# Is my barrel trimmer cutting right?



## tbfoto (Nov 15, 2015)

It's been a while since I've been able to get some shop time but I have my lathe set up and got a couple blanks out and glued in some tubes to make a slimline pen. However when using my barrel trimmer it leaves the tube raised above of the wood. Is that normal. Wood is Holly. Standard slimline kit with 7mm tubes. Using the correct barrel trimmer shaft.
Any suggestions, or is this correct? I don't remember it doing this before.
I thought the whole idea of the barrel trimmer was to cut everything smooth.


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## qquake (Nov 15, 2015)

Mine does that too sometimes, but not other times. The last one was an acrylic blank, and it did it on one end, but not the other. I haven't been able to figure out why.


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## KenV (Nov 15, 2015)

That happens when the fit between the trimmer head and the trimmer shaft is not especially good and there is a gap that allows the brass to slide into the gap.  

One way to avoid is to be careful not to over mill.  Mill until the cutter just touches the brass.   

This will clean up when you seal and sand the ends.   If much is present, it comes off with a file quickly.   Some pens are sensitive to length so check and you may need to be a tad long on the other end.


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## tbfoto (Nov 15, 2015)

KenV said:


> That happens when the fit between the trimmer head and the trimmer shaft is not especially good and there is a gap that allows the brass to slide into the gap.
> 
> One way to avoid is to be careful not to over mill.  Mill until the cutter just touches the brass.
> 
> This will clean up when you seal and sand the ends.   If much is present, it comes off with a file quickly.   Some pens are sensitive to length so check and you may need to be a tad long on the other end.


 
Ok thanks, I'll check the fit of my barrel trimmer. Maybe I'll just pull it apart and then put it back together again (never thought it it) and see if it works any better.


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## CREID (Nov 15, 2015)

Ken is right, when he says the fit between the head and the trimmer shaft is not good. I have the Whiteside (expensive set) and it does the same thing. I looked at the rockler set in the store and it would do the same thing. Rockler and someone else has a 7 mm one piece that wouldn't do that but it was 35$. I plan on building something to do 7 mm or buying one of the ones available for the lathe that would do all sizes, since it would not be much more than the 35$ for a special one just for 7mm. Note that this does not happen on the larger sizes because the head fits inside the diameter of the larger tubes and inside the tenon on the shaft.
Just my 2 1/2 cents

Curt


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## MikeL (Nov 15, 2015)

This has happened to me in the past except the reason on my incident was because the tube was not glued very well. As I made one end flush I apparently started pushing the brass out the other end.


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## wouldentu2? (Nov 15, 2015)

I had two end mills and when I mixed up the cutters I found one of the shafts was cut at 90 degrees  and the other had a radius which was not allowing the cutter to get flush with the shaft.


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## qquake (Nov 15, 2015)

I have a piloted endmill I use sometimes, and it does it. But that's because it takes 1/4" shaft pilots, and if I put a letter D drill blank in it, the letter D is only .246". I would think a dedicated 7mm barrel trimmer wouldn't do that, but mine does.


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## Sappheiros (Nov 15, 2015)

I had this happen to me too, before.  Great advice.


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## MTViper (Nov 16, 2015)

tbfoto said:


> Ok thanks, I'll check the fit of my barrel trimmer. Maybe I'll just pull it apart and then put it back together again (never thought it it) and see if it works any better.


 
While you've got it apart, you might as well clean off any glue, sawdust, acrylic chips that stuck to the cutter and use your diamond hone to sharpen the edges.  Will cut much nicer if you do.


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## Sappheiros (Nov 16, 2015)

I myself have sanded the end of the brass tubing down.  Maybe not the best idea, but it's worked.


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## Sabaharr (Nov 16, 2015)

Or you could put a wooden disk on your faceplate with an adhesive sanding disk, mount it to the head stock and select the right transfer punch for your tube size mounted in your drill chuck in the tailstock and sand them to length at exactly 90° flush for the cost of a 1 inch square of sandpaper.


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## Jim Smith (Nov 16, 2015)

Another idea might be to scrap the barrel trimmer and switch to the sanding disc jig that Rick (rherrell) sells.  I got tired of blanks chipping out with my barrel trimmer, especially circuit board blanks and some snake skin blanks.  About 18 months ago I switched over to the sanding disc method with Rick's jig, I haven't had any more problem at all.  I sure wish I had switched over a lot sooner than I did.

Jim Smith


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## Paul in OKC (Nov 16, 2015)

Like said above. Clearance between the shaft and cutter. There are some pen mills that have a 3/16" hole in the cutter, and a shoulder on the shaft that prevents this. Couldn't tell you where they come from. I built my own from an air craft countersink with a 3/16" hole and made the pilot with some letter D drill rod. Works great, but in cost a bit more than a regular mill did, but it is good HSS.


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## CREID (Nov 16, 2015)

Sabaharr said:


> Or you could put a wooden disk on your faceplate with an adhesive sanding disk, mount it to the head stock and select the right transfer punch for your tube size mounted in your drill chuck in the tailstock and sand them to length at exactly 90° flush for the cost of a 1 inch square of sandpaper.



