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Re: Question about turning down and runout

MERTON B BAKER
 

Speaking of collets, HSM had an article on making a drawtube type 5-C collet
attachment for a big lathe a while back, and I copied the idea and made one
for 3-C collets to fit on my HF 7x10 by scaling it down a bit. I already
had a couple of 3-C Collets so the whole project was fairly simple. I have
pix if anyone is interested. Off list, please The closer was drilled &
bored for the collet shank, and then turned MT #3 on the outside, set in
place in the spindle taper with the mallet, faced flush with the spindle
flange, and then taper bored for the closing taper. this puts the collet
nose nearly flush with the face of the spindle flange, and gives you the use
of the whole 10" of bed. I cut & spliced the unthreaded portion of the LS,
& moved the pillow block to the very end of the bed so the carriage could
use all of it.

Mert

-----Original Message-----
From: 7x12minilathe@...
[mailto:7x12minilathe@...]On Behalf Of GadgetBuilder
Sent: Thursday, December 06, 2012 4:06 PM
To: 7x12minilathe@...
Subject: [7x12minilathe] Re: Question about turning down and runout


There are some things you can do that may improve your chuck's runout, see:
< >

It is possible to get work running very close to true in a 3 jaw using this
approach: < >
Not everyone's cup of tea but it works well for me. Even when the end of
the work near the chuck runs true it can take some fussing to get the far
end to run true at the same time.

Hex and square collets are available for some collet types, most commonly
for 5C. This would require a 5C collet chuck for your lathe which can be
purchased or built (not a beginner project). 5C collets have a small range
per collet so this would require use of standard sizes of hex stock - 1/4
being a common size.

John

--- In 7x12minilathe@..., "Exibar" <exibar@...> wrote:

So you guys are saying that I'm pretty much within the tolerances of the
machine?
What I'm gunna have to do is re-run this experiment, but keep careful
notes and post them here to get thoughts on if I'm just being way too anal
or if I truly have an issue.... I'm an IT computer security engineer by
day, so I tend to think way down to the 1's and 0's sometime LOL

RE: collets... Some pieces I want to make are made from 1/4" hex
stock... Do they make hex collets? Or can I use. Quarter inch "regular"
collets for hex stock?

Great information guys! Thank you very much :-)

Mike B
Sent via BlackBerry by AT&T

-----Original Message-----
From: Vince Vielhaber <vev@...>
Sender: 7x12minilathe@...
Date: Thu, 6 Dec 2012 14:10:27
To: 7x12minilathe@...<7x12minilathe@...>
Reply-To: 7x12minilathe@...
Subject: RE: [7x12minilathe] Re: Question about turning down and runout

On Thu, 6 Dec 2012, gerry waclawiak wrote:

Congrats Mike B you have just discovered the problem with most 3 jaw
chucks, that of repeatability when re-chucking.

There are a couple of things that you can do to minimise.

If you can arrange all machining operations without re-chucking then
your parts will be pretty much spot-on. This is often possible with a little
thought about the sequence you use for the necessary operations

If you absolutely must re-chuck then mark a jaw and the part with a felt
tip pen or similar and re-chuck matching the marks - that should reduce your
run-out considerably.

If you can get 0.005" with the stock 3 jaw with re-chucking that is
pretty respectable, if you want better you need to invest in a 4 jaw
independent to go with your dial indicator


Or consider using collets.


Vince.
--
Michigan VHF Corp.
The Foggy Mist Emporium



------------------------------------

Yahoo! Groups Links
Re: Question about turning down and runout

 

¿ªÔÆÌåÓý

Using a round collet to hold hex stock?would be awkward, Mike. You would have to avoid getting a corner of the stock coinciding with a slit in the collet.
?
If you had a 4-jaw, you could try making a tube of the same internal diameter as the across corners dimension of the hex, slitting it down one side?to form a single slit collet, then use the 4-jaw to close that down on the hex, and also to shuffle it around until it ran true. But how to ascertain?when?hex (or square) stock is running true is a question to which I don't know the answer. I bet someone on here does, though.
?
Andy
To: 7x12minilathe@...
From: exibar@...
Date: Thu, 6 Dec 2012 22:02:47 +0000
Subject: Re: [7x12minilathe] Question about turning down and runout

?
It certainly does help! Thank you all very much!

I can't seem to find MT3 hex collets.. But plenty of 5c hex collets... Only 5c chuck I saw was almost 300 bucks... That ain't gunna happen.... Anyone know of a source for MT3 hex 1/4" collets? Or a cheap 5c chuck?

How accurate could I get putting a hex into a round collet? Or is that just silly to even think about?

Thanks all!
Mike B
Sent via BlackBerry by AT&T
From: John Kiely
Sender: 7x12minilathe@...
Date: Thu, 6 Dec 2012 13:13:44 -0800 (PST)
To: 7x12minilathe@...<7x12minilathe@...>
ReplyTo: 7x12minilathe@...
Subject: Re: [7x12minilathe] Question about turning down and runout

?

I favour a 4 jaw chuck as the other guys have mentioned. You will need a good DTI?to go with it! Two chuck keys for the 4 jaw makes lining up easier.
If using a minilathe with a 4 jaw chuck you might have to shorten the arms/wings on the Chuck Key to fit on the inside/offside of the lathe. Space there is on certain lathes is at a premium.
If you are turning softer metals just beware that the metal can score and dig in to the chuck jaws resulting in the work piece drifting. In this case, use lighter cuts and don't squeeze the jaws too tight.
Collets are expensive, for a small run you could try a piece of hard wood in the jaws. Drill a hole with?a drill bit in the?tailstock?to fit your work piece and use a screw to hold the piece in place. It's not very hardwearing but for a small amount of use and softer metals?it's perfect.
If you don't have a 4 jaw chuck you can always try using some shims between the jaws and the workpiece to get everything bang on?
For perfect accurate and repeatable work look in to using collets as others have already suggested.
Hope some of this helps?
?
John Kiely (IRL)

From: Exibar To: 7x12minilathe@...
Sent: Thursday, December 6, 2012 5:52 PM
Subject: [7x12minilathe] Question about turning down and runout

Ok, so here's an interesting 'something' that I'd like thoughts on...

