What size bearings for Grizzly contact wheel?

[Ironhead]

Hi, Im new here, I have a 2x72 grinder I built myself.

I have the grizzly 10" contact wheel and I am planning on having it bored out for sealed bearings this week. The machine shop wants me to pick up the bearings that I want to use but I'm unsure of what size I should get. I know the contact wheels for the KMG are 1/2" bore and mentioned that to the machinist and he thought that was too small. I used some 1/2" bore bearings in my homemade MDF contact wheel and never had any issues with them, only had issues with the MDF.

I'm curious what everybody thinks about this.

[piggy]

Are you swapping out the 6 or 8" wheel that comes on the Grizzly? All the axles I have seen are 1/2" w/ exception of contact wheel which is 5/8 or 7/8". why a machine shop is that expensive? Use a 1/2 bolt through the middle leave it long on one side and use pillow blocks it would be sturdier and easy enough to do. I sent u some instructions. If your not sure of what your doing then do hire someone grinders and their wheels are not something to experiment with when it comes to safety.

[Ironhead]

Thanks for the video link Piggy, I always enjoy seeing what others have built.

This contact wheel is for a grinder I have built myself that is very simular to the KMG made by Beaumont Metal Works. They use 1/2" ID bearings on all of their contact wheels and looking at some bearing specifications I know the loads and rpm of the wheel will be well within these specs. I no longer have a metal lathe big enough to bore the wheel myself so I talked with a local machinist that I know that will take the time to do this right and make sure the wheel runs tru. He mentioned that he thought a 1/2" bore bearing was on the small side and questioned why I wanted to use them. I was only thinking of using the 1/2" bearing because thats what I see being used by a few manufacturers and in other grinder builds. I have only made one knife with a hollow grind so far with my original homemade contact wheel and it worked great. It simply wasnt very durable and was damaged when I moved back in January. I am upgrading to the Grizzly wheel to try more hollow grinds and if I stick with it I may buy a 14" wheel. If I used the same bearing ID I could simply bolt it onto my existing tool arm.

I am just wondering if anybody has come to the conclusion that the bearings were undersized and had wished they were larger from the start. I dont really want to use the pillow blocks to mount the contact wheel because I have several tables or grinding rests that mount to the left side of the tool arm. The cost difference between the bearings plus the machinist would be a lot less than fabricating new tool rests specificaly for this contact wheel.

[AUBE]

Basically the bigger the bearing, the less issues with heat you will have and the longer the bearings will last. With that said a 2" wheel will spin at higher rpm so if a 1/2" id bearing works on a 2" wheel, it shouldn't be a problem on a 10" wheel. The 1/2" id bearings I use on my 2" wheels have lasted years.

[Taz575]

I did something similar for my KMG. I used the Grizzly 8" wheel and got two of these from McMaster Carr: 4768K2 High-Speed/High-Load Steel Ball Bearings with Shaft Collar Mount

They are 3/4" ID bearings with the inner race extended so you can set screw it to a drive shaft. I got a piece of solid 1.5x1.5" aluminum 20" long and had the machinist ream the ID of the wheel to just over .75" (it was a hair under .75), mill a pocket on each side and press the bearings into the wheel, drill and ream a 3/4" hole for the drive shaft in the Aluminum bar and then install (drill/tap) 2 set screw holes. Cost $60 for all of the labor, plus the bearings and stuff. Works like a charm on my KMG!

[R. Yates]

Originally Posted by Taz575

I did something similar for my KMG. I used the Grizzly 8" wheel and got two of these from McMaster Carr: 4768K2 High-Speed/High-Load Steel Ball Bearings with Shaft Collar Mount

They are 3/4" ID bearings with the inner race extended so you can set screw it to a drive shaft. I got a piece of solid 1.5x1.5" aluminum 20" long and had the machinist ream the ID of the wheel to just over .75" (it was a hair under .75), mill a pocket on each side and press the bearings into the wheel, drill and ream a 3/4" hole for the drive shaft in the Aluminum bar and then install (drill/tap) 2 set screw holes. Cost $60 for all of the labor, plus the bearings and stuff. Works like a charm on my KMG!

Awesome Set-up and works very well for me also .

Sam

[Ironhead]

Hi guys, I did get my wheel bored out last week.

I ended up going with a 1/2" bore bearing but got one with an outer diameter of 1-3/8" and a thickness of 7/16" (General 22208-77). They are rated at 5000 rpm with a static load of 746lbs each. I'll never even approach that im sure. My grinder as it is right now will only turn the 10" contact wheel at 551 rpm. Oh and the bearings only cost $8.50 each and the machine shop charged $47. IBT where I bought my bearings wanted $26 each for 3/4" pillow blocks alone, I never did price any 3/4" ground shafting and I already tried cold rolled round and some O-1 rod and neither would fit in the wheel. I figure that by the time I got all the pieces bought and assembled, figureing a little in for my labor I would be over the $68.82 that this little project cost me.

[Taz575]

Very nice!! McMaster sells shafting and stuff like that, it wasn't super expensive at all. Some of the steel rods were like $10 for 12" of 3/4" rod, 1/2" should be less. Just look for "drive shafts", they should be pretty close to what you need and they may be a little more than the solid rods because they should fit a bit better.