# Substitute drill bit sizes



## ramaroodle

I am making a pen for a customer that requires 10.5mm and .492" bits.  Don't know how I missed it but I don't have those sizes (usually i forget to buy bushings). What I did notice was that the tubes fit in 13/32 and 31/64 inch holes.  They are a little snug but can still be inserted with 2 finger pressure.

Can I use epoxy to coat the inside of the blank then coat the tube and slide them in with some plumbers putty in the end of the tube, or do I need to buy the 2 bits?

Thanks in advance.

Andy

EDIT: Just got a call from Ed @ Exotic Blanks where I bought the kit.  As usual his advice and customer service were priceless.  Thanks Ed.  If anybody is interested in what he said reply to this post and I will repeat it.


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## TonyL

You can (I don't know about the plumbers putty) but you risk an out of round barrel hole and poorly fitting tube. I, personally, who obtain the recommended drill bit.


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## gtriever

. 492 inches works out to 12.5mm, and like Tony, I'd recommend that you buy the correct bits.  I found a 1.0 - 13.0 (0.5mm increment) Metric Drill set on Amazon at a reasonable price. That would contain most of the metric bits that you'd ever need.


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## Curly

For one pen I would use the drill bits you have and then follow with a bit of sanding. Slit the end of a dowel with your bandsaw/handsaw/hacksaw and wrap some sandpaper around it so it trails in the direction of rotation when you put it in a drill. Spin it a couple seconds and it should open the hole a touch more. Basically you open the hole with a home made flap sander.


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## magpens

Specifying drill requirements for a kit of 10.5mm and 0.492" is inconsistent regarding units but I have seen this.

The specs should be both in metric or both in inches.

As Art said, the 0.492" spec converts to 12.497mm, so why don't they say 12.5mm ?

If you specify both in inches, 10.5mm = 0.413" and 12.5mm = 0.492" for the starting point of this discussion.

Now, you said you have drills of size 13/32" = 0.406" and 31/64" = 0.484" which give you tight fits.

You can use a few strokes of a round (rat-tail) file to slightly enlarge the drilled holes.
I personally prefer to use a straight-sided adjustable reamer.

I think it would be advisable to enlarge the holes after drilling in this way.

Drilled hole size is not absolutely critical for making pens. . For one thing, the hole rarely turns out to be the size of the drill you use because during drilling the material expands a little bit, and when you remove the drill bit the material contracts a little bit. . Different materials (eg. wood versus acrylic) will have different expansion and contraction.

As long as your drilled hole is close in size to (and a little larger than) the brass tube size you will be ok.

 The hole should not be too much bigger than the brass tube, but it should be slightly bigger in order that there is room for the glue. . If your hole is too tight a fit on the brass tube, there will be very little glue to grip the brass tube.

Drill sizes specified in the kit instructions are basically just a guide ... a kind of "one size that is likely to work for most materials under most conditions by most pen makers".

 In summary, I think your drill bit sizes will work OK if you enlarge them slightly with a round file.

 I recommend that you get a digital caliper from a tool store to measure the brass tubes you use as there can be small variations from kit to kit.

If you can afford to buy a variety of drill sizes (fractional sizes, letter sizes, metric sizes) you will be able to get hole sizes that best match your brass tubes after you have done some experimenting and gain experience.


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## ramaroodle

Curly said:


> For one pen I would use the drill bits you have and then follow with a bit of sanding. Slit the end of a dowel with your bandsaw/handsaw/hacksaw and wrap some sandpaper around it so it trails in the direction of rotation when you put it in a drill. Spin it a couple seconds and it should open the hole a touch more. Basically you open the hole with a home made flap sander.



Basically the same advice Ed gave me.  I found a 1-13mm set on Amazon for $45.  I figured by the time I buy just 2 bits and pay shipping I might as well get the set and not have to deal with the additional aggravation factor of sanding out the tube.  Seemed like a no brainer, but.... I think for this pen I'll give the flapper technique a try on some scrap before spending the $.


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## leehljp

Harbor Freight has a 115 piece drill bit set for $47.99 that can be had with a 20% off coupon for about $39.00. For drilling wood, this is a great help for those situations where you need a different size.

https://www.harborfreight.com/115-Pc-Titanium-M2-High-Speed-Steel-Drill-Bit-Set-61543.html

This set, plus under "Library>References (top of the page) there are drill charts and conversions that will list the nearest sizes in mm, inch and decimal. GREAT reference charts. I have two sets printed out and one on the wall for quick reference. Had that for over 10 years and one of the most handy things in my shop.


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## Charlie_W

I try to use a drill bit that is 0.010” larger than the tube to allow room for glue...and paint when needed.
Two thumbs up for a digital caliper and the large box of bits with fractional, number and letter bits. These are a great help. Also, a center point in the blank for the drill to start in helps keep it from wandering.


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## ramaroodle

Charlie_W said:


> I try to use a drill bit that is 0.010” larger than the tube to allow room for glue...and paint when needed.
> Two thumbs up for a digital caliper and the large box of bits with fractional, number and letter bits. These are a great help. Also, a center point in the blank for the drill to start in helps keep it from wandering.



Yesh.  Since I can get same or next day with Amazon here in Seattle I cancelled the $45 drill bit set but kept the $13 center point set part of the order.  Between that, the sanding flapper and the HF big box-o-bits set only 10 minutes away I have lots of options.

