Expanding Mandrel

[jbaklund]

rod w,

I like your solution, and your mandrel looks clean. As has been said on this thread it's a cheaper route to go. Baklund R&D's mandrels hold evenly across the face, they are hardened, and they are more expensive. Also make them a custom sizes and shapes.
View attachment ImageUploadedByModel Engines1421020481.963286.jpgView attachment ImageUploadedByModel Engines1421020643.067881.jpg

 

[Nitrous]

Instead of a tapered pipe plug, I just use a tapered tap on the hole then use a socket cap screw. As the cap screw hits the tapered part of the thread the mandrel will expand enough to hold the part.

We're only talking about making the mandrel just small enough to slip the part on that you want to turn concentric.

Paul.

This might be something to accomplish your goal. https://www.leevalley.com/en-ca/sho...5528-individual-beall-ix-collets?item=44J0788
(I have nothing to do with this company ~but info the link is verboten, please delete. )

 

[SmithDoor]

This might be something to accomplish your goal. https://www.leevalley.com/en-ca/sho...5528-individual-beall-ix-collets?item=44J0788
(I have nothing to do with this company ~but info the link is verboten, please delete. )

This is a old thread from 2013.

It is good subject probably more since then too.

Back the early 1970’s I purchased a used KO Lee Expanding Mandrel ½ to 11/16" . It turnout to be the most use full size.
I have always had this in tool chest.
I later purchased from ⅜ to 3¾" very handy
But still 95% it only 2 sizes I used ⅜ to 11/16" The next size was other one used most time.

If work for some else I always hade the ⅜ to 11/16 with me as most shops had none. If did the set was missing to smaller size.

The main resin I used 1" as was in size used in my product line.


So if you looking and wanting sizes I would buy if I starting out just 2 ⅜ to 11/16"

Have fun
Dave

 

[SmithDoor]

This might be something to accomplish your goal. https://www.leevalley.com/en-ca/sho...5528-individual-beall-ix-collets?item=44J0788
(I have nothing to do with this company ~but info the link is verboten, please delete. )

FYI.
The 5C type is great for production work. But use them you setup 5C on the lathe. But I rarely used 5C just the 3 and 4 jaw chucks.
I even had 4jaw on a 1½ stub to fit on 3jaw.
I could simple work fast
FYI my engine lathe only has A1 chuck mount and heavy chuck.
Even my mini lathe I have today thinking doing of stub mounted chuck.

Dave

 

[rickhann]

Here is a simple description of a self-locking stub mandrel I have used with good results that I picked up from the Model Engineer Magazine years ago.
Turn a piece of round stock to a slip fit for the part you want turned.
Mill a flat on the stub mandrel to the depth of a small pin diameter.
Slip the part on the stub mandrel and insert pin on top of the milled flat.
Rotate the part and it will lock up.
Machine the part. When finished, reverse the rotation and it will free itself.
I use this method to machine faces of model engine cylinders.

Rick

 

[SmithDoor]

Here is a simple description of a self-locking stub mandrel I have used with good results that I picked up from the Model Engineer Magazine years ago.
Turn a piece of round stock to a slip fit for the part you want turned.
Mill a flat on the stub mandrel to the depth of a small pin diameter.
Slip the part on the stub mandrel and insert pin on top of the milled flat.
Rotate the part and it will lock up.
Machine the part. When finished, reverse the rotation and it will free itself.
I use this method to machine faces of model engine cylinders.

Rick

Here two use all time
⅜ to ½ and ½ to 11/16"
The ⅜ to ½ I purchased new. Very handy tool to have in the tool chest

Dave