? First of all, I went through and ensured that my lathe is spot on with alignment, shaft not bent, chuck is spinning true (well, less than .003, about .0025 runout), etc etc

? So, I take a 6 inch piece of .050" round bar I got from Lowes, chuck it up ( 4", 3 jaw chuck), check with dial gauge and it's running true (needle swings about .001ish) and turn down about an inch and quarter down to 5/16'ths....? Check the new section and it's dead on, dial indicator barely vibrates it moves so little....
? ? I then part it off, remove the large piece from the chuck and then chuck up the freshly turned down section....? And what happens?? It has over .010" of runout....? What the heck?? Shouldn't that be running true?
? If I turn it in the chuck and then retighten, I can lessen the runout down to slight over .005...? But this is a piece that was running dead nuts on before...


? I haven't pulle my crossslide off and cleaned inspected that assembly, I always suspect the gibs...? I should check LMS for a new set of gibs... At least to cross that off the list...

? Any thoughts guys?? Is this odd or too be expected?? I don't recall ever running into this type of issue before :-(


? Thanks!
? Mike B
Sent via BlackBerry by AT&T

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Re: Question about turning down and runout

 

It certainly does help! Thank you all very much!

I can't seem to find MT3 hex collets.. But plenty of 5c hex collets... Only 5c chuck I saw was almost 300 bucks... That ain't gunna happen.... Anyone know of a source for MT3 hex 1/4" collets? Or a cheap 5c chuck?

How accurate could I get putting a hex into a round collet? Or is that just silly to even think about?

Thanks all!
Mike B
Sent via BlackBerry by AT&T
From: John Kiely <john_kiely@...>
Sender: 7x12minilathe@...
Date: Thu, 6 Dec 2012 13:13:44 -0800 (PST)
To: 7x12minilathe@...<7x12minilathe@...>
ReplyTo: 7x12minilathe@...
Subject: Re: [7x12minilathe] Question about turning down and runout

?

I favour a 4 jaw chuck as the other guys have mentioned. You will need a good DTI?to go with it! Two chuck keys for the 4 jaw makes lining up easier.
If using a minilathe with a 4 jaw chuck you might have to shorten the arms/wings on the Chuck Key to fit on the inside/offside of the lathe. Space there is on certain lathes is at a premium.
If you are turning softer metals just beware that the metal can score and dig in to the chuck jaws resulting in the work piece drifting. In this case, use lighter cuts and don't squeeze the jaws too tight.
Collets are expensive, for a small run you could try a piece of hard wood in the jaws. Drill a hole with?a drill bit in the?tailstock?to fit your work piece and use a screw to hold the piece in place. It's not very hardwearing but for a small amount of use and softer metals?it's perfect.
If you don't have a 4 jaw chuck you can always try using some shims between the jaws and the workpiece to get everything bang on?
For perfect accurate and repeatable work look in to using collets as others have already suggested.
Hope some of this helps?
?
John Kiely (IRL)

From: Exibar <exibar@...>
To: 7x12minilathe@...
Sent: Thursday, December 6, 2012 5:52 PM
Subject: [7x12minilathe] Question about turning down and runout

Ok, so here's an interesting 'something' that I'd like thoughts on...

? First of all, I went through and ensured that my lathe is spot on with alignment, shaft not bent, chuck is spinning true (well, less than .003, about .0025 runout), etc etc

? So, I take a 6 inch piece of .050" round bar I got from Lowes, chuck it up ( 4", 3 jaw chuck), check with dial gauge and it's running true (needle swings about .001ish) and turn down about an inch and quarter down to 5/16'ths....? Check the new section and it's dead on, dial indicator barely vibrates it moves so little....
? ? I then part it off, remove the large piece from the chuck and then chuck up the freshly turned down section....? And what happens?? It has over .010" of runout....? What the heck?? Shouldn't that be running true?
? If I turn it in the chuck and then retighten, I can lessen the runout down to slight over .005...? But this is a piece that was running dead nuts on before...


? I haven't pulle my crossslide off and cleaned inspected that assembly, I always suspect the gibs...? I should check LMS for a new set of gibs... At least to cross that off the list...

? Any thoughts guys?? Is this odd or too be expected?? I don't recall ever running into this type of issue before :-(


? Thanks!
? Mike B
Sent via BlackBerry by AT&T

------------------------------------

Yahoo! Groups Links

<*> To visit your group on the web, go to:
? ? http://groups.yahoo.com/group/7x12minilathe/

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Re: Narrow angle center drill

 

On Thursday, December 06, 2012 03:57:31 am you wrote:
I took a picture of the center drill in question next to the 60¡ã one from my set from LMS.>
>
Any ideas as to what it's tued for?
Chuck
just a guess
if you use it to flair out the end of a thru hole you'd get a venturi tube
those are used in a lot of things but are usually tucked in where you cant see them

Brian
--
Nemo Me Impune Lacessit
Re: Question about turning down and runout

 

I favour a 4 jaw chuck as the other guys have mentioned. You will need a good DTI?to go with it! Two chuck keys for the 4 jaw makes lining up easier.
If using a minilathe with a 4 jaw chuck you might have to shorten the arms/wings on the Chuck Key to fit on the inside/offside of the lathe. Space there is on certain lathes is at a premium.
If you are turning softer metals just beware that the metal can score and dig in to the chuck jaws resulting in the work piece drifting. In this case, use lighter cuts and don't squeeze the jaws too tight.
Collets are expensive, for a small run you could try a piece of hard wood in the jaws. Drill a hole with?a drill bit in the?tailstock?to fit your work piece and use a screw to hold the piece in place. It's not very hardwearing but for a small amount of use and softer metals?it's perfect.
If you don't have a 4 jaw chuck you can always try using some shims between the jaws and the workpiece to get everything bang on?
For perfect accurate and repeatable work look in to using collets as others have already suggested.
Hope some of this helps?
?
John Kiely (IRL)

From: Exibar
To: 7x12minilathe@...
Sent: Thursday, December 6, 2012 5:52 PM
Subject: [7x12minilathe] Question about turning down and runout

Ok, so here's an interesting 'something' that I'd like thoughts on...

