# Undercutting tool



## Johnturner (Jul 5, 2017)

Fellow pen turners
When I am doing modified slimlines I find myself having to undercut the end that will be up against the new center piece for a better fit.
What is a good tool to do this?
John


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## Lou Currier (Jul 5, 2017)

Hmmm...I've never done that....pics please I'm a visual person


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## TimR (Jul 5, 2017)

Johnturner said:


> Fellow pen turners
> When I am doing modified slimlines I find myself having to undercut the end that will be up against the new center piece for a better fit.
> What is a good tool to do this?
> John


John, when you say undercut, what do you mean? What's happening at the center? Are you using a pen mill or very square sanding disc setup to true the ends of the blanks?

Reactions: Agree 2


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## Johnturner (Jul 7, 2017)

I will be busy for the weekend - Pix Monday

Reactions: Like 2


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## Johnturner (Jul 9, 2017)

Here are the pix (a day early).
As you can see there is a gap between the bottom and the "band".

TimR 
Your solution seems obvious - Usually the gap is between he "band" and the top.
Maybe it's so obivious I didn't think of it. I'll try that.


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## TimR (Jul 9, 2017)

John, from what I'm seeing you have the gap all around, the shadow throwing me off a bit.
When I zoom in, it seems like I'm seeing a small fillet of material keeping the gap from closing up. If so, it's most likely the blanks just needing to be trued before assembling onto mandrel. You are using pen bushings too, right? Use of a pen mill and correct bushings should make this a non-issue.
Although...describe "modified slimline" mods. Kinda looks like a "comfort" kit with a custom band.

Reactions: Agree 1


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## Lou Currier (Jul 9, 2017)

Never seen this happen I would agree with Tim on the squaring issue.


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## Johnturner (Jul 10, 2017)

After I glue the tubes in I always true up the ends. When modifying the Slimline I take off about 1/8nd.nd inch down to the tube then drill out the "band" material and glue it on the tube. So I can't re-true because the tube is in the way. I don't know how to draw in these but it would be eaiser. Picure a half a pen blank with about 1/8 in tube sticking out of one end. I need to undercut the blank on the tube to get a good fit with the band.


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## TimR (Jul 10, 2017)

John, can you take the pen apart, zoom and point to the part of the pen that is projecting out and requiring you to undercut the mating side?


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## rocky1 (Jul 10, 2017)

Top picture honestly looks to me like you have a bit too much tube sticking out. Can you pull it apart and shorten the tube a hair? 

If not, which side is the spacer glued too? If it's glued to the top half, what about putting a thin piece of white spacer in the gap? If glued to the bottom half, what about filling it? Or, cut a spacer to fit, split it, and glue it in place?


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## DKMD (Jul 10, 2017)

I don't see the purpose of exposing the tube on the lower section. Why not turn the lower section to mate flush with the custom center band? With this style, you only need the bushings at the clip and nib... the rest could just be mashed together on the mandrel.


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## Schroedc (Jul 10, 2017)

I understand what you're doing, for cuts like that I take my skew, lay it on its side and use just the point to get in there to undercut after getting close with my other tools.


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## DKMD (Jul 10, 2017)

Alternatively, you could glue the tube in to the blank leaving it proud on one end then glue your center band material onto the proud tube. You would just need to make sure that the end of the main blank and band blank were perpendicular to the drill hole and cut flush.

Reactions: Agree 1


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## Johnturner (Jul 10, 2017)

Doc
I'm not sure I get what you are saying.
Here is where I need the undercutting.


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## Johnturner (Jul 10, 2017)

DKMD said:


> Alternatively, you could glue the tube in to the blank leaving it proud on one end then glue your center band material onto the proud tube. You would just need to make sure that the end of the main blank and band blank were perpendicular to the drill hole and cut flush.



Doc
that would leave the cap end without a tube??Wouldn't it?

Reactions: Agree 1


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## TimR (Jul 10, 2017)

Johnturner said:


> Doc
> I'm not sure I get what you are saying.
> Here is where I need the undercutting.
> View attachment 130860


John, this begs the question...why is there excess tube beyond the blank?? Does it start out flush and get crushed by the bushing? I'm baffled. 
You can do as Colin @Schroedc suggested to create the undercut, but there's no apparent reason why the tube is extending beyond the blank that I can see.

Reactions: Agree 2


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## Schroedc (Jul 10, 2017)

TimR said:


> John, this begs the question...why is there excess tube beyond the blank?? Does it start out flush and get crushed by the bushing? I'm baffled.
> You can do as Colin @Schroedc suggested to create the undercut, but there's no apparent reason why the tube is extending beyond the blank that I can see.



He's deliberately exposing the tube to add a layer to it. Similar to turning off some wood for the old flat top pens that got a trim ring pressed on after turning or putting a tenon on the old style Euro pens


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## Lou Currier (Jul 11, 2017)

That I understand but if the tenon is cut right the custom center band should sit flush.


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## gman2431 (Jul 11, 2017)

If I'm following this correctly... why dont you just glue up your blank for the material for the band at the right length and square it all up with the mill then turn the whole thing like ya Would a normal pen? Seems like you're doing a ton of extra work


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## Johnturner (Jul 11, 2017)

Cody I think you ae right I was following someone else's instructions. 
In the picture that tube 2as not the one exposed I do not know why that wasn't better while milling.
Thank you Everybody - On other mater, I broke my foot so the boss has forbidden any workshop visits for a while.
Again Thanks and I will try sall of these ideas when I get back to the shop!

Reactions: Sincere 2


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