- Joined
- Nov 5, 2016
- Messages
- 1,419
Right after I refurbished the machine and dusted the chuck I did the 5 block test on my new to me Brown & Sharpe 2B surface grinder and all blocks were within 0.00015" of each other. I decided to do an additional test to help me learn the limitations of my ~1935 well used machine.
I put 2 pieces of bar stock (fairly soft mystery metal) on my magnet and spread them out as far as I dared. They were each 1-5/16" high, 3/4" thick and 12-1/4" long. Most likely much bigger than anything I would ever grind.
I rough ground both sides, dressed the wheel and finished both sides. I didn't take many pains trying to get a perfect finish, just let it spark out on the final couple passes.
I miked the pieces and then checked them with my tenth's indicator on my surface plate. Each individual bar was 0.0002" thicker in the middle than on the ends. One bar was 0.0002" thicker overall than the other one. So, the extreme spread was 0.0004" overall for both pieces.
Hey, it could have been a LOT worse on an old machine like this! For my use and what I have invested I am very happy with the results. If I had both pieces side by side (as in grinding parallels) they would have been within a couple tenths, plenty good enough for me.
Now I have a better idea of what I've got and if the day comes when I need to get things as close as possible I'll have to "play" with things to see how close I can get them.
I know a lot of people would think this is way out of tolerance for them (and I'm sure it is), but for me and my use it's fine!
YMMV,
Ted
Both sides roughed, wheel dressed and ready to finish 1st side.
On the surface plate for inspection.
I put 2 pieces of bar stock (fairly soft mystery metal) on my magnet and spread them out as far as I dared. They were each 1-5/16" high, 3/4" thick and 12-1/4" long. Most likely much bigger than anything I would ever grind.
I rough ground both sides, dressed the wheel and finished both sides. I didn't take many pains trying to get a perfect finish, just let it spark out on the final couple passes.
I miked the pieces and then checked them with my tenth's indicator on my surface plate. Each individual bar was 0.0002" thicker in the middle than on the ends. One bar was 0.0002" thicker overall than the other one. So, the extreme spread was 0.0004" overall for both pieces.
Hey, it could have been a LOT worse on an old machine like this! For my use and what I have invested I am very happy with the results. If I had both pieces side by side (as in grinding parallels) they would have been within a couple tenths, plenty good enough for me.
Now I have a better idea of what I've got and if the day comes when I need to get things as close as possible I'll have to "play" with things to see how close I can get them.
I know a lot of people would think this is way out of tolerance for them (and I'm sure it is), but for me and my use it's fine!
YMMV,
Ted
Both sides roughed, wheel dressed and ready to finish 1st side.
On the surface plate for inspection.