? First of all, I went through and ensured that my lathe is spot on with alignment, shaft not bent, chuck is spinning true (well, less than .003, about .0025 runout), etc etc

? So, I take a 6 inch piece of .050" round bar I got from Lowes, chuck it up ( 4", 3 jaw chuck), check with dial gauge and it's running true (needle swings about .001ish) and turn down about an inch and quarter down to 5/16'ths....? Check the new section and it's dead on, dial indicator barely vibrates it moves so little....
? ? I then part it off, remove the large piece from the chuck and then chuck up the freshly turned down section....? And what happens?? It has over .010" of runout....? What the heck?? Shouldn't that be running true?
? If I turn it in the chuck and then retighten, I can lessen the runout down to slight over .005...? But this is a piece that was running dead nuts on before...


? I haven't pulle my crossslide off and cleaned inspected that assembly, I always suspect the gibs...? I should check LMS for a new set of gibs... At least to cross that off the list...

? Any thoughts guys?? Is this odd or too be expected?? I don't recall ever running into this type of issue before :-(


? Thanks!
? Mike B
Sent via BlackBerry by AT&T

------------------------------------

Yahoo! Groups Links

<*> To visit your group on the web, go to:
? ? http://groups.yahoo.com/group/7x12minilathe/

<*> Your email settings:
? ? Individual Email | Traditional

<*> To change settings online go to:
? ?
? ? (Yahoo! ID required)

<*> To change settings via email:
? ? 7x12minilathe-digest@...
? ? 7x12minilathe-fullfeatured@...

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? ? 7x12minilathe-unsubscribe@...

<*> Your use of Yahoo! Groups is subject to:
? ? http://docs.yahoo.com/info/terms/
Re: Question about turning down and runout

 

There are some things you can do that may improve your chuck's runout, see: < >

It is possible to get work running very close to true in a 3 jaw using this approach: < >
Not everyone's cup of tea but it works well for me. Even when the end of the work near the chuck runs true it can take some fussing to get the far end to run true at the same time.

Hex and square collets are available for some collet types, most commonly for 5C. This would require a 5C collet chuck for your lathe which can be purchased or built (not a beginner project). 5C collets have a small range per collet so this would require use of standard sizes of hex stock - 1/4 being a common size.

John

--- In 7x12minilathe@..., "Exibar" <exibar@...> wrote:

So you guys are saying that I'm pretty much within the tolerances of the machine?
What I'm gunna have to do is re-run this experiment, but keep careful notes and post them here to get thoughts on if I'm just being way too anal or if I truly have an issue.... I'm an IT computer security engineer by day, so I tend to think way down to the 1's and 0's sometime LOL

RE: collets... Some pieces I want to make are made from 1/4" hex stock... Do they make hex collets? Or can I use. Quarter inch "regular" collets for hex stock?

Great information guys! Thank you very much :-)

Mike B
Sent via BlackBerry by AT&T

-----Original Message-----
From: Vince Vielhaber <vev@...>
Sender: 7x12minilathe@...
Date: Thu, 6 Dec 2012 14:10:27
To: 7x12minilathe@...<7x12minilathe@...>
Reply-To: 7x12minilathe@...
Subject: RE: [7x12minilathe] Re: Question about turning down and runout

On Thu, 6 Dec 2012, gerry waclawiak wrote:

Congrats Mike B you have just discovered the problem with most 3 jaw chucks, that of repeatability when re-chucking.

There are a couple of things that you can do to minimise.

If you can arrange all machining operations without re-chucking then your parts will be pretty much spot-on. This is often possible with a little thought about the sequence you use for the necessary operations

If you absolutely must re-chuck then mark a jaw and the part with a felt tip pen or similar and re-chuck matching the marks - that should reduce your run-out considerably.

If you can get 0.005" with the stock 3 jaw with re-chucking that is pretty respectable, if you want better you need to invest in a 4 jaw independent to go with your dial indicator

Or consider using collets.


Vince.
--
Michigan VHF Corp.
The Foggy Mist Emporium
Re: Narrow angle center drill

tdhofstetter
 

That was my first kneejerk thought - it's got about the sort of included angle that an engraving bit might have. It doesn't seem to have an engraver's point, though - it seems (at least from what I can see) to have a drilling point.

My guess is that it wasn't shipped from the factory looking like that, that it was originally a normal center drill, but modified for some specific purpose, say for use as a specialized tapered reamer or something.

-- Tim --

--- In 7x12minilathe@..., "chucketn" <chunk07@...> wrote:

In annother forum, it was suggested the bit in question could be an ingraving bit for a pantograph, what do ya'll think? I'd think it would be too fragile for that.

Chuck
Re: Question about turning down and runout

MERTON B BAKER
 

Amazing, isn't it? OK, here's what went on: 1. Your chuck is running true,
but that's the chuck body. Are the jaws holing the 6" long piece of 1/2"
stock truly centered? Possibly, but not probably.

2. Now, that bar is running true. Where? Out at the end? Or next to the
chuck? If you just checked it out at the end, It's entirely possible that
the bar is bent a few thou, and your chuck is holding it a few thou off, &
you have a cancellation of error. Turn a 1.5" section down, and all errors
disappear, it runs true. ANY time you turn something in your lathe held
only in the chuck, it will run true on the turned part. It will also be
straight, and if your lathe spindle it lined up true with the carriage
travel along the bed, it will not be tapered, either.

3. Cut that freshly turned, straight piece off, and put it in the chuck.
If you find that it does not run true in that case, you have discovered that
the chuck does not hold things exactly centered with the lathe axis.

