Anorak Bob
6th August 2012, 07:49 PM
I had been talking to Gregory Q earlier today about how in the days before surface plate ownership it was easy to be ignorant of your machine and your machining deficiencies. Sort of out of sight out of mind.
This morning I thought while I had my little CarbaTec granite plate out I would check the upper section of my swivel base.The bottom face of the thing blued up like a Mohawk's haircut.:o I was starting to feel a bit sick about what was going to be revealed when I attempted to blue the all important upper face. I was thinking that my cutting the tee slot and the subsequent thinning of the cast iron ( the base was originally about 40 mm thick ) had caused the base to bow. If that was the case I reckon the project would have made its way into the Sulo bin. Turned out the top was OK . Blued evenly. What I think has happened is that when I clamped it to the faceplate there has been distortion due to there being a recessed section above the tee slot. Pulling it down has lifted the sides and its why the sides are lower than the middle after turning and removal from the faceplate.
I would never have anticipated that the cast iron would bend to that extent. Maybe a fraction of a pussy whisker but enough to prevent flatness.
Out with the DTI and the Sandvik scraper. See how much I can remember from April's 'fest.
BT
This morning I thought while I had my little CarbaTec granite plate out I would check the upper section of my swivel base.The bottom face of the thing blued up like a Mohawk's haircut.:o I was starting to feel a bit sick about what was going to be revealed when I attempted to blue the all important upper face. I was thinking that my cutting the tee slot and the subsequent thinning of the cast iron ( the base was originally about 40 mm thick ) had caused the base to bow. If that was the case I reckon the project would have made its way into the Sulo bin. Turned out the top was OK . Blued evenly. What I think has happened is that when I clamped it to the faceplate there has been distortion due to there being a recessed section above the tee slot. Pulling it down has lifted the sides and its why the sides are lower than the middle after turning and removal from the faceplate.
I would never have anticipated that the cast iron would bend to that extent. Maybe a fraction of a pussy whisker but enough to prevent flatness.
Out with the DTI and the Sandvik scraper. See how much I can remember from April's 'fest.
BT