A couple of comments that might help, or might confuse you..
It is a bit lengthy, but, lots of info that might help..
I typed this while I was on hold, waiting to talk with someone, went back, wrote more and went back again to finish, if it seems choppy.. I went back and posted some things up to..
Here you go.. Hope tis helps...
You might have fun with this.. I built it back in November of 2014 using Skate board trucks and a Wooden drive wheel.. I had never seen anything using either of these combos before, but, but can't say they didn't exist..
Here is a quick video I shot for a friend Immediately after.. https://www.youtube.com/watch?v=RsTc3c7upSE
Then a more detailed video about the build later when I had time to make and upload it after lots and lots of questions about how I built it.. https://www.youtube.com/watch?v=gtFQt4k1kA8&t=207s
The Skateboard wheels work just fine..
I have a grinder I built November 2014 that gets used pretty regularly..
I hear some people have trouble with bearings, wheels, etc.. I have not..
One thing to note.. The ABEC rating is about manufacturing tollerances.. The higher you get, the tighter the tollerances, the tighter the bearing,, the less metal dust that gets in..
I used the ABEC9 bearings and the wheels and bearings are something I just use and never think about..
My wheels are 2-3/4" tall and 2" wide..
You can get longboard wheels that are taller and wider.. I have seen 3" diameter and 2-1/4 wide..
All use bearings that are 5/16, or 1mm larger if you can find the odd ball ones..
I actually used the Trucks that came with the wheels, instead of using just 5/16" bolts..
I am still on my first set of bushings for the trucks, but, I have loosened them, flipped them around and put them back on to get the trucks/wheels tracking straight again..
I just looked at them.. No wear on any of the wheels, except when I let something catch one of the wheels and cut it, but, it is the same as it was when I damaged it.. No further wear..
I only crowned my Drive wheel,, and,, Yes,, It is just two pieces of 5/4 deck boards cut in a circle, glued and screwed together, put on the motor shaft and crowned with a Farriers file..
It is still doing exactly what it is supposed to do.. Just the wood only..
So, keep your eyes out for a skateboard in case you need more bearings and wheels...
I am pretty sure yours are ABEC3 from the looks, so, will probably get metal dust in them..
Mine are sealed with the Rubber seals.. The sides of them have black shiny vinyl look, like other high speed bearings.. You can change them quickly..
I noticed you are interested in Motor sizes..
Mine is a 1/3rd Hp from a washing machine.. An old motor I had a 1/8" x 8" cut off disk on that I sharpen drill bits with.. The Drive pully is 5 inches. I primarily slack grind metal parts that I cut/weld, etc.. I have not started grinding knives, but, I have not bogged the grinder down eating the metal I have to eat.. I would imagine I could, but, it would be a heavy grind for me..
I'm not sure what size belts you ordered.. I might have missed it..
Your wheels look pretty wide.. It won't hurt anything. I prefer 2-1/4" wide wheels for 2" wide belts.
I usually like the same width belt and wheel on the platten wheels.. Sometimes I use them to profile the inside edges of pipe for saddles, etc.. Also to round an inside edge, etc.. Personal Preference..
Your platten will wear over time.. you may consider a second sacrificial layer of steel the width of the belt when you can.. If you can get some High Heat Glass (from an old oven or Fireplace), it is very hard and what some upgrade to down the road. The belt will slide easier on it and create less heat/friction.. You might also enjoy a little sharper edge on each side of the belt, if you are grinding plunge lines on knives, etc.. Just a thought..
Ok.. I just now see the 2" x 72" belts arrived and the motor looks plenty strong to me.. I don't know, but, older motors seem pretty tough compared to some new ones I have played with. I think you will be happy,, and if you build another, you can use it to do that too.. Ha..
Looking at your setup now, with the belt installed...
If you have trouble with tracking because of your verticle (home made box steel) wabbling around, you can pull it and lay it vertical and pull down on the back with a spring (about 30 pound spring is minimum, but, a good spring weight), or you can get a compression spring, like you have below the box and rig it up on a piece of pipe welded to your top square tube and let the arm rest on it..
If you drill through the vertical square to put a bolt, go ahead and drill out some water or gas pipe to fit snug to your bolt when you run it through.. Remove as much wiggle there as you can..
Think about it like this.. The more solid the grinder parts are, the more solid and consistent your belt tracking will be.. You can see when you adjust the belt for tracking. It does not take much movement of the wheels to change everything..
Ha.. Ok.. I see the tracking setup you have.. The Hex bolt looks pretty snug to me..
If not, pry the two sides of the larger box and slip a washer in one one side,, better if you get two sides.. It should stiffen it up if you have a problem there..
You want it snug, but, not super tight.. A Nylox nut on the other side would be good if you have trouble with it getting loose, or you an take a punch and ding the threads and then back off on the bolt just a bit to solve that problem the quick way.. Not too much, in case you want to take it off later..