Fear not. most chucks don't. None of mine do, either, but all work turned
in my lathes runs true where it's been turned, even if not elsewhere. The
same is true of your lathe also. Not if you take it out of the chuck and
then put it back in though. If you very carefully mark the work at the #1
chuck jaw and make a serious effort to get it back the same way it came out,
It will run fairly true, but never perfectly so.

That is why, if I'm making a part for someone else to run on his lathe, I
carefully machine all the areas that will go onto the spindle on his lathe,
(Not on the chuck, mind you.), without removing the work from mine. Then,
when he gets the part, and puts it on his spindle, who cares if the parts I
left unfinished run true or not. Once he turns 'em on his lathe, while
fixed to his spindle, either bolted on with the locating step matching,
screwed on the spindle, or in the taper, they will always run true on it.

The 3 jaw chuck is a speedy time saving convenience, and one that holds
everything put in it so it runs true, will cost you over ten times what the
ones you see in most catalogs will. For a little less, you can buy one
that, despite the jaws not holding things perfectly, have adjustments so you
can come very close.

Mert

-----Original Message-----
From: 7x12minilathe@...
[mailto:7x12minilathe@...]On Behalf Of Exibar
Sent: Thursday, December 06, 2012 12:53 PM
To: 7x12minilathe@...
Subject: [7x12minilathe] Question about turning down and runout


Ok, so here's an interesting 'something' that I'd like thoughts on...

First of all, I went through and ensured that my lathe is spot on with
alignment, shaft not bent, chuck is spinning true (well, less than .003,
about .0025 runout), etc etc

So, I take a 6 inch piece of .050" round bar I got from Lowes, chuck it up
( 4", 3 jaw chuck), check with dial gauge and it's running true (needle
swings about .001ish) and turn down about an inch and quarter down to
5/16'ths.... Check the new section and it's dead on, dial indicator barely
vibrates it moves so little....
I then part it off, remove the large piece from the chuck and then chuck
up the freshly turned down section.... And what happens? It has over .010"
of runout.... What the heck? Shouldn't that be running true?
If I turn it in the chuck and then retighten, I can lessen the runout
down to slight over .005... But this is a piece that was running dead nuts
on before...


I haven't pulle my crossslide off and cleaned inspected that assembly, I
always suspect the gibs... I should check LMS for a new set of gibs... At
least to cross that off the list...

Any thoughts guys? Is this odd or too be expected? I don't recall ever
running into this type of issue before :-(


Thanks!
Mike B
Sent via BlackBerry by AT&T

------------------------------------

Yahoo! Groups Links
Re: Question about turning down and runout

 

Collets also come in hex and square.



On Thu, 6 Dec 2012, gerry waclawiak wrote:

Collets are another possibility if you only want to turn cylindrical stock over a relatively small range of diameters ,they are very quick and accurate fo repeat work and small scale production.

For the average hobbyist however I think a 4 jaw independent takes a lot of bearing for versatility in the range of sizes and sections that can be gripped and you can also turn eccentrically. Not as quick as collets but just as accurate and pretty fast with proper technique.

Gerry W
Leeds UK

To: 7x12minilathe@...
From: vev@...
Date: Thu, 6 Dec 2012 14:10:27 -0500
Subject: RE: [7x12minilathe] Re: Question about turning down and runout


























On Thu, 6 Dec 2012, gerry waclawiak wrote:



Congrats Mike B you have just discovered the problem with most 3 jaw chucks, that of repeatability when re-chucking.
There are a couple of things that you can do to minimise.
If you can arrange all machining operations without re-chucking then your parts will be pretty much spot-on. This is often possible with a little thought about the sequence you use for the necessary operations
If you absolutely must re-chuck then mark a jaw and the part with a felt tip pen or similar and re-chuck matching the marks - that should reduce your run-out considerably.
If you can get 0.005" with the stock 3 jaw with re-chucking that is pretty respectable, if you want better you need to invest in a 4 jaw independent to go with your dial indicator


Or consider using collets.



Vince.

--

Michigan VHF Corp.

The Foggy Mist Emporium















Vince.
--
Michigan VHF Corp.
The Foggy Mist Emporium
Re: Question about turning down and runout

 

On Thu, 6 Dec 2012, Exibar wrote:

So you guys are saying that I'm pretty much within the tolerances of the machine?
What I'm gunna have to do is re-run this experiment, but keep careful notes and post them here to get thoughts on if I'm just being way too anal or if I truly have an issue.... I'm an IT computer security engineer by day, so I tend to think way down to the 1's and 0's sometime LOL

RE: collets... Some pieces I want to make are made from 1/4" hex stock... Do they make hex collets? Or can I use. Quarter inch "regular" collets for hex stock?

Great information guys! Thank you very much :-)
Yes, they make hex collets.

Vince.
--
Michigan VHF Corp.
The Foggy Mist Emporium
Re: Question about turning down and runout

 

¿ªÔÆÌåÓý

Collets are another possibility if you only want to turn cylindrical stock over a relatively small range of diameters ,they are very quick and accurate fo repeat work and small scale production.

For the average hobbyist however I think a 4 jaw independent takes a lot of bearing for versatility in the range of sizes and sections that can be gripped and you can also turn eccentrically. Not as quick as collets but just as accurate and pretty fast with proper technique.

Gerry W
Leeds UK


To: 7x12minilathe@...
From: vev@...
Date: Thu, 6 Dec 2012 14:10:27 -0500
Subject: RE: [7x12minilathe] Re: Question about turning down and runout

?
On Thu, 6 Dec 2012, gerry waclawiak wrote:

> Congrats Mike B you have just discovered the problem with most 3 jaw chucks, that of repeatability when re-chucking.
>
> There are a couple of things that you can do to minimise.
>
> If you can arrange all machining operations without re-chucking then your parts will be pretty much spot-on. This is often possible with a little thought about the sequence you use for the necessary operations
>
> If you absolutely must re-chuck then mark a jaw and the part with a felt tip pen or similar and re-chuck matching the marks - that should reduce your run-out considerably.
>
> If you can get 0.005" with the stock 3 jaw with re-chucking that is pretty respectable, if you want better you need to invest in a 4 jaw independent to go with your dial indicator

Or consider using collets.

