Bridgeport Manual to CNC conversion...

[Davek0974]

So, welded interconnect plate, relieve, then machine square etc.

Then build the motion parts in Alu ?

[Davek0974]

Hmmm,

Just been playing speeds & feeds for my single flute 5mm tool...

Manufacturer specs...
12k Rpm
2.5m DOC
1800mm/min feed - insane i think?

My previous settings...
12k rpm
2.5mm DOC
900-1000mm/min feed

F&S Calculator recomendations...
12k rpm
1.8mm DOC
280mm/min feed - much lower ?

Maybe these lighter settings will be better?

Its only the bigger tool that has issues so does seem to be a stress problem, I will also attach a bungee cord to the head to try and remove any rotational slack in the quill.

[Davek0974]

Ok, did some tests, first was to measure slack in the z axis at the adaptor in line with the high speed spindle - I have 0.02mm vertical (with reasonable force) and 0.15mm rotational around the quill - no doubt the source of my trouble.

Left cuts in the first picture below was at the feed recommended by my S&F calculator shown in the last post, 2 passes of 1.25mm ea, top cut is with me applying pressure to the motor while cutting to remove slack, the lower cut is with it running free as normal.

Both cuts look fine, no burr on the lip and pretty much perfect.

The right cuts in the first pic show results of a single 2.5mm DOC pass, same feed rate, again with hand pressure on the top pass and free on the lower.

Both cuts are acceptable this time but they show signs of vibration on the bottom surface - this is not an issue here as this tool is a roughing tool and will cut right through on these parts.

the second pic is just a closer view of the vibration on the second cuts.

Seems I just have to back off on the fast pedal a bit and let her do her thing, plus fit a bungee cord to remove the slop.

[redtom99]

Ok, did some tests, first was to measure slack in the z axis at the adaptor in line with the high speed spindle - I have 0.02mm vertical (with reasonable force) and 0.15mm rotational around the quill - no doubt the source of my trouble.

Left cuts in the first picture below was at the feed recommended by my S&F calculator shown in the last post, 2 passes of 1.25mm ea, top cut is with me applying pressure to the motor while cutting to remove slack, the lower cut is with it running free as normal.

Both cuts look fine, no burr on the lip and pretty much perfect.

The right cuts in the first pic show results of a single 2.5mm DOC pass, same feed rate, again with hand pressure on the top pass and free on the lower.

Both cuts are acceptable this time but they show signs of vibration on the bottom surface - this is not an issue here as this tool is a roughing tool and will cut right through on these parts.

the second pic is just a closer view of the vibration on the second cuts.

Seems I just have to back off on the fast pedal a bit and let her do her thing, plus fit a bungee cord to remove the slop.

[Davek0974]

Started modifying my conversion - I am powering the knee with a servo so i can send it tool length offsets, this will give me full Z travel with any length tool, hopefully.

Got the motor mount fitted today, hopefully get the limits and home switch fitted tomorrow:)

[Davek0974]

Got the limits and home switch fitted today, moving switches and fixed cams so I could do it all with two switches :)
Top switch is limit and bottom is home.



had to alter my plan of homing to top as with the vise fitted the bed will crash...



All the way down, a lot of cranking....



Wired the limit switch into the loop, just the home to take back to cabinet...

[Davek0974]

I'd forgotten how busy it was in the cabinet :)



The knee axis servo drive will have go on the right-side wall i think.

Hopefully get the drive temporarily fitted tomorrow and powered up the day after.