Gallery, Projects and General > How do I??
Stainless Oscillating Pistons?
Darren:
I knurled a bit of stainless to grip PTFE, sure held on tight, but whether it would be tight enough for an engine I don't know :scratch:
bogstandard:
David,
Have the pistons oversize to begin with.
Drill and tap the piston and screw in the rod until it is really tight, you could put a bit of loctite on it to help grip.
Remount the piston rod in the chuck, and using razor sharp HSS tooling, preferably with a nose radius, take the piston down to size in one cut. It might take a bit of playing about to get to the right size, use a bit of ali or brass first to get the cutter into the right position and then lock up your cross slide gib. If you try to take fine cuts on PTFE it will 'string' badly. Plus a lot of airbourne dust will be produced, which isn't good for you in large quantities.
So to step thru it.
Cut pistons to length, but oversized on diameter (you can wack off 1/2" in one cut). The larger the cut the better, less dust.
Drill and tap pistons and fit rods.
Using a bit of ali or brass, bring the cutter to give you size, and lock cutter in position when size is reached. Retry for size just in case cutter has moved during lock up. It shouldn't be a tight fit in the bore, just a nice sliding fit. You can't lap in a PTFE piston.
Mount up pistons using rod in the chuck.
Take one smooth cut to bring piston down to size.
Check for fit in bore.
Hope it works for you, and if you have any questions or complaints, I am on holiday for the next few months.
Bogs
Stilldrillin:
Darren, Bogs,
Some great ideas/ info there. Thanks very much! :thumbup:
Will Loctite stick ok to PTFE?
I have no worries over the working temperature of Loctite, as my 3 exhaust pipes haven`t fallen off yet!
I`m more than a little pleased about that part of the experiment...... :clap:
Questions? Complaints! Whooo?....... ME!!!!???? Nah!
Ah`m no trubble to nubdy...... No need for a holiday neither..... :thumbup:
Many thanks,
David D
Darren:
David there are special glues that will stick to PTFE, but most normal off the shelf type won't very well if at all.
I've no idea about locktite though.
Stilldrillin:
--- Quote from: Darren on April 12, 2009, 07:05:19 AM ---David there are special glues that will stick to PTFE, but most normal off the shelf type won't very well if at all.
I've no idea about locktite though.
--- End quote ---
Darren,
I like your idea of knurling the conrod. :thumbup:
I`ll have a little experiment with loctite, this afternoon....... :wave:
David D
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