Vince.
--
Michigan VHF Corp.
The Foggy Mist Emporium
Re: Question about turning down and runout

 

So you guys are saying that I'm pretty much within the tolerances of the machine?
What I'm gunna have to do is re-run this experiment, but keep careful notes and post them here to get thoughts on if I'm just being way too anal or if I truly have an issue.... I'm an IT computer security engineer by day, so I tend to think way down to the 1's and 0's sometime LOL

RE: collets... Some pieces I want to make are made from 1/4" hex stock... Do they make hex collets? Or can I use. Quarter inch "regular" collets for hex stock?

Great information guys! Thank you very much :-)

Mike B
Sent via BlackBerry by AT&T
From: Vince Vielhaber <vev@...>
Sender: 7x12minilathe@...
Date: Thu, 6 Dec 2012 14:10:27 -0500 (EST)
To: 7x12minilathe@...<7x12minilathe@...>
ReplyTo: 7x12minilathe@...
Subject: RE: [7x12minilathe] Re: Question about turning down and runout

?

On Thu, 6 Dec 2012, gerry waclawiak wrote:

> Congrats Mike B you have just discovered the problem with most 3 jaw chucks, that of repeatability when re-chucking.
>
> There are a couple of things that you can do to minimise.
>
> If you can arrange all machining operations without re-chucking then your parts will be pretty much spot-on. This is often possible with a little thought about the sequence you use for the necessary operations
>
> If you absolutely must re-chuck then mark a jaw and the part with a felt tip pen or similar and re-chuck matching the marks - that should reduce your run-out considerably.
>
> If you can get 0.005" with the stock 3 jaw with re-chucking that is pretty respectable, if you want better you need to invest in a 4 jaw independent to go with your dial indicator

Or consider using collets.

Vince.
--
Michigan VHF Corp.
The Foggy Mist Emporium
Re: Question about turning down and runout

 

On Thu, 6 Dec 2012, gerry waclawiak wrote:

Congrats Mike B you have just discovered the problem with most 3 jaw chucks, that of repeatability when re-chucking.

There are a couple of things that you can do to minimise.

If you can arrange all machining operations without re-chucking then your parts will be pretty much spot-on. This is often possible with a little thought about the sequence you use for the necessary operations

If you absolutely must re-chuck then mark a jaw and the part with a felt tip pen or similar and re-chuck matching the marks - that should reduce your run-out considerably.

If you can get 0.005" with the stock 3 jaw with re-chucking that is pretty respectable, if you want better you need to invest in a 4 jaw independent to go with your dial indicator

Or consider using collets.


Vince.
--
Michigan VHF Corp.
The Foggy Mist Emporium
Re: Question about turning down and runout

 

¿ªÔÆÌåÓý

Congrats Mike B you have just discovered the problem with most 3 jaw chucks, that of repeatability when re-chucking.

There are a couple of things that you can do to minimise.

If you can arrange all machining operations without re-chucking then? your parts will be pretty much spot-on. This is often possible with a little thought about the sequence you use for the necessary operations

If you absolutely must re-chuck then mark a jaw and the part with a felt tip pen or similar and re-chuck matching the marks - that should reduce your run-out considerably.

If you can get 0.005" with the stock 3 jaw with re-chucking that is pretty respectable, if you want better you need to invest in a 4 jaw independent to go with your dial indicator


Gerry W
Leeds UK


To: 7x12minilathe@...
From: bert.berlin@...
Date: Thu, 6 Dec 2012 18:17:56 +0000
Subject: [7x12minilathe] Re: Question about turning down and runout

?
Is the part spec'ed for use in one of the space telescopes? If not, accept a level of precision that will do the intended job, and move on.
bert

--- In 7x12minilathe@..., "Exibar" wrote:
>
> Ok, so here's an interesting 'something' that I'd like thoughts on...
>
> First of all, I went through and ensured that my lathe is spot on with alignment, shaft not bent, chuck is spinning true (well, less than .003, about .0025 runout), etc etc
>
> So, I take a 6 inch piece of .050" round bar I got from Lowes, chuck it up ( 4", 3 jaw chuck), check with dial gauge and it's running true (needle swings about .001ish) and turn down about an inch and quarter down to 5/16'ths.... Check the new section and it's dead on, dial indicator barely vibrates it moves so little....
> I then part it off, remove the large piece from the chuck and then chuck up the freshly turned down section.... And what happens? It has over .010" of runout.... What the heck? Shouldn't that be running true?
> If I turn it in the chuck and then retighten, I can lessen the runout down to slight over .005... But this is a piece that was running dead nuts on before...
>
>
> I haven't pulle my crossslide off and cleaned inspected that assembly, I always suspect the gibs... I should check LMS for a new set of gibs... At least to cross that off the list...
>
> Any thoughts guys? Is this odd or too be expected? I don't recall ever running into this type of issue before :-(
>
>
> Thanks!
> Mike B
> Sent via BlackBerry by AT&T
>
Re: 7x Lathe Transmission Gear Specs?

 

¿ªÔÆÌåÓý

Like John L I don't throw much either. The old plastic gears from my Sieg mini-mill (same basic? bits as the mini-lathe) gives a module of about 2.2 also so I'd go for Module 2.25, the closest (they run in 0.25mm increments)

The change gears are Module 1

Gerry W
Leeds UK


To: 7x12minilathe@...
From: andyf.1108@...
Date: Thu, 6 Dec 2012 18:01:58 +0000
Subject: [7x12minilathe] Re: 7x Lathe Transmission Gear Specs?

?
I'm sorry I said they were Mod 1.5.

