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Post by screwbolts on Mar 15, 2009 11:42:00 GMT -5
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Post by Harley on Mar 15, 2009 13:19:09 GMT -5
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Post by screwbolts on Mar 15, 2009 17:13:12 GMT -5
Yes It is, $.34 , I will check shipping between them.
Ken
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Post by screwbolts on Mar 16, 2009 6:25:19 GMT -5
Is there anyone that is in need of some vent liner drills?
The minimum shipping cost from either of the above Outfits is nearly the price of the drills.
I would be interested in sourcing these for you with a combined order, that would bring the cost down to all that ordered.
I would collect orders and funds then place the order, then repack and send to you. If there is interest, I would order the drills then send you your part of the order by Parcel post, less. than $1.50 for that.
Other size bits could be ordered also, if there is enough interest, we could figure pricing on less than 12 bit minimum. It is just that the minimum is 12 for each size.
Ken
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Post by Guessed on Mar 16, 2009 7:35:40 GMT -5
It's been my experience that you'll need most of a dozen bits to finish a box of Holo- Kromes. And a #2 center drill will c'sink the threaded end first so that you don't lose so many drills on break through (it's not really a flame funnel, it was designed to support the tip of the drill at break through with a uniform surface so it won't grab and pull. Plus, it gets through the surface hardening that screw forming imparts to the flat-head with short, stout tooling instead of long slender drills). Go with a 135 degree grind and stay away from carbide as it doesn't flex in hand fed presses and is mostly designed for shallow hole printed circuit board apps. My choice has been a #68 cobalt bit in a pin chuck after blowing up a ten pack of these .80 mm's getting a dozen useable vents. drillcity.stores.yahoo.net/10newwirsizp.html. For my next batch, I'm going to try pecking the #68 drill about 1/8" short of break through and then flipping the screw and popping it with the center drill in an attempt to eliminate break through loss. |
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Post by Harley on Mar 16, 2009 8:09:26 GMT -5
I ordered a dozen carbide bits from this same Drill City source, and had the same frustrating experience that "Guest" reports. I didn't understand until seeing his post. I've always gotten 8-11 VL's from Cobalt.
I just clicked on the Drill City link, above, and all I see is carbide; where's the cobalt?
Harley
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Post by Guessed on Mar 16, 2009 9:08:55 GMT -5
My cobalt tooling comes from Travers.com # 01-021-468 for the #68's and 01-094-002 for the #2. And to throw the order over the minimum, # 85-600-930 is the pin chuck you'll need to stack onto your Jacob's. And/Or a box of 71-761-002's. Plus a piece of # 73-017-330 'cuz most everybody always wanted one in solid aluminum. And a set of 01-002-902's for a gauge set. And they carry the dowel pin reamers and tool steel round stock needed to convert to a bushing plug. And,,,my credit card hurts (cursed Internet).
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Post by edge on Mar 16, 2009 12:22:35 GMT -5
IMO, a Cobalt drill will be much more user friendly for the casual user. Carbide drills in very small diameters are very brittle  edge. |
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Post by smokeless77 on Mar 16, 2009 12:46:46 GMT -5
Edge, you are right, I tried the carbide drills from drill city i dont think i got one hole finished, all 5 broke. Unless they were poorly made.
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Post by Harley on Mar 16, 2009 15:17:38 GMT -5
Smokeless77, that's what I was saying, they all broke. I thought maybe Drill City was selling bad stuff; now I see it was my fault for ordering carbide.
Harley
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Post by Guessed on Mar 16, 2009 15:28:04 GMT -5
(mumbling disgruntledly)
Edge is 100% correct that cobalt is the choice for hand fed machines, because the visual indication that cobalt is being over-fed is that it will flex, but the visual indication carbide is being over-fed is that it snaps. However, carbide drills in very small diameters are no more brittle than carbide drills in very large diameters, Rockwell wise. They just do not tolerate anywhere near as much axial load as the fat ones, though. I immediately knew why I was screwt after snapping the second carbide bit and was able to get the dozen holes with the remaining eight bits because I've been spinning metal for 3 decades and learned a few tricks (that, and I took my set-up off the Wilton and put them in a Bridgeport at a .0015 feed rate before touch-off with the stop set in .025 increments while spinning a 1/4" R-8 as fast as it would go). I realized all my broken drillcity bits were not poorly made, but designed to be fed by a ball screw at 10,000 rpm through 1/16" thick phenolic-- not deep holed at low rpm through alloy steel with an inconsistent and excessive feed rate. When I order my next batch of cobalt #68's I am going to try the Ti coated cobalt to see if there is any greater tooling life. And I hold high hope for my 'meet in the middle' theory to keep the cutting edges of the drill bits from suffering the stress and dulling of break through.
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Post by Harley on Mar 16, 2009 15:47:07 GMT -5
"Guessed", this has been an education for me; thanks for posting and please join us. A couple of questions/points:
1. I understand the logic of your "meet in the middle" theory to reduce the breakthrough stress on the bit; I'm wondering, though, if defacing the end of the screw that encounters the flame of powder ignition will shorten the life of that screw as a vent liner; I'm referring to drilling through the "surface hardening" that you referred to in your first post.
2. Please post detailed instructions for setting the feed rate, stop set, etc on my 30 year old, Sears, $85 drill press.
Harley
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Post by Guessed on Mar 16, 2009 16:34:30 GMT -5
Thank You for the invite Harley(co-incidentally, I was out in the garage between posts and just got the engine pulled from my shovelhead FLH). But due to a few personality flaws of mine, I must always remind myself that I am a guest here and only valued for my first hand, on topic, experience relating to the MLII (if I drink enough after a 12 hour graveyard shift, I might explain that one).
To address your first ? ; It's not so much a surface hardening or case hardening as a work hardening the the screw acquires. I would guess that the amount of material that is machined away by the center drill will decrease the life of the vent by the same % as the depth of the c'sink compared to the total length of the hole. I am also going to take some of my remaining Holo-Krome vent liners and hang them by the threaded end from a junk magnet over a pan of salt water. That way, when I'm in the field, the gun will automatically be lined up with the Earth's magnetic fields for better long range accuracy........ or I could slowly heat them up with an acetylene torch till they get hot enough to fall off the magnet into the salt water, thus rendering them harder than a high school boy's *******, and see how they wear.
For your set-up ?'s, it would be easier for you to post a phone # for me to call, as I'm a two fingered typist.
And the asterisks stand for calculus class, along the same lines as; Did you hear what happened to the newlyweds who didn't know the difference between K-Y jelly and window putty? All the glass fell out of their windows (drum rimshot). You've all been a great audience and have a safe trip home.
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Post by Guessed on Mar 16, 2009 16:53:24 GMT -5
(Guests can't edit)
The #2 center drill spots the threaded end of the flat head--the end facing the primer, not the hex hole facing the flame. The hex is the end I start the #68 from. And it makes a handy reservoir for the Tap-Magic fluid. I've got cans of the old stuff that's been taken off the market because if we lived in California it might give us cancer if we drank it.
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Post by smokeless77 on Mar 16, 2009 17:20:45 GMT -5
Harley, when i got the hi speed drills from grainger, for under $10.00 for 5,I drilled 80 v/ls and broke just 2-3 still have 2 left. That's when i new it had to be the carbide bit's.
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Post by Harley on Mar 16, 2009 18:03:15 GMT -5
Guest, with your sense of humor I was certain you'd know I was anything-but-serious about setting up the P.O.S. Sear's drill press; it would make a decent stocking stuffer for a toddler.
I just proved I was conceptually challenged: I pictured the wrong end of the screw as being cupped.
Don't move to California if it means giving up your preferred drink.
Smokeless77, can you point me to the drills on the Grainger site? I've been looking, but can't locate them.
Harley
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Post by edge on Mar 16, 2009 18:26:40 GMT -5
IMO, drilling is all about technique. Most likely you will have a very fast spindle speed, and you will fill the hex with fluid/oil, and then you need to find the feedrate! This will be hit or miss until you get the knack!! Heavy enough to keep the drill moving, but not so fast that you see it bend. If it seems to stop drilling with a consistent pressure then you can increase the pressure until it breaks through the hard spot that you made or change the drill....or it breaks!!! PECK, PECK, PECK Don't drill too far before letting the drill out of the hole ( yes just like a sabot you will blow it ), or it will harden the metal and ruin the drill. 0.050 per peck might be a good place to start. Buy 2 dozen drills and chalk up the first dozen to experience  edge. |
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Post by smokeless77 on Mar 16, 2009 19:24:20 GMT -5
Harley try these numbers.
#1G853 aircraft grade cobalt 1/32= 0.0312 $4.02 ea.
#1F743 high-speed steel G/P 1/32= 0.0312 $1.46 ea.
#1F935 high-speed steel G/P drill # 66 = 0.0330 $ 1.52 ea.
#1F937 high-speed steel G/P drill # 67 = 0.0320 $ 1.52 ea.
Harley if you go on graingers site go to page 2907 to start, there is more to look at.
John
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Post by rexxer on Mar 16, 2009 20:30:29 GMT -5
To be quite honest the majority or the problems with the small carbide drills are rpm1 ,you guys really can't come even close to the rpms needed to drill with a 1/32 carbide drills with a drill press. I'm not exactly sure but I would guess in the neighborhood of 10,000-25,000 rpm. The next thing would be spindle balance or run out. Carbide won't take much of that either. Feed rate is critical but I think clearing the chip with such a small drill is more critical.Last is I beleive the cap screws are cased hardened as so seems, entry and exits would be the most breakage. These are my opinions and I'm sticking to them. Really if drilling at slower speeds you need to peck,and clear the chip. When the drill gets too dull it will either sit there and work harden the material of break.Bottom line is its going to take a few drills to make a few vent liners!
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Post by Harley on Mar 16, 2009 21:24:42 GMT -5
Thanks, John, I've copied it all.
Harley
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Post by screwbolts on Mar 18, 2009 18:20:48 GMT -5
offer withdrawn.
Ken
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