Raised tube edge after sanding mill?

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Alex D

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Oct 3, 2013
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As my experience has increased, I have started to notice more problems with my pens (funny how that works).

The most recent one is that I have a very, very small gap between the ends of the barrels and the kit components (finial, nib, etc.).

It is such a small gap that I hadn't been overly concerned with it, but as I get better, I want to improve my end result.

So, this morning, as I was looking at my latest pen, I think I figured out the problem, but now I need your help figuring out how to fix it.

I do my final truing using Rick Herrell's sanding mill (v1.0) and for some reason, the blank material is sanding down just a hair more than the tubes. As a result, the component bottoms out on the tube, leaving a hairline gap between the parts.

Just to be perfectly clear, I am confident this is a user error and not something wrong with the sanding mill (you should have seen things before I got the mill!).

Any thoughts on what I am doing wrong and how to correct it?

I use commercial sanding sleeves with the mill.

I have been using 80 grit, could it be that the "grit" is large enough that it kind of "misses" the tube, but grinds the softer blank material?

What grit do you all use with the mill?


Thanks!
Alex
 
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bobleibo

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Hi Alex
I use a barrel trimmer in my drill press and hold the blank in my hand and can get so close you can't see any gap with the naked eye. Just takes practice. I've screwed up far more than my fair share.
- make sure the guiding sleeve is exact. If you don't have one, make it...easy to do.
- whether you use that or Ricks sanding mill, do not push too hard. Let the sander sneak up on the blank.
- there is nothing wrong with leaving the blank material just a hair proud of the brass tube as long as it is squared up exactly 90 degrees.
- do not allow the blank to rock back and forth when using either jig. Even a micro amount will cause grief.
- go slow, you can always keep sanding but you can't add material back on.

What grit are you using to sand? Too course and it can take material away from the blank around the brass tube.

Good luck......
 

Alex D

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As far as I can tell, everything is square.
I have been using 80 grit and sanding sleeves. Based on Bob's comment, I'm thinking I should move up to at least 100, possibly 120.

Thanks,
Alex
 

jttheclockman

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Hello Alex

Good to see that you are trying to improve on your technique and produce a cleaner product. First I will say the gap you are seeing sometimes is a product of the kit components. The Sierra was notorious for this. Now there are way too many kits and who knows what is showing up. The end cap or sometimes the centerbands are somewhat crowned. May be a by-product of manufacturing. You can do a straight edge test to see for yourself. Machinist square or draftsman square will give you this.

The things that you can control are your sanding methods. You touched briefly on one of them. Yes 80 grit is way to course for sanding ends. I will use as a final sanding paper 220 grit. Now depending on what it is I am sanding I may have to start with a courser grit. When you use a course grit as you mentioned the sanding particles are actually so large they are cutting into the surrounding softer material (wood) before they touch the metal. Thus you are leaving a crown with the center the high spot.

What you also do not want to use is velcro backed sand paper. This goes for using on a lathe too. Again what happens the velcro is too soft to give full support to the blank as you sand. By the time the metal hits bottom you now have allowed the surrounding particles to sand away the edges. Always use sticky back paper that is not soft. Use or finish up with about 220 grit. If you need to start lower grit than work your way up.

Good luck.
 

flyitfast

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I agree with others above. The 80 grit is extremely aggressive and it will cut the wood before it will do the brass tube. Unless you have a lot of excess material before you get to the brass, I would use something a lot less aggressive - maybe 220-280.
Gordon
 

TonyL

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Assuming all of your equipment is square, perhaps the transfer punch/rod is too narrow for the tube? I ensure that I use a transfer punch that fits as snugly as possible, but allows the tube (and blank material) to still move freely. I also have two sets of transfer punches: one I use for dissembling pens (and used to hammer blows LOL), and another set just for my sanding jig. I also allow just enough of the transfer punch to protrude from the sanding jig to minimize any play (there may not be any, but it makes me feel better) . I also use, when I don't have a transfer punch size that I am happy with (which is rare), the barrel trimmer guide rods (as my transfer punch).

Being a man of little patience for doing things I don't enjoy - sanding is one of them - I have used Diablo 5 inches adhesive sanding disks from 40 to 220 grit. I found 80 grit to 120 to work best for me, but I sand very gently and continue to inspect the ends of the barrel until I barely see exposed brass. Each time the blank "kisses" the sanding disk, I rotate the blank by a quarter turner. And I do hold the blank somewhat firmly, but with my finger tips against the side of the transfer punch when sanding. I have actually gotten the the point where I can hear the change in sound (over and above a full size dust collector and air cleaning) when exposed brass is hitting the sand paper. (BTW, I am not bragging about being able to hear this; I have played the guitar for 40 years and still use an electronic tuner LOL)

Naturally,I make sure the tubes are cleaned, the sandpaper is clean and flat, and the MDF disk is secured firmly to my head stock. I also relatively frequently clean the sand paper with one of those large gumming erasers. I have found this practice to suit the results that I want and my lack of patience for sanding. I am not recommending it. I think all have to find what works for them assuming the equipment is not misaligned and not installed incorrectly. I would bet dollars to donuts that you already have accounted for these things. I am also sure that some steps are unnecessary. I hope you find a solution that you like.
 
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Alex D

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Oct 3, 2013
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Redondo Beach, CA
Thank you all for the great tips. I think the first thing to try is a higher grit. I only use the adhesive backed paper on both my sanding mill and my stand alone disk sander.

Ironically, I just realized I am actually using a lower grit on my mill than I am on the mill! Whoops.

I will report back after I switch the grit.

Thank you!
 

lorbay

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I use a countersink to clean out the small burr on the inside of the brass tube. You can also go a little deeper to lower the tube if needed without affecting the kit components.
Lin.
 

JimB

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West Henrietta, NY, USA.
I use 150 grit if I have a lot of material to remove before the final steps. Then I use either 320 or 400. Change your grit and sand very lightly.
 

Brian G

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I'd still check for square before doing anything else. Use a barrel-sized scrap from a too ugly to turn pen blank, drill a hole mostly all the way through, and then sand the "unholey" end to face it. Heavily color the unholey end with a pencil, and mount it to your sanding jig as if you were facing the final turning.

Lightly "face" your scrap without rotating it, and check the end. If your system is square, the pencil coloring should be evenly removed. If you can't tell for sure, then rotate 90-degrees and sand several times.

If the pencil coloring is evenly removed, then you're sufficiently square. If your system is too far out of square, you might have a "point" of pencil coloring in the center of your scrap. Basically, you'd be sanding to a point, not flat.
 
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