Mandrel problems

[rayf6604]

I've been having problems with my pen mandrel, it doesn't run true at the tail stock end there is a slight wobble on it although turned blanks appear to be true. Is this a common problem/feature? I replaced the mandrel shaft but it's made no difference and I don't remember it doing it when I first started using it. Any light that anyone can shed on this will be appreciated.

 

[bellringer]

it might just be it been made unconcentric you could use a dial gauge indicate to check or it might be shit in the morse taper

 

[chas_41_uk]

or it might be shit in the morse taper

Is that a technical term Alex

 

[rayf6604]

My Morse taper is spotless I can tell you :p

 

[bellringer]

Is that a technical term Alex

yes i got bored of proper pencil pusher engineering speak

 

[Goulss]

Have you tried the Kiss test? To check alignment of head and tail stock.

 

[Jim]

Has it been over tightened Ray ..

 

[mattyts]

Get 2 centers and bring them up to eachother,that should tell if the headstock,bed and tailstock are in line.

Be careful not to overtighten your revolving center so it doesn'tform a bow shape,a cheap DTI can be had off eBay which you can use to check all the tapers and mandrels for run out.

What mandrel type do you have? Try slackening and retightening to 'reset' the mandrel

 

[rayf6604]

My mandrel came from penkitsuk it was cheap. I stopped using my standard live center as the mandrel has ruined the point on it so I got a rotur mandrel saver . It runs true at the mt end it's just at the tail end and the shaft is new. The kiss test is fine. If I don't reasonably tighten the tail stock the mandrel vibrates in the saver

 

[Buckeye]

Are you making sure that the mandrel saver clears the threaded end of the mandrel?

Peter

 

[jameshj]

Is it running true with no pen blanks loaded?

 

[wm460]

I had a mandrel that the hole in the end was too small, it ruined the point on one live center, So I drill it out with a centre drill problem solved.

 

[rayf6604]

Are you making sure that the mandrel saver clears the threaded end of the mandrel?

Peter

When I bring up the tail stock to the threaded end the thread rubs the inside of the hole on the saver. I can't seem to make it sit squarely inside. I think that's the problem isn't it? Maybe the rotur mandrel saver only works right with rotur mandrel s?

 

[jameshj]

Does the mandrel run true without blanks loaded ?.

 

[rayf6604]

Does the mandrel run true without blanks loaded ?.

That I don't know without checking which I'll do tomorrow

 

[Buckeye]

When I bring up the tail stock to the threaded end the thread rubs the inside of the hole on the saver. I can't seem to make it sit squarely inside. I think that's the problem isn't it? Maybe the rotur mandrel saver only works right with rotur mandrel s?

You need to make sure that the mandrel saver is not touching the threaded area you need solid metal, not thread.

Peter

 

[rayf6604]

You need to make sure that the mandrel saver is not touching the threaded area you need solid metal, not thread.

Peter

If I have solid metal inside the saver that means I couldn't use the brass nut on the end of the mandrel, should I not be using the brass nut and just using the pressure of the saver against the bushings?

 

[bellringer]

chuck the nut away that the savers job

 

[Grump]

Ray it sounds like you are using the knurled nut and the mandrel saver????
This is wrong, use the mandrel saver only, directly against the bush.
Please tell me I am wrong!!

 

[Terry]

As Grump says Ray you don't need the nut. The mandrel saver puts pressure onto the bushes and this allows the mandrel shaft to float freely without fear of buckling under pressure!!!