Re: [Metal-Shapers-and-Planers] OT big lathe in Texas
Maybe the one on the left is smaller
animal
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On 5/24/23 10:13 PM, Nick Andrews wrote:
I asked seller for details. Too big for my shop. Lodge and Shipley 18"
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I asked seller for details.? ?Too big for my shop. Lodge and Shipley 18"
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Re: Leveling a model 37 15x8 SB lathe
Sent by my iPhone On May 11, 2023, at 4:47 PM, Rick Swineford <terrapinsystems@...> wrote:
?I made some levelers from 2" x 3/8" flat stock.? I drilled a large divot in the center then epoxied a 1/2" carriage…..
You lost me, but that’s just me…how about a photo to illustrate the installed leveler. ?That would help us appreciate your concerns. ?
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Leveling a model 37 15x8 SB lathe
I made some levelers from 2" x 3/8" flat stock.? I drilled a large divot in the center then epoxied a 1/2" carriage bolt in the divot.? I then took a nut threaded it onto the bolt, then 2 heavy washers then inserted them into the mounting holes of the legs.? Another washer and nut went on top.? It is now level.? My concern is that the bolt down hole on these feet that I used for the levelers are on the side of the leg casting, not through the bottom of the inside of the leg.? Lots of pressure on that flange casting.? This is a manual change gear lathe.? I guess my option now is to measure the height of each leg and build shims to replace the levelers.
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Re: Fixing 16" Apron Leak
Actually after looking at it some more tonight, I think I will leave it for now.? The leak is manageable.? Eventually the apron will need to come off to fix it.
--
1969 16" x 6' South Bend Lathe
Garage full of old Mopars........
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I am finally getting my 1969 16" lathe running after moving to my new shop over the last 18 months.? I figure its a good opportunity to fix my pesky oil leak at the apron.? It is leaking at the back plate.
My question is can I get the plate off the back without taking the apron off?? I'm not keen on taking the apron off again, and it I do, I probably will allow it to continue to leak.? If I recall correctly, it used a paper gasket - is that correct?
Thoughts?
--
1969 16" x 6' South Bend Lathe
Garage full of old Mopars........
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Re: 1922 Model 37 15"x8' Max RPM
in my experience you don't need big cuts or high speeds to use carbide tooling.
i cut and thread all the time with my SB13 inch at maybe 300 to 1000 rpm with standard carbide inserts.
maybe carbide on our wiggly hobby machines got a bad rep years ago with dumb and dull negative rake brazed tools.? try a decent brand ( Shars quality at a minimum ) positive inserts.
BTW, now that diamond wheels are cheaper, you can sharpen those cheap brazed carbide tools into quite useable edges.
also, good brazed carbide tools are fine ... we used Hardinge brazed tools to make a zillion contract parts.? i used my resharpened cheap chinese carbides for roughing .. or cutting down shanks on? large diameter drills and reamers for use in my hobby lathes.
just some thoughts and good luck.
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Re: 1922 Model 37 15"x8' Max RPM
There are 3 parts to the answer to this. First, the rating of the V belts. If they are modern, I'd stake my reputation on the answer being that those would be OK up to a shaft speed of at least 3000 rpm, so that isn't the limiting factor (but always worth considering with questions of this type).
Secondly, the chucks or whatever you hold the work in. They have been known to burst if oversped. A case in point, my Colchester Triumph 2000 (= Clausing 15") has a top speed of 2000 rpm. You must use only the speed capable chucks supplied with it. Both the large (needs the gap piece taken out) and small faceplates have their own speed limits indelibly inscribed on them, much lower than the capability of the spindle drive..
Third, the bearings of all the shafts. Layshaft bearings are unlikley to be problematical so long as they are adequately lubricated, as a bit of extra clearance will not affect function, or if rolling elements, likely to be well below the speed rating. It is the headstock bearings that must be considered
In an oil lubricated journal bearing that is running properly, heat is generated, not due to metal on metal contact, but due to the shearing of the viscous oil. The faster you go, with an oil of a given viscosity, the more heat is generated. It is in the nature of most equipment that the bearing housing has a higher mass (thermal inertia) and is better cooled than the shaft. Both grow with rising temperature, but the shaft therefore grows more, thereby reducing the clearance in the bearing. Reducing the clearance increases the shear rate and hence the production of heat. One of 2 things can now happen. Either the temperature rise levels out due to the heat being conducted away (normal running) or the clearance continues to reduce until it vanishes entirely, resulting in a thermal runaway and seizure.
