Re: [Emc-users] Jitter, latency , rtapi error

[Gene Heskett]

On Wednesday 07 March 2018 22:05:40 jeremy youngs wrote:

> Doubtfull, if the interface is wired so the + terminals are connected
> to the 5 volt buss, and a logic zero at the output then becomes the on
> signal, tied to the 4060's - terminals. It will likely run just fine
> on faster signals. The diff is that if the logic signal is tied to the
> + terminal, the pullup from the interface to turn on the opto's in the
> 4060, isn't near as strong as the logic zero sinking ability. I have a
> variety of drivers, and none of them are running as slow as the
> choices in stepconfig. Set the polarity of the signals in the hal file
> so that the step signals are negative for a logic one. You may want to
> check that with a real scope.
>  Invert pins to sink instead of source , more current handling
> ability. Run the other script in terminal, for 30 minutes copy report,
> paste here . Will do , that will take a bit of fanagalling as no
> internet at the shop , so be patient ( should have tomorrow evening or
> so ) , you said run something, can I run linuxcnc?

I believe thats what I wrote.

No net at the shop? Scary, how do you update?. All my machines are net 
connected, but the only firewall is dd-wrt reflashed into the router. No 
one has gotten thru it in a decade, one of the internets best kept 
secrets.

>  I believe the on board video is Intel , don't Know if 915 . It gives
> the same rtapi error regardless of video used.
> The old motherboard ate ram at a pretty decent rate

One thing I've noted is that 4GB of dram seems to be a sour spot, and 
gets into swap very easily. 2GB or 8GB is much less of a problem, with 
memory allocation being much more tightly controlled at 1 or 2 GB than 
at 4 GB. I have an r-pi 3b, with only a gig of ram, and with 7 days of 
uptime, is only into swap about 7 megs and it has done a few hours work 
in that 7 days. Had a power bump last week else its uptime would be 60+ 
days.

> I figured the caps 
> were bad and a reconditioned Mobo was less than the caps , I figured
> the Mobo would help the rtapi , no such luck. I about have this y
> ballscrew contained , still not the final revision but it will be
> better than before , and I will get to use in stock screws so that's a
> plus.

Contained? please elaborate. "stock screws" generally are metal to metal 
threads and waste 90+ percent of the motors power in frictional losses 
compared to ball screws.

> Also is there a tutorial on smi ? Perhaps YouTube? I will myself but I
> have been puzzled about this and isolcpus , it's kinda my
> understanding that those were for previous versions of rtai .
> Thank you for your time Gene .

I believe there is a discussion about smi on . 
Might have to search for it.  Whether its still valid I'm not positive 
and will assume the final word is in the wiki.

isolcpu's has I believe been deprecated, I don't know that I am using it 
on any of my 4 current machines. OTOH, I am running 2.8-pre on all 4 
machines. There could be some diffs between the latest 2.7 and 2.8-pre.

> --
> Check out the vibrant tech community on one of the world's
> most engaging tech sites, Slashdot.org! http://sdm.link/slashdot
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users



-- 
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 

--
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Jitter, latency , rtapi error

[Gene Heskett]

On Wednesday 07 March 2018 19:23:32 jeremy youngs wrote:

> Hello fellas ,
> I have this optiplex 2.8 GHz . I'm trying to figure if I should pitch
> it and try something else. I have reviewed the docs on latency and
> after 24 hours running I get what I think are good numbers, a Max
> jitter of 8882 and a service thread of 27405 . By comparing the given
> examples in the docs, I would think this machine would do rather well.
> It has a new Mobo , a pcie graphics card , and a pci epp card . It is
> rosewill and the graphics is an ati iirc.
> Latest bios available, no hyperthreading option, only disable multiple
> CPU core ( makes no difference)
> I have always gotten rtapi error: unexpected realtime delay on task
> one . 

I have seen that. Generally associated with the use of ati or nvidia 
closed src video drivers neither of which is allergic to shutting down 
the IRQ's when they think they are busy.. I have 2 of the optiplex 
myself.  One is a utility box I keep for programming mesa cards, the 
other is running my G0704 via a 5i25 mesa card.. The onboard video on 
both is i915, an intel video, not ati, but thats this particular pair, 
other optiplexes may not have intel video.

I've had relatively little of that sort of problems running the linux 
version of the i915 driver.

> I have my steppers set to kelling 4060? ( The only kelling 
> setting in stepconfig) these are the slowest of them all. I have
> eliminated optos . I get good performance from the machine and don't
> really want to punt. I've done the upgrades in hopes of solving the
> rtapi error. I've installed new cmos battery as well. Do I need even
> slower step settings?

