Chucking a Piston in 3 jaw lathe chuck

[Agr516]

Got it. Thanks Brad and Old-Cat

 

[cuttinties]

Sorry. New to the game.

What's a "draw bar"?

My lathe came without a boring bar holder. I either have to find or make one.

MS250 project done, except for possible custom piston domes.

I have enough 4047 to tig piston domes forever.

Through the center of your chuck you push a bar and tighten up. You'll use a wrist pin slid through a hole drilled in the bar. Place the piston on the end of the bar, push the bar through pull snug and tighten the chuck. The flat part of the skirt will be on the chuck with the draw bar being held, not the piston. I would give a better description but I don't really have time until this evening.

 

[drf255]

Think mine is bronze bushed

 

[Mike Gott]

The draw bar method works well, I've only cut a couple chainsaw pistons but have cut lots of pistons for pulling engines this way. I also made a hand mandral for cutting the squish chamber after reading Tree Monkey's post, tried it on a test cylinder and worked well. Good luck! I'll try to post some pics this weekend when I start my 2186 project along with asking a bunch of questions for experts, it will be my first full porting job doing all the work myself

 

[caffeine1fg]

Here is my setup, all done on a lathe except for the milled slot in the arbor.

 

[Mike Gott]

That's looks real nice!


Sent from my iPhone using Tapatalk

 

[tree monkey]

I made steel collets

 

[drf255]

View attachment 405399

I made steel collets

Is that how you cut your popups?

 

[drf255]

Ordered 4 jaw chuck, boring bar holder with bar and cutter.

I'm all in for around $500 for a small atlas lathe.

Don't think I did too bad.

 

[drf255]

So I found and purchased a 4 tooth chuck.

The chuck is non self centering. Each tooth moves individually.

My lathe shaft doesn't have a dead center in it.

How does one find centerline here?

 

[MarcS]

I like to setup the indicator on top of the part like this guy, most people seem to set the indicator off to the side. Also, a back plunger indicator is handy and stays out of the way of the chuck wrench. You may want to look into some night classes at a local tech college, a few hours a week with a skilled machinist/tool maker showing the basics would help a lot.

 

[jar944]

Its going to take you a bit of time to dial it in the first couple hundred times.

but you will get faster

 

[drf255]

I'm not foolish enough to expect precision machine work to be fast and easy.

 

[MarcS]

I'm not foolish enough to expect precision machine work to be fast and easy.

You are on your way to being a good machinist!

 

[super3]

A bit quicker than the vid posted above.
Make an indicator holder for the tool post to position the dial indicator in the center line of your material.
Find the low point and zero the dial there. Now rotate to the high point. Move the dial to 1/2 of that reading, rotate the chuck (forward rotation) to the nearest jaw. Use 2 chuck keys on the jaws opposite one another and move both jaws together to zero on the dial. Rotate chuck to the next jaw and repeat to zero on the dial.

 

[jar944]

Noga knockoff
http://www.shars.com/products/view/1407/135_Lbs_Holder_Power_Magnetic_Base

 

[drf255]

A bit quicker than the vid posted above.
Make an indicator holder for the tool post to position the dial indicator in the center line of your material.
Find the low point and zero the dial there. Now rotate to the high point. Move the dial to 1/2 of that reading, rotate the chuck (forward rotation) to the nearest jaw. Use 2 chuck keys on the jaws opposite one another and move both jaws together to zero on the dial. Rotate chuck to the next jaw and repeat to zero on the dial.

Yes. I saw a video of that on Youtube this am. Looked easy, but then again...

Biggest fricken problem I got is that I'm fixing the lathe and could do it myself if I had another lathe! I coulda repaired some parts instead of replacing them.

 

[super3]

Yes. I saw a video of that on Youtube this am. Looked easy, but then again...

Quickest way I have found.

Biggest fricken problem I got is that I'm fixing the lathe and could do it myself if I had another lathe! I coulda repaired some parts instead of replacing them.

Don't we know. I am fortunate enough to have access to another lathe 1/2 mi away to make parts for mine.

 

[Chris-PA]

I guess I'm not sure why a 3 jaw isn't good enough. I just used one to do the pop up on my Poulan clamshell. I cut a piece of 0.010" Nomex paper we use here and wrapped the piston with that - it's tough and kept the surface from marring. I had to fiddle with it to get it oriented flat - I put an old exhaust valve in the drill chuck on the tail support so I would have a good perpendicular reference so I could get the wobble out of the face.

The requirements for centering the pop up are not really very severe. The combustion chamber is not usually machined and you're going to want some clearance - so what if it's +/- 0.005" or even a bit more?

 

[drf255]

I got the 4 jaw to spin jugs.