Cheap mill abuse...don't choke

I'm fascinated and impressed with what you've been able to accomplish so far. This is a lot of top speed operation, has there been any noticeable heating in the motor or spindle?
 
MrWhoopee said:
I'm fascinated and impressed with what you've been able to accomplish so far. This is a lot of top speed operation, has there been any noticeable heating in the motor or spindle?
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Haha! Yeah the motor started warming up last night. I got greedy yesterday morning, and fed the disk down too far. It was making good sparks, but it ended up tripping the breaker. For the most part, I've been taking it in short runs so as not to heat the table. Now I'm at the point where I'm making extremely light passes. Just enough to hear the disk scraping on what I suspect to be the low spots, and just an occasional spark on what I think are the high. So, there isn't a lot of load on the motor except for the system drag.

I haven't even thought about checking the spindle, though. Of course, I had just taken it apart, cleaned and greased it last week. I would have waited if I had thought I would be doing this. I'll be repeating that process once I'm done here.
 
Steady as she goes. I see this process as looking a lot like using a tool post grinder, where a relatively flimsy setup holds a wobbly, vibrating grinding disk and work is done slowly- to good result, because the grinding disk ultimately does make contact in plane. I'm also interested in seeing what you can achieve with this method!
 
It should be noted that I'm learning on the job here. The lesson for last night was how large a role temperatures play on this game. The attached picture shows the layout of measurements right after grinding (black), and after sitting for over an hour (blue).

The other thing I'm learning is that I need to switch over to the indicator to map out the table more often. I'm thinking I may have already done more grinding than necessary if I had been more methodical about measuring before cutting.
 

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Shotgun said:
It should be noted that I'm learning on the job here. The lesson for last night was how large a role temperatures play on this game. The attached picture shows the layout of measurements right after grinding (black), and after sitting for over an hour (blue).

The other thing I'm learning is that I need to switch over to the indicator to map out the table more often. I'm thinking I may have already done more grinding than necessary if I had been more methodical about measuring before cutting.
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I think you are doing an outstanding job given the tools available, regardless of your level of experience.

This is a great lesson/example of how higher degrees of precision multiply the difficulty. Without higher precision equipment, hitting .0001 is not just 10x harder than hitting .001.
 
MrWhoopee said:
This is a great lesson/example of how higher degrees of precision multiply the difficulty. Without higher precision equipment, hitting .0001 is not just 10x harder than hitting .001.
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I'm thinking this might have gone better if I had used a conical grinding wheel. I think there is some flex in this wheel.

Cooter, I was using some water based cutting oil initially, but it mixed with the grinding dust to form a paste that clogged up the disk. In fact, another lesson learned last night was to clean the disk with some degreaser periodically. When it clogs, it just pushes around, rubbing the top, leaving a mess of grind marks. 5 minutes of scrubbing the face with deagreaser and a tooth brush, and it cuts to a mirror finish.
 
Shotgun said:
I'm thinking this might have gone better if I had used a conical grinding wheel. I think there is some flex in this wheel.

Cooter, I was using some water based cutting oil initially, but it mixed with the grinding dust to form a paste that clogged up the disk. In fact, another lesson learned last night was to clean the disk with some degreaser periodically. When it clogs, it just pushes around, rubbing the top, leaving a mess of grind marks. 5 minutes of scrubbing the face with deagreaser and a tooth brush, and it cuts to a mirror finish.
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Yes, ideally a cup wheel would be the choice.

Perhaps plugging the drains and filling the t-slots with water would help to absorb the heat from the metal without actually wetting the grinding disc.
 
Think I might try this with my Bridgeport table. It's had a few "hot suppers" and been left to rust at odd points in its life. Loving the surface finish you've achieved!
 
MrWhoopee said:
Perhaps plugging the drains and filling the t-slots with water would help to absorb the heat from the metal without actually wetting the grinding disc.
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That picture I posted of the measurement differences between warm and cold. . .well, the warm was "slightly warm to the touch". I don't know that water would do anything other than make a mess. Maybe it might catch some of the grit?

Anyway, I don't have drains. I'd have to sponge it out afterwards.

I did a few passes at lunch, but first I ran a diamond dresser across the face. Put the dresser in a vice, set it on the table, then ran the table across the bottom of the disk. It cut much cleaner, scalping the section I had measured to be high spots, and leaving the sharpy on the place I measured to be low.
 
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