Doubtfull, if the interface is wired so the + terminals are connected to 
the 5 volt buss, and a logic zero at the output then becomes the on 
signal, tied to the 4060's - terminals. It will likely run just fine on 
faster signals. The diff is that if the logic signal is tied to the + 
terminal, the pullup from the interface to turn on the opto's in the 
4060, isn't near as strong as the logic zero sinking ability. I have a 
variety of drivers, and none of them are running as slow as the choices 
in stepconfig. Set the polarity of the signals in the hal file so that 
the step signals are negative for a logic one. You may want to check 
that with a real scope.

It might be illuminating to launch "linuxcnc -lENTER" from a terminal 
screen as that will log anything suspicious to the terminal screen. 
Leave it run, preferably doing something, for half an hour, then quit 
and copy/paste the screen to another message here. That will give us an 
idea of how serious a problem you have.

-- 
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 

--
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

[Emc-users] Jitter, latency , rtapi error

[jeremy youngs]

Hello fellas ,
I have this optiplex 2.8 GHz . I'm trying to figure if I should pitch it
and try something else. I have reviewed the docs on latency and after 24
hours running I get what I think are good numbers, a Max jitter of 8882 and
a service thread of 27405 . By comparing the given examples in the docs, I
would think this machine would do rather well.
It has a new Mobo , a pcie graphics card , and a pci epp card . It is
rosewill and the graphics is an ati iirc.
Latest bios available, no hyperthreading option, only disable multiple CPU
core ( makes no difference)
I have always gotten rtapi error: unexpected realtime delay on task one .
I have my steppers set to kelling 4060? ( The only kelling setting in
stepconfig) these are the slowest of them all. I have eliminated optos . I
get good performance from the machine and don't really want to punt. I've
done the upgrades in hopes of solving the rtapi error. I've installed new
cmos battery as well. Do I need even slower step settings?
--
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Tapping not slipping

[Gene Heskett]

On Wednesday 07 March 2018 12:54:51 Greg Bentzinger via Emc-users wrote:

> My personal choice has been a CAT40 with rigid Bilz #1 holder, or a
> U200 shank with very minimal tension compression and Bilz #1 holder
>
> Bilz holders appear a bit pricey but you won't need many sizes and you
> can swap taps and holders while keeping the same offset - I'd say mine
> repeat to about 0.0025"
>
> I have put the shank in a CNC and just swapped tap holders on jobs
> which had too many different threads. I also have some 3/4" shank
> tension/compression #1 holders - but they are like 4 inches long. I
> can't use these on a BP style 3 axis CNC with only 5" Z quill travel.
> I hope to some day add a "W" axis so I can use the knee to compensate
> for tool length.
>
> OK - I know this won't work for Gene... but may help others.
>
> I don't think you will find tap drive R8's simply based on how it
> would have to be made.
>
> But you could buy some 3/4" Drill rod. Chop off a chunk that is the
> length of the shank and flats. Drill the corners then the center of
> the drive square and mill a square pocket about 1/4" deep with maybe a
> 3/32" EM.
>
> Turn the part around and drill til it just breaks into the square,
> then bore/ream to shank size. You would put this drive bushing in a R8
> solid Weldon type 3/4" endmill holder. Mark where the set screw would
> contact bushing then bore a clearance hole with a 2F endmill so the R8
> holder set screw is able to clamp directly on the tap shank.
>
> Usually long before I have to worry about a tap slipping I have chosen
> to thread mill.
>
> You can buy cheap Chicom import threading insert boring bars that you
> can grind extra clearance on and mount on center in a ER32 or even
> 3/4" Weldon that will work for thread milling.

Thats been considered. Even thought of getting a boring head. But had to 
find something cheaper. And locking it into the R8 to stop the slippage 
would appear to solve the majority of the shortcomings of the collet 
based offerings. So, like Erik, make them. Brass rod on order.

> There are many ways to skin this cat - but with 9 lives just be sure
> its dead before you start.
>
> Greg
>
Chuckle. BTDT. Took a while to heal too.

-- 
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 

--
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

[Emc-users] Tapping not slipping

[Greg Bentzinger via Emc-users]

My personal choice has been a CAT40 with rigid Bilz #1 holder, or a U200 shank 
with very minimal tension compression and Bilz #1 holder

Bilz holders appear a bit pricey but you won't need many sizes and you can swap 
taps and holders while keeping the same offset - I'd say mine repeat to about 
0.0025"

I have put the shank in a CNC and just swapped tap holders on jobs which had 
too many different threads. I also have some 3/4" shank tension/compression #1 
holders - but they are like 4 inches long. I can't use these on a BP style 3 
axis CNC with only 5" Z quill travel. I hope to some day add a "W" axis so I 
can use the knee to compensate for tool length.

