Well finally bit the bullet to make my hercus mill a bit more usable. With minimal workspace in the Z axis stopping a few jobs from advancing towards completion I did my research on what others had done to combat this problem As usual the "Hercus Area" was quite useful as well as a few youtube machinist chanels. Seemed there was 3 areas that needed alteration ie base block, extended z axis screw and extended z axis dovetail slide.
The base block was made from welding together 4 sections of 150mm C section. Next to ensure the top & bottom were parallel I use the shaper to clean up the top & bottom faces. Required a millimeter or two of steel to be removed to clean the faces up. Hot rolled steel although looking to be flat & square is far from it. After shaping I adapted my T&C grinder to become a surface grinder and trued up the shaped faces
mill base grinding.jpgmill base shaper1.jpgmill extended dovetail.jpgmill dovetail shaped.jpgmill upgraded.jpg
Next step was extending the table screw. After measuring up the existing screw it appeared to be a non standard thread @ 18.7mm OD x 14 TPI & LHand. Cut a 10" piece of 3/4 bar, machined down the blank, made a HSS tool for a LH Acme thread and proceeded to cut the thread. With minimal fiddling it fitted the existing acme nut beautifully. Next bit was the tricky bit. I cleaned up the end of existing screw and bored a 1/4 hole in the the bottom of it. The new section was turned down one end to form a 1/4' pin and the 2 sections were pressed together. Minor tweeking was needed to get the mating threads in line to allow the nut to moved effortlessly between the new and old thread.
Last piece was to extend the slide. Found some Cast Iron and shaped it flat both sides Calculated dovetail angle using an improvised bevel. It was some weird angle like 51 degrees. Anyway thanks to Mr Shaper I managed to cut them and once again used my makeshift T&C surface grinder to clean up the dovetail faces. This was attached to the base block with 3 cap head screws and shimmed to suit the rough block surface.The front of the dovetail extension face has since been flycut and the base block painted to match the mill. Mill still machines nice and square as it did before the upgrade. All in all not too difficult a job to do with the big added benefit of having a more usable workspace. Unfortunately I get a bit engrossed in my work and forget to take pictures.
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