Decided to try one of those vibration tests on MY grinder.

[Drew Riley]

As some of you know, I recently designed and built my own grinder. Over the past few days, I've seen at least a couple of "vibration tests" using nickels, so I figured I try one myself.
Then I thought I'd turn it up a notch...

Couple of notes: Grinder is at full speed (2x setting on an 1800 RPM for 3600 RPM), and I decided to use a flat platen instead of the typical 8" or 10" contact will, as you get a little more surface area contact with the belt, it's more prone to belt bump as it goes over the platen, and there are twice as many bearings. In other words, if you're gonna see vibration, I imagine you'll see more in a flat platen than a contact wheel. I may be wrong, but that's the thinking. In reality, it's probably negligible if there's any difference at all.

Also, note that the grinder is on a $40 import pedestal that's not exactly "sturdy", and the motor is an import and probably the cheapest 3 phase motor you can buy, so if this thing was gonna vibrate, it'd be vibrating.

I'll let the video speak for itself:

[video=youtube;blKD9m5Fv34]https://www.youtube.com/watch?v=blKD9m5Fv34[/video]


Now, does this mean much in the grand scheme of things? I don't know. I will say that I'm very impressed with the wheels I got from eBay (VWJackStraw, if I recall the name correctly), and for a cheap motor, I'm not disappointed.

 

[Teppojutsu]

Nice

 

[Teppojutsu]

No super glue jk

I just saw the Northridge video today my self .

I don't know what it means in the grand scheme either but you would think
If there where any bad vibes the coins would roll ?

I think I'm going to pull the trigger on a grinder soon

Seems like your grinder is G2G

 

[Drew Riley]

No super glue jk

I just saw the Northridge video today my self .

I don't know what it means in the grand scheme either but you would think
If there where any bad vibes the coins would roll ?

I think I'm going to pull the trigger on a grinder soon

Seems like your grinder is G2G

I was very tempted to glue some coins hanging off the side and/or bottom of the tools arms, as a joke.
In my opinion, these tests probably tell more about the concentricity/balance of the wheels, and maybe the motor, than anything else. I suppose if you mounted something crooked or bound up a bearing, it'd potentially show some bad vibes. Or if you had some bad belt wobble or a bad belt seam, or some really cheap bearings. A belt/pulley drive train would show a little bit more vibes potentially too, but I think as long as your wheels are balanced, you've got a really good head start.

Honestly, the air circulation was probably a bigger hang up on balancing the coins than the vibrations. Lots of air moving off the motor fan and the belts. That, and it's not exactly easy to balance coins on a perfectly flat and level surface to begin with, much less then you've got air movement and rotating wheels.

 

[LARRYZ10]

I played along and made a 1 minute video of my grinder with a nickel on the tool arm but I have to say now that this test only shows that the grinder runs fairly smooth. Let's remember what is really important in a grinder and that is how well it grinds a bevel and how versatile it is to configure to finish the edges of tangs and finger cutouts and flatten steel. Once you get a grinder that grinds a nice bevel you look for things that make your life easier like adjustable tool rests and angled tool rests for swedges and perhaps the ability to turn sideways. After all the object is not to balance nickels but rather to grind beautiful blades. The smoothest grinder in the world would be horrible if the platen wasn't really flat or the contact wheel had severe runout or poor balancing. Just my opinion again. Larry

 

[Brock Cutlery]

I was very tempted to glue some coins hanging off the side and/or bottom of the tools arms, as a joke.
In my opinion, these tests probably tell more about the concentricity/balance of the wheels, and maybe the motor, than anything else. I suppose if you mounted something crooked or bound up a bearing, it'd potentially show some bad vibes. Or if you had some bad belt wobble or a bad belt seam, or some really cheap bearings. A belt/pulley drive train would show a little bit more vibes potentially too, but I think as long as your wheels are balanced, you've got a really good head start.

Honestly, the air circulation was probably a bigger hang up on balancing the coins than the vibrations. Lots of air moving off the motor fan and the belts. That, and it's not exactly easy to balance coins on a perfectly flat and level surface to begin with, much less then you've got air movement and rotating wheels.

I don't know that this test is really teaching us anything about a grinder. It wood working I think this test shows stability so that your cuts don't jump and enlarge or create jagged cut lines.
That said, I really like your grinder. Is it a kit or your own design, and either way, are plans available? I am about ready to build my second grinder.

 

[Drew Riley]

I don't know that this test is really teaching us anything about a grinder. It wood working I think this test shows stability so that your cuts don't jump and enlarge or create jagged cut lines.
That said, I really like your grinder. Is it a kit or your own design, and either way, are plans available? I am about ready to build my second grinder.

I agree with you and Larry. Despite running smooth enough to balance a dime on edge at full speed, I suppose there could still be some glaring issues with any grinder, and again, this is definitely more of a testament to the wheel maker than the grinder maker (which in many cases are the same person/company), which can still speak to quality of course, but how much? I have used grinders that vibrated excessively, but it was an issue with a bent shaft or a bad bearing, and very easily fixed.

The grinder above is my own design, though no plans are currently available. I had some tentative plans to put together a couple of these to sell, though I MAY go the route of releasing some detailed plan packages in the future. I'm not sure I want to give up that "quality control" however, as there are certain steps that have to be done pretty precisely to make everything come together correctly. Logistics of it all are still in the works.