But I think that's what John L told me some months back :)

Andy

--- In 7x12minilathe@..., John Lindo wrote:
>
> I stand corrected.
> Module = PCD (Metric) / # teeth??
> Managed to dig out my old broken plastic gears (never throw anything away) and??
> measured PDM (Pitch Circle Diameter). of both 21 tooth = 45.5 mm dia Module 2.2??
> 29 tooth 63 mm dia. module 2.17 Possibly both rounded off to Module 2 ??
> Cutters normally sold in sets of 8 for MOD ranges of ??0.3 to 8 ??to cut from 12 teeth to rack.
> Thanks
> John L
>
>
> >________________________________
> > From: drmico60
> >To: 7x12minilathe@...
> >Sent: Thursday, December 6, 2012 3:02 PM
> >Subject: [7x12minilathe] Re: 7x Lathe Transmission Gear Specs?
> >
> >
> >??
> >Hi John, Andy and others,
> >I have rechecked my measurements and still come up with Mod 2.2 for the spindle gears. John L's machine is a Real Bull from Amadeal whereas mine is a Sieg version of the minilathe. Is this yet another diifference between the two machines?
> >What is the origin of the OP's machine?
> >Mike
> >
> >--- In 7x12minilathe@..., John Lindo wrote:
> >>
> >> Ian
> >> Andy is correct ????1.5 module.
> >> I went through the heartache of machining new Hi/Low gears out of brass.All the gears were to be fly cut????
> >> off????separate????arbors for each pair and brazing together after finish machining.
> >> This gear cutting project was due to braking one set of plastic gears while turning an????intermittent????cut at a 100 mm diameter.
> >> I bought another plastic set and decided to make my own.Out of brass.Silly mistake.
> >> After making 3 special high speed steel fly cutter bits and a boring bar holder to suit the small and large gears (although all 4 gears are 1.5 module)????
> >> and applied the correct????relief????angles etc.even used slitting saws to cut between teeth to the various root????diameters to help in metal removal.
> >> the chatter and banging (although feeding in several passes) seemed to be beating my Weiss mill (the Rolls of the Chinese mills) to pieces.I gave up.
> >> I still have the cutters if you want them.just send me a PM of your address.
> >> Also check out out of Hong Kong???? they have good offers.
> >> It's possibly better to buy the off the shelf steel gears and save your tooling and machines for other projects.
> >> Again,my Real Bull lathe runs fine with steel gears,but noisy,I was told that the noise will reduce in time,I am still waiting.
> >> I????regularly????apply lithium (white) grease through my cut out hatch.see link.and it does????quieten????it down.
> >>
> >>
> >> possibly the new brushless High torque lathes have not this problem gear problem.
> >> Who would of thought we could travel around the world after the Wright brothers barely got off the ground.
> >> Anyway.
> >> Also I drop oil directly onto the H/L shift mechanism through the????inspection????hatch.,note from the photos the other lube tube is oiling the plumber block of the feed screw.
> >> Again no need to remove the back cover.The plastic tube is attached to a nipple on top of the bearing block.
> >> Using an inspection cover you can also do regular greasing of the tapered roller bearings without having to dismantle the spindle.
> >> Regards
> >> John L
> >> Spain.
> >>
> >>
> >>
> >>
> >>
> >> >________________________________
> >> > From: Andy Franks
> >> >To: 7x12minilathe@...
> >> >Sent: Thursday, December 6, 2012 10:33 AM
> >> >Subject: RE: [7x12minilathe] Re: 7x Lathe Transmission Gear Specs?
> >> >
> >> >
> >> >????
> >> >Ian, I believe the gears inside the headstock are Mod 1.5.
> >> >????
> >> >You can check this by measuring the outside diameter of one of them in millimetres; preferably one with an even number of teeth. If that measurement is approximately equal to (N + 2) x 1.5 where N is the number of teeth, then they are Mod 1.5.
> >> >????
> >> >If I'm wrong and????they are a different Module, use the formula Mod = OD/(N + 2). The gears????are made in China, so don't expect it to work out exactly.
> >> >????
> >> >In terms of diametral pitch, Mod 1.5 is just under 17DP, so if you prefer to work in DP, 16 DP would work OK. Actually, these gears only have to mesh with each other so don't have to be to any particular standard, as????long as they are about the right overall????size.
> >> >????
> >> >Will it be difficult to cut the smaller gear without the cutter hitting the larger one to which it is attached?
> >> >????
> >> >Metal headstock gears are available from LMS. They are probably noisier than the plastic ones.
> >> >????
> >> >Andy
> >> >????
> >> >
> >> >
> >> >________________________________
> >> > To: 7x12minilathe@...
> >> >From: iannovak19@
> >> >Date: Thu, 6 Dec 2012 06:31:07 +0000
> >> >Subject: [7x12minilathe] Re: 7x Lathe Transmission Gear Specs?
> >> >
> >> >????
> >> >Thank you for your reply. I am not so worried about the specs of the gears that are right behind the cover. I am looking for specs (pressure angle, diameter, spacing between gears, pitch diameter etc.) for the Hi-Low gears inside the cast spindle head stock.
> >> >
> >> >These gears are the most important for the lathe, and the most likely to break compared the the carriage travel speed adjustment gears.
> >> >
> >> >If they turn out to be straightforward to make with the help of the experienced instructors, it could be a valuable learning experience and a economic decision.
> >> >
> >> >Thank you,
> >> >
> >> >Ian
> >> >
> >> >--- In 7x12minilathe@..., SirJohnOfYork wrote:
> >> >>
> >> >> Metric. Module 1. Center hole is 12mm and on most lathes the keyway is
> >> >> 3mm (there were some 7x mini-lathes with 4mm
> >> keyways, check yours if in
> >> >> doubt.) Thickness is 8mm, but I made some using 5/16" thick plate that I
> >> >> happened to have handy and they work well.
> >> >>
> >> >> You can look at LMS to see the replacement gear sets here
> >> >> <> for the plastic and here
> >> >> <> for the steel sets, which list all of the
> >> >> factory gear sizes minus the two 80 tooth gears which are sold
> >> >> separately, here <> (plastic) and here
> >> >> <> (steel).
> >> >>
> >> >> Useful sizes not included on the older lathes are 21 and 32 tooth
> >> >> gears, with the 21 gear
> >> being most helpful for doing closer
> >> >> approximations of metric threads with a 16tpi leadscrew (or I believe
> >> >> inch threads with a metric leadscrew, not sure where you are located or
> >> >> whether you have a U.S inch or metric leadscrew machine.).
> >> >>
> >> >> LMS's Change Gear Page
> >> >> <> is real handy
> >> >> for finding workable gear combos for threads not listed on the machine
> >> >> labels or instructions, and for seeing how the 21 tooth gear can make
> >> >> for more accurate approximations and such. To see the A, B, C & D gears
> >> >> illustrated on that page, you need to first enter in a desired thread
> >> >> and click Calculate, then scroll down to see the pictures. There is a
> >> >> spacer that is normally behind the D gear than can be swapped to
> >> in
> >> >> front of it for those gear combos where an "any" gear is specified, so D
> >> >> will mesh directly with B (instead of with C as per normal).
> >> >>
> >> >> Cheers,
> >> >> John Z.
> >> >> York, Pa. USA
> >> >>
> >> >> On 12/5/2012 10:40 PM, Ian wrote:
> >> >> >
> >> >> > Hello. I have the resources to make my own metal gears in my machine
> >> >> > shop at school. I would like to be able to make my own set of
> >> >> > replacement Metal Gears for my 7x Mini lathe.
> >> >> >
> >> >> > I am looking for help in finding information about the dimensions and
> >> >> > specifications of the gears located in the head stock.
> >> >> >
> >> >> > Thank you,
> >> >> >
> >> >> > Ian
> >> >> >
> >> >>
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >>
> >
> >
> >
> >
> >
>
Re: Question about turning down and runout

