Out of round barrels

Signed-In Members Don't See This Ad
P

PerryS

Member
Joined
Dec 31, 2011
Messages
7
Location
SEABECK WA
Hi All,

I'm having a problem with out of round barrels. It's happening during the sanding process. I can feel vibration develop as it's happening. I'm not using much pressure on the blank. What am I doing wrong.

Perry
 
Signed-In Members Don't See This Ad
Wood, plastic (do you know what KIND of plastic)?

Sounds like it has to be heat, what else changes from turning to sanding?

Have you checked the blanks before you sand? Otherwise how do you know this is happening at the "sanding stage"?
 
What is in the tailstock, supporting the mandrel?
Are you USING a mandrel?

The more you tell us, the more likely you are to get a correct answer.
 
ed4copies said:
What is in the tailstock, supporting the mandrel?
Are you USING a mandrel?

The more you tell us, the more likely you are to get a correct answer.
Click to expand...

Turning unstabelized spalted alder. Used thin superglue to stableize. Using a live center in the tailstock. Speed Lathe metal lathe with the speed turned all the way up. I've thought it could be heat also. I'm using a mic, they are round before sanding and off .008 after 220 sanding. I'm using the B mandrel (larger diameter).
 
Here's couple guess's since we can't see your set up or watch you work.

Excessive pressure from tailstock bowing mandrel.

If you are convinced they are round prior to sanding, are you using a run-out gauge to determine this? Then my guess is you are applying way to much pressure while sanding.
 
Perry has identified and reported that the problem is happening during sanding. This is a very common problem and I think many others have out of round pen barrels and it is happening during sanding and not during turning. But, out of round pen barrels can also happen during turning for several reasons....tail stock too tight, brass nut too tight, dull tools, bent mandrel, etc.

Constant is correct in his answer. Wood on one side of a pen barrel can sand differently or quciker than wood on the opposite side. Grain alignment and orientation often cause portions of a pen barrel to sand quicker than other parts. Hence, one side gets thinner than the other side and the result is an out of round pen.

I think many penturners, and especially beginners, sand too much. Instead of turning the barrels to the correct diameters, they stop short and sand to the final dimensions. And doing this they must sand off so much wood that thebarrel goes out of round. Turn more and sand less is a possible solution. Using less pressure when sanding is also possible solution. Learning to use a skew and sand starting at 320 also helps.

Do a good turn daily!
Don

PerryS said:
Hi All,

I'm having a problem with out of round barrels. It's happening during the sanding process. I can feel vibration develop as it's happening. I'm not using much pressure on the blank. What am I doing wrong.

Perry
Click to expand...
 
Are you using a 60° Live Center? The centers that come with most wood lathes are NOT 60° and are made for turning wood or soft material other than metal. Since the mandrel IS metal, it requires a "made for metal live center" which is usually 60°. The live center that comes with wood lathes will wobble.

As mentioned, the pressure of sanding is often more than with the chisel of choice and as a result on non-60° live centers can cause it to be off center at that point (sanding) while being on center during turning.

I agree with Constant too as to pressure can cause soft wood to sand faster than a hard side.
 
Great info guys. Thanks. Yes to the 60 degree tailstock. Possable that I'm sanding too much now that I'm trying to get out all the scratches I see in the 10x loop.
 
Hi mate,
When I sand I cut my sandpaper cleanly with scissors into strips around 3/4 inch wide allows less pressure or more uneven pressure during sanding, helps me, also I only turn half a pen at a time,helps me.

Have success regards Peter.
 
You must log in or register to reply here.
Back
Top Bottom