- Joined
- Jan 20, 2016
- Messages
- 173
I am not trying to disrespect anyone. I know lots of folks swear by the 5 block test, but it does seem to really tell me anything. Typically the table/saddle are worn near center of travel but not hardly at all on ends of travel, such that the machine is grinding a large radius. Have done the 5 blocks on such machines, and the blocks are the same size. Seems like all the 5 blocks tell you is that the chuck was ground such that it is moving in exact same motion as the table. All the blocks the same size but table still grinding in a large radius. On such a machine you can grind shorter parallel parts, but can't grind anything long straight/flat.
I've always taken a good straight edge and 2 dowel pins. Place the dowels on ends of the chuck, turn on magnet, place straight edge over the dowels. mount indicator on spindle and indicate top of the straight edge while moving table slow and normal speeds. You will see lift at the ends if center of table is worn, or even rocking when you reverse direction.
I don't get too worried about backlash as long as less than about .040. Much more than that you don't have any flats left on the acme screw between threads and it wears fast. All the wheel graduations are telling you is where you last were, so more worried about repeating back to same point, which a worn screw with backlash will do. If you are trying to plunge a second slot 3.0000 over just by using the screw you are not going to have good results on most grinders, even when you have a good DRO.
I personally loved the Mitsui grinders when I ran them full time, but they are expensive used. I could not find one close to me for less than $5k, but I did find a filthy Boyar Shultz 20 miles from my house for $500 with .030 backlash and a bit of a lift in the table. It works good for what I do with it at home.
I've always taken a good straight edge and 2 dowel pins. Place the dowels on ends of the chuck, turn on magnet, place straight edge over the dowels. mount indicator on spindle and indicate top of the straight edge while moving table slow and normal speeds. You will see lift at the ends if center of table is worn, or even rocking when you reverse direction.
I don't get too worried about backlash as long as less than about .040. Much more than that you don't have any flats left on the acme screw between threads and it wears fast. All the wheel graduations are telling you is where you last were, so more worried about repeating back to same point, which a worn screw with backlash will do. If you are trying to plunge a second slot 3.0000 over just by using the screw you are not going to have good results on most grinders, even when you have a good DRO.
I personally loved the Mitsui grinders when I ran them full time, but they are expensive used. I could not find one close to me for less than $5k, but I did find a filthy Boyar Shultz 20 miles from my house for $500 with .030 backlash and a bit of a lift in the table. It works good for what I do with it at home.