"hole dominant system"

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Hobot

Hobot

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Joe Piska in NY educated me with this so passing it on. Joe's building one up modeled off Ms Peel's set up so will see if gets as slap happy as it made me. hobot

Good that you bought a stock spindle. Note the super smooth ground finish on the O.D. That's what you need to run against any kind of plain bearing, bronze or plastic.
Your are right about those MKIII machined slots. They won't matter if you don't use them the way the MKIII does.

Most engineers (myself included) use the "hole dominant system" when we design stuff. That means basically you try to make the hole a standard size,
(weather metric or American standard) and make your shafts a little under-size for sliding fits, and a little oversize for press fits. The reasoning is that its a lot easier to turn a custom shaft than it is to bore a custom hole.
In their infinite wisdom, Norton engineers also followed the "hole dominant system" when they could, and the swing arm is a perfect example. For the cradle hole you want .8750 which is exactly a standard 7/8".
This should be easy to do since all you have to do is buy or borrow a 7/8" reamer. Try to borrow one if you can or get a machine shop to do it for you. A 7/8" high speed steel reamer will set you back close to $100 bucks.

One other word of caution: When reaming you want to drill or bore within say 1/64 (.015") of the finished size. Then with plenty of cutting fluid use a drill press or a milling machine for the finished ream. The ream will follow the
drilled hole, so you need to get the hole drilled straight and accurate using a machine tool. If you try this with a hand drill you will most likely ruin your cradle.

When done right the hole should have a nice smooth accurate bore that is exactly 7/8". Your spindle will fit in so smooth and tight you will not be able to feel it wiggle around.
Click to expand...
 
A better way is the ISO system that also takes into account the tolerances of both the hole and the shaft to give classes of fit. Now for example this is a table of the metric tolerances for various nominal hole sizes http://www.tribology-abc.com/calculators/iso_holes.htm , H7 is typically the clearance and tolerance you will get from a non adjustable reamer. This is the corresponding table for the shaft
http://www.tribology-abc.com/calculators/iso_shafts.htm

Then if you go down this page a bit
http://www.roymech.co.uk/Useful_Tables/ ... LIMITS.htm
there is a heading "Example limits and fits using hole basis" so for example the swingarm pivot would probably be H7 g6
 
Its mostly beyond my need to know thank you, real stuff I farm out to those like yourself, so I can remain a dumb ass pilot with a grin. hobot
 
Thinking about it your post is pretty much just a practical representation of what I put up (most reamers I have seen are actually marked H7, being nominal to slightly oversize), one of the nice things about it though is the ability to see what machining processes are requred for certain types of fits, loose running to press fits
 
This on point opposite for the ream-fit of the tranny bush kits, shafts are a set OD so the holes have to give. I just can't be expert at everything, especially as a well equipped machinist. I like learning more about its process but so do I like learning about rocket wing technology with crazy dudes trying to fly it right down to the surface w/o a chute. Costly novice mistakes I defer to pro's in awe.
 
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