OK - I know this won't work for Gene... but may help others.

I don't think you will find tap drive R8's simply based on how it would have to 
be made.

But you could buy some 3/4" Drill rod. Chop off a chunk that is the length of 
the shank and flats. Drill the corners then the center of the drive square and 
mill a square pocket about 1/4" deep with maybe a 3/32" EM.

Turn the part around and drill til it just breaks into the square, then 
bore/ream to shank size. You would put this drive bushing in a R8 solid Weldon 
type 3/4" endmill holder. Mark where the set screw would contact bushing then 
bore a clearance hole with a 2F endmill so the R8 holder set screw is able to 
clamp directly on the tap shank.

Usually long before I have to worry about a tap slipping I have chosen to 
thread mill.

You can buy cheap Chicom import threading insert boring bars that you can grind 
extra clearance on and mount on center in a ER32 or even 3/4" Weldon that will 
work for thread milling.

There are many ways to skin this cat - but with 9 lives just be sure its dead 
before you start.

Greg

--
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Where are you getting R8 square collets for driving taps?

[Gene Heskett]

On Wednesday 07 March 2018 11:38:41 andy pugh wrote:

> On 7 March 2018 at 14:55, Gene Heskett  wrote:
> > Price is scary, and still leaves the collet free to slip. I think
> > I'd rather sacrifice an R8 by grinding a key slot into it for a cap
> > screw in the side of a brass tap holder,
>
> Or just make a complete R8.
>
> Here is a 3D model (viewable online) of an idea.
> http://a360.co/2Fl8AXO
>
Unfortunately, both palemoon and firefox crash and go away on that link. 
Did you mean .com? Humm, but thats a 404.

Thanks Andy.

> It's a solid R9 bored for the tap shank with a slot milled through to
> make flats to engage the tap flats.
> (in theory you could mill only just deep enough to make a 3-sided
> drive square).
> And I guess with a bit more work, an insert to add a clampable 4th
> side. But the design shown is a fairly simple bit of lathe work, with
> a couple of simple milling ops.
>
> I think that Aluminium would probably be entirely adequate.



-- 
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 

--
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Tap Hat photo

[Gene Heskett]

On Wednesday 07 March 2018 06:57:58 Erik Christiansen wrote:

> On 07.03.18 05:45, Gene Heskett wrote:
> > On Wednesday 07 March 2018 02:00:46 Erik Christiansen wrote:
> > > To go in a collet, you wouldn't need the fat splined adapter to
> > > take the die holder. I can take this one off as it's only held on
> > > with grubscrews. Two of the four tap-gripping grubscrew holes can
> > > be seen half way up the tap holder body.
> >
> > And you intended to make one for every tap size you commonly use?
> >
> :-) That's why the adaptor for the die holder is only attached with
>
> grubscrews. Four or five 1/2" holders, one for each tap that I use,
> then drop in to one adaptor. And the holders are quick to make. (I
> have some zero rake carbide tipped drill bits. Medium fine brass
> granules just pour out the flutes of the horizontal drill in a golden
> river, without any need to back out before it's done. And you can feed
> at a most gratifying rate.)
>
> I'll have to buy some larger brass bar for holders for 8 mm and up, or
> just use steel, which isn't as much fun.
>
> Erik
>
I have an ER-40 kit that will pass a 7/8" rod, maybe even an inch, but my 
R8's quit at 7/8", so I just ordered 6 foot of 7/8" #360 brass rod. Now 
I need to round up grub screws, and some short 3mm cap screws as I am 
going to sacrifice a 7/8" R8 by grinding a notch in it for the head of a 
3mm cap screw seated deep. Since the R8 is pinned, why not pin the 
adapter?  And with 7/8" of brass, 3mm grub screws ought to get a decent 
grip on the taps butt for smallish taps. For bigger taps, increment the 
grub screw. Figure the grub screw diameter as close to the width of the 
flat w/o exceeding it.

Straight flute drill bits sound good too. But I've not acquired any of 
those yet. :( But they are on my wish list. And maybe add a couple 
lincurves and offsets to the mill, keyed to a home switch on the table 
that doesn't exist yet. That should keep me busy... Better yet, make a 
jig to bore the grub screw holes. I like that better, as this 4" table, 
even with a motor on it, is a P.O.S., with little or no ability to 
center a 3 jaw thats mounted on it.

