kitless newbie questions

[duncsuss]

Hi --

I'm hoping to move away from using kits to make fountain pens. This morning I drilled and tapped a scrap piece of acrylic acetate to receive the nib unit from a regular kit (M10 x 1 threads) and immediately realized I have a lot of questions -- I'd be grateful for any and all advice.

I don't have a collet chuck yet, so I gripped the blank in my regular chuck fitted with "pen blank drilling jaws", and put a center drill in a Jacobs chuck in the tailstock ...

Q 1: how large a center bit should I choose?

The plan is to tap this out to M10 x 1, so the hole I'm going to drill will be 9mm. (Actually it will be 23/64ths since I don't own a 9mm drill bit yet. This works out to 9.128mm.)

Assuming I don't have a center bit the exact same size, should I drill a starter hole larger than this? Smaller?

Q 2: ... and how deep should the starter hole be?

I guessed at larger, and drilled deep enough that the full width of the center bit cut into the blank, meaning the bottom of the starter hole had a countersink and narrow hole in the middle.

Then I swapped out the drill bit for the 23/64ths brad-point bit and drilled through the blank.

Q 3: Is it better to drill a smaller bore hole (e.g. 6mm or 7mm) then follow up with the 9mm?

Q 4: When I've drilled a starter hole with a center bit, is it better to use a brad-point or regular drill bit when drilling the real hole?

To finish off this exercise, I tapped the hole, trued the end of the "barrel" (also cutting away the part that was angled due to the countersink portion of the center bit), and finally reamed away a couple of turns of thread so the section would screw in fully.

The finished piece functions surprisingly well -- the section screws in nicely, though when I look closely I can see that I should have reamed a little deeper.

Also, I didn't turn the barrel down to the diameter of the section, so there's a step at the joint. Turning it flush would have left the barrel wall less than 1mm thick and I didn't have the nerve to go any further.

Q 5: What's the practical limit on wall thickness (or thin-ness) for acrylic acetate where the inside is threaded to receive the section?

Thanks & best regards,

Duncan

 

[LL Woodworks]

Welcome to the journey - most of your questions are answered in articles in the library - this one helped me tremendously as a custom FP maker.

http://content.penturners.org/library/pens/kitless_pen.pdf

Keep the faith and let us see your efforts!
Good luck

 

[duncsuss]

Welcome to the journey - most of your questions are answered in articles in the library - this one helped me tremendously as a custom FP maker.

http://content.penturners.org/library/pens/kitless_pen.pdf

Keep the faith and let us see your efforts!
Good luck

Thanks Lynn -- that document answered Q 3 but I'm still in the dark on the other questions.

It isn't easy to search the contents of uploaded documents, makes it much harder to find out where the information is hidden away

 

[Wingdoctor]

I am not an expert on this but I do see one problem. A center drill is normally an angle ground standard twist drill bit. In question 2 you stated that you followed the center drill with a brad point bit. That does not work well as a brad point bit has the spur in the center to make contact first and to guide the bit. With the large center drilled hole is did not have anything to contact with the spur and therefore would tend to wobble around a bit. Most of the time the center drill is smaller than the following drill and it is good practice on fragile material to drill in steps. Start with a smaller than finished size drill and using 2 or 3 bits work your way to full diameter. The last drill will only take a small cut and it should be a very smooth hole. The starter drill only goes in far enough to make a guide for the following bits. Say 1/4" max. in my experience. I hope this helps a little.

 

[Timebandit]

Hi --

I'm hoping to move away from using kits to make fountain pens. This morning I drilled and tapped a scrap piece of acrylic acetate to receive the nib unit from a regular kit (M10 x 1 threads) and immediately realized I have a lot of questions -- I'd be grateful for any and all advice.

I don't have a collet chuck yet, so I gripped the blank in my regular chuck fitted with "pen blank drilling jaws", and put a center drill in a Jacobs chuck in the tailstock ...

Q 1: how large a center bit should I choose?

Whatever size you have. It doesnt matter, just as long as it isnt larger than the bit you will be drilling with.

The plan is to tap this out to M10 x 1, so the hole I'm going to drill will be 9mm. (Actually it will be 23/64ths since I don't own a 9mm drill bit yet. This works out to 9.128mm.)

Assuming I don't have a center bit the exact same size, should I drill a starter hole larger than this? Smaller?