I have done this. It wears out that little area of sandpaper very fast. :befuddled:

Curt


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## randyrls (Nov 16, 2015)

There is a pen mill that has a narrow shaft so the cutter cuts the brass on the 7mm tube.  Alas I don't remember where I got it.  Arizona Silhouette??

But Rherrell's sanding trimmer shown here  listed as "Offset Lathe Sanding Jig" works like a charm!


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## Rink (Nov 16, 2015)

Several pens ago...I decided to abandon the end mills and sand the ends of my blanks flush w/ the tubes. One of the better decisions in my penturning journey. IMHO, safer and more precise.

I use a Ridgid stationery belt sander, and the PSI jig.  The PSI jig...I give it about a 6 out of 10. It was smaller than I anticipated, and without a sliding mitre gauge for the sander table, I clamp a scrap piece of plywood to the table to align the jig at 90 degrees to the belt.  The whole thing looks a little wonky, but it works way better than the end mills, at least for me. And no blowouts!


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## lwalper (Nov 17, 2015)

My vote's for the sanding rig. My pen quality improved as soon as I figured that one out. Thanks Rick for the good equipment!


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## Sabaharr (Nov 17, 2015)

CREID said:


> Sabaharr said:
> 
> 
> > Or you could put a wooden disk on your faceplate with an adhesive sanding disk, mount it to the head stock and select the right transfer punch for your tube size mounted in your drill chuck in the tailstock and sand them to length at exactly 90° flush for the cost of a 1 inch square of sandpaper.
> ...


 
That's why I said a 1" square of sandpaper on the disk at a time. Guess I was a little lax in explaining that part. Brain traveling faster than I can type. The rherrell jig is an adaptation of this and allows you to use the outer part of a sanding disk so it does not wear it out as fast. I upgraded to it once I discovered how well sanding on the lathe accomplished blank squaring.


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## jttheclockman (Nov 17, 2015)

CREID said:


> Sabaharr said:
> 
> 
> > Or you could put a wooden disk on your faceplate with an adhesive sanding disk, mount it to the head stock and select the right transfer punch for your tube size mounted in your drill chuck in the tailstock and sand them to length at exactly 90° flush for the cost of a 1 inch square of sandpaper.
> ...




I do this all the time. What I use is sticky back sandpaper and only use a small piece. I then just move it around the disc till there is no more worn out space. Cut a new piece and replace. Works great. Sandpaper does not have to be perfect circle on the disc. Just needs to line up with the transfer punch in the center.



When using a trimmer you got good info above. It is important to make sure the cutter is sitting against the stop of the bits. I use a carbide cutter because i trim metals with mine and never had a problem. Here is an example.


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## csr67 (Nov 17, 2015)

lwalper said:


> My vote's for the sanding rig. My pen quality improved as soon as I figured that one out. Thanks Rick for the good equipment!



Same here,but I recently went from sanding on the lathe to using a 12" HF disk sander.  I can end trim a dozen blanks in about a minute on that powerhouse!  I've been using my Rick's sanding jig with transfer punch and just holding it against the squared up miter gauge.

What I really need to do is get Rick to machine up an adapter that would give allow his jig to fit into the miter bar on my disk sander!  Hmmm......


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## robertkulp (Nov 18, 2015)

Toss the pen mill and get Rick Herrell's squaring/sanding jig. I've had mine almost a year and haven't touched my pen mill since. His tool rests and posts are incredible, too.

http://www.penturners.org/forum/f172/custom-made-penturning-tools-accessories-92501/


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## maxwell_smart007 (Nov 18, 2015)

So to be clear - is the consensus that these trimmers that exhibit this problem are just poorly designed? (i.e. too wide a center hole). 

Any way to fix the problem without scrapping the trimmer and trying a different setup?


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## twinsen (Nov 18, 2015)

maxwell_smart007 said:


> So to be clear - is the consensus that these trimmers that exhibit this problem are just poorly designed? (i.e. too wide a center hole).
> 
> Any way to fix the problem without scrapping the trimmer and trying a different setup?



I think sometimes the metal just bends inward instead of cutting. I just take a pocket knife to it. Comes off real easy if the knife is sharp. Though, for those of you who reload, just use you inside the neck de-burring tool.


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## Skie_M (Nov 19, 2015)

maxwell_smart007 said:


> So to be clear - is the consensus that these trimmers that exhibit this problem are just poorly designed? (i.e. too wide a center hole).
> 
> Any way to fix the problem without scrapping the trimmer and trying a different setup?



Consensus is ... poor design implementation.


The cutter head needs to have a smaller diameter cutting radius in order to trim 7mm tubes with the blank ends, and be wide enough to handle 3/4" blanks easily, yet also have 4 or more cutting heads in order to be not so aggressive as to tear blanks apart while in use...   especially carbide cutter heads.

A 3/16ths center hole design with a mandrel that fits inside and flares out to the proper diameter for 7mm tubes would be ideal, especially coupled with a 4-head cutting design.  Use of trimmer tubes to center larger pen diameters on the 7mm mandrel is also an excellent idea, to make it a universal style cutter.


As the design fault centers on the action of the cutter head itself (it can't cut smaller than the 7mm tube without modification), the old design needs to be scrapped to make way for the new design.


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