Sitting here, watching the snow coming down in BIG flakes at a 45 degree 
angle, but not sticking yet as its 36F, I don't think I'll go see the 
Missus today as she just called and warned me to stay home. So I guess 
I'll go fix a bite, and call it breakfast.

Thanks Erik.

-- 
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 

--
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Where are you getting R8 square collets for driving taps?

[andy pugh]

On 7 March 2018 at 14:55, Gene Heskett  wrote:

> Price is scary, and still leaves the collet free to slip. I think I'd
> rather sacrifice an R8 by grinding a key slot into it for a cap screw in
> the side of a brass tap holder,

Or just make a complete R8.

Here is a 3D model (viewable online) of an idea.
http://a360.co/2Fl8AXO

It's a solid R9 bored for the tap shank with a slot milled through to
make flats to engage the tap flats.
(in theory you could mill only just deep enough to make a 3-sided
drive square).
And I guess with a bit more work, an insert to add a clampable 4th side.
But the design shown is a fairly simple bit of lathe work, with a
couple of simple milling ops.

I think that Aluminium would probably be entirely adequate.

-- 
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

--
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Where are you getting R8 square collets for driving taps?

[Gene Heskett]

On Wednesday 07 March 2018 06:42:26 andy pugh wrote:

> On 7 March 2018 at 04:05, Gene Heskett  wrote:
> > So the only way is to buy R8's with square bores,
>
> I don't think that is the only way at all.
>
> You could make solid ER32 "collets" with grub screws in the end.
> (getting the extractor flange right would be a challenge).
> Bored true they would hold the tap true, with drive from the grub
> screws on the square.
> Needs one per tap size, but it's an easy CNC turning job.
>
I think the 3/4" brass rod idea, bored thru for each tap, with grub 
screws to grab the square butt, and a key slot cut in a 3/4" R8 to lock 
it to a cap screw seated in the side of the 3/4" brass rod, one per tap 
size, might be the best idea.

> I recently (and accidentally) bought a pair of floating tap holders.
> There is no reason that those would not work for rigid tapping, and
> they add a bit of relaxation to the process in the event of a problem.
> Those take a DA collet and have a pair of grub-screws to grip the
> flat.
>
> ER collets specifically for tapping exist (with a square in the back)
> https://www.ebay.com/itm/Techniks-1-2-ER25-Rigid-Tap-Collet/1221226735
>10

Price is scary, and still leaves the collet free to slip. I think I'd 
rather sacrifice an R8 by grinding a key slot into it for a cap screw in 
the side of a brass tap holder, to lock it from slipping in the R8, and 
make a dozen or more, about an inch long. Like you said, once the code 
is written, it can make as many as I have brass on hand. I now have the 
Sheldons bent spindle corrected, and an ER-40 kit that sits in the 
shop-made 5C adapter, and running within a thou several inches away from 
its collet. I'll have to measure, but I believe it can pass a 3/4" rod, 
length arbitrary to about 3 feet as theres a storage shelf to the left 
of the lathe it will hit. If I add the rear spider I made, I should be 
able to maintain it pretty true.

Now, to find the 3/4" brass in 3 foot hunks.

> You could add a pair of drive grub-screws to a standard round R8
> collet. You might need to soften it off to allow tapping, though.
> At which point you might as well make your own, again it's a simple
> turning job. You wouldn't need to heat treat for your volume of work.
> It would not need to be a split collet. Bored for the tap diameter and
> relying on screws for grip and retention it ought to be fine.



-- 
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 

--
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Tap Hat photo

[Erik Christiansen]

On 07.03.18 05:45, Gene Heskett wrote:
> On Wednesday 07 March 2018 02:00:46 Erik Christiansen wrote:
> > To go in a collet, you wouldn't need the fat splined adapter to take
> > the die holder. I can take this one off as it's only held on with
> > grubscrews. Two of the four tap-gripping grubscrew holes can be seen
> > half way up the tap holder body.
> >
> And you intended to make one for every tap size you commonly use?

:-) That's why the adaptor for the die holder is only attached with
grubscrews. Four or five 1/2" holders, one for each tap that I use, then
drop in to one adaptor. And the holders are quick to make. (I have some
zero rake carbide tipped drill bits. Medium fine brass granules just
pour out the flutes of the horizontal drill in a golden river, without
any need to back out before it's done. And you can feed at a most
gratifying rate.)