It doesnt have to be the same size. Its just a starting point. The bit will do the rest.

Q 2: ... and how deep should the starter hole be?

Doesnt have to be deep. Doesnt even have to be the 60 degree point. Just the very tip of it if you want. The only point to a center drill is that they are short and strong. If you were to drill a pilot hole with the same size as the tip of the center drill with a regular bit, you would have to worry about the bit flexing and not starting in the center. The short stout center drill is ideal for this and will not flex. The bit will do the rest.

I guessed at larger, and drilled deep enough that the full width of the center bit cut into the blank, meaning the bottom of the starter hole had a countersink and narrow hole in the middle.

Then I swapped out the drill bit for the 23/64ths brad-point bit and drilled through the blank.

Q 3: Is it better to drill a smaller bore hole (e.g. 6mm or 7mm) then follow up with the 9mm?

Depends. If you are just drilling one hole at that size, i see no problem with just drilling with the 9mm. I use 3 different bits in my pens, not for ease of drilling, but interior dimensions, so i drill with the smallest bit first, which also happens to be the deepest hole that i need to drill. I only drill about 1/2" with the 9mm.

Q 4: When I've drilled a starter hole with a center bit, is it better to use a brad-point or regular drill bit when drilling the real hole?

If you are using a brad point it, it is pointless to use a center drill. Thats what the brad point on the bit is for, for centering. i personally dont like brad point bits and always use the center drill and a jobber bit.

To finish off this exercise, I tapped the hole, trued the end of the "barrel" (also cutting away the part that was angled due to the countersink portion of the center bit), and finally reamed away a couple of turns of thread so the section would screw in fully.

The finished piece functions surprisingly well -- the section screws in nicely, though when I look closely I can see that I should have reamed a little deeper.

Also, I didn't turn the barrel down to the diameter of the section, so there's a step at the joint. Turning it flush would have left the barrel wall less than 1mm thick and I didn't have the nerve to go any further.

Q 5: What's the practical limit on wall thickness (or thin-ness) for acrylic acetate where the inside is threaded to receive the section?

This will vary, but you wont be able to make you barrel the same dimension as your front section, or your threads wont engage. The barrel has to be slightly larger, the depth of the threads, in order for the cap threads to engage. So there has to be a step, but what i do is a chamfer that step so that its a slop and you dont feel the 90 degree drop of that most hate. Putting a chamfer will make it pleasant to hold at the transition. Wall thickness will vary with material.
Thanks & best regards,

Duncan

Replies in Blue. Hope this helps

 

[duncsuss]

... a brad point bit has the spur in the center to make contact first and to guide the bit. With the large center drilled hole is did not have anything to contact with the spur and therefore would tend to wobble around a bit.

Makes perfect sense -- thanks!

Q 1: how large a center bit should I choose?
Whatever size you have. It doesnt matter, just as long as it isnt larger than the bit you will be drilling with.

Got it!

Q 2: ... and how deep should the starter hole be?
... with a regular bit, you would have to worry about the bit flexing and not starting in the center. The short stout center drill is ideal for this and will not flex.

Got it!

Q 3: Is it better to drill a smaller bore hole (e.g. 6mm or 7mm) then follow up with the 9mm?
Depends ...

Got it!

Q 4: When I've drilled a starter hole with a center bit, is it better to use a brad-point or regular drill bit when drilling the real hole?
... always use the center drill and a jobber bit.

Got it!

... you wont be able to make you barrel the same dimension as your front section, or your threads wont engage. The barrel has to be slightly larger, the depth of the threads, in order for the cap threads to engage ...

Hell, I knew that. (Just didn't think of it :biggrin

Many thanks for this invaluable guidance -- now I have to go to the tool store and buy some metric jobbing bits. Oh waily waily waily. :wink:

 

[duncsuss]

further questions

I bought taps and dies for M10 x 1 (for the Berea section to barrel) and for M12 x 0.75 (for the cap to barrel).

I was going to buy M14 x 0.75 also, but saw the o.d. of the die is 1.5" where the other dies (and the die holder I bought) are only 1".

Is there a source of M14 x 0.75 dies that are 1" o.d. ?

The 1.5" die holder isn't expensive, but its shank is larger -- 3/4 inch -- and that's bigger than my tailstock drill chuck will take.

Is there a simple solution that I'm overlooking?

Thanks!