On a belt driven lathe, seizure is not desperately serious, as the belt will slip, although you should beware of results like chucks unscrewing themselves and setting off across the workshop. Generally speaking, the bearings will not be damaged. I have a Myford ML7 (whitemetal bearings) and the railway has a SB 14.5" (cast iron) that both do this if set to the highest speed on a cold start. Generally speaking, a very few seconds later, they have unseized and are fit for running. After an hour of running, a hand on the bearing caps detects a distinct temperature rise.
The reason that seizure happens mostly on cold start is that the oil is then most viscous, the heat input therefore the highest, and the temperature differential between shaft and housing highest. The home of neither of the above lathes is temperature controlled and they can be operated with cold soak temperatures anywhere between sub zero and 40 degrees C. Over this range of temperature, the same oil has an absolutely massive range of viscosity and therefore heat generation.
So what does all the above mean for your lathe with bronze bearings. First and foremost, it may well be MORE, not less, prone to thermal runaway, simply because bronze expands thermally at about double the rate of ferrous metals. An entirely bronze housing would be less prone to seizure as it would expand away from the shaft quickly, but shells in an iron housing are constrained externally and therefore have a tendency to grow inwards.
SB recommend a certain bearing clearance and a certain oil viscosity. Stick with those for a start, and run your lathe at max speed for a bit without anything screwed onto the shaft and the belts slack enough to slip if it seizes so no damage occurs. If seizure occurs, evaluate how quickly it frees off when stopped. If it takes more than about 10 seconds, you have the options of either increasing the bearing clearance or reducing the oil viscosity. if it takes less than 10 seconds, you will probably find that waiting 30 seconds for temperatures to equalise and then starting again will not result in further seizure*. If it still seizes, then you are back to looking at bearing clearances and oil viscosity. If your machine passes this test on a warm day, try it again on a cold day before trusting it!
We all want our headstock bearings to run with as little clearance as possible in the interests of accuracy, and this is why later lathes have rolling element bearings that are adjusted to give zero clearance, but with built in provision for expansion. You need to be aware that a lathe on journal bearings relies on the oil to centre the shaft and hold it there on something resembling a spring, and the higher the rotation speed, the stiffer will be that spring. Ideally, we could close up our bearings for slow speed work and open them up a little for high speed. Better still, it would be automatic.
High speed grinding spindles can be like that by having conical bearings with absolutely minimal clearance, and thin oil. Longitudinal expansion of the shaft slackens the bearing. Neat idea, but a bit much trouble to go to when refurbishing a 100 year old lathe.
* I have a 1932 built Deutz 12HP single cylinder 2 stroke Diesel engine in a 2' gauge loco, and some years back it ran its big end due to an oil supply failure. I fished it out, repaired the oil supply fault, whitemetalled and bored the big end bearing, and stuck it all back together. Just occasionally, if I don't keep the revs down following a cold start, it seizes. 10 seconds later it can be restarted. You may imagine the inertia of the flywheel on an engine like this, but so long as I knock the fuel off as soon as it starts to bind, I get away with it. Once stinking hot, it's fine.
Hope this helps,
Eddie
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------ Original Message ------
From: "Rick Swineford" <terrapinsystems@...>
To: [email protected]
Sent: Wednesday, 26 Apr, 23 At 16:56
Subject: [SouthBendLathe] 1922 Model 37 15"x8' Max RPM
I am putting a model 37 back into service. About 40 years of its life was just sitting at my dad's garage. He had modified it to run off a 220v 1PH motor tied to a truck 4 spd transmision by dual v belts. Then dual v-belts driving the flat-belt cone pulley, 2nd from the bull-gear. I have used it for very minor work over the last 30 years and am now going through it since I am retired. I want to use carbide inserts and need more RPM. I just mounted a digital tach on it and in high gear I am only getting 318 RPM. The books show just under 600 RPM for the max. A gunsmith owned it previously and when I pulled the spindle caps off found bronze bushings which I believe he made. I pulled the caps off to drill and tap for drip oilers. I have ordered a pulley for the motor which will bring it to about 1000 RPM max. Am I exceeding the capability of these bearings/drivetrain? I have attached photos of the bearings.
