Grinder for pottery

[gailpar@comcast.net]

What RPM speed should my bench grinder be? What about grit size for the wheel? I rarely need to use it but want to get the safest grinding wheels there are for the dripping glaze. I've heard horror stories about the wheel disintegrating and causing severe injury.....Thanks!!

Gail Par

 

[Bill Kielb]

I prefer when possible to use the diamond wheels already glued to a batt. They are low speed and the course one can remove a decent amount of glaze fairly quickly with the medium and fine able to produce a glass smooth finish. To use these the surface must be wet which really keeps the dust down. Here is a video of which a part is devoted to these wheels by a potter just discovering them. https://youtu.be/yRWtKHTgU00

For small fixes or tight places I go with diamond disks for the Dremel, but really safety goggles / face shield and respirator as well as an exhaust is essential.

For larger tough items as well as kiln shelves  I go with a diamond wheel in a die or angle grinder, with all the safety equipment above  as well and a diamond wheel rated to fit the grinder.

Regular tool grinders I find difficult to use and not entirely suitable for ceramics as well as the safety shields can rarely be used effectively with the shapes typically being ground .......... and when the wheel fractures it can be a bit dangerous.

Hope that helps.

 

[neilestrick]

Bench grinders are not good for grinding pots. Aside from the safety issues, it's difficult to aim for the right spot, you can't see what you're doing, and it's really easy to crack the pot. The spot being ground tends to heat up very quickly, and that localized heat causes the pot to crack due to uneven expansion. For removing drips, the greenish gray stone Dremel bits work very well. For sanding bottoms, you can use wet/dry sandpaper 220 grit, or like Bill said you can attach sandpaper or diamond discs to a bat, that you spin on the wheel head. Use water whenever possible, to keep the pot cool and keep the dust down.

[liambesaw]

I use lapidary discs, they come in 12 inch and in a variety of grits.  And they're diamond, and they're cheap.  So just glue one to a plastic bat and bobs ur uncle.

[Mark C.]

I’m old school.  I use diamond wheels and two dremel s with green stones as well as diamond bits and a 8 inch green stone on a bench grinder with all guards removed 

I should add I have lots of years at this to be safe use a face shield for max protection     The green stones work best on glaze and clay vs the grey silicon carbide ones.  They are bit harder to find

[Sorcery]

I'm with old school. Guards? I thought those were part of the packaging, like that little paper you gotta remove from inserted batteries! Lol!

Gail, of you're already at "rarely", which is way above Par BTW, just make it Never!

But seriously, are you grinding pieces or shelves? Toss the piece and wash the shelves! You may not need a grinder!

Careful not to go into an unhealthy fear, they're not THAT dangerous! Wear a face shield and be comfortable, lest you catch a finger.

Sorce

 

 

[Mark C.]

my grit size on bench grinder (green stone) is 60 grit if i recall-the more the better for removing glaze

i acutally have two bench grinders one has tool rest and guards in place for sharpening tools one is a  brass wire wheel for rough clay bottom smoothing (our white slab body) the other is for taking off glaze . i also have a 4 inch makita with masonary at kiln for shelve work

also i have two Dremel tools at kiln as well.

[Min]

On 1/18/2021 at 12:31 PM, gailpar@comcast.net said:

What RPM speed...

To some degree you can vary the coarseness of the abrasive by changing the speed. Speeding it up will make it act like a finer grit, slowing it down makes it more like a coarser grit. For safety the maximum rpm of any grinding wheel is set by the manufacturer, they can explode going overspeed.