Rollerball questions

[InkyMike]

Hello everyone

I'm working on prototyping a section for a kitless rollerball using the Schmidt refills.
I think I've got my depths dialed in for the section length - where I'm struggling are the hole diameters.

Below are the sizes I've mic'd - drilling the mic'd sizes they are too tight - and then the size holes that actually fit in parenthesis - Using bits for the diameters that fit fewl a tad loose to me.

Size/Fit

3/32 / (7/64) - tip
3/16 / (11/64) - collar
15/64 / (1/4) - shaft

What I'm wondering is, if I drill to the mic'd diameter, if I'll gain enough room if I use the same size reamer (I.e. a 3/32 reamer for the 3/32 hole.) I've only done a little research and there don't seem to be options between these sizes unless I'm missing something (which admittedly I very well could be.)

Thanks much for any thoughts

 

[TDahl]

I have only used two drill bits for my bespoke Rollerballs. For the tip portion, I have used a #39 bit (2.48 mm or .0975" diameter). For the body portion of the refill, I have used a 15/64 bit. These dimensions fit the Schmidt P 900 M refill.

 

[InkyMike]

Thank you - I hadn't considered the numbered (or lettered) bits. Do you not create a locker for the collar? (I suppose if the tip shaft is the correct diameter, it wouldn't matter)

 

[TDahl]

Thank you - I hadn't considered the numbered (or lettered) bits. Do you not create a locker for the collar? (I suppose if the tip shaft is the correct diameter, it wouldn't matter)

I'm not sure what you mean by a locker for the collar, but the tip portion of the section should support the refill with no play. The 15/64 bit will also give a snug fit on the body of the refill. As long and your depth in the body of your pen matches the length of the refill, you should be fine.

One thing I might add is to leave a little extra material on the nose. It is very easy to take off approximately 1 - 2 mm of material and sanding/finishing.

 

[InkyMike]

Sorry - autocorrect. I meant to say pocket - you can see the step in the image. But as you said, if the tip portion is correct, drilling a little
further to account for that with the body diameter drill should be fine and a lot less hassle. I don't know why I didn't think of that.

As for the extra - yes - I've factored in a little bit extra that I'll face/finish off at the end after shaping the come.

I appreciate the help!

 

[Jarod888]

As suggested above, number and letter bits are your friends.

You may also be able to find a large set of metric bits. Typically, they go from 1 mm to 13mm in .1mm increments.

Something else to consider. You may be heating up the material, causing it to expand slightly. Then when it cools down, the hole has shrunk.

 

[InkyMike]

It's funny, I was at Harbor Freight the other day and saw they had a set of numbered bits. I almost bought them.

I like the idea of the expanded metric bits. I've ordered the odd one here or there for specific purposes. I'll look in to that as well.

As for heating and cooling - I suppose it's possible but I've used both aluminum and Delrin drilling slowly on the lathe. I suspect my bit is a tad off or the refills are. Either way I need just a hair more room so I'll try the #39 first.

Thanks!

 

[rixstix]

It's funny, I was at Harbor Freight the other day and saw they had a set of numbered bits. I almost bought them.

I had a full HF drill index. I finally realized that the cause of many of my issues were crooked & out of round bits.

I bit the bullet & bought a set based on @rherrell comment. A little spendy but American made, straight, round & sharp.

 

[InkyMike]

That's why I ended up not buying it - I've had hit and miss luck with their bits.

@rherrell - do you have particular brand recommendations? May be a while before I pull the trigger on complete sets but I'd like to start looking in to it.

Thanks!

 

[InkyMike]

Update. @TDahl - I realized we were talking about two different refills. You mentioned the 900 refill - I've been working with the 888 - mostly because that's what I have on hand, and it works in my other pens/kits.

I ended up going with a 33 bit for the tip, as there is some taper on it and that accommodates the widest point - for the body, a D bit works great. I guess ultimately for manufacturers they might taper the hole for the tip. It's a tad larger than I had hoped but I think it will work.

 

[rixstix]

Update. @TDahl - I realized we were talking about two different refills. You mentioned the 900 refill - I've been working with the 888 - mostly because that's what I have on hand, and it works in my other pens/kits.

Question? Are you talking capped or capless? Many rollerball refills require to be capped. There are some that are designed to be capless. The 888/5888 are not designed to be capless AFAIK.

Just curious.

 

[InkyMike]

Sorry - I should have been more specific - I'm working on capless rollerball designs

 

[mredburn]

Norseman drill bits are American made and worth the money. They do have a 115 piece fractional/ number set and the 118m metric set. You may want to purchase just the sizes you will need.