Boring 14mm Cylinder Diameter

[stanifm1]

Hello all,

I am looking to build Jan Ridder's puppy 2 Stroke engine.

How would I go about boring the cylinder surface?

I'm a complete newbie, so from what I gather its: Centre Drill > Drill within in 0.25mm > 14mm Reamer / Bore

The lathe I have access too can only take 10mm drill bit max size, so is there any way to do the 14mm bore with that max size?

 

[xpylonracer]

Hi Stan
You can get Blacksmiths drills, these have the shank reduced in diameter, I believe the minimum shank is still 1/2" though.
You could turn the shank of a 1/2" drill down to 10mm to fit the chuck or:
Drill to the 10mm diameter and then bore the remaining material to get to your 14mm diameter bore. You obviously need a boring tool that will enter a 10mm hole, remember it is always best to use the largest boring tool that will enter the drilled hole, it reduces the chance of tool chatter and leaves a better finish, also you need to take 1 or more 'spring cuts', that is a cut without making any adjustment to the depth of cut. Do the spring cut before getting anywhere near your finish diameter so you can better judge the final cut setting. As a newbie take light cuts and adjust the feed rate to suit, you will hear when you have things right and the swarf will be clean cut. If you are boring past the end of the cylinder make sure the tool doesn't come into contact with the chuck jaws.
Emgee

 

[barnesrickw]

Look up Silver and Deming drill bits. They come with a smaller, usually 1/4 inch shank.

 

[Brian Rupnow]

Be VERY careful with that "drill to within 1/4 millimeter". In a perfect world that works, but in my world the drill either has a slight bend or pulls to one side because of unequally sharpened cutting facets, and then your piece is ruined because your hole has suddenly gone oversize. If you are going to ream, use an "on size" reamer, drill to withing about 1/2 to 3/4 millimeter before reaming, and forget about boring. I have made 16 engines, both steam and i.c. and never bored any of the cylinders. I just use an "on size" reamer and then run a 3 stone brake hone though the bore a few times to take out any ridges, then lap with a .05 mm undersize aluminum plug and 600 grit lapping paste. EDIT--most reamers have a soft shank which can be turned down to suit a smaller chuck.

 

[xpylonracer]

Brian, you didn't read the question, the guy is a newbie and asks how to bore the cylinder to 14mm from his max drill size of 10mm.
Your method certainly works for you as proven by your excellent work, but if you want a bore that's parallel with the turned cylinder OD boring is a good method, provided of course the lathe is turning parallel.
Emgee