Here is the full list of all 49 Grindstone achievements.
Unlock all other achievements
Complete a level with the Detonator Suit, Fireball Sword, Fire Arrow, and Firewalker Potion
Complete a level with the Vine Sword, Poison Arrow, Poison Shield, and Plague Doc Outfit
Survived Jjary, again (and again and again)
Use the OK Boomerang over lava
Defeat MjeatBöll
Complete a level with any 3 pieces of gold gear and the Grindstone Garb
Defeat Jjurk-Creepethuth
Complete a level with the Ranger Outfit and any 3 arrow types equipped.
Defeat MekkaMortie
Collect 50 magma rocks
Collect 50 ice
Complete 3 Creep hideouts
Collect 50 gold
Kill 200 Jerks
Collect 50 crowns
Defeat Creepzïlla
Collect 50 Vine Hjeart seeds
Kill 50 Slobs
Collect 50 poison mushrooms
Eat 3 of Helgä's snack items
Kill 10000 Creeps
Cause a Jerk to die from poison
Create a 45-Chain Grindstone
Collect 50 iron
Collect 50 ectoplasm
Defeat SkjellyKjing
Collect 50 bones
Collect 50 guts
Collect 50 batwings
Collect 1000 grindstones
Complete a Greed Grind without dying
Make a Jerk melee another Jerk
Dodge 3 attacks with the Gladiator Outfit
Complete a Quick Grind without dying
Complete a Fortune Grind without dying
Complete a level with the Spinny Sword, Arrow, and Pickaxe
Kill 20 Jerks
Collect 50 wood
Spare a Royal Slob
Mine gold using the Goldrush Garb and Pickaxe
Survived your first boss
Kill 5 Slobs
Kill 1000 Creeps
Create a 30-Chain Grindstone
Start a level with only 1 heart
Wake up in the Inn
Complete Level 1
Create a 15-Chain Grindstone