sky_king602002
 

Is the part spec'ed for use in one of the space telescopes? If not, accept a level of precision that will do the intended job, and move on.
bert

--- In 7x12minilathe@..., "Exibar" <exibar@...> wrote:

Ok, so here's an interesting 'something' that I'd like thoughts on...

First of all, I went through and ensured that my lathe is spot on with alignment, shaft not bent, chuck is spinning true (well, less than .003, about .0025 runout), etc etc

So, I take a 6 inch piece of .050" round bar I got from Lowes, chuck it up ( 4", 3 jaw chuck), check with dial gauge and it's running true (needle swings about .001ish) and turn down about an inch and quarter down to 5/16'ths.... Check the new section and it's dead on, dial indicator barely vibrates it moves so little....
I then part it off, remove the large piece from the chuck and then chuck up the freshly turned down section.... And what happens? It has over .010" of runout.... What the heck? Shouldn't that be running true?
If I turn it in the chuck and then retighten, I can lessen the runout down to slight over .005... But this is a piece that was running dead nuts on before...


I haven't pulle my crossslide off and cleaned inspected that assembly, I always suspect the gibs... I should check LMS for a new set of gibs... At least to cross that off the list...

Any thoughts guys? Is this odd or too be expected? I don't recall ever running into this type of issue before :-(


Thanks!
Mike B
Sent via BlackBerry by AT&T
Re: 7x Lathe Transmission Gear Specs?

 

I'm sorry I said they were Mod 1.5.

But I think that's what John L told me some months back :)

Andy

--- In 7x12minilathe@..., John Lindo <bechetboat@...> wrote:

I stand corrected.
Module = PCD (Metric) / # teeth??
Managed to dig out my old broken plastic gears (never throw anything away) and??
measured PDM (Pitch Circle Diameter). of both 21 tooth = 45.5 mm dia Module 2.2??
29 tooth 63 mm dia. module 2.17 Possibly both rounded off to Module 2 ??
Cutters normally sold in sets of 8 for MOD ranges of ??0.3 to 8 ??to cut from 12 teeth to rack.
Thanks
John L


________________________________
From: drmico60 <mikey.cox@...>
To: 7x12minilathe@...
Sent: Thursday, December 6, 2012 3:02 PM
Subject: [7x12minilathe] Re: 7x Lathe Transmission Gear Specs?


??
Hi John, Andy and others,
I have rechecked my measurements and still come up with Mod 2.2 for the spindle gears. John L's machine is a Real Bull from Amadeal whereas mine is a Sieg version of the minilathe. Is this yet another diifference between the two machines?
What is the origin of the OP's machine?
Mike

--- In 7x12minilathe@..., John Lindo <bechetboat@> wrote:

Ian
Andy is correct ????1.5 module.
I went through the heartache of machining new Hi/Low gears out of brass.All the gears were to be fly cut????
off????separate????arbors for each pair and brazing together after finish machining.
This gear cutting project was due to braking one set of plastic gears while turning an????intermittent????cut at a 100 mm diameter.
I bought another plastic set and decided to make my own.Out of brass.Silly mistake.
After making 3 special high speed steel fly cutter bits and a boring bar holder to suit the small and large gears (although all 4 gears are 1.5 module)????
and applied the correct????relief????angles etc.even used slitting saws to cut between teeth to the various root????diameters to help in metal removal.
the chatter and banging (although feeding in several passes) seemed to be beating my Weiss mill (the Rolls of the Chinese mills) to pieces.I gave up.
I still have the cutters if you want them.just send me a PM of your address.
Also check out out of Hong Kong???? they have good offers.
It's possibly better to buy the off the shelf steel gears and save your tooling and machines for other projects.
Again,my Real Bull lathe runs fine with steel gears,but noisy,I was told that the noise will reduce in time,I am still waiting.
I????regularly????apply lithium (white) grease through my cut out hatch.see link.and it does????quieten????it down.


possibly the new brushless High torque lathes have not this problem gear problem.
Who would of thought we could travel around the world after the Wright brothers barely got off the ground.
Anyway.
Also I drop oil directly onto the H/L shift mechanism through the????inspection????hatch.,note from the photos the other lube tube is oiling the plumber block of the feed screw.
Again no need to remove the back cover.The plastic tube is attached to a nipple on top of the bearing block.
Using an inspection cover you can also do regular greasing of the tapered roller bearings without having to dismantle the spindle.
Regards
John L
Spain.





