fine tuning an 1100?

i don't have any projects coming up and had some time the last couple days. yesterday i cleaned my machine and changed the coolant. today i noticed that my y axis gib seemed a bit loose. while pushing on one end and pulling on the other (along the y axis), i could twist my table about .003" with a dti about 8" from the spindle. maybe i am just missing it but i don't see anything covering adjusting the gibs in the manual except for the z axis. i am not sure how to adjust the z axis the way they show in my manual since mine has a brake on the z axis stepper. i think my machine is a in between model with 3 digit drives but has the z brake.

anyways, i pulled all the sheet metal off the stand and removed the bellows. i adjusted the y axis gib until i was less than .001" ove movement with that same setup. i really have no idea how to properly adjust the gibs (in all axis') and want to make sure i have it as good as i can before i reassemble everything.

are there instructions i am missing in the manual about adjusting the jibs? if they aren't in the manual, what is the accepted technique to get them right?



the next thing i am wondering about is tram. with a dti mounted to the head and reading on the table surface, i had about .0005" deviation over the entire x travel. i consider this great. i also ran the dti reading on the inside of the center t-slot and had less than .0002" over the entire travel. again, very good in my opinion. i don't remember the exact reading off the y axis but it seemed great too. i do not have anything accurate enough at the moment to check the squareness of the z travel in relation to the table.

i then mounted my dti in the spindle and read against the table. they y axis was dead nuts but the x axis had about a .0004" deviation in about a 1.5" diameter swing. it is low toward the control cabinet side. i can correct it by putting slight upward pressure on the cabinet. i do get slight scallops when i face a part and i am assuming this is the cause of that. i have read about shimming between the base and stand but everything else seems so close i don't want to mess that up. is this something i should deal with or just live with it?

That sounds pretty far out of tram to me - I would recommend retramming your machine if you have the time. I posted about going through this process a few months ago. It's not terribly hard to accomplish, but it is fairly involved overall. If you have an engine hoist, an additional bottle or scissor jack, and some brass shim stock, you've got all you need to retram your 1100. I used a 4"x12" cylinder square with a spindle-mounted test indicator reading off the X and Y axis deviations as the column traversed in Z in order to perform my tram measurements, but a swinging test indicator like you used is sufficient too. I'd recommend a larger swing than 1.5" for greater sensitivity though. When I finished the process (it took me two tries to get it right) I found that my surface finishes actually improved from when the machine was new. Given that I had a serious finish problem when I started, it was certainly worth it, but if I had even a somewhat questionable surface finish I'd still say it would be worth going through the hassle of tramming your column.

the 1.5" swing diameter was just what my dti was with the stylus at 90*. i was just using what i had on hand but i will rig up something to get a larger swing when i do it for real.

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Originally Posted by 300sniper

the 1.5" swing diameter was just what my dti was with the stylus at 90*. i was just using what i had on hand but i will rig up something to get a larger swing when i do it for real.

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im just going by the pictures here, but can you not loosen the head bolts, and get a little play? this is of course assuming that its actually tram, and not squareness of the Z.

ive got a bit of tram to correct in my new machine too. not quite as much as yours, but its in the y axis so im debating the different ways to correct it.

my preference is not to shim the column, as my thought (correct or not) is that a solid connection to the base is critical for rigidity. shimming always strikes me as... not ideal.

what about setting the gibs? any advice on that? i need to get the sheet metal back on the machine tomorrow.

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Originally Posted by 300sniper

what about setting the gibs? any advice on that? i need to get the sheet metal back on the machine tomorrow.

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they should tighten the same way as the z. loosen off the "narrow" end of the gib first. then snug the opposite end a little at a time, just enough to remove the slop. then tighten the small end again (not too tight). then test the full travel to make sure nothing binds.

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Originally Posted by 300sniper

what about setting the gibs? any advice on that? i need to get the sheet metal back on the machine tomorrow.

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its the same as the Z. Acessing X is easy, just look under the X table towards the back of the machine. Y is on the right, under the way covers. No need to remove sheetmetal to adjust them either.

The adjusters look exacty like the Z. The process should be outlined in the manual..

Just make sure not to over tighten them. If you do, then you will create backlash from compressing the ball screws and bearing etc...

David

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my preference is not to shim the column, as my thought (correct or not) is that a solid connection to the base is critical for rigidity. shimming always strikes me as... not ideal.

