lathehand
Cast Iron
- Joined
- Jan 31, 2005
- Location
- San Francisco Bay Area
Let's assume a knee type milling machine with dovetail ways for all three axes. My questions are on the design and machining of the oil grooves in the surfaces of the dovetails. The two horizontal axes are the easiest so let's begin there. The oil grooves will be in the short element - the saddle - and for the table the two flat surfaces are above the angled surfaces.
I've seen two different styles of grooves - a straight longitudinal groove down the center of the flat surface with several short grooves at right angles and extending almost to the edges of the surface, and a zig-zag set of grooves extending lengthwise. Either of these appear to do an adequate job of oiling the flat surfaces of the table ways.
My first question is how to oil the angled surfaces. For the table the angled surfaces are below the flat surfaces. At several locations the flat surface groove can be cut through into the angled surface so that oil can flow downwards. Now, what to do next? Cut matching grooves down the angled surface with what? A cow-mouth cold chisel? A linear groove would not be necessary but the metering unit needs to be large enough to supply both surfaces.
Or it is better to run a separate metered line to a hole through the angled surface from the outside of the saddle? Then the question is how to distribute the oil the length of the angled surface? That is not an easy chisel job for the fixed surface and my first look at machining a groove suggests that a special T shaped end mill would have to be made if a circular section groove is desired. A woodruff key cutter could cut a square corner groove. I don't know if I could grind each tooth of a woodruff key cutter to a radius. That still leaves making the cross cuts with a chisel.
OK, we've worked out the fixed angled surface, but the gib lubrication is another problem. These are tapered gibs so I'm thinking that the best way is to drill a hole through the saddle and into the center of the gib. That hole should be elongated into a slot to allow for the movement of the gib. Oil grooves may be milled in the working surface of the gib from that hole. This appears to be a better method of oiling the gib surface than from the associated flat surface. The gib surface is slightly below the flat way and this is a leakage path which would affect the pressure in the flat way distribution groove and there would be no pressure in the angled surface groove.
On the saddle to knee dovetail the angled surfaces are above the flat surfaces. Can they be oiled by pressure from the flat way? That still leaves the gibbed surfaces which so far appear to be best oiled by a separate line.
Last but not least is the vertical dovetails for the knee to column. Does it make any difference where the oil enters the dovetail - center, top, or bottom? The only way to get oil to angled surfaces is through a separate line to each. Well, that might not be right. The oil is under pressure and could flow horizontally from the flat way into the angled way.
Well, it looks like running separate lines to each surface is going to be the best way, even though it might be more work. That decision then leaves one major question: how to machine the distribution groove down the length of the fixed angled surfaces of the dovetails? The three gibs can be milled in a vertical mill. They are just a bit tricky to hold down.
That about does it for the six sliding surfaces and leaves the three leadscrews. Just drip some oil over them? Drill an oil hole in the nut and feed the oil in there? That makes 9 lubrication points and the Bijur kit for Bridgeports has 9 metering units so I maybe got something right.
What have you guys seen and/or done for lubrication of knee and column type machines? As a friend of mine says, "inquiring minds wish to know."
TIA
Carl
I've seen two different styles of grooves - a straight longitudinal groove down the center of the flat surface with several short grooves at right angles and extending almost to the edges of the surface, and a zig-zag set of grooves extending lengthwise. Either of these appear to do an adequate job of oiling the flat surfaces of the table ways.
My first question is how to oil the angled surfaces. For the table the angled surfaces are below the flat surfaces. At several locations the flat surface groove can be cut through into the angled surface so that oil can flow downwards. Now, what to do next? Cut matching grooves down the angled surface with what? A cow-mouth cold chisel? A linear groove would not be necessary but the metering unit needs to be large enough to supply both surfaces.
Or it is better to run a separate metered line to a hole through the angled surface from the outside of the saddle? Then the question is how to distribute the oil the length of the angled surface? That is not an easy chisel job for the fixed surface and my first look at machining a groove suggests that a special T shaped end mill would have to be made if a circular section groove is desired. A woodruff key cutter could cut a square corner groove. I don't know if I could grind each tooth of a woodruff key cutter to a radius. That still leaves making the cross cuts with a chisel.
OK, we've worked out the fixed angled surface, but the gib lubrication is another problem. These are tapered gibs so I'm thinking that the best way is to drill a hole through the saddle and into the center of the gib. That hole should be elongated into a slot to allow for the movement of the gib. Oil grooves may be milled in the working surface of the gib from that hole. This appears to be a better method of oiling the gib surface than from the associated flat surface. The gib surface is slightly below the flat way and this is a leakage path which would affect the pressure in the flat way distribution groove and there would be no pressure in the angled surface groove.
On the saddle to knee dovetail the angled surfaces are above the flat surfaces. Can they be oiled by pressure from the flat way? That still leaves the gibbed surfaces which so far appear to be best oiled by a separate line.
Last but not least is the vertical dovetails for the knee to column. Does it make any difference where the oil enters the dovetail - center, top, or bottom? The only way to get oil to angled surfaces is through a separate line to each. Well, that might not be right. The oil is under pressure and could flow horizontally from the flat way into the angled way.
Well, it looks like running separate lines to each surface is going to be the best way, even though it might be more work. That decision then leaves one major question: how to machine the distribution groove down the length of the fixed angled surfaces of the dovetails? The three gibs can be milled in a vertical mill. They are just a bit tricky to hold down.
That about does it for the six sliding surfaces and leaves the three leadscrews. Just drip some oil over them? Drill an oil hole in the nut and feed the oil in there? That makes 9 lubrication points and the Bijur kit for Bridgeports has 9 metering units so I maybe got something right.
What have you guys seen and/or done for lubrication of knee and column type machines? As a friend of mine says, "inquiring minds wish to know."
TIA
Carl