________________________________
From: Andy Franks <andyf.1108@>
To: 7x12minilathe@...
Sent: Thursday, December 6, 2012 10:33 AM
Subject: RE: [7x12minilathe] Re: 7x Lathe Transmission Gear Specs?


????
Ian, I believe the gears inside the headstock are Mod 1.5.
????
You can check this by measuring the outside diameter of one of them in millimetres; preferably one with an even number of teeth. If that measurement is approximately equal to (N + 2) x 1.5 where N is the number of teeth, then they are Mod 1.5.
????
If I'm wrong and????they are a different Module, use the formula Mod = OD/(N + 2). The gears????are made in China, so don't expect it to work out exactly.
????
In terms of diametral pitch, Mod 1.5 is just under 17DP, so if you prefer to work in DP, 16 DP would work OK. Actually, these gears only have to mesh with each other so don't have to be to any particular standard, as????long as they are about the right overall????size.
????
Will it be difficult to cut the smaller gear without the cutter hitting the larger one to which it is attached?
????
Metal headstock gears are available from LMS. They are probably noisier than the plastic ones.
????
Andy
????


________________________________
To: 7x12minilathe@...
From: iannovak19@
Date: Thu, 6 Dec 2012 06:31:07 +0000
Subject: [7x12minilathe] Re: 7x Lathe Transmission Gear Specs?

????
Thank you for your reply. I am not so worried about the specs of the gears that are right behind the cover. I am looking for specs (pressure angle, diameter, spacing between gears, pitch diameter etc.) for the Hi-Low gears inside the cast spindle head stock.

These gears are the most important for the lathe, and the most likely to break compared the the carriage travel speed adjustment gears.

If they turn out to be straightforward to make with the help of the experienced instructors, it could be a valuable learning experience and a economic decision.

Thank you,

Ian

--- In 7x12minilathe@..., SirJohnOfYork <steelchipper@> wrote:

Metric. Module 1. Center hole is 12mm and on most lathes the keyway is
3mm (there were some 7x mini-lathes with 4mm
keyways, check yours if in
doubt.) Thickness is 8mm, but I made some using 5/16" thick plate that I
happened to have handy and they work well.

You can look at LMS to see the replacement gear sets here
<> for the plastic and here
<> for the steel sets, which list all of the
factory gear sizes minus the two 80 tooth gears which are sold
separately, here <> (plastic) and here
<> (steel).

Useful sizes not included on the older lathes are 21 and 32 tooth
gears, with the 21 gear
being most helpful for doing closer
approximations of metric threads with a 16tpi leadscrew (or I believe
inch threads with a metric leadscrew, not sure where you are located or
whether you have a U.S inch or metric leadscrew machine.).

LMS's Change Gear Page
<> is real handy
for finding workable gear combos for threads not listed on the machine
labels or instructions, and for seeing how the 21 tooth gear can make
for more accurate approximations and such. To see the A, B, C & D gears
illustrated on that page, you need to first enter in a desired thread
and click Calculate, then scroll down to see the pictures. There is a
spacer that is normally behind the D gear than can be swapped to
in
front of it for those gear combos where an "any" gear is specified, so D
will mesh directly with B (instead of with C as per normal).

Cheers,
John Z.
York, Pa. USA

On 12/5/2012 10:40 PM, Ian wrote:

Hello. I have the resources to make my own metal gears in my machine
shop at school. I would like to be able to make my own set of
replacement Metal Gears for my 7x Mini lathe.

I am looking for help in finding information about the dimensions and
specifications of the gears located in the head stock.

Thank you,

Ian
Re: Narrow angle center drill

 

In annother forum, it was suggested the bit in question could be an ingraving bit for a pantograph, what do ya'll think? I'd think it would be too fragile for that.

Chuck
Re: Question about turning down and runout

Jerry Durand
 

On 12/06/2012 09:52 AM, Exibar wrote:
I then part it off, remove the large piece from the chuck and then chuck up the freshly turned down section.... And what happens? It has over .010" of runout.... What the heck? Shouldn't that be running true?
If I turn it in the chuck and then retighten, I can lessen the runout down to slight over .005... But this is a piece that was running dead nuts on before...
you're using a scroll chuck and the first time you put it in you got lucky.

--
Jerry Durand, Durand Interstellar, Inc. www.interstellar.com
tel: +1 408 356-3886, USA toll free: 1 866 356-3886
Skype: jerrydurand
Question about turning down and runout

 

Ok, so here's an interesting 'something' that I'd like thoughts on...

First of all, I went through and ensured that my lathe is spot on with alignment, shaft not bent, chuck is spinning true (well, less than .003, about .0025 runout), etc etc

So, I take a 6 inch piece of .050" round bar I got from Lowes, chuck it up ( 4", 3 jaw chuck), check with dial gauge and it's running true (needle swings about .001ish) and turn down about an inch and quarter down to 5/16'ths.... Check the new section and it's dead on, dial indicator barely vibrates it moves so little....
I then part it off, remove the large piece from the chuck and then chuck up the freshly turned down section.... And what happens? It has over .010" of runout.... What the heck? Shouldn't that be running true?
If I turn it in the chuck and then retighten, I can lessen the runout down to slight over .005... But this is a piece that was running dead nuts on before...


I haven't pulle my crossslide off and cleaned inspected that assembly, I always suspect the gibs... I should check LMS for a new set of gibs... At least to cross that off the list...

Any thoughts guys? Is this odd or too be expected? I don't recall ever running into this type of issue before :-(


Thanks!
Mike B
Sent via BlackBerry by AT&T
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