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1922 Model 37 15"x8' Max RPM
I am putting a model 37 back into service.? About 40 years of its life was just sitting at my dad's garage.? He had modified it to run off a 220v 1PH motor tied to a truck 4 spd transmision by dual v belts.? Then dual v-belts driving the flat-belt cone pulley, 2nd from the bull-gear.? I have used it for very minor work over the last 30 years and am now going through it since I am retired.? I want to use carbide inserts and need more RPM.? I just mounted a digital tach on it and in high gear I am only getting 318 RPM.? The books show just under 600 RPM for the max.? A gunsmith owned it previously and when I pulled the spindle caps off found bronze bushings which I believe he made.? I pulled the caps off to drill and tap for drip oilers.? I have ordered a pulley for the motor which will bring it to about 1000 RPM max.? Am I exceeding the capability of these bearings/drivetrain?? I have attached photos of the bearings.
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Re: Breaking carbide inserts parting off?
You said there is an issue with chatter. ? Are the gibs adjusted properly on the compound and cross slide? ? Do you lock the carage firmly? ?Dont let the tool protrude any further than needed.
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Re: Breaking carbide inserts parting off?
I did, but didn't get the drawing. Was just the casting, but was also cheap... Like me. :)
Bill in OKC?
William R. Meyers, MSgt, USAF(Ret.)
Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement.? SEMPER GUMBY!
Expect in one hand, expectorate in the other. See which one gets full first.
On Friday, April 21, 2023 at 03:46:55 PM CDT, mike allen <animal@...> wrote:
??? ??? Yea , looks like it can be cut down some . These folks
sell the drawings separate so a guy/gal can make their own with
what they have . I don't see why it really has to be made from CI?
but maybe someone else here can school me/us on that matter . the
plans are only $ 6.00 for the tool post or the cross slide . I
thought I had read somewhere at one time that if you bought the
plans & then bought the casting later they would credit you on
the plans when purchasing the casting ?
??? ??? IIRC OKC Bill bought a crossslide kit from a guy that
bought it & never made it .
??? ??? animal
On 4/21/2023 1:29 PM, Andrei wrote:
Looks like that rear parting tool is designed for 12 inch and
bigger lathes. You can probably shave down the casting and alter
the dovetails to make it work on your Sheldon.?
Andrei
Sent: Friday, April 21, 2023 3:31 PM
To: [email protected]
<[email protected]>
Cc: [email protected]
<[email protected]>
Subject: Re: [SouthBendLathe] Breaking carbide inserts
parting off?
?
??? ??? They have a rear mounted parting tool tool post they
also sell .? I should buy the crossslide & just have it
here for when I'm ready to make one . I need to learn
dovetails first .
??? ??? Rear Tool Post
??? ??? animal
On 4/21/2023 12:20 PM, Nick
Andrews wrote:
This is on my 11" Sheldon lathe.? No, haven't tried
snugging the gibs but did lock the saddle.? I guess if I
am taking the time to make something, tweaking the gibs
shouldn't seem like such a chore...
Interesting casting.? Do you then just bolt your tool
post on directly somehow?
On Fri, Apr 21, 2023 at
1:49?PM mike allen < animal@...> wrote:
??? ??? I've seen some of those parting tool supports
that folks make on youtube in the past . Folks seem to
like them ,? but then again its the guy that made it
that says its bitchin . These folks make a longer
crossslide casting that you machine to finish that
allows you to put a tool post behind the work so your
parting tool is mounted upside down , some folks say
this is a huge improvement when parting . This is one
of my projects on my list to make sometime . Are you
locking the saddle & tightening the crossslide
& compound gibs? when parting ?
