Homemade precision nuts
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You can make your own precision (zero backlash) nuts with a low melt point bismuth allow, Cerrosafe is one of the more popular trade name.
Print a nut shell with maybe 1 mm clearance over the threads.
Add an undercut to key the cast nut permenatly to the shell.
If you make a mistake casting it, don't worry just remelt it, same goes if you wear it out, it's reusable!
The casting might be too perfect, so you may need to lap the threads by running it back and forth over the nut with a lubricant, and a fine abrasive.
I use a double boiler of water to melt it.
1/2 lbs cost about $14.00 usd.
Cerrosafe shrinks during the first 30 minutes of cooling and then at the end of an hour, is EXACTLY chamber size.
At the end of 200 hours it will have expanded approximately .0025". This factor is well known by all toolmakers
Cerrosafe melts between 158° - 190° F.
For some reason Cerrosafe does not show up on ebay, use this term: low melt bismuth.
McMaster Carr calls it: Low Melting Temperature Casting Alloys, and is quite expensive.
There are sellers on Amazon as well.
You can make your own precision (zero backlash) nuts with a low melt point bismuth allow, Cerrosafe is one of the more popular trade name.
Print a nut shell with maybe 1 mm clearance over the threads.
Add an undercut to key the cast nut permenatly to the shell.
If you make a mistake casting it, don't worry just remelt it, same goes if you wear it out, it's reusable!
The casting might be too perfect, so you may need to lap the threads by running it back and forth over the nut with a lubricant, and a fine abrasive.
I use a double boiler of water to melt it.
1/2 lbs cost about $14.00 usd.
Cerrosafe shrinks during the first 30 minutes of cooling and then at the end of an hour, is EXACTLY chamber size.
At the end of 200 hours it will have expanded approximately .0025". This factor is well known by all toolmakers
Cerrosafe melts between 158° - 190° F.
For some reason Cerrosafe does not show up on ebay, use this term: low melt bismuth.
McMaster Carr calls it: Low Melting Temperature Casting Alloys, and is quite expensive.
There are sellers on Amazon as well.