I'll have to buy some larger brass bar for holders for 8 mm and up, or
just use steel, which isn't as much fun.

Erik

--
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Where are you getting R8 square collets for driving taps?

[andy pugh]

On 7 March 2018 at 04:05, Gene Heskett  wrote:

> So the only way is to buy R8's with square bores,

I don't think that is the only way at all.

You could make solid ER32 "collets" with grub screws in the end.
(getting the extractor flange right would be a challenge).
Bored true they would hold the tap true, with drive from the grub
screws on the square.
Needs one per tap size, but it's an easy CNC turning job.

I recently (and accidentally) bought a pair of floating tap holders.
There is no reason that those would not work for rigid tapping, and
they add a bit of relaxation to the process in the event of a problem.
Those take a DA collet and have a pair of grub-screws to grip the flat.

ER collets specifically for tapping exist (with a square in the back)
https://www.ebay.com/itm/Techniks-1-2-ER25-Rigid-Tap-Collet/122122673510

You could add a pair of drive grub-screws to a standard round R8
collet. You might need to soften it off to allow tapping, though.
At which point you might as well make your own, again it's a simple
turning job. You wouldn't need to heat treat for your volume of work.
It would not need to be a split collet. Bored for the tap diameter and
relying on screws for grip and retention it ought to be fine.

-- 
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

--
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Tap Hat photo

[Gene Heskett]

On Wednesday 07 March 2018 02:00:46 Erik Christiansen wrote:

> Hi Gene,
>
> Here's a posed pic with die holder removed for clarity, showing the
> Tap Hat aligned vertically by a centre drill. (Imagine that the chuck
> is still over a hole just drilled in a clamped-down workpiece, with
> the drill bit swapped for the centre drill for the next hole in a
> sequence, since it's more rigid and convenient than the longer drill.)
> You'll need to zoom in a bit to see the detail.
>
> To go in a collet, you wouldn't need the fat splined adapter to take
> the die holder. I can take this one off as it's only held on with
> grubscrews. Two of the four tap-gripping grubscrew holes can be seen
> half way up the tap holder body.
>
And you intended to make one for every tap size you commonly use?

> It may be that in addition to using the largest diameter for which you
> have a collet, using brass might increase grip, as the steel collet
> can impress its micro-roughness on the brass, even if only as elastic
> deformation, rather than slipping on a harder steel surface. (Pure
> theoretical mental-coggery, but perhaps worth the experiment.)

Note in that regard already made, just haven't verified it yet.

> Best of luck in avoiding expensive solutions.
>
> Erik

Looks interesting, and doable.  Thanks Erik.

-- 
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 

--
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Where are you getting R8 square collets for driving taps?

[Gene Heskett]

On Wednesday 07 March 2018 02:38:37 Marcus Bowman wrote:

> On 7 Mar 2018, at 06:28, Erik Christiansen wrote:
> > On 07.03.18 00:58, Gene Heskett wrote:
> >> And the grub screws stayed tight?
>
> I made a whole tapping system for my pillar tool, for small taps,
> using the 4-grubscrew technique, and I have used it successfully for
> years. I only use it for threads below M3, though, and only for manual
> tapping. One flaw is that although the grubscrews stay fairly tight,
> most of the time, they do have a tendency to work loose because of the
> angle of the twisting force, which is roughly parallel to the flat of
> the squares, at the tangent point of the imaginary same-diameter
> circle. Another more annoying problem is that there is nothing much to
> stop the tap from tending to slip along its long axis, as the screws
> slacken slightly. What they need is a conical hole, a vee or a flat
> with shoulders ground into the shank, to stop the sliding. For larger
> taps, that would be easier to arrange, but I suspect the forces
> involved with those larger taps would tend to magnify the problems.
>
> Is the answer not to use a thread mill? Expensive - yes - but more
> controllable and easier to cut the thread in several passes, I think.
> I've no experience, except of looking at my shockingly expensive
> thread mill cutter and wondering about its life expectancy.
>
>
> Marcus
>
I actually have one of those, bought in my younger and dumber days. But 
its never been used as its 3/4" OD. Minimum practical hole would be at 
least 1.5". In HSS, life would be what, 4 tapped holes in clean steel? I 
might use it someday, if I ever need to tap for a >1.5" bolt... I can't 
imagine using it for anything but a monster woodworking vices nut.
>
> --
> Check out the vibrant tech community on one of the world's
> most engaging tech sites, Slashdot.org! http://sdm.link/slashdot
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users



-- 
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 

--
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users