I use CBN wheels (Cubic Boron Nitride) wheels that the CBN compound is plasma sprayed and bonded to the aluminum wheel so I never have to dress any wheels except for an occasional cleaning with a soft, white carborundum dressing stick. I run them both with the wheel guards removed entirely. CBN wheels won't 'explode' like a conventional bonded wheel will so no need for the wheel shields at all.
Bonded wheels all require careful handling and checking to see if they have internal or external cracks from mis handling. CBN wheels don't. They never crack and the aluminum rims the grit is bonded to run true with no vibration what so ever.
The other nice thing about CBN wheels is, they never need radius dressing, ever and the life of them is at least 10 times the life of a bonded wheel, probably more, as I've ground somewhere around 250 loops on mine with no visible degradation of the wheels. The downside is initial cost. CBN wheels will cost about 5 times as much as the bonded wheels but the CBN wheels don't shed abrasive either so they are much less messy as well.
Only reason I run CBN wheels is I grind loops for my arborist customers so I grind a boatload of loops. If I was just grinding my own loops, I'd most likely use the bonded (stone) wheels.
One thing to keep in mind with CBN wheels is, the loops must be pre cleaned to remove any swarf before grinding. I run all the loops through a large ultrasonic cleaner with a Lye-water solution to remove any swarf and then I rinse them in clear water, then grind them and then soak them in oil so they don't corrode. After the oil soak, I drain them and they are done.