??? ???
??? ??? animal
On 4/21/2023 11:25 AM, Nick Andrews wrote:
Now I know that for some folks parting off in
the lathe is routine, but for some of us it's a
real PITA.? Or can be.? I've tried using a nice
HSS blade in a holder with lots of oil and
freshly-ground tip and still got it pulling to one
side, and now a 1-inch tall steel blade with
carbide insert for the first time last night.?
Yeah, I broke the insert.? And yes, it was a
cheapo chinese insert.? As delivered, the holder
body was not well made and the bottom of the slot
for the tool was tapered, causing a tilt in the
cutoff blade of about 3 degrees or so.? Imagine
that from an ebay seller!? So I put it in the the
vise and milled the slot more parallel, which
corrected the vertical angle of the cutoff blade,
mostly.? I tried to minimize stick-out but still
got too much chatter.? Part isn't that far out
from the 4-jaw, but a tailstock center might've
helped on chatter.
This is on a piece of 1.5" steel rod I got left
from a construction project, no idea what alloy.?
Maybe I have the wrong speed going and need to
crank it up for carbide cutting.? Heard people say
many home lathes struggle to spin fast enough for
carbide but that seems unlikely.? Haven't tested
higher revs yet, wanted to get your thoughts.
I saw a youtube video this morning? where a guy
made a little foot from a piece of CRS that he
bolted through his tool holder that sits on the
top of the cross slide to keep it from bending
down which seems interesting, but not sure if I
could do that or not on my lathe.??
|
Re: Breaking carbide inserts parting off?
Speaking as someone that struggled with parting, it is something
that requires knowing the lathe you are using. Square, center, and
lock the tool tight. Lock the carriage and compound. It would not
hurt to snug the cross lock just enough that you can still move it
with effort. Do not extend your tool further than necessary. Watch
for tool movement that would indicate something is not tight. Use
back gear and go slow. Recently, I have been using .004" on the
automatic cross feed of my SB9A at around 100 rpm with excellent
results. The auto cross feed prevents feeding too fast and frees my
hand to drip oil and catch the part. The flat belt will slip in the
event of a problem.
A couple of days ago, I tried parting some mystery metal. Turns out
after several attempts that it had been surface hardened. I had to
cut through the first few thou with a carbide turning tool before
switching to my HSS parting tool.
On 4/21/2023 4:50 PM, Andrei wrote:
toggle quoted message
Show quoted text
The GTN2 inserts seem to be the smallest you can find easily. I
saw Shars selling them for their parting tools. I never used
one, but I have been tempted a few times to purchase.?
Parting in the front tool post on relatively small or
light lathes can be a pain. I have a Myford ML7 at home. It's
in nice nick, and I have NEVER succeeded in parting at the
front. The tool digs in and snaps pretty well as soon as it
touches. Fortunately, I have a rear toolpost that works a
treat. If you look at a manual capstan lathe, parting is
ALWAYS done from the back. I have recently acquired a rear
toolpost for the railway's Colchester Triumph 2000 (AKA
Clausing 15") and that will happily run a 4mm HSS blade.
Internal screwcutting has now been promoted to my most feared
operation in place of parting (I have to make 3 off 1 1/8 BSP
nuts for steam pipe unions as soon as the 1 7/8 A/F Hex leaded
gunmetal turns up).
The tool needs to be absolutely sharp. If you need to
apply an increasing force to drive it in, that is a
recipe for disaster.
If a hand ground blade, polish with a diamond file.
The tool must be narrow, and the smaller the lathe, the
narrower the tool.
I front part successfully with carbide on our 14.5" SB
with taper turning attachment because that won't
conveniently take a rear toolpost, but wouldn't use
anything wider than a 3mm cutter. It is, nonetheless,
nerve wracking.
If you look at
(e.g.) the Iscar catalogue you will see dozens of
different chip geometries on the same size of tip.
Pick one with the correct geometry for the material
you are cutting.
