Help! Do I have a

[Bev Polmanteer]

bent mandrel or what. Yesterday I was turning a couple perfume pens. I wanted to get both ends turned down exactly the same which I have a hard time doing sometimes, so I took the blanks off the mandrel and put them back on the opposite way. When I started turning them I realized that the first cut only cut part of the blank, was lighter on part of it and completely missed part of it. So, I put it back on the mandrel the way it was. I had the same problem that way too. Now I know that it was ok when I turned it round - what happened? I am really lost on this one![?] I have never noticed this problem before. Is the mandrel bent? could it be that I didn't have my support set perfectly straight? PLEASE HELP!! Check the 'Show your pens' for pics of the perfume pens, they seem to be okay.

 

[AdamB]

I had a bent mandrel... heck it's still out in the shop. It's there to remind me to always check before I turn.

The way I check is to chuck up the mandrel without anything on it. then on my lathes slowest speed very gently push a sharpie up to it until it just touches the mandrel. do this in a number of places. If the mandrel is bent you will get lines on one side and not the other.

Just bend the mandrel back toward true.

then wipe the mandrel down with ethel alcohol (rubbing alcohol) to take off the sharpie, and then check it again. rinse and repeat until the mandrel is running true.

When the mandrel is running true you will get perfect lines all the way around.

 

[mrcook4570]

Originally posted by Always Practicing
<br />then wipe the mandrel down with ethel alcohol (rubbing alcohol)

Rubbing alcohol is isopropyl alcohol. Ethyl made Jack and Jim famous []

 

[Mikey]

Once a mandrel is bent, it will normally go back out of round pretty easy. At the price of some of the replacements, it is not worth the time it would take to make everything true.

 

[rtjw]

Check and make sure that you dont have the mandrel nut too tight. Also if the mandrel is in the morse taper too tight it will bow. Also check the tailstock.

 

[Bev Polmanteer]

Thanks guys, I checked the tail stock and it lines up perfectly with the end of the mandrel. Haven't had time to try the marker yet. I think just to be safe I'll give Ryan a call and get another one.

 

[knottyharry]

Bev,
Check out what RTJW had to say...the nut can be the culprit sometimes..I check mine often to see if it has tightened up.
Also a problem I had early on was in the tailstock. I would just push it up and into the mandrel, and lock it in place.
Not a good idea....Now I run it up close, lock it in place the tunr the hand wheel till it just starts the center to spinning good and then lock it in.
Harry

 

[William Young]

bev;
i install mine exactly the same way as harry described.

also, another way to check it for straight is to roll it over a dead flat cast iron table saw or jointer table.
if it rolls smooth , it is straight. if it bumps and needs to be persuaded to roll, it is bent.
w.y.