Panhard Cylinder Liner Rebore Update 2

Today I collected the tooltips that I had modified, and also fitted the vee belts, that had arrived in the post earlier in the week, to the Whatton Boring Bar. After struggling to get them onto the pulleys, and replacing the top cover, I fitted a new indexable tips to the short tool tip holder.

I centralised the bar over the liner and went to adjust the tip using the micrometer, and discovered the tooltip was not catching the micrometer anvil, because it cuts slightly lower now it misses the anvil tip. I will have to make a larger diameter adaptor to sleeve & cap over the anvil of the micrometer, which might add say 0.1” thick overall externally, to make reading the actual size easier. A bit of machined silvered steel to the rescue, aided by a helpful chap on a tool grinder down the road.


If you look at the picture above you can see the cutting edge is much lower than the centre line of the old carbide tip.


This is the 12mm square shank tool converted in the long holder with a 8mm square shanked version in the background. The original tip is in the foreground.


I started to machine the liner, and the motor never stalled at all, so finally a little success, and the first shallow cut was of a very good surface finish. Next I tried a slower roughing cut, and after about halfway down the liner, some strange swishing/grating noises started to reverberate from the bar. I couldn’t see what was happening, as the heavier cut was creating a fair amount of dust, (note to me, need a vacuum source to remove cutting dust). When I looked at the bore after the cutting process had finished, I had a perfect bore for about half the length of the liner, then a series of ridges or ringed undulations. :eek

I had to leave off at that point and sort out a few other jobs, but it would appear the back edge of the tooltip was catching the bore, which is easily remedied by grinding an increased taper behind the tooltip face, but more importantly & slightly worrying is the only way it could ring the bore was if the tooltip was moving. I am going to try with the longer tooltip holder to see if the short tool holder was rocking slightly, and therefore pushing into the liner. I will also double check the gigs that take up the play on the bar as it travels downwards. The latter wasn’t an issue before, but I have to check.

Anyway I am pleased that the motor/tooltip stall with the original carbide tipped tools isn’t repeating itself, just got to work on this new problem.

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