Work support is
vital. Cut at no more than 1/4 diameter distance from
the chuck or collet, and ensure they are TIGHT. Ensure
there is at least 1.5 x diameter still in the chuck.
If not, add a centre at the outer end whether you
think it needs it or not. Neglect of any of this could
result in the job deflecting badly in the chuck
(etc.).
Trace and
rectify any source of toolpost deflection under load.
Have the compound slide set so that the sliding part
is not overhanging the fixed part, and ensure that the
leading corner of the toolpost is over solid metal.
With the job moving downwards as in front cutting, any
deflection results in the tool moving into the job,
increasing the cutting force, which increases the
deflection etc. With the job moving upwards as in rear
cutting, the tool tends to deflect away from the job
(phew!) This is why folk construct tool props for
front parting.
On small lathes,
part off at a relatively low speed, regardless of tool
type.
Not sure about
small quantities of cutting oil, but if parting
something that normally takes coolant, even if
optional, I would use coolant flow during parting, if
available. Obviously not for cast iron or cheap brass.
Parting in
stages that create a swarf anti jamming gap as
described by someone else works well, especially if
using the sort of carbide tip that is moulded to curl
the edges of the swarf inwards and you are cutting
material that produces springy swarf in spiral coils.
That stuff can spring out towards flat as soon as it
leaves the tip, and jam in the groove. Intermittent
cutting helps by breaking that sort of swarf into
shorter coils.
The cross feed
during parting generally needs to be done manually,
and slower than the slowest available powered feed.
I think that's
all for the moment.
Eddie
------ Original Message ------
From: "mike allen" <animal@...>
To: [email protected]
Cc: [email protected]
Sent: Friday, 21 Apr, 23 At 20:31
Subject: Re: [SouthBendLathe] Breaking carbide inserts parting off?
They have a rear mounted parting tool tool post they also sell . I should buy the crossslide & just have it here for when I'm ready to make one . I need to learn dovetails first .
Rear Tool Post
animal
On 4/21/2023 12:20 PM, Nick Andrews wrote:
This is on my 11" Sheldon lathe. No, haven't tried snugging the gibs but did lock the saddle. I guess if I am taking the time to make something, tweaking the gibs shouldn't seem like such a chore...
Interesting casting. Do you then just bolt your tool post on directly somehow?
On Fri, Apr 21, 2023 at 1:49?PM mike allen < animal@...> wrote:
I've seen some of those parting tool supports that folks make on youtube in the past . Folks seem to like them , but then again its the guy that made it that says its bitchin . These folks make a longer crossslide casting that you machine to finish that
allows you to put a tool post behind the work so your parting tool is mounted upside down , some folks say this is a huge improvement when parting . This is one of my projects on my list to make sometime . Are you locking the saddle & tightening the crossslide
& compound gibs when parting ?
animal
On 4/21/2023 11:25 AM, Nick Andrews wrote:
Now I know that for some folks parting off in the lathe is routine, but for some of us it's a real PITA. Or can be. I've tried using a nice HSS blade in a holder with lots of oil and freshly-ground tip and still got it pulling to one side, and now a 1-inch
tall steel blade with carbide insert for the first time last night. Yeah, I broke the insert. And yes, it was a cheapo chinese insert. As delivered, the holder body was not well made and the bottom of the slot for the tool was tapered, causing a tilt in the
cutoff blade of about 3 degrees or so. Imagine that from an ebay seller! So I put it in the the vise and milled the slot more parallel, which corrected the vertical angle of the cutoff blade, mostly. I tried to minimize stick-out but still got too much chatter.
Part isn't that far out from the 4-jaw, but a tailstock center might've helped on chatter.
This is on a piece of 1.5" steel rod I got left from a construction project, no idea what alloy. Maybe I have the wrong speed going and need to crank it up for carbide cutting. Heard people say many home lathes struggle to spin fast enough for carbide
but that seems unlikely. Haven't tested higher revs yet, wanted to get your thoughts.
I saw a youtube video this morning where a guy made a little foot from a piece of CRS that he bolted through his tool holder that sits on the top of the cross slide to keep it from bending down which seems interesting, but not sure if I could do that or
not on my lathe.
|
Re: [sheldonlathe] Breaking carbide inserts parting off?
