Friday 2 June 2017

Tool post pillar

Not quite Shiz-specific but until I get around to removing the Z axis drive for the final(??) time in order to bung up the gap with shim and/or Loctite 638, I have a couple of things to do.

Some time ago (while stuck in the armchair workshop), I finally bought a Multifix "40 position" toolholder system from Create Tools. This is a Chinese-made version of the original Swiss design and although it's not give-away cheap, it's still quite a bit more "cost effective" than buying from the EU and seems to be very well made. It's never quite clear what is going on out there but I suspect there may even be some form of licensing agreement in place. I wouldn't be surprised if they actually make (or simply resell?) these systems to the EU and US suppliers.

Anyway, it works fine but the stackup of overhangs and moving parts between the carriage and the cutting edge of the tool is somewhat suboptimal. For some operations (particularly parting off), you need excellent rigidity. Some people have taken to removing the top slide and mounting the toolpost directly to the cross slide. Although this prevents you from using the topslide for operations like chamfering and threadcutting (at 29 degrees typically), that may be a price worth paying to avoid brown trouser moments and be able to use man sized feeds and speeds. When using indexable tooling with carbide inserts, you need rigidity and you need to operate your machine near max rpm and max power for them to work properly. It's "go big or go home" time.

This is what you find when you remove the original top slide. There is a central pin to locate the base of the top slide and a couple of bolts to lock it up in position. I plan to use them - and add a couple for good measure. Any excuse to butcher my machine...



So I checked Grabcad to see if I could find a model of the Multifix "A" sized system - and bingo! I was in luck. Pretty nicely modelled and it imported into Fusion 360 without any major issue. Strange colours used but I shouldn't be churlish.

Then a quick rummage in the stock pile (didn't take long, as it isn't very big) and I found a couple of suitable lumps to base a pillar design on. No point designing something (for instance a tool setter!!) if you can't obtain the stock required to make it. I have a rather nice piece of 63mm diameter 4140 steel (lots of chrome and molybdenum, so gives a beautiful surface finish) and the cast iron base from inside an Ikea JANSJĂ– LED lamp. Assuming it's actually cast iron and not Chinese industrial slag, this should clean up nicely to form a suitable base.

This is what I came up with:

GA:
Section view:
Pillar drawing:
Base drawing:


I've ordered a couple of M16 x 80 hex socket cap head bolts from Bolt World which will most likely arrive before I've finished it. I have all the other fasteners already.

The steel for the pillar is already chucked up and ready to go. Hopefully I will have time this weekend to get cracking on it....



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