Yet another pivot pin/drilling/tapping question

Chiro75

Chiro75

Joined
Feb 4, 1999
Messages
5,786
I know I said I wasn't going to do this, but I've looked at some machining books at the library to edumacate myself (they just don't teach this stuff to chem majors or in chiropractic!) to no avail. So, here's the rundown:

1) What I want to do: make a balisong (butterfly knife).

2) Basic plans: I will be using "sandwich" construction (i.e. like a normal folder rather than using solid, machined handles) and I'd like to use Zen pins, too. These are pins that take place of the tang pins on most balis. Additionally, I am going to use pretty thin (about the thickness, maybe a little more, of a normal folder's liners) stainless steel for the liners of the handles and overlay either G-10 or carbon fiber on top, using a couple screws to hold everything together. So that means...

3) What I need help with is all this screw stuff! I will need to drill and ream two holes in the blade for pivot pins. These need to be pretty precise, as far as I can tell! So, I know I will need to drill slightly undersize, then ream to the dimensions of the pivot pins, which I think are 3/16" diameter. I also need to drill and ream the handles for the Zen pins, which I think (I'm finding out) are simply smaller diameter pivot pin assemblies (probably 1/8" if they make them that small? I guess whatever the smallest pivot pin assembly is, that's probably what to use for Zen pins). Finally, I will need to drill and tap some sort of microscopic screws for keeping the handle scales (G-10 or CF) attached to the stainless steel liners. So these screws need to be tiny to be out of the way, but also have enough threads to really grab the liner material. Whew.

4) Specific questions and needs:

a) Pivot pins: what size of drill bit do I use for the initial hole, and what size of reamer do I use to finish the hole? "Slightly undersize" means nothing to me, especially when standard drill bits make such large jumps in size. Do I need a mix of standard and metric for this? If so, what exactly for a 3/16" diameter pivot assembly?

b) Same question for the Zen pin assemblies. Since these are stop pins rather than pivot pins, in function, the reaming and all that doesn't need to be super precise. I just need the pins to fit nicely in the holes I make. Koval offers a couple of choices in 1/8"/0.125" so I assume that's what I'd use. Alternatively, I could possibly use their hardened steel made for stop pins and simply grind them to the height of the liners and use the scales to hold them in place, in which case I have a choice of 1/8" or 3/32".

c) Finally (I/m so sorry!), what about the screws for the scales/liners? What, exactly, should I use for the screw (remember, I want tiny heads with enough threads to hold the liners)? So I need screw size, tap size and drill bit size for the screws. Super thanks in advance!!!
 
For 3/16 pivot pins, use a no. 15 (.180)drill. Ream 3/16".

If you don't want to buy the number drills, then use a 11/64 (.1719) drill.

Get yourself a set of fractional, number (wire size) and if you want everything, a set of letter drills. That'll give you any size you need. Enco used to sell all the sets together in one box.

Get a drill chart that includes tap sizes and drills.

I don't know what a Zen pin is, but if it's the stop pin that indexes the blade open and closed, and is a straight pin that needs to be a press fit,the hole must be about .001" smaller than the pin, and there is no standard drill made that size. If this is a 2-piece slip-fit pin, then drill with a no. 33 (.113) drill, then ream 1/8"

I'd suggest using 1-72 flat head screws on the scales. If you're tapping steel, use a no.53 (.0595) drill, and then tap. If the material is titanium, use a 1/16" drill before reaming 1/8".

It's important to use tapping fluid for all these tools. Do NOT USE LUBRICATING OIL.

For a very loose reamed fit, ream dry. For a little tighter, but still loose fit, use water. For a close fit, use sulphur based cutting oil.

Your super thanks have been received. You're quite welcome. What else do you need?
:)
 
Actually, looking at MSC Direct I have the choice of "plug" or "taper" for taps. Which one should I use?
 
Oops, and two more:

1) For reamers should they be the left twist/right cut type or straight flutes?

2) For a countersink for a 1-72 screw, would I use this (from MSC): "HSS Straight Shank Machine Screw Counterbores Size: 1 Pilot Hole Diameter: 0.072 In. Countersink Diameter: 0.156 In. Included Angle°: 82 Material: HSS" or am I all wrong?