I made these before,? parted off using a hss blade. The cuts were somewhat dished,? but it was an interrupted cut with the slots already there.?
On Fri, Apr 21, 2023, 4:26 PM Gene Heskett < gheskett@...> wrote: On 4/21/23 14:25, Nick Andrews wrote:
> Now I know that for some folks parting off in the lathe is routine, but for
> some of us it's a real PITA.? Or can be.? I've tried using a nice HSS blade
> in a holder with lots of oil and freshly-ground tip and still got it
> pulling to one side, and now a 1-inch tall steel blade with carbide insert
> for the first time last night.? Yeah, I broke the insert.? And yes, it was
> a cheapo chinese insert.? As delivered, the holder body was not well made
> and the bottom of the slot for the tool was tapered, causing a tilt in the
> cutoff blade of about 3 degrees or so.? Imagine that from an ebay seller!
> So I put it in the the vise and milled the slot more parallel, which
> corrected the vertical angle of the cutoff blade, mostly.? I tried to
> minimize stick-out but still got too much chatter.? Part isn't that far out
> from the 4-jaw, but a tailstock center might've helped on chatter.
>
> This is on a piece of 1.5" steel rod I got left from a construction
> project, no idea what alloy.? Maybe I have the wrong speed going and need
> to crank it up for carbide cutting.? Heard people say many home lathes
> struggle to spin fast enough for carbide but that seems unlikely.? Haven't
> tested higher revs yet, wanted to get your thoughts.
>
> I saw a youtube video this morning? where a guy made a little foot from a
> piece of CRS that he bolted through his tool holder that sits on the top of
> the cross slide to keep it from bending down which seems interesting, but
> not sure if I could do that or not on my lathe.
You s/b able to, getting it the precise length is the secret. Do not
hold up on the tool holder bottom, but as directly under the edge of the
tool itself as you can get. Target shooters rifle rest sand bags will
help by absorbing the chatter before you hear it.
>
>
>
>
>
>
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, 1940)
If we desire respect for the law, we must first make the law respectable.
? - Louis D. Brandeis
Genes Web page <>
|
Re: Breaking carbide inserts parting off?
The GTN2 inserts seem to be the smallest you can find easily. I saw Shars selling them for their parting tools. I never used one, but I have been tempted a few times to purchase.?
toggle quoted message
Show quoted text
Parting in the front tool post on relatively small or light lathes can be a pain. I have a Myford ML7 at home. It's in nice nick, and I have
NEVER succeeded in parting at the front. The tool digs in and snaps pretty well as soon as it touches. Fortunately, I have a rear toolpost that works a treat. If you look at a manual capstan lathe, parting is ALWAYS done from the back. I have recently acquired
a rear toolpost for the railway's Colchester Triumph 2000 (AKA Clausing 15") and that will happily run a 4mm HSS blade. Internal screwcutting has now been promoted to my most feared operation in place of parting (I have to make 3 off 1 1/8 BSP nuts for steam
pipe unions as soon as the 1 7/8 A/F Hex leaded gunmetal turns up).
The tool needs to be absolutely sharp. If you need to apply an increasing force to drive it in, that is a recipe for disaster.
If a hand ground blade, polish with a diamond file.
The tool must be narrow, and the smaller the lathe, the narrower the tool.
I front part successfully with carbide on our 14.5" SB with taper turning attachment because that won't conveniently take a rear toolpost, but wouldn't use anything wider than a 3mm cutter. It is, nonetheless, nerve wracking.
If you look at (e.g.) the Iscar catalogue you will see dozens of different chip geometries on the same size of tip. Pick one with the correct geometry for the material you are cutting.
Work support is vital. Cut at no more than 1/4 diameter distance from the chuck or collet, and ensure they are TIGHT. Ensure there is at least 1.5 x diameter still in the chuck. If not, add a centre at the outer end
whether you think it needs it or not. Neglect of any of this could result in the job deflecting badly in the chuck (etc.).
