Mailing List flyrotary@lancaironline.net Message #15470
From: Russell Duffy <13brv3@bellsouth.net>
Subject: Porting tool questions
Date: Wed, 19 Jan 2005 14:22:59 -0600
To: Flyrotary List <flyrotary@lancaironline.net>
Message

I have a nice new 1/4" shaft, 90 degree die grinder, and would be willing to also buy a straight one if needed (though I don't see why it would be).  I've been told the weapon of choice for porting is a carbide bur, but a quick look at McMaster-Carr makes my brain hurt.

First, I see Double, and Single cut burs.  These are defined as:

Double Cut— Cross-fluted pattern removes metal faster, produces smaller chips, allows better control, and gives coarser finish than single cut.
Single Cut— For use where more gradual stock removal and finer finishes are required.

Sounds like you'd probably start with the double cut, and finish with the single.  I'm sure you need to smooth it further than what the single will do, so what do you use for that?  Flapper wheels?  Polishing compound? 
 
Next, there's a baffling array of shapes and sizes of these things.  They can be purchases individually, or in sets.  My normal temptation is to go for a set, but I usually find that I use 2 or 3 of the items in a set, and never touch the others.  If that's the case, I'd be  better off to just buy a couple each of the most used shapes.  They also have extra long burs, which also seem like they'd be useful.   
 
You can see these at http://www.mcmaster.com/ .  Put 2470 in the search box, which will take you to that page.  At the top, you can advance to the next two pages as well, which also contain 1/4 shank carbide burs.   Any suggestions would be most appreciated. 
 
With my level of porting skill, I'm convinced I can outperform Tracy.  Unfortunately, I don't believe Tracy will let me port his engine :-)
 
Rusty (beware sharp spinning objects)
    
 
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