Tube Flaring Cause

[leehljp]

Here is a question that might bring out some opinions but I would like a discussion on this. I especially would appreciate responses from those that work with metal and metal forming equipment.

What probably causes flaring of tubes the most? Too much pressure or slippage?

In this post (click here) Keith (Russel) asks about flaring the tubes if the live center and drive center are too tight in the mandrel-less set-up.

I am a learner so I am open to opinions and learning the truth. It is my opinion from observations that "slippage" causes more flaring than over tightening the tail stock wheel itself (within reason).

I am aware from experience that differential speeds between two metals will cause deformity quick. It can be done by pressure alone but it is easier with the differential speeds of the brass tube and drive centers, IMO. And this is caused by too little tail stock pressure, or too much sanding, finishing and buffing pressure, again in my thinking.

I will say that once bushings are off, AFTER turning to near size, there should not be enough pressure from sanding and finishing to slow or stop the blank.

Opinions and insights on the most probable cause of tube flaring? (Outside of the assembly process.)

 

[Jim Smith]

Hank,

When I first read about mandrel-less turning, especially when bushings are not used, I immediately thought that the tubes would flare under the pressure from the live/dead centers. That is the main reason I have not started working this way. If bushings are used, I would think that if the tail stock was not very precisely lined up with the head stock, the offset could cause a slight "wobble" resulting in the tubes to flaring. I have no direct experience with this, however if/when I go mandrel-less, I'm sure I be able to speak with great experience about tubes flaring.

Just a couple of possibilities...

Jim Smith

 

[leehljp]

Hank,

When I first read about mandrel-less turning, especially when bushings are not used, I immediately thought that the tubes would flare under the pressure from the live/dead centers. That is the main reason I have not started working this way. If bushings are used, I would think that if the tail stock was not very precisely lined up with the head stock, the offset could cause a slight "wobble" resulting in the tubes to flaring. I have no direct experience with this, however if/when I go mandrel-less, I'm sure I be able to speak with great experience about tubes flaring.

Just a couple of possibilities...

Jim Smith

Thanks Jim for your input. I will say from reading on this forum that if the wobble is there from head stock and tail stock being not perfectly aligned, it will most certain show up on mandrels too. IF they are not aligned, neither CNC bushings nor CNC'd mandrels will cure that. :wink:

 

[JimB]

Hank, I don't have much to contribute on this but what I can say is I've sanded and finished about 15 pens between centers without the bushings. In about 1/3 of cases I've had a little slippage but I immediately corrected it with a little tightening of the tail stock. I haven't expeienced any tube flaring that I'm aware of as all the pens went together without a problem.

Sorry, I know that doesn't really help.

 

[randyrls]

Here is a question that might bring out some opinions but I would like a discussion on this. I especially would appreciate responses from those that work with metal and metal forming equipment.

Hank; I would still use the bushings even when not using a mandrel. Stepped bushings apply the pressure to the blank end. The pressure is only in the direction of the tube, and isn't any expansion pressure on the brass tube.

I just got some pieces of stock to see how difficult it is to make decent quality bushings.

 

[leehljp]

Hank, I don't have much to contribute on this but what I can say is I've sanded and finished about 15 pens between centers without the bushings. In about 1/3 of cases I've had a little slippage but I immediately corrected it with a little tightening of the tail stock. I haven't expeienced any tube flaring that I'm aware of as all the pens went together without a problem.

Sorry, I know that doesn't really help.

Jim,

This is when I have noticed flaring - when there is slippage from slightly too loose on the tail stock combined with too mush pressure in sanding. Like you, I tighten up with the Tail Stock wheel when there is slippage at all. In these cases, I do not see flaring.

This is what I am looking for - situations when flaring occurs and when it does not. The reason is - There are occasional comments on flaring, and generally it is just assumed that it is from too much tail stock pressure. I don't agree with that assumption, but I am not going to directly challenge that until there is a bit of information to the contrary.

Thanks for your input.

 

[rherrell]

Hank, I really don't have an answer to your question as to EXACTLY how flaring occurs but I do think I "might" have a remedy for it. I make my own centers from Delrin. I put one in my Beall chuck at the headstock and one in a "revolving" drill chuck in the tailstock. I use this set-up for sanding and applying CA after removing the blank from the bushings. The Delrin seems to grip better than metal with less pressure. While I can't say "for sure" that this prevents flaring, I can say that it has never been a problem for me.
Here's a photo, they always help.:wink:

 

[nava1uni]

If there is slippage then the metal will get warm and since brass is a soft metal I would think that it could easily flare. I have found some flaring when I take a pen apart, but then I use a reverse reamer that I bought from AS. It works really well on both the ID and the OD of the tubes.

 

[skiprat]

but then I use a reverse reamer that I bought from AS. It works really well on both the ID and the OD of the tubes.

OK, I'll bite. :biggrin: I'm not afraid to ask daft questions:redface:

First, what is a 'Reverse Reamer'
Second, how does it work on a barrel that is already turned and flared?

Thanks

 

[leehljp]

If there is slippage then the metal will get warm and since brass is a soft metal I would think that it could easily flare. I have found some flaring when I take a pen apart, but then I use a reverse reamer that I bought from AS. It works really well on both the ID and the OD of the tubes.

Cindy, I was out this evening and with a dozen blanks tubed and needing prepping - i.e. turning them to round and down to about 1 mm. On a couple, I pulled up the tail stock solidly and locked it. I did not turn the wheel for final tightening on those two. Light touch with the blade and spinning occurred. Quickly checking, - yes the tubes were flaring. None of the others were flared.

In this case, too loose and flared tubes. Not from too tight.

I wanted to get info on this because a few people are afraid of using the mandrel-less method without bushings (for finishing) for fear of flaring with the dead drive and live center. From what I see, the problem is not "too tight" but "too loose".

I just like to get to the bottom of problems and find out what the real culprit is when possible.

 

[rherrell]

Here Steven, http://tinyurl.com/6j3ux5
They work great on minor flares and chamfering the inside of "round things"!
Hank, one more thing to think about. I was removing wood from some old tubes and decided to try different methods. My Delrin centers helped "a little" but by far the best results were when I took LIGHT cuts. Normal pressure caused flaring and light pressure didn't. Something else to think about.:wink::biggrin:

 

[lwalden]

I got lost on the reverse reamer/flare correction part as well.......I have the same tool Rick provides a link to, and it is great if you need to ream/chamfer a tube (usually when I've got to "energetic" with the barrel trimmer), however I don't see how you can use it to reduce the flaring on a tube that's already glued into a blank....????