fw3
Plastic
- Joined
- Sep 25, 2021
- Location
- Maryland, USA
Note for mods: I read Machinery Discussion Guidelines and noticed that y'all want to discourage threads about Home Shop Grade import machines. Unfortunately, my thread is about a Home Shop Grade import machine . That being said, I think my thread is more about technique and less specific to the machine I have. At the end of the day, if this post is deemed inappropriate for this forum then please remove and I'll understand. Thanks!
So, anyway, hello! I'll go ahead and say right up front that I'm an absolute beginner and rank amateur. I'm operating entirely under the assumption that most of my problems are a result of user error and/or ignorance, haha. I purchased a small, benchtop mill from Little Machine Shop (specifically this one) and I've been having a blast learning how to use it. My problems started when I noticed that my 3" face mill was double cutting (I'm not sure if that's the correct term but it was cutting on the advancing side and then again on the trailing side). A little bit of research indicated that my mill was probably out of tram so I decided to take care of that. Now I'm way, way down the rabbit hole and want to make sure I'm not just spinning my wheels.
With that out of the way, here's some info about my setup and what I'm trying to do so I can (finally) ask my questions.
[The Setup]
I've read that the first step to doing a full tram is making sure you have parallelism between the head and the column. For reference here, I'm attempting to use Rollie's Dad's Method which I've seen all over the entire internet.
I'm measuring this by attaching a test indicator (with half 0.0001" graduations) to the column and measuring the runout (on the X axis side) of the straightest 1/2" rod I could find held in a collet. With the spindle, X, Y, and Z carriages locked, I'll measure the runout very close to the collet and center the indicator's dial so the that the middle of the sweep is 0 - by that I mean if the total runout of the shaft is 4 thou then the indicator will sweep from -2 to +2. Once I've recorded that, I'll unlock the Z axis, move the head up as much as I can - due to the length of the shaft in my setup, that's about 4 inches vertically - re-lock Z and measure the runout again. Obviously, the total runout further away from the collet will be greater. However, if the head and column are parallel, the sweep of the indicator should still be centered on zero. If the sweep is not centered then I'd need to adjust and/or shim the head in whichever direction it was tilted to bring it parallel. Once that's done, I'd move the indicator to the front (Y axis) of the shaft and repeat the process.
Finally, I have my indicator mounted thusly:
[My questions]
Since I realize I wrote something of a novel here, I've bolded my actual questions to make them a little easier to find.
Section 1: Is this even what I'm supposed to be doing?!
Visual Aid: Here's a video showing varying amounts of deflection based on how hard I lock the Z axis:
1. Obviously, I want to maximize rigidity when I'm taking a measurement - that means locking down everything that can be locked (right? right?!? ). However, I'm getting between 0.001-0.004" of deflection when I lock the Z axis depending upon how hard I crank down on the lock handle. I'm guessing that some slight deflection is unavoidable but is this a normal amount of deflection to expect?
2. How can I ensure that I'm applying consistent locking pressure? If, when locking the Z axis, I do it lightly and only cause 0.001" of deflection for the first measurement but then, after moving the head up to take the second measurement, I lock it more tightly and cause 0.003" of deflection then my measurements will appear to be off. In reality, however, the measurements could indicate parallelism and the actual issue was how tightly I locked the Z axis. Am I missing something or overthinking it?
Section 2: This seems wrong but I don't know enough about it to say why ?!
3. I'm noticing that the range swept by the indicator during a single spindle rotation is not always the same and that seems very strange to me. Specifically, up near the collet, I have about 0.001" of total runout, which seems super good to me! However, once I zero the dial in the middle of the sweep, the indicator does not always show +0.5 to -0.5. It seems to cycle between +0.5/-0.5 and +0.25/-1.25 almost like there's a wobble or eccentricity somewhere.
Stranger still, the wobble seems to happen every other spindle rotation. I've tried 3 different shafts in the collet as well as about every combination of lock/unlocking the Z axis, the spindle lock, and the handle lock- no matter what I do, the wobble persists. What could be causing this inconsistent reading?
Here's a video showing the wobble. I drew a black dot on the spindle to help stay oriented and I'll break down the readings for each rotation of the spindle.
These measurements were taken with the drive belt disconnected to ensure the motor wasn't somehow influencing the readings.
Rot 1 - Indicator sweeps up to +2, down to -2, and back to 0. My assumption here is that this would continue to happen every single rotation.
Rot 2 - Needle is noticeably shy of +2 (maybe +1.8?), goes down to -2.5, returns to 0.
Rot 3 - +1.8, down to -2, back to 0.
Rot 4 - +2, -2.5, 0
Rot 5 - +1.5, -2, 0
Rot 6 - +2, -2, 0
Rot 7 - +1.5, -2.5, 0
Rot 8 - +2, -2, 0
At first I thought I was somehow influencing it by how I was turning the spindle (from the top, by hand, with the drawbar wrench) but I've tried several different methods (including other people) and the pattern is always the same with the wobble.
Just in case it helps, here's a full video of the measurements both near the collet then with the head cranked up a few inches.
[Wrap Up]
Overall, I'd appreciate any sort of confirmation that I'm on the right path, guidance as to what I should be doing differently, and advice on how to proceed.
