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Posted: 2/12/2012 8:33:28 PM EDT
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Leveling table on KBT mill. It's not much of a mill, but it's a mill none the less.
The tool to level table to mill head should be in next week. Any pointers, tips, how to's, suggestions, rattlesankes or bear traps to look out for and any general information would be greatly appreciated. Thanks in advance, david. |
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Leveling table to mill head.
Freind is lending me his tool with dial gages. Same freind who's been coaching me some on his Bridgeport. We are going over the process Friday. Thought I'd ask a few questions in an effort to wrap my head around job some before we get together. He tends to go through things a little quicker than my absorption rate. |
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You need to level the machine first. Once the machine is level then tram the head in. This. Having the entire machine level makes other machining operations and setups easier. It doesn't affect knee mills so much, but lathes are particularly sensitive to being setup out of level with a key resulting issue being bed twist. Even a seemingly beefy lathe bed will twist over time if not setup properly leveled and supported and this twist will cause all manner of issues when trying to produce accurate parts. |
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Sweep the biggest radius possible. Posted Via AR15.Com Mobile Use the largest point you have in the dial indicator....smaller needle points don't take impacts very well and can damage the indicator Many dial indicators see their last useful days tramming heads in 
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tram the head over the area and setup where your table is usually going to be first. Usually with it around the middle of its travel. Once it is tramed in then take an indicator and run the bed from one extreme to the other. If the bed and its ways are really good you wont see the needle move. More than likely you will see a bit of movement from the table dipping when a majority of the table is left or right of the knee. You may see the bed bounce up and down due to bearing and screw slop or the screw may be slightly bent. Sometimes you will find that the table may be not be truely flat anymore. This is getting past tramming and more into inspecting how true the mill can be.
The two indicator head will get you there quicker but you still need to spin the tram indicator 180 degrees to make sure the mounting pin is true and not bent. And any old school machinist will still make you sweep a single indicator because "its better". I've never gotten one to really tell me why it's better. |
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Or that. Lol How do you calibrate it? Posted Via AR15.Com Mobile I've always wondered that. You place the unit on your surface plate, or if you don't have one you place it on an undamaged area of your mill table and zero both indicators. You then install it in the mill and bring the table up until the indicators have moved a bit. Adjust tram until both indicators read the same. I have one of the variants of those and they sure make tramming faster. |
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Or that. Lol How do you calibrate it? Posted Via AR15.Com Mobile I've always wondered that. You place the unit on your surface plate, or if you don't have one you place it on an undamaged area of your mill table and zero both indicators. You then install it in the mill and bring the table up until the indicators have moved a bit. Adjust tram until both indicators read the same. I have one of the variants of those and they sure make tramming faster. Does the dual indicator set op have any other practical uses? |
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Or that. Lol How do you calibrate it? Posted Via AR15.Com Mobile I've always wondered that. You place the unit on your surface plate, or if you don't have one you place it on an undamaged area of your mill table and zero both indicators. You then install it in the mill and bring the table up until the indicators have moved a bit. Adjust tram until both indicators read the same. I have one of the variants of those and they sure make tramming faster. Does the dual indicator set op have any other practical uses? You can use it to tram in on a sine bar to set angles. |
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Or that. Lol How do you calibrate it? Posted Via AR15.Com Mobile I've always wondered that. You place the unit on your surface plate, or if you don't have one you place it on an undamaged area of your mill table and zero both indicators. You then install it in the mill and bring the table up until the indicators have moved a bit. Adjust tram until both indicators read the same. I have one of the variants of those and they sure make tramming faster. Does the dual indicator set op have any other practical uses? You can use it to tram in on a sine bar to set angles. We have a couple in the shop where I work and they well worth the cost and will pay for it's self in time saved in set up... |
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I use a 6" tram bar at work. Take a Sharpie and put a dot on the table. Bring tram bar down on dot and zero. Turn the tram bar 180* and run the table 2X the length of the tram bar to get the indicator on the dot. Then turn 90* and run the table that way. Takes table flatness out of the equation if you're checking at the same spot.
Three axis machines only take a couple of minutes. Five axis machines can take 2 to 4 hours depending if its a dual end configuration. |
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I use a 6" tram bar at work. Take a Sharpie and put a dot on the table. Bring tram bar down on dot and zero. Turn the tram bar 180* and run the table 2X the length of the tram bar to get the indicator on the dot. Then turn 90* and run the table that way. Takes table flatness out of the equation if you're checking at the same spot. Three axis machines only take a couple of minutes. Five axis machines can take 2 to 4 hours depending if its a dual end configuration. Wouldn't this setup method leave you open to the possiblity that your table climbs or dips as it travels? Just because its the same spot on the table doesn't mean its the same elevation since the table has been traversed twice the bar length. What i'm worried about is if the x ways are not truely parrallel to the y ways then one will have to actually tram the head at a small angle in to planes so that the z-axis is actually normal to the table as defined by the tables travel? A good tight machine usually wont have a problem, a used mill may. I've seen rebuilders mix and match bridgeports in a frankienstein way to get a good looking mill, but the axis wont run parrellel and normal to each other because they have been worn and lapped on different machines for 50 years. |
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If the table ain't flat the only indication that matters is the scrap yard scale. Ymmv.
Mech- to test that all you need is an angle block. Its accuracy is the result of your test, but a well ground block and interapid 312 should get you close enough for Bridgeport work. Posted Via AR15.Com Mobile |
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Start with the Z travel first (laser in the spindle and check it as you move the head up and down).
Once you know that the head is squared to the column in Z axis, then tram the column to the bed (X and Y), Most will only tram X and Y axis, and when the head is raised or lowered, the end mill is all over the map for different height cuts. |
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