this is a "haarmann" surface grinder. the company is obsolete. it has hydraulic traverse and electro-mecanical cross feed. it has a flat way in front and a v-way in the back. it was capable of grinding "parallel shaped" parts to under 0.0004" over 8", but i was getting a taper of the same magnitude over a shorter distance cross wise. the chuck is 12"x6". i decided i want more precision out of it. i have made a lot of measurements and would like to ask for advise on how to proceed.
1. the table top is 14"x5.5". it is scraped. it is essentially flat, being high in the middle by maybe 0.0002" traverse wise. this was measured with a 400 mm beveled straight edge (din 00) using the light gap method and also a 0.0002" shim (pull test). should i scrape that out?
2. the traverse ways are worn convex. this makes sence. as i dont have a parallel of the lenght and precision needed i measured it again with the straight edge aligned to within 0.0004", interrogating it with a large radius indicator tip. the result is in fig.1. i have a flat area of about 9" traverse wise and then the straight edge rises by about 0.0008" on the ends. however in the area marked by the arrows the table kicks up by over 0.002". (the front and rear measurements are not really consistent, because i have to move the table.)
3. the cross ways are worn convex also. this doesnt make sence, since there is little overhang unless a lot of large parts were ground on the grinder. as can be seen in fig. 2 the area about 1" from the edges is very flat, then it rises rapidly by 0.0004". this was measured with a 200 mm parallel adjusting for its inaccuracy.
currently im not planning to attack the ways, i can make do with the 9"x10" area of flatness. however the table kicking up that much in one spot is a mystery. first a visual and tactile inspection of the portruding ways yields nothing remakable. there are some scores but they are smooth. but more important, the ways are fully retracted at that point so what can make them jump? some mechanical interferrence? even if the hydraulic rod was bent it cant have a hump in it like that.
btw, i dont have a helper at tis time, so im not taking the table off. and i have an additional needle valve to reduce oil flow, so the ways are oily but nothing is running out now.
Edit: there is another funny thing. when the table moves to the left zero is at point B. when to the right its at A. (fig. 1). when i stop the table between these points it drops by about 0.0002" in about 2 second. it stays stable if i stop at any other location. an additional twist is that measuring directly on the table the "kick up area" is narrower but is clearly about 1" to the right. no idea what to think of that. am i chasing some kind of oil bubble? first i thought of moving the chuck to the left to avoid it, but with its location as the straight edge shows that not possible any more.
1. the table top is 14"x5.5". it is scraped. it is essentially flat, being high in the middle by maybe 0.0002" traverse wise. this was measured with a 400 mm beveled straight edge (din 00) using the light gap method and also a 0.0002" shim (pull test). should i scrape that out?
2. the traverse ways are worn convex. this makes sence. as i dont have a parallel of the lenght and precision needed i measured it again with the straight edge aligned to within 0.0004", interrogating it with a large radius indicator tip. the result is in fig.1. i have a flat area of about 9" traverse wise and then the straight edge rises by about 0.0008" on the ends. however in the area marked by the arrows the table kicks up by over 0.002". (the front and rear measurements are not really consistent, because i have to move the table.)
3. the cross ways are worn convex also. this doesnt make sence, since there is little overhang unless a lot of large parts were ground on the grinder. as can be seen in fig. 2 the area about 1" from the edges is very flat, then it rises rapidly by 0.0004". this was measured with a 200 mm parallel adjusting for its inaccuracy.
currently im not planning to attack the ways, i can make do with the 9"x10" area of flatness. however the table kicking up that much in one spot is a mystery. first a visual and tactile inspection of the portruding ways yields nothing remakable. there are some scores but they are smooth. but more important, the ways are fully retracted at that point so what can make them jump? some mechanical interferrence? even if the hydraulic rod was bent it cant have a hump in it like that.
btw, i dont have a helper at tis time, so im not taking the table off. and i have an additional needle valve to reduce oil flow, so the ways are oily but nothing is running out now.
Edit: there is another funny thing. when the table moves to the left zero is at point B. when to the right its at A. (fig. 1). when i stop the table between these points it drops by about 0.0002" in about 2 second. it stays stable if i stop at any other location. an additional twist is that measuring directly on the table the "kick up area" is narrower but is clearly about 1" to the right. no idea what to think of that. am i chasing some kind of oil bubble? first i thought of moving the chuck to the left to avoid it, but with its location as the straight edge shows that not possible any more.
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