This stuff is pretty complicated. I'm sure it gets easy when you figure out what you need and that's all you have to worry about (i.e. using the same size parts on different folders), but sheesh! The figuring is the tough part when you don't have any education in these matters. Plus, it ain't cheap. Using import stuff from MSC I'm looking at around $70 or so just for this one knife. Maybe I'll become a balisong factory after this, but I doubt it! :D Plus I need to buy the pivot assemblies and all that for hardware, which is another $16. Not a cheap project, really. Wouldn't be so bad if I knew that it would turn out okay, but there are no guarantees!
 
Chiro75 said:
Actually, looking at MSC Direct I have the choice of "plug" or "taper" for taps. Which one should I use?
Click to expand...

a plug tap is for getting threads at the bottom of a hole use the Tapered
I'd say just use a straight ream but test your holes first.
d/t chart
http://www.knivesby.com/drill-tap-chart.html

countersink for a 1-72 screw depends on the screw head you have?
 
None of the examples you gave, 75.

Always use a <<<< spiral point>>>> tap for small screws. It's much stronger and pushes the chips ahead instead of bing in the flutes.

Get a simple single flute 82 degree hss c'sink about 3/8 to 1/2" diameter.

You'll have to get your lotto tickets elsewhere. :D

Straight flute right hand reamer.
 
Don Robinson said:
Get a simple single flute 82 degree hss c'sink about 3/8 to 1/2" diameter.
Click to expand...

with all due respect Don isn't 3/8 to 1/2" for counter sinking a bit over size
for 1-72 screw work , is he counter sinking or going flush with the head?

I do stand corrected on the taps I was thinking larger taps
when the choice of the two came up.
I had to look (close) at mine they are spiral point also.
 
I wish there was a little icon for boggled mind! Geez. It'd be like if I said in a conversational tone to you "No problemo, amigo. You simply have a PR-T at C6 that we'll take as an MRB supine, but also that shoulder pain is a result of the viscerosomatic reflex coming from the gallbladder due to an overactive motor signal to the papilla of Vater from T5-T9 originating in the semilunar ganglion."

I thought I had things pretty nicely figured out, but now I feel like I'm at square one again. Maybe this will make things easier: where do I buy all this stuff? If I have a good online source, which I thought MCS Industrial was but I didn't see some of these choices, I can piece things together a bit better maybe.
 
Steve
I have problems at C5 and C6 left leg numbness and burniong pain in the back
upper L disk probmles with right arm burning pain when I sneze or do something the worng way :(

look at the tap drill chart it will help you get use to getting what you need
the tap drill is for the hole before tapping
1-72 #53 dismal size.0595

a body drill is for the wire size of your screw (out side of the threads,)
this would be the through hole
in the handle material so the threads won't hang up.

I just have numbers for my local supplier which I don't think that will help you.
 
You've got some disc problems! I hope you're seeing your chiropractor! Thanks for the info. What a difference between making fixed blades and doing something like a folder. What a pain! :D
 
Steve
when you have what you need and put them in a spl place with your screws
with reorder numbers you'll have no problems ,

no chiropractor yet :( but I've been to many x-rays, CT's and MRI's

Early degenerative, a bloated disk, bone spurs, and narrowing of the nerve
passages,
I sure could use written proof, that an earlier documented injury
caused all this. called injury due to an injury.
 
All too often in my practice I'll have people say "Yeah, hurt myself at work, but I don't want to make a work comp claim..." I should point them here. Sorry to hear about it! A good chiropractor could possibly do wonders for you, but depends on what's wrong and how bad.
 
Okay... here's a summary of what I guess I need. Please correct if wrong...I've also listed what I'm still unsure about:

-For the 3/16" pivot pins I need a #15 drill bit (62 cents each for HSS or $14 for carbide) and a 3/16" ream, which could be a straight ream but may need a fluted ream, meaning I need to buy both? I think I'll flip a coin and hope for the best!

-For the Zen pins I need 1/8" pivot assemblies or hardened stop pin material (same size diameter) and a #33 bit with a 1/8" ream.

- For the 1-72 screws (I'll go with a flathead) I need a #53 drill bit and a 1-72 taper tap.

- I still need to clear up the countersinking issue. If I buy the flathead stainless steel screws from Halpern, which countersink would I need to simply sink the head a little ways to make it flush with whatever handle scale material I choose?

- What about tapping fluid? I couldn't find specs on MSC website. They pointed me toward a cutting fluid for all ferrous and non-ferrous materials. I'd like something that works with Ti or SS. Any specific brand suggestions?