It occurs to me that I'm likely overcomplicating or overanalyzing things but I don't really have anyone I can ask in person so here I am.
For anyone who actually managed to read all of that, please have mercy and thanks in advance!
So, anyway, hello! I'll go ahead and say right up front that I'm an absolute beginner and rank amateur. I'm operating entirely under the assumption that most of my problems are a result of user error and/or ignorance, haha. I purchased a small, benchtop mill from Little Machine Shop (specifically this one) and I've been having a blast learning how to use it. My problems started when I noticed that my 3" face mill was double cutting (I'm not sure if that's the correct term but it was cutting on the advancing side and then again on the trailing side). A little bit of research indicated that my mill was probably out of tram so I decided to take care of that. Now I'm way, way down the rabbit hole and want to make sure I'm not just spinning my wheels.
With that out of the way, here's some info about my setup and what I'm trying to do so I can (finally) ask my questions.
[The Setup]
I've read that the first step to doing a full tram is making sure you have parallelism between the head and the column. For reference here, I'm attempting to use Rollie's Dad's Method which I've seen all over the entire internet.
I'm measuring this by attaching a test indicator (with half 0.0001" graduations) to the column and measuring the runout (on the X axis side) of the straightest 1/2" rod I could find held in a collet. With the spindle, X, Y, and Z carriages locked, I'll measure the runout very close to the collet and center the indicator's dial so the that the middle of the sweep is 0 - by that I mean if the total runout of the shaft is 4 thou then the indicator will sweep from -2 to +2. Once I've recorded that, I'll unlock the Z axis, move the head up as much as I can - due to the length of the shaft in my setup, that's about 4 inches vertically - re-lock Z and measure the runout again. Obviously, the total runout further away from the collet will be greater. However, if the head and column are parallel, the sweep of the indicator should still be centered on zero. If the sweep is not centered then I'd need to adjust and/or shim the head in whichever direction it was tilted to bring it parallel. Once that's done, I'd move the indicator to the front (Y axis) of the shaft and repeat the process.
Finally, I have my indicator mounted thusly:
[My questions]
Since I realize I wrote something of a novel here, I've bolded my actual questions to make them a little easier to find.
Section 1: Is this even what I'm supposed to be doing?!
Visual Aid: Here's a video showing varying amounts of deflection based on how hard I lock the Z axis:
1. Obviously, I want to maximize rigidity when I'm taking a measurement - that means locking down everything that can be locked (right? right?!? ). However, I'm getting between 0.001-0.004" of deflection when I lock the Z axis depending upon how hard I crank down on the lock handle. I'm guessing that some slight deflection is unavoidable but is this a normal amount of deflection to expect?
2. How can I ensure that I'm applying consistent locking pressure? If, when locking the Z axis, I do it lightly and only cause 0.001" of deflection for the first measurement but then, after moving the head up to take the second measurement, I lock it more tightly and cause 0.003" of deflection then my measurements will appear to be off. In reality, however, the measurements could indicate parallelism and the actual issue was how tightly I locked the Z axis. Am I missing something or overthinking it?
Section 2: This seems wrong but I don't know enough about it to say why ?!
3. I'm noticing that the range swept by the indicator during a single spindle rotation is not always the same and that seems very strange to me. Specifically, up near the collet, I have about 0.001" of total runout, which seems super good to me! However, once I zero the dial in the middle of the sweep, the indicator does not always show +0.5 to -0.5. It seems to cycle between +0.5/-0.5 and +0.25/-1.25 almost like there's a wobble or eccentricity somewhere.
Stranger still, the wobble seems to happen every other spindle rotation. I've tried 3 different shafts in the collet as well as about every combination of lock/unlocking the Z axis, the spindle lock, and the handle lock- no matter what I do, the wobble persists. What could be causing this inconsistent reading?
Here's a video showing the wobble. I drew a black dot on the spindle to help stay oriented and I'll break down the readings for each rotation of the spindle.
These measurements were taken with the drive belt disconnected to ensure the motor wasn't somehow influencing the readings.
Rot 1 - Indicator sweeps up to +2, down to -2, and back to 0. My assumption here is that this would continue to happen every single rotation.
Rot 2 - Needle is noticeably shy of +2 (maybe +1.8?), goes down to -2.5, returns to 0.
Rot 3 - +1.8, down to -2, back to 0.
Rot 4 - +2, -2.5, 0
Rot 5 - +1.5, -2, 0
Rot 6 - +2, -2, 0
Rot 7 - +1.5, -2.5, 0
Rot 8 - +2, -2, 0
At first I thought I was somehow influencing it by how I was turning the spindle (from the top, by hand, with the drawbar wrench) but I've tried several different methods (including other people) and the pattern is always the same with the wobble.
Just in case it helps, here's a full video of the measurements both near the collet then with the head cranked up a few inches.
[Wrap Up]
Overall, I'd appreciate any sort of confirmation that I'm on the right path, guidance as to what I should be doing differently, and advice on how to proceed.
It occurs to me that I'm likely overcomplicating or overanalyzing things but I don't really have anyone I can ask in person so here I am.
For anyone who actually managed to read all of that, please have mercy and thanks in advance!