Trace and rectify any source of toolpost deflection under load. Have the compound slide set so that the sliding part is not overhanging the fixed part, and ensure that the leading corner of the toolpost is over solid
metal. With the job moving downwards as in front cutting, any deflection results in the tool moving into the job, increasing the cutting force, which increases the deflection etc. With the job moving upwards as in rear cutting, the tool tends to deflect away
from the job (phew!) This is why folk construct tool props for front parting.
On small lathes, part off at a relatively low speed, regardless of tool type.
Not sure about small quantities of cutting oil, but if parting something that normally takes coolant, even if optional, I would use coolant flow during parting, if available. Obviously not for cast iron or cheap brass.
Parting in stages that create a swarf anti jamming gap as described by someone else works well, especially if using the sort of carbide tip that is moulded to curl the edges of the swarf inwards and you are cutting
material that produces springy swarf in spiral coils. That stuff can spring out towards flat as soon as it leaves the tip, and jam in the groove. Intermittent cutting helps by breaking that sort of swarf into shorter coils.
The cross feed during parting generally needs to be done manually, and slower than the slowest available powered feed.
I think that's all for the moment.
Eddie
------ Original Message ------
From: "mike allen" <animal@...>
To: [email protected]
Cc: [email protected]
Sent: Friday, 21 Apr, 23 At 20:31
Subject: Re: [SouthBendLathe] Breaking carbide inserts parting off?
They have a rear mounted parting tool tool post they also sell . I should buy the crossslide & just have it here for when I'm ready to make one . I need to learn dovetails first .
Rear Tool Post
animal
On 4/21/2023 12:20 PM, Nick Andrews wrote:
This is on my 11" Sheldon lathe. No, haven't tried snugging the gibs but did lock the saddle. I guess if I am taking the time to make something, tweaking the gibs shouldn't seem like such a chore...
Interesting casting. Do you then just bolt your tool post on directly somehow?
On Fri, Apr 21, 2023 at 1:49?PM mike allen < animal@...> wrote:
I've seen some of those parting tool supports that folks make on youtube in the past . Folks seem to like them , but then again its the guy that made it that says its bitchin . These folks make a longer crossslide casting that you machine to finish that
allows you to put a tool post behind the work so your parting tool is mounted upside down , some folks say this is a huge improvement when parting . This is one of my projects on my list to make sometime . Are you locking the saddle & tightening the crossslide
& compound gibs when parting ?
animal
On 4/21/2023 11:25 AM, Nick Andrews wrote:
Now I know that for some folks parting off in the lathe is routine, but for some of us it's a real PITA. Or can be. I've tried using a nice HSS blade in a holder with lots of oil and freshly-ground tip and still got it pulling to one side, and now a 1-inch
tall steel blade with carbide insert for the first time last night. Yeah, I broke the insert. And yes, it was a cheapo chinese insert. As delivered, the holder body was not well made and the bottom of the slot for the tool was tapered, causing a tilt in the
cutoff blade of about 3 degrees or so. Imagine that from an ebay seller! So I put it in the the vise and milled the slot more parallel, which corrected the vertical angle of the cutoff blade, mostly. I tried to minimize stick-out but still got too much chatter.
Part isn't that far out from the 4-jaw, but a tailstock center might've helped on chatter.
This is on a piece of 1.5" steel rod I got left from a construction project, no idea what alloy. Maybe I have the wrong speed going and need to crank it up for carbide cutting. Heard people say many home lathes struggle to spin fast enough for carbide
but that seems unlikely. Haven't tested higher revs yet, wanted to get your thoughts.
I saw a youtube video this morning where a guy made a little foot from a piece of CRS that he bolted through his tool holder that sits on the top of the cross slide to keep it from bending down which seems interesting, but not sure if I could do that or
not on my lathe.
|
Re: Breaking carbide inserts parting off?