Wow. Maybe I'll have to make two balis simply to pay for all the materials! :D

I should buy 10 of everything and make "folders for idiots" toolkits, actually! :D
 
Dan Gray said:
with all due respect Don isn't 3/8 to 1/2" for counter sinking a bit over size
for 1-72 screw work , is he counter sinking or going flush with the head?

I do stand corrected on the taps I was thinking larger taps
when the choice of the two came up.
I had to look (close) at mine they are spiral point also.
Click to expand...

For flat hd. screws, those sizes are OK, if you get a single flute c'sink, as I suggested. It will c'sink anything from around 1/32" up to full diameter. It cuts all the way to it's sharp point. You only need to c'sink a flat hd. screw a little past flush. It's also useful for c'sinking larger holes.
 
Chiro75 said:
Okay... here's a summary of what I guess I need. Please correct if wrong...I've also listed what I'm still unsure about:

-For the 3/16" pivot pins I need a #15 drill bit (62 cents each for HSS or $14 for carbide) and a 3/16" ream, which could be a straight ream but may need a fluted ream, meaning I need to buy both? I think I'll flip a coin and hope for the best!

-For the Zen pins I need 1/8" pivot assemblies or hardened stop pin material (same size diameter) and a #33 bit with a 1/8" ream.

- For the 1-72 screws (I'll go with a flathead) I need a #53 drill bit and a 1-72 taper tap.

- I still need to clear up the countersinking issue. If I buy the flathead stainless steel screws from Halpern, which countersink would I need to simply sink the head a little ways to make it flush with whatever handle scale material I choose?

- What about tapping fluid? I couldn't find specs on MSC website. They pointed me toward a cutting fluid for all ferrous and non-ferrous materials. I'd like something that works with Ti or SS. Any specific brand suggestions?

Wow. Maybe I'll have to make two balis simply to pay for all the materials! :D

I should buy 10 of everything and make "folders for idiots" toolkits, actually! :D
Click to expand...

Read the posts more carefully, Grasshopper. You want a SPIRAL POINT tap, not a taper point.

:eek:

Get the stright flute reamer, as suggested.

MSC or Enco has all this stuff, including tapping fluid. And cutting oil.

Use the index. :rolleyes:

Sorry, I couldn't resist that!!! ;)

Order MSC's full catalog, it has everything for metalworking. The mail man will deliver it in a wheelbarrow. :)
 
Aw crap. Okay, on the spiral point tap, "bottoming" or "plug" type and do I want a ground thread limit of H1 or H2???????????????????????? Or does it not matter?

Also, when I worked in a bike shop we used to have to tap stuff all the time. We had a cool little handle that fit any taps or reamers we were using that was basically a collar that you tightened down with a little T-handle on it. I couldn't find anything like this on MSC and I'm sure it's simply because I don't know what the doggarn thing is called. I don't want to have to order 2-3 different handles for the different taps and reamers, so is there something universal I could use?

Or better yet, who wants to drill and ream and tap some holes in some material I'll send them? :D
 
Chiro75 said:
Aw crap. Okay, on the spiral point tap, "bottoming" or "plug" type and do I want a ground thread limit of H1 or H2???????????????????????? Or does it not matter?

Also, when I worked in a bike shop we used to have to tap stuff all the time. We had a cool little handle that fit any taps or reamers we were using that was basically a collar that you tightened down with a little T-handle on it. I couldn't find anything like this on MSC and I'm sure it's simply because I don't know what the doggarn thing is called. I don't want to have to order 2-3 different handles for the different taps and reamers, so is there something universal I could use?

Or better yet, who wants to drill and ream and tap some holes in some material I'll send them? :D
Click to expand...

H2 is standard, and is what you want.

Get a spiral point plug tap.

The tap wrench is called,,,,,, (drum roll) A tee handle tap wrench.
Get the right size for your taps. Probably the smallest size.

Ream the holes with your drill press.
 
Gracias, amigos! I'll just have to reasses this mess when I get my blue book. I used to have one, but it's about 5 years old. I forgot that the book tells you some good info that the website neglects to mention. I suppose I need to bite the bullet and try some stuff out, if it's wrong then replace it. Instead of a "one-off" I'll make two balisongs at once and sell one off or something to finance the project. Thanks and I'll keep everyone updated!
 
Most knifemakers I know started out by selling one for enough money to make two more. Your tools aren't expendable, though. Don't add them to the price. Add the supplies you purchased and used and price the first knife at twice that.

As you improve in skill, add some more to the price to cover overhead and labor.

Don't quit your day job for a while, though. ;)
 
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