small mill for machining steel. Max spend £500 including computer

[Andrew Wilding]

I fancied a change of tack so I have started checking and improving the geometry of the axes.

First check is the perpendicularity of the knee. This is the set up for the first method




This was the second method which I was planning on checking the first method with, however the results of this method were not very consistent so I abandoned it.



The results show an error of about 0.001" out of plane using the first method which can be improved with a bit of judicious scraping.



I has previously used the gound side surface of a parallel as my reference. This was not a very good reference so the next task is to scrape a reference surface. Oh joy - blue fingers over the weekend then! Once the horizontal surfaces are complete I will then check the other two surfaces of the dovetail are parallel.

[Andrew Wilding]

I have made a straight edge to fully scrape in my dovetails. Before I used a piece of round plate which was not that good.



after scraping to 20-25 spots per inch

[Andrew Wilding]

some more scraping updates:

dovetails on the knee were scraped parallel



Horizontal ways on table were scraped parallel to top of table (measured with mic)

Back way scraped to front face.



front way scraped parallel to back way using smae method as the knee.

old rack and pinion spindle bearing removed to increase travel by 1"



saddle scraped to knee by blueing knee ways.

x horizontal ways scraped parallel to y horizontal ways. Gauge block used to measure tops of undulations (indicator tip is too small and waviness was being measured)


table to knee perpendicularity checked and scraped etc. Precision pin and blocks used to provide reference to compare table way direction.



The scraping reference book that I managed to find in the library, interesting but by the time I had found this I had done most of the work! The cat did not think much of it.








nearly finished the scraping! I will be glad when I have a fully square and straight mill.

[Andrew Wilding]

Final alignment checks to see if I have met the Connelly prescribed 0.001" in 18" accuracy:
one side was trammed to y axis then other face of block measured to z axis.



block clamped to z ways and y axis traveresed



similiar done to x axis.

results:
x-y 0.001" in 18
y-z 0.0015 in 18
x-z 0.0015 in 18
I am going to leave it at that as I am loosing the will to live!

[Andrew Wilding]

final mechanical assembly:





Just final wiring with shielded multi core back to controller and I am done, oh and I have to learn how to use the thing!