Machining the miniature Burrell cylinder cavity was quite interesting. Mainly because the cylinder was flat on one side and so the machining was an incomplete circle. This meant I needed to use the rotary table.
I use the Warco HV4 rotary table quite a lot. To the extent that it has developed some slight slack. Now, I tried tightening it some time ago with reasonable success. But not perfect.
I now realise one of the issues was I was adjusting it as a standalone piece. Much better to bolt it down to the milling table and fit the taper chuck. That way I had leverage and could feel any slight movement.
Adjusting the HV4 Rotary Table
At this point it is best to bolt it down with clear sight of the rear of the table.
You just need it so that you can apply some force to the rotating part of the table and feel any movement. I also put an MT2 taper in the centre of the table and bolted that into place with a drawbar bolt. This way I had a bit more leverage.
Note: the drawbar bolt I use to fix the taper only reacts on the cast iron rotary part of the table, not the backplate/washer.
There are 8 hex or allen key bolts visible on the back of the rotary table.
Just to orientate ourselves:
- 4 off caphead bolts are used to tighten the washer to the cast iron rotating table.
- 4 off grub screws are standoff bolts that space the washer away from the cast iron rotating table.
So, effectively you want the washer and rotating table to be tight, but also flat/parallel to the bearing surface.
I found I had to:
- rotate the worm drive out of use so the table can be rotated by hand
- loosely tighten the caphead bolts, not too tight or the table won’t rotate
- adjust the grub screws so that you can just feel they are bottoming out
- tighten the caphead bolts, I tighten one and then the opposite one.
- if you cannot rotate the table then backoff slightly until you can
- adjust the grub screws to be tighter and so back the washer off
- you can now use the leverage to feel for play in each direction
- go back around steps 4 to 7 until the table has no play, but can still rotate
I could not find any information in the Warco manual on adjusting the table and so just experimented until this worked. Take your time as this adjustments will really pay off. My table is now tight and without play, but rotates smoothly.
The expectations of life depend upon diligence; the mechanic that would perfect his work must first sharpen his tools.Confucius
Machining the Burrell Cylinder Cavity
The hard part on this machining task was adjusting the rotary table. Once that was done the machining was rather easy.
Here I am using a 5mm ballnose carbide slot drill (MillingCutter.store). I cut this to a depth of 2mm.
The table was then rotated through a known angle, this just takes a bit of care with the first outside loop.
The table was then moved over 0.25mm and another pass completed. The 0.25mm step being made for each pass and the angle decreased as the loops around get smaller.
There were some tiny ridges left at the end, but these were very fines and easily removed with a small piece of emery cloth.