I have read most of the threads on this subject so although no new ground will probably be broken here, here is my start at a DIY bearing methods.
3 pieces I have or I have ordered.
0.375 Ream
The drill rod is precision ground, -0.0002 to 0 tolerance.
I will attempt to bore and ream the bronze rod on my 80 year old Southbend lathe.
Will attempt to polish with my hillbilly wet fine grit sandpaper on a foam mandrel. I will try that first before investing in a hone.
This will just determine if I can machine a tight tolerance smooth running bearing in the radial direction.
Do I have any hope of success?
3 pieces I have or I have ordered.
0.375 Ream
The drill rod is precision ground, -0.0002 to 0 tolerance.
I will attempt to bore and ream the bronze rod on my 80 year old Southbend lathe.
Will attempt to polish with my hillbilly wet fine grit sandpaper on a foam mandrel. I will try that first before investing in a hone.
This will just determine if I can machine a tight tolerance smooth running bearing in the radial direction.
Do I have any hope of success?
I am wondering about drilling 0.5" rod to a wall thickness of just 0.062" (Actually significantly less for running clearance)
Possibly 5/8" bronze bearing rod?
One other thought would be bronze tubing drilled out/trued up to the required clearance..
What sort of cutting tools do you have for surfacing the inside of the bearing?
Ask any of my friends - I am a pretty lousy machinist. 😀 😀
Possibly 5/8" bronze bearing rod?
One other thought would be bronze tubing drilled out/trued up to the required clearance..
What sort of cutting tools do you have for surfacing the inside of the bearing?
Ask any of my friends - I am a pretty lousy machinist. 😀 😀
In a book about Stirling hot air engines, it mentions using a wooden lap, made slightly smaller than the bore, slotted, and a wood screw in the end to expand it. You could do something like that using valve grinding paste, or even toothpaste, or you could glue abrasive paper to it, peal it of and replace with a finer grade as you go. The most important thing to remember is the lap MUST be softer than the workpiece.
This piece is just to test the machining. If successful I insert the sleeve in another machined cylinder with a flange (material tbd) that will mount to the plinth.
I did search and the bronze bushings are a little bit oversized relative to what seems to be the ideal annular clearance (<0.0005"). But I did find drill bushings that look interesting. Pricey but might be workable. Thanks for the idea.
How are you going to mount the bushings, if they're a press fit, that will reduce the clearance. I think on kingpin bushes, you press them in, then ream them out.
Buying of the shelf bushings is not going to work. They are not tightly toleranced enough. I used something called a Prüfstift in German. A rod with a tolerance below 0,002 mm used for measuring purposes.
The bushing is a high tech plastic specifically made for bushings paired with steel rods that I’ve pressed into a brass housing then drilled and reamed to an almost tight fit.
Its a dead silence bearing. Not even with a stetoscope you can hear it.
The bushing is a high tech plastic specifically made for bushings paired with steel rods that I’ve pressed into a brass housing then drilled and reamed to an almost tight fit.
Its a dead silence bearing. Not even with a stetoscope you can hear it.
Depends on what material you press them in, but yes that is a consideration that will be considered.
I will hope the tolerances of the product specified by the supplier are true.
The precision ground drill rod I ordered is specified at 0.375" diam, -0.0002, +0.0000
The drill bushing in post 10 is spec'd at 0.375 +0.0001 to 0.0005
So max clearance = 0.0007", min clearance 0.0001" . If the parts conform to the specification.
But if this is not the case I will be back for information on your components. Thank you.
IMHO you do not want a steel drill bushing. You want something like bronze/brass/oilite etc. Spec something that you can bore to match the spindle dia. +.0002-.0004" after it's pressed into the main body.
jeff
jeff
Just remember, bill firebraugh does it with two slotted pieces of plastic... just saying, there's engineering and there's engineering...