Finally- Grinder Review

TL;DR: It’s a good value—a great motor on a good frame.

I’ve been working with Wayne Coe’s grinder since 4th of July weekend, and have put in at least an hour a night shaping or refinishing pieces. I’m going to start with what I would improve or change about the design, and leave you with what I appreciate about the Moe Grinder.

*Assembly: As regular readers know, I had some difficulty in setting up the motor—there were seemingly endless tracking issues until I moved the drive wheel face to the end of the drive spindle. This eliminated the ‘grinding into the motor housing’ issue. User error/ignorance? Possibly. I hope the issue has been sufficiently beaten to death, and if not, I recorded my solution for posterity in my version of the instructions.


*Belt wobble: I found it quite difficult to make a belt track square to the contact wheels and to the platen itself. Frequently the belt would wobble back and forth like a tire without enough air. Much of the wobble was eliminated by moving the tool arm forward about ¼” while the tension was off of the belt, then letting the tension wheel do its job. But not all of the wobble. I had an unnamed bladesmith friend (UBF) take a look at it last night and he chalked up much of the remaining wobble to the belt I was using. When I put on a precision engineered 3M Trizact belt the wobble all but disappeared. He said that even on his grinder (which he’s used for the better part of a decade successfully) there is a hint of belt motion. Keeping the belt very tight also eliminated much of the problem I was having with the belts scooting to one side when pressure was applied to the flat of the platen.


*Belt Changing: This is a very minor issue, and it’s really more of a preference. The arm on the tension wheel isn’t very long and it’s on the same side as the tool-arm adjustment t-handle. This makes retensioning belts awkward at best. A handle inside the belt area would let me use my right hand to keep tension off the wheel, while my left hand tightens and moves the tool arm. Again, minor, but awkward.


*Square tracking: Another issue I had been having was that the belt would not align with the wheels and platen. Even when the contact wheels were each the same ¼ turn off of full-tight, the platen was cockeyed. UBF suggested putting a thin washer on the lower platen bolt between the platen and the frame, to move the bottom of the platen out that distance. What a difference 1/16” makes. The belts now track almost perfectly. UBF also said that even the best belts aren’t going to be perfectly squared on a platen, and he has to move his belts toward the edge of the platen when doing plunge cuts. So I have to chalk THAT up to inexperience, rather than a design issue.


*Fasteners: I very much appreciate the “one size fits all” approach attempted here. And I also very much appreciate that unlike other grinders I don’t need to keep a set of wrenches handy to make my adjustments. But the washers that are supplied are a problem. The washer that keeps the tool arm tightened in the guides is badly deformed from my torquing the handle to get sufficient pressure, making adjustments to the tool arm an issue. I will be doubling up on the washers, and may employ a split ring washer to help with tension. Also the washer that is used between the platen/contact wheel arm and the main tool arm is covered in some kind of fiber material. I had an issue last weekend in which I was edge grinding a radius in a guard using the 8” wheel, then I moved to the platen—the platen spun, throwing the piece and grinding my thumb in the process, as well as putting the 2” wheel dangerously close to my face. The fiber backed washer was immediately removed and I noticed that the face was both smooth and had some kind of metallic buildup. A homebrew washer that I had chiseled some teeth into was added. The arm can still swing if I push on the 8” wheel, but it takes considerable force to do it now.


*Tool rest: Actually I don’t have a real opinion on its functionality because I haven’t been able to get it to stay in place such that I felt like it was usable. I like the concept of the sliding round bars, but IMO this kind of part must be square to prevent rolling.



So what do I like?

*Value: This is actually a helluvalota grinder for the money. I looked last night and to purchase the legendary (and rightfully so!) KMG grinder, just the flat platen and variable speed motor will cost as much as Wayne’s setup (as of this printing). The KMG also seems to require additional doo-dads, and would require additional arms and wheels to do hollow grinding. KMG-clones are comparatively priced to the original KMG. I am not considering the KMG clones like the no-weld grinder or grinder in a box in my price figuring, only ready-to-go out-of-the-box grinders. Clearly, I don’t have whatever skill it is that’s required to drill a straight hole, much less get two pieces or metal to line up- without the use of a welder and grinder.


*Versatility: As hinted at above, being able to grind on a flat, and having both 2” and 8” contact wheels available in the original price is a great deal. Wayne also points out that the unit can be set up for horizontal grinding. I’m not sure how mine would need to be arranged to make that happen, but I’ve seen it (I believe a much longer cable between the VFD and motor would make this much easier). In addition, the adjustability of the arms allows for smaller 1” wheels at the 2” position or a larger 10” wheel instead of the 8” wheel. Wayne doesn’t offer either of those as options, but the wheels are available.


*Accessibility: Though there are other units that have contact wheels included in the base price, they do not allow said contact wheel to move into a position for easy access. With the Moe Grinder, the 8” and 2” contact wheels can be positioned as the primary tool.


*Versatility 2: UBF has said that he’s been able to source 2x132” belts for less than 2x72” belts. Having the motor separate from the frame would let UBF use these longer belts (without having to rig up additional arms and tensioners).


So overall, despite –my- issues with being jinxed during setup (I swear I have a gremlin in the shop) I am growing to like the Moe Grinder more each time I use it. I definitely appreciate the flexibility of the machine, especially since I’ve made the small changes mentioned above. I plan to come up with a way to add a rigid tool rest, and will update again when that happens.

So Where's the Review?

I'm working on it. I want to be fair to the machine, and to my (lack of) skill with it. So far the only issue I'm really having is wobbly belts BUT it's just as likely that it's the inexpensive belts that I'm using, as it is that there's an issue with the grinder. I did adjust the torque on the bolts that hold the guide wheel and the contact wheels- that helped a bunch. I have about a dozen 3M Gator belts on the way, too, so I'll get a chance to see how precision belts behave.

However, I have written my version of the assembly instructions, and Wayne liked them so much he included them with a grinder he sent out yesterday.  Take a look:

https://docs.google.com/document/pub?id=1Sc28VPKRdCENfvvmFEhsfciTIpUiJ3j7AfSqPqtwJ0c

[EDIT- the previous embedding didn't work very well. Try the link instead.]

Finally Finished the Grinder Build

I received the grinder frame on Tuesday, along with the assembly instructions. While I managed to disassemble my car's engine and reassemble it with parts I modified myself, I am not the most mechanically inclined person. I had a helluva time putting it together- over 9 hours, not counting the time at work or away from the garage that I spent swearing and pulling my hair. But I -did- get it put together and it -does- work! I spent a little time tonight getting used to the speed controller and acquainting myself with a 2" wide belt. I think the results speak for themselves: