Re: [Emc-users] makeing tap hats, from brass rod

[andy pugh]

On 20 May 2018 at 15:26, Gene Heskett  wrote:

>> https://www.ebay.com/itm/131375282525
>
> That looks a lot like an engraving bit, same as I use for making PCB's,

No, not at all. Engraving bits have the tip off to one side.

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916

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Re: [Emc-users] makeing tap hats, from brass rod

[Gene Heskett]

On Sunday 20 May 2018 10:17:27 andy pugh wrote:

> On 20 May 2018 at 02:41, Gene Heskett  wrote:
> > Good idea but the drill bit doesn't seem to want to self center,
>
> Spotting drills work better than centre drills if you are not actually
> making a centre hole for a lathe to use.
>
> https://www.ebay.com/itm/131375282525

That looks a lot like an engraving bit, same as I use for making PCB's, 
and I have several of those, 60 degree sharp tips.  Another idea, thanks 
Andy.

-- 
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] makeing tap hats, from brass rod

[Gene Heskett]

On Sunday 20 May 2018 09:57:29 Erik Christiansen wrote:

> On 19.05.18 21:41, Gene Heskett wrote:
> > I have all these brass slugs fixed so they are keyed into a scallop
> > in the edge of a 7/8" R8 collet that fits the head of a 4mm capscrew
> > in the lower end of the slug. So the next operation is to set it
> > into the spindle, and position it so the rotation center is directly
> > over the drill bit, chosen to be a fairly wiggle free fit on the
> > shank of the tap that will be held in this one.
> >
> > Good idea but the drill bit doesn't seem to want to self center,
> > despite moveing the table and the drill bit around looking for the
> > magic spot. I haven't tried a small center-drill yet. Is that the
> > fix, or do I need to treat the bit in a drill doctor?  Or both?
>
> Aligning the tailstock on the lathe seems worth doing, Gene, but if
> you need some taphats beforehand, then a small center-drill is the
> answer. I don't drill a hole on the lathe or mill without
> center-drilling first. It's not worth it as a .243 aimed from across
> the street is more precise.
>
> ...
>
> > But how best to prevent the drill bit from doing the sailors
> > hornpipe dance when the brass first touches it?  Thats the $64
> > question.
>
> You can get quite a few small center-drills for $64 - a lot less of
> the medium & bigger ones. But ISTR that the good ones are cobalt
> steel, and that's why they do fine even in SS, I find.
>
> Erik

I think its off with a vertical tilt. I can shift it left right, and get 
it close enough to hold a center drill, but needs some shimming to level 
it and bring it to the correct height, thats off about 15 thou. But with 
the condition of the barrel, I only have the idea of grinding a 3/4" rod 
to the same taper so it projects out far enough to measure the barrels 
shift as it move in and out. I really think it could be bent or worn so 
its not on axis. But I need to invent a way to verify its alignment 
thats better than my eyeballs. I bought a couple ball bearing centers, 
but neither ones point is anywhere near the axis of the mt2, I can 
rotate them in the barrel and see the points shifting on a dial, a long 
ways, 20 thou on the worst one. ebay crap, less than a $25 bill. The 
worn, chipped tip live center I got with it is much more accurate.
And the solid but somewhat oxidized plain one is the best I have.

Don't know if I'll have time today, the local AM stations nighttime low 
power transmitter took a dump last night, so I need to go see what 
smoked this time. Trouble is, its old enough to legally smoke in public, 
some POS that LPB made decades ago, and of course LPB is gone 20+ years 
ago. Just barely transistorized. And definitely built by the lowest 
bidder.  Sigh...  Such is the life of a dying breed, me.

-- 
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] makeing tap hats, from brass rod

[andy pugh]

On 20 May 2018 at 02:41, Gene Heskett  wrote:

> Good idea but the drill bit doesn't seem to want to self center,

Spotting drills work better than centre drills if you are not actually
making a centre hole for a lathe to use.

https://www.ebay.com/itm/131375282525

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916

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Re: [Emc-users] makeing tap hats, from brass rod

[Erik Christiansen]

On 19.05.18 21:41, Gene Heskett wrote:
> I have all these brass slugs fixed so they are keyed into a scallop in 
> the edge of a 7/8" R8 collet that fits the head of a 4mm capscrew in the 
> lower end of the slug. So the next operation is to set it into the 
> spindle, and position it so the rotation center is directly over the 
> drill bit, chosen to be a fairly wiggle free fit on the shank of the tap 
> that will be held in this one.
> 
> Good idea but the drill bit doesn't seem to want to self center, despite 
> moveing the table and the drill bit around looking for the magic spot. I 
> haven't tried a small center-drill yet. Is that the fix, or do I need to 
> treat the bit in a drill doctor?  Or both?

Aligning the tailstock on the lathe seems worth doing, Gene, but if you
need some taphats beforehand, then a small center-drill is the answer. I
don't drill a hole on the lathe or mill without center-drilling first.
It's not worth it as a .243 aimed from across the street is more precise.

...

> But how best to prevent the drill bit from doing the sailors hornpipe 
> dance when the brass first touches it?  Thats the $64 question.

You can get quite a few small center-drills for $64 - a lot less of the
medium & bigger ones. But ISTR that the good ones are cobalt steel, and
that's why they do fine even in SS, I find.

Erik

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Re: [Emc-users] makeing tap hats, from brass rod

[Gene Heskett]

On Saturday 19 May 2018 22:03:58 andy pugh wrote:

> On 20 May 2018 at 02:41, Gene Heskett  wrote:
> > But how best to prevent the drill bit from doing the sailors
> > hornpipe dance when the brass first touches it?  Thats the $64
> > question.
>
> I would take a completely different approach, I would make a fitting
> for the lathe spindle that takes R8 tooling.
>
My tailstock has yet to be aligned. I could grab these in an ER-40 collet 
which has under a thou of runout, and do it that way I suppose.

> I haven't done this on my lathe, because I use BT30 tooling, but I do
> have a fixture for that.
>
> On my old lathe it was a block that screwed on to the spindle nose,
> but the Holbrook has a big enough spindle that the adaptor is MT4.5 on
> the OD to fit the lathe spindle and BT30 on the inside for
> mill-spindle tooling.

Whereas my bigger lathe has a short MT5 internally, in which I have an 
adapter to 5C, then to an ER-40. Getting all that to run true after 
finding the spindle was bent, was at least 2 weeks worth of fun as I had 
to start by trueing up the MT5. Getting all that running true meant 
working on register clearance, so I could move the chuck enough to put 
it back plumb, and grinding the faceplates back to true. And a hundred 
dollar bill to grizzly for the makings of a new 5C adapter that actually 
ran true.

But since the ER40 has sub thou runout now, that may not be such a bad 
idea. I'll look at it tomorrow.

Thanks Andy.

-- 
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] makeing tap hats, from brass rod

[andy pugh]

On 20 May 2018 at 02:41, Gene Heskett  wrote:

> But how best to prevent the drill bit from doing the sailors hornpipe
> dance when the brass first touches it?  Thats the $64 question.

I would take a completely different approach, I would make a fitting
for the lathe spindle that takes R8 tooling.

I haven't done this on my lathe, because I use BT30 tooling, but I do
have a fixture for that.

On my old lathe it was a block that screwed on to the spindle nose,
but the Holbrook has a big enough spindle that the adaptor is MT4.5 on
the OD to fit the lathe spindle and BT30 on the inside for
mill-spindle tooling.


-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916

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