Last weekend I went to have a look on an old surface grinder (Erma). I don't really need one, but sometimes one would be nice to have (planer and shear blades, knives, odd parallels etc.). The small ones are really rare here in Finland. This is the first one I've seen while looking for them during this autumn.
The obvious fault with the machine is that there is no magnetic chuck. However, the price for the machine is not that high (250€=$290). A suitable magnetic chuck costs about the same.
I did some tests with a dial indicator. There is no runout in the spindle. The table seems to move as it should. There was 0.02 mm z-direction difference from left to right. It was more or less linear.
It didn't have a diamond dresser (or anything else with it) so I wasn't able to true the stone. However, I did a small test with a piece of steel attached to a drill press vice. There was obviously a little bit of chatter. I don't have a reference surface, but using my parallels and looking in front of a light it seemed to be quite flat. More or less comparable to having two parallels together. The stone was attached to the spindle using plastic bushings.
The biggest worry I have is that the ways seem to be quite worn on both ends. Middle part is in good condition. When the table is in the middle there is no up and down movement, but when moved to either extreme I can make it rock a little (~0.04 mm).
I've never worked with a surface grinder before, so I need bit of help in deciding whether to buy this or not.
The obvious fault with the machine is that there is no magnetic chuck. However, the price for the machine is not that high (250€=$290). A suitable magnetic chuck costs about the same.
I did some tests with a dial indicator. There is no runout in the spindle. The table seems to move as it should. There was 0.02 mm z-direction difference from left to right. It was more or less linear.
It didn't have a diamond dresser (or anything else with it) so I wasn't able to true the stone. However, I did a small test with a piece of steel attached to a drill press vice. There was obviously a little bit of chatter. I don't have a reference surface, but using my parallels and looking in front of a light it seemed to be quite flat. More or less comparable to having two parallels together. The stone was attached to the spindle using plastic bushings.
The biggest worry I have is that the ways seem to be quite worn on both ends. Middle part is in good condition. When the table is in the middle there is no up and down movement, but when moved to either extreme I can make it rock a little (~0.04 mm).
I've never worked with a surface grinder before, so I need bit of help in deciding whether to buy this or not.