Just found the .MOV you posted.. The 1/2" nut under your top Platten wheel is/was loose..
Looks like you have it tracking very well.. The rythmic sound you hear is the motor is my guess. My old motor sounds the same when I put pressure on the belt, but, it has been that way for 3 years now.. Ha..
I know you realized you didn't compensate for the extra thickness of the Idle/tracking wheel thickness being further out from the rest of the wheels.. All of the wheels are riding on the right side, but the tracking wheel rides to the left..
The only time that will bother you is if you want to grind on the left side of the belt edge on the platten and need to move the belt over...
Red the above comment about putting a second layer of thicker material on your platten to get a sharper edge,, but, I can't see the left side of the platten, and you may not be able to adjust your platen back if you welded it, rather than bolting it, but, I am betting you bolted it, so, you can add some thicker steel and/or High Temp Ceramic Glass and get it stiffer and give it something to wear out you can replace easily.. If this is your first grinder, you will find it will become one of the most used tools in your shop..
I built the Grinder I built as a prototype to see if I could build a cheap $3000 Belt grinder, because the first time I ever saw one was at a "Hammer Inn" I was invited to, and there were 15 families sharing one Club Grinder.. I figured I could build one cheap and with simple tools, since that was about what all of the families would be dealing with.. One night in the shop and I had a working prototype.. Ha.. All the while, I was saying,, If this works,, I am going to weld up a nice one..
3 years later, and I am finally getting around to making my plans up to build mine..
I have looked at hundreds of them since then, and they have evolved quite a bit in the last 3 years..
It is going to be an Interesting project for sure..
I really hate to go with the All Aluminum Wheels though.. The Softer Skateboard wheels are great in my opinion.. When you look at the hard core Kinfe grinders,,, they love their Rubber Contact wheels, and I have even seen some cover those wheels with Felt, when they want to get a good polish using the Grinder. You hardly feel the belt seam with a softer wheel.. Somewhere in the 60-70 hardness area..
I am going to try to get some larger Skateboard wheels.. I have seen some 3.5" in diameter and 2-1/4 wide.. But, they still have the 5/16" bolts and bearings.. Seems to me that they are going to be flexing when you really start hogging metal off and putting a higher tension on the belts when you have a bit heavier spring tension, etc,, on a more professional machine..
I am going to try to Freeze the One soft wheel that I have left,, and stiffen it up a bit and get polish sharpen a HSS lathe bit and see if I can cut a larger hole for some larger bearings..
The Bearings are already 7/8" OD, and all I have to do is get to 1-1/8" to get some good bearings with a 1/2" ID..
The most popular 2"x72" grinder bearing is the 1616 bearings.. They are 1.125"OD x .5"ID(bearing)x .375" width.. The Skate board wheels are 22mm(0.866")OD x 8mm(.315")ID(bearing) x 7mm(.276")..
So,, as you can see,, you don't have too far to go to get from one bearing to the other..
Thought I would give you a few ideas for now or down the road, if you want some options.. Options are always good things..Ha..Ha..
Here is the right kind of Skate board bearings to replace what you have. http://www.ebay.com/itm/182497741900
Here is a set of the larger bearings that are used on most main brands of 2x72" grinders.. I just bought 2 sets of these a day or two ago to use on my new grinder with lots of accessories.. http://www.ebay.com/itm/391801829448
One more thing.. BELTS...
Depending on what you want to do.. I hear knives are in the picture, so, here goes..
Here is a good article to bookmark to get you started.. http://usaknifemaker.com/abrasive-belt-basics-what-kind-should-i-buy.html
There are a couple of main/popular types of abrasive belts for grinding..
Cheaper to More Expensive..
AO Belts = Aluminum Oxide
They are the Medium Duty Belts.. Also the best belts to use in grits above the agressive belts..
They are much cheaper, but, wear out faster too, but, you can use them for other things when they wear out. Handles, etc..
So,, Belt Prices are very close to each other when you consider life expectance and intended use..
Use these belts in the Higher ranges.. 120 to 800 grit.. You can get J-Flex belts in this range too..
A little more aggresive and a little more expensive.
Ceramic can be 3x more expensive than AO, but, usually lasts 3 to 4 times longer.
These are for heavy metal grinding and tool steels.. Use lower grits on these belts.. 36-60 grit.
Actually, you will be starting with Ceramic and moving up..
Then, there are leather, felt, film and several other types of finishing belts..
You will most likely use more of the lower grit ceramic belts, becuase you do most of the heavy grinding and then, you are working your scratches out and fine tuning your blades, so, won't use as many of the other belts..
Then, you will hear all sorts of belts out there, gator, Blaze, Trizac, etc.. You are on your own there.. Start basic and get the feel and then pick up a belt or two here and there and you will know the difference and see if it is of more value to you..
Hope the grinder works out.. I'll try to keep up with the post if you have any questions.