HELP! Barrel Trimmer is damaging brass tube??

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JackP

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Apr 25, 2021
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Canada
Hi everyone, beginner pen turner here. I bought all my supplies around a year ago and finally decided to give it a try. I've made 2 pens so far, just as experiments to see what I need to be doing differently here and there, and overall, it has been going smoothly. HOWEVER. I have one major concern about the barrel trimmer and pilot shaft. I have a problem where after squaring the ends of my blanks, the brass tube seems to get warped or misshaped and no longer slides onto the mandrel without serious force. After the first time this happened, I tested the tubes to make sure they actually fit on the mandrel (which I can't see why they wouldn't fit), and they slid on no problem. Any ideas? I use the barrel trimmer on my drill and not the drill press, although I've seen countless people use their drill on YouTube and they don't have this problem. I'm not convinced that the drill press would solve any issues. Any help is very much appreciated!
Thanks!!
 
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Drewby108

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Apr 30, 2022
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Spokane, WA
Only two thoughts pop into my head to explain this. The first being that you have a burr formed on the inside of the tube and need to use a knife or something to clean it up. The second is the the reamer part isn't the right size and damaging the tube. I'm still fairly new, so I could be way off.
 

monophoto

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Mar 13, 2010
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Saratoga Springs, NY
the brass tube seems to get warped or misshaped and no longer slides onto the mandrel without serious force.

I would speculate (pure guesswork) that the trimmer may be creating a burr on the inside of the tube that interferes with inserting the mandrel rod.

The fact that you are using a hand drill to drive the trimmer means that you could inadvertently tip everything to one side which then causes the end of the trimmer (designed to shear away any glue that might have accumulated inside the tube) to nick the inside of the tube and raise a burr.

I suppose it is also theoretically possible that if you are using green wood to make blanks, the wood could distort as it dries and create a kink in the tube. But frankly, I would think that's a pretty unlikely situation. Many years ago, I turned a weed pot from green wood, and lined the inside with a glass testube. However, I made the hole too small, so the test tube was a very snug fit, and when the wood dried, it cracked the glass.
 

RobS

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Jun 20, 2016
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Carlsbad, CA
Here is the main link to Rick's page @rherrell is the best way to go.


Additionally I picked up this set to use with a pen mandrel shaft:
https://www.pennstateind.com/store/PKTRIMSET.html

Where I use Rick's sanding jig to hold a pen mandrel, and I use the needed barrel Trimming sleeve to adapt to a 3/8 or 10mm pen.

you can also get one of these to go with it, an already made chuck mounted sanding disc.
 

Woodchipper

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Mar 15, 2017
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Cleveland, TN
I have used a pen mill for several years with no problem except for a dull cutting head. However, I have aluminite blanks which need some TLC. Here is what I came up with: drill chuck in the quill, DIY sanding disk on a face plate and installed on the headstock, transfer punch to fit the tube. Slide the blank on the punch and carefully sand both ends. I take my time and measure with calipers to ensure the correct length. This will be my preferred way now. Easy to set up.
 

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MRDucks2

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Jul 17, 2017
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Washington, IN
Look in the hole and tell us what you see. An edge burr will be a rough edge at the end(s) of the tube. Issues with the pilot bit catching will leave a mark and/or shiny areas within the tube.

Also check for any glue in the ends of the tubes, also. Reamer may not get the glue out. I use a chainsaw file for glue. There is a long tapered reamer from Harbor Freight that works well on the burrs. I use it on every blank, reamed or sanded.
 

alanemorrison

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Jan 15, 2019
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Are you sure that the problem is not dried adhesive in the tube?
I like my barrel trimmer, which is kept sharp and has never caused any problems like you mention.
If you examine the tube, as mentioned above, then you will know better.

If you take other peoples advice and throw away your barrel trimmer, then throw it my way!!!
 

grpass

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Jan 27, 2020
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Grants Pass, Oregon
Are you sure that the problem is not dried adhesive in the tube?
I like my barrel trimmer, which is kept sharp and has never caused any problems like you mention.
If you examine the tube, as mentioned above, then you will know better.

If you take other peoples advice and throw away your barrel trimmer, then throw it my way!!!
Yep, I use my barrel trimmer all the time with no issues. I do however use a drill press.
 

jttheclockman

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Feb 22, 2005
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I agree with the majority here and suggest try sanding your blanks square. It will pay off in the end. But to address the trimmer itself, many years ago there was a bad batch of trimmers circulating from various vendors and it had to do with the cutter not being square if I recall. Some would cut too much in the middle of the cutter and some would cut too much to the outer edge. Good luck.
 

randyrls

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Harrisburg, PA 17112
If you are using a 7mm brass tube the likely problem is the burr that pushes the brass inward. I always use a champher tool to remove any burrs on the brass tube ends. Hmmm.... I couldn't find the one I have, it looks like an
arrow head and can remove both inside and outside burrs. Of course it can only remove outside burrs from bare brass tubes. :)

I do that when cutting custom length tubes for special purposes.

Chamfer Tool.jpg
 

jttheclockman

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If you are using a 7mm brass tube the likely problem is the burr that pushes the brass inward. I always use a champher tool to remove any burrs on the brass tube ends. Hmmm.... I couldn't find the one I have, it looks like an
arrow head and can remove both inside and outside burrs.


View attachment 338603
Have been using that reamer for years. :) Love it.
 

wouldentu2?

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Jan 27, 2011
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Oak Creek WI
It's a burr, use a round tapered file to clean it up. Get one that will go thru the tube but just barely. It removes any glue on the inside. Available at any hardware type store.
 
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I broke down and bought the full Woodpecker Ultra-Shear Pen Mill Ci and yes, it was expensive but very much worth it. You can use it in a drill press or on the lathe. It has a mandrel for basically every size brass tube and carbide cutters that do the trim work. So you are fitting into the tube exactly so there isn't play to damage the tube and getting a fine finish on the end of the blank.
 

Paul in OKC

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Oklahoma City, OK, USA.
Always a pen mill user here, 20+ years. A couple of thoughts, if you are getting a burr on the end of the tube, the cutter inside diameter is close to the tube diameter and can 'fold' over the edge a bit. Use something to knock that burr off. You can do it with a utility knife. If you are going a bit past the tube when milling, be aware of when the mill hits the tube. You will get a feel for that with practice.
 
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