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Why? If someone isn't sure why not help them. Sorry Jack but that seems a bit dismissive to me. It's a true old cliche - no question is stupid if you don't know the answer even if you can't see it the first time. Tug

K2, Hi I began as an amateur in 1972 but trained and earnt a living by machining from 1980 so have seen both sides and understand your concern. Today with the advent of CNC and absolutely incredible machining centres machining has moved on a pace since my day not only in the machines but in...

I'm not sure what actually is the cause of this particular phenomenon with this material but I've been aware of it for many years. Just this morning I have experienced it using a 3.8 drill but not to the extent as the previous photo. It's as if the hole drilled is microscopically 'tapered' as...

Charles I have never given thought to 'heat treat' it first. That's a thought for the future so will try heating the end of a bar sometime to see if that improves matters. Thanks for the tip. Ken There is a distinct machining difference between drawn and cast bronze. I use the latter a lot...

Hi Ken - thanks for your thoughts but yes I am aware of reducing the cutting edge to negative rake when drilling 'brass' to prevent snatching and particular so when opening up previously drilled holes. However there is a distinct difference from most brass that has that tendency to the drawn...

Its a well known trick to grind a drill slightly offcentre when drilling drawn Phosphor Bronze to prevent the material grabbing the drill - a very difficult material to drill even with extreme care and even then it does not always work - as below. Step drilling isn't the answer in this material...

Peter - Next to bad deformation marks on screw on cylinder heads where the wrong tool has been used for removal I don't think there is anything worse that offends my eye as much as seeing plier teeth marks on a prop driver !! Most collet types will ease with heat - I use a heat gun as opposed to...

Me too 'CT' - first thing I learnt though was the difference between a slot drill to an endmill - as Goldstar says the clue is in the name but like so many attributions possibly only on this side of the pond ;) and as already said - taking the corners of a FB drill helps prevent potential...

Hello Greg, Well I've stripped quite a few engines over time but don't ever recall any rear bearings with what I would deem a loose fit on the shaft. Doesn't mean I disagree with you just I can't recall having witnessed it. To me though to have the shaft 'loose' in the rear bearing seems to...

Hi Greg, I have always understood 'crowding' to be when a ball race is stressed beyond it's running tolerances the balls squeezed by an excess external force, either radial or axial. Perhaps I'm wrong with that terminology. However in this engine if there is insufficient clearance between the...

Petertha, I was under the impression this was a 'concept' drawing to ascertain the layout as opposed to a drawing to work to but I would agree that as drawn the red arrow area is a little 'thin' and most definitely the tapered hole for the collet should go all the way through the prop driver...

You are getting close Patrick ;) Just make sure that the gap behind the rear race inner is nothing more than a scrape - literally a scrape. It needs to just pull the bearing together slightly before coming up tight - too much and you will have the same situation at the other end - crowding the...

Unless held by something extremely rigid a centre cutting cutter, 2 or 3 or more flute is unlikely to cut a similar sized hole as the cutter itself unless the centre of said hole is previously relieved (drilled). Any slightest give either in the holding of the cutter, the spindle or the machine...

Well that's exactly what I've been saying from the outset Jason but unless I'm not explaining myself very well it doesn't seem to have come across as such. I think it would be very fair to say that in the world of home made engines none did those of us who do so better service than Ron Chernich...

Hi 'DP' (Greg?) Are you not meaning radial clearance as I cannot see why axial clearance would allow bearings to slip in their housings. The effect of adding a shim is no different from having a crankshaft fractionally longer than the make up of the crankcase length between the rear of the...

Hello Tim, yes I guess a strong narrow banded wavy washer would work but my thinking on this is only just that - a thought. I'm pleased to see you refer to it as a notion :) So many engines have been set up 'the other way' I feel there's little to be gained in trying. If it was a really viable...

Hello David , It depends of course on how deep and what diameter the hole is but there are several options. The first and easiest is to 'flat bottom' the drill but that does require grinding the existing one or modifying another of the same diameter. The end is ground square then a 5-10*...

That was exactly my point to the person who suggested this on the other forum. Not practical at all unless one can load the front outer ring in the opposite direction to the load on the inner - hence my thought that, as the crankshaft is acting as the spacer - which for all intents and purposes...

Tim , Yes I did point that out previously (post#12). Loading Crowding of the front race is very easy to do if the freedom isn't there This issue came up on another forum some time back. An insistance that any twin bearing spindle should be preloaded being stated . At first, I found it...

Can't quite agree with Jens here as the front end as drawn still has the potential to crowd the front race. This is because of that small relief you show behind the inner ring. Unless the tolerances are very exact, tightening the prop will force that inner against the balls and into the outer...