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The shims I designed covered the entire interface of the column to the base. I cut various strips of brass stock, in 0.001 increments, and arranged them according to the gradient needed for correction. There are two shims needed, one for the left column side and one for the right. This left me with close to full contact between the column and base, depending on the elasticity of the brass stock I suppose. The trick is to build up a series of thinner segments overlaid on a thicker substrate. For example, I used 0.020 for the substrate, and a variety of thicknesses for the individual segments, so that the overall thickness across the shim increased only in 0.001 increments. The best way would be to use a series starting with a reasonable thickness, like 0.005, 0.006, 0.007, 0.008, 0.009, etc. I found shim stock less than 0.005 thick to be difficult to work with, but managed anyhow. You need to punch holes or slots for the column bolts, and slots for the alignment dowels. Be careful not to pull the column off the dowels, so the column will slide back into place easily after you insert the shims.

There are many ways to build a better shim, of course, such as using a surface grinder and magnetic sine plate to chuck a steel shim and grind the full surface properly, but I got pretty good results using just a variety of brass shim stock to construct my low-budget fix.

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Originally Posted by bobeson

The shims I designed covered the entire interface of the column to the base. I cut various strips of brass stock, in 0.001 increments, and arranged them according to the gradient needed for correction. There are two shims needed, one for the left column side and one for the right. This left me with close to full contact between the column and base, depending on the elasticity of the brass stock I suppose. The trick is to build up a series of thinner segments overlaid on a thicker substrate. For example, I used 0.020 for the substrate, and a variety of thicknesses for the individual segments, so that the overall thickness across the shim increased only in 0.001 increments. The best way would be to use a series starting with a reasonable thickness, like 0.005, 0.006, 0.007, 0.008, 0.009, etc. I found shim stock less than 0.005 thick to be difficult to work with, but managed anyhow. You need to punch holes or slots for the column bolts, and slots for the alignment dowels. Be careful not to pull the column off the dowels, so the column will slide back into place easily after you insert the shims.

There are many ways to build a better shim, of course, such as using a surface grinder and magnetic sine plate to chuck a steel shim and grind the full surface properly, but I got pretty good results using just a variety of brass shim stock to construct my low-budget fix.

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a full shim makes alot of sense. im used to seeing people stick a 1" wide bit at the back or side etc.

i actually performed an interesting fix on my machine today. i backed off the spindle cartridge and put a shim in under the collar. worked perfectly. theres just enough play in the spindle bore i guess to allow it.

tormachs also have cartridges, so this may be an option there.

my manual is describing setting the z gib so the head doesn't fall down on it's own and takes about 5 lbs of force to start it downward with the machine powered off (going off of my memory of what i read the other day). the problem is, mine has the brake on z stepper and the manual appears to be describing one without the brake. i don't have any instructions on disabling the z axis brake, if that is what needs to be done. with the machine powered off, how much force should it take to move the x and y axis then since gravity isn't working with them?

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Originally Posted by 300sniper

my manual is describing setting the z gib so the head doesn't fall down on it's own and takes about 5 lbs of force to start it downward with the machine powered off (going off of my memory of what i read the other day). the problem is, mine has the brake on z stepper and the manual appears to be describing one without the brake. i don't have any instructions on disabling the z axis brake, if that is what needs to be done. with the machine powered off, how much force should it take to move the x and y axis then since gravity isn't working with them?

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You have and old manual. Download the latest from Tormach. They use a new process.

David

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Originally Posted by 300sniper

the next thing i am wondering about is tram. with a dti mounted to the head and reading on the table surface, i had about .0005" deviation over the entire x travel. i consider this great. i also ran the dti reading on the inside of the center t-slot and had less than .0002" over the entire travel. again, very good in my opinion. i don't remember the exact reading off the y axis but it seemed great too. i do not have anything accurate enough at the moment to check the squareness of the z travel in relation to the table.

i then mounted my dti in the spindle and read against the table. they y axis was dead nuts but the x axis had about a .0004" deviation in about a 1.5" diameter swing. it is low toward the control cabinet side. i can correct it by putting slight upward pressure on the cabinet. i do get slight scallops when i face a part and i am assuming this is the cause of that. i have read about shimming between the base and stand but everything else seems so close i don't want to mess that up. is this something i should deal with or just live with it?

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Maybe I'm missing something, but what you did in the first paragraph doesn't sound like what's usually called tramming the mill. The process you describe in the second paragraph is more commonly accepted as tramming the mill, but you usually want to use a larger circle to increase the sensitivity of the test. For the Y you can use a circle that is a little smaller in diameter than the Y width of the table; the X test can be a little bigger.

While you are at it, try pushing down (or pulling up) moderately hard on the table while the indicator tip is extended fairly out from the spindle along X and note how much deviation you get. It can be a sobering experience.

Mike