I have people that I work with who want pens.  I give them the PSI book and a print out of available laser blanks and they pay for the kit, bushings, blank and shipping and I charge $40 for making the pen. (does that seem fair? maybe $50?)  I'm trying to avoid spending more on supplies than I'm making on the pen while I recoup the money I've spent so far.



magpens said:


> In summary, I think your drill bit sizes will work OK if you enlarge them slightly with a round file.
> 
> If you can afford to buy a variety of drill sizes (fractional sizes, letter sizes, metric sizes) you will be able to get hole sizes that best match your brass tubes after you have done some experimenting and gain experience.



Thanks _*magpens*_ for the detailed info.  Looking at various charts, as an example, some show an "S" bit at .348 and others as .347 so there is even some variation in what is standard.  I even get slightly different readings off of bits that are supposed to be the same size with my calipers.


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## pngeezer

My local Ace Hardware has a display with quite a few # bits and their decimal equivalents. I'm confident that I can find a bit that's really close there.


Sent from my iPad using Penturners.org mobile app


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## ramaroodle

This is very strange.  After putting a round file in a drill chuck and testing it for the right technique to widen the holes in a couple of practice 2x4's I drilled my olive wood blank.  For some reason the fit of the tubes was perfect if not even a little sloppy without having to widen the hole!


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## ed4copies

ramaroodle said:


> This is very strange.  After putting a round file in a drill chuck and testing it for the right technique to widen the holes in a couple of practice 2x4's I drilled my olive wood blank.  For some reason the fit of the tubes was perfect if not even a little sloppy without having to widen the hole!




This blank was drier.


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## magpens

ramaroodle said:


> This is very strange.  After putting a round file in a drill chuck and testing it for the right technique to widen the holes in a couple of practice 2x4's I drilled my olive wood blank.  For some reason the fit of the tubes was perfect if not even a little sloppy without having to widen the hole!



There you go ... blanks are variable in their response to drilling.

With regard to putting your round file in a drill chuck ... what do you then do ?

Do you hold the drill chuck in your hand ? . I hope so.

I would not use it on the lathe with power on ... not very controllable !!


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## ramaroodle

ed4copies said:


> ramaroodle said:
> 
> 
> 
> This is very strange.  After putting a round file in a drill chuck and testing it for the right technique to widen the holes in a couple of practice 2x4's I drilled my olive wood blank.  For some reason the fit of the tubes was perfect if not even a little sloppy without having to widen the hole!
> 
> 
> 
> 
> 
> This blank was drier.
Click to expand...

That's kinda what I figured.



magpens said:


> Do you hold the drill chuck in your hand ? . I hope so.
> 
> I would not use it on the lathe with power on ... not very controllable !!



Actually, I put it in my cordless drill and it worked quite well on my test blanks except I didn't need it.  The file was true and spun like a drill bit.


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## ramaroodle

Just as a followup, this is the finished product.


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## monophoto

leehljp said:


> Harbor Freight has a 115 piece drill bit set for $47.99 that can be had with a 20% off coupon for about $39.00. For drilling wood, this is a great help for those situations where you need a different size.
> 
> https://www.harborfreight.com/115-Pc-Titanium-M2-High-Speed-Steel-Drill-Bit-Set-61543.html
> 
> This set, plus under "Library>References (top of the page) there are drill charts and conversions that will list the nearest sizes in mm, inch and decimal. GREAT reference charts. I have two sets printed out and one on the wall for quick reference. Had that for over 10 years and one of the most handy things in my shop.



Great suggestion - I bought one of those sets a few years ago, and have adopted the discipline that those bits are used ONLY for wood.  Drilling wood is generally a less demanding activity, and dedicating one set of bits to wood assures that they stay sharp longer.  If I break a bit (and I have), I can replace it individually at Ace Hardware.  I have other bits that I use for metal.  

The Harbor Freight set comes in carbon steel, TiN coated, and cobalt steel versions.  The set Hank suggested is the inexpensive carbon steel version that I think is fine for low stress applications with wood.

Another tool that is really handy to have along with that set of bits is iEngineer - an iPhone app (also available for folks of the Android persuasion).  This app provides dimensions for fractional, numbered, and lettered bits (and if you purchase the option metric add-on), metric bits also.  It also includes useful screw/nut thread information.


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## ramaroodle

monophoto said:


> Another tool that is really handy to have along with that set of bits is iEngineer - an iPhone app (also available for folks of the Android persuasion).  This app provides dimensions for fractional, numbered, and lettered bits (and if you purchase the option metric add-on), metric bits also.  It also includes useful screw/nut thread information.



Got it. Thanks.  Well worth the $1.99.


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## monophoto

monophoto said:


> The Harbor Freight set comes in carbon steel, TiN coated, and cobalt steel versions.  The set Hank suggested is the inexpensive carbon steel version that I think is fine for low stress applications with wood.



One additional comment - these sets currently come in metal 'library' boxes.  While this is very convenient, but construction of the boxes isn't the best, and the 'foldout' portions are held in place with tiny machine screws and nuts.  Over time, the nuts work loose leavings the foldouts flopping.

It's not difficult to tighten the nuts, but the process is a bit fiddly - my fingers are too fat to fit into the space where the nut attaches to the screws.  But I've found that long needle nose pliers, or even hemostats, can be used to hold the nut in place while the screw is tightened.  I suppose that applying some locktite to the threads would solve that problem, but I'm not at that point yet.


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