Parting in the front tool post on relatively small or light lathes can be a pain. I have a Myford ML7 at home. It's in nice nick, and I have NEVER succeeded in parting at the front. The tool digs in and snaps pretty well as soon as it touches. Fortunately, I have a rear toolpost that works a treat. If you look at a manual capstan lathe, parting is ALWAYS done from the back. I have recently acquired a rear toolpost for the railway's Colchester Triumph 2000 (AKA Clausing 15") and that will happily run a 4mm HSS blade. Internal screwcutting has now been promoted to my most feared operation in place of parting (I have to make 3 off 1 1/8 BSP nuts for steam pipe unions as soon as the 1 7/8 A/F Hex leaded gunmetal turns up).
The tool needs to be absolutely sharp. If you need to apply an increasing force to drive it in, that is a recipe for disaster.
If a hand ground blade, polish with a diamond file.
The tool must be narrow, and the smaller the lathe, the narrower the tool. I front part successfully with carbide on our 14.5" SB with taper turning attachment because that won't conveniently take a rear toolpost, but wouldn't use anything wider than a 3mm cutter. It is, nonetheless, nerve wracking.
If you look at (e.g.) the Iscar catalogue you will see dozens of different chip geometries on the same size of tip. Pick one with the correct geometry for the material you are cutting.
Work support is vital. Cut at no more than 1/4 diameter distance from the chuck or collet, and ensure they are TIGHT. Ensure there is at least 1.5 x diameter still in the chuck. If not, add a centre at the outer end whether you think it needs it or not. Neglect of any of this could result in the job deflecting badly in the chuck (etc.).
Trace and rectify any source of toolpost deflection under load. Have the compound slide set so that the sliding part is not overhanging the fixed part, and ensure that the leading corner of the toolpost is over solid metal. With the job moving downwards as in front cutting, any deflection results in the tool moving into the job, increasing the cutting force, which increases the deflection etc. With the job moving upwards as in rear cutting, the tool tends to deflect away from the job (phew!) This is why folk construct tool props for front parting.
On small lathes, part off at a relatively low speed, regardless of tool type.
Not sure about small quantities of cutting oil, but if parting something that normally takes coolant, even if optional, I would use coolant flow during parting, if available. Obviously not for cast iron or cheap brass.
Parting in stages that create a swarf anti jamming gap as described by someone else works well, especially if using the sort of carbide tip that is moulded to curl the edges of the swarf inwards and you are cutting material that produces springy swarf in spiral coils. That stuff can spring out towards flat as soon as it leaves the tip, and jam in the groove. Intermittent cutting helps by breaking that sort of swarf into shorter coils.
The cross feed during parting generally needs to be done manually, and slower than the slowest available powered feed.
I think that's all for the moment.
Eddie
toggle quoted message
Show quoted text
------ Original Message ------
From: "mike allen" <animal@...>
To: [email protected]
Cc: [email protected]
Sent: Friday, 21 Apr, 23 At 20:31
Subject: Re: [SouthBendLathe] Breaking carbide inserts parting off?
They have a rear mounted parting tool tool post they also sell . I should buy the crossslide & just have it here for when I'm ready to make one . I need to learn dovetails first . Rear Tool Post animal
On 4/21/2023 12:20 PM, Nick Andrews wrote:
This is on my 11" Sheldon lathe. No, haven't tried snugging the gibs but did lock the saddle. I guess if I am taking the time to make something, tweaking the gibs shouldn't seem like such a chore...
Interesting casting. Do you then just bolt your tool post on directly somehow?
On Fri, Apr 21, 2023 at 1:49?PM mike allen < animal@...> wrote: I've seen some of those parting tool supports that folks make on youtube in the past . Folks seem to like them , but then again its the guy that made it that says its bitchin . These folks make a longer crossslide casting that you machine to finish that allows you to put a tool post behind the work so your parting tool is mounted upside down , some folks say this is a huge improvement when parting . This is one of my projects on my list to make sometime . Are you locking the saddle & tightening the crossslide & compound gibs when parting ? animal
On 4/21/2023 11:25 AM, Nick Andrews wrote:
Now I know that for some folks parting off in the lathe is routine, but for some of us it's a real PITA. Or can be. I've tried using a nice HSS blade in a holder with lots of oil and freshly-ground tip and still got it pulling to one side, and now a 1-inch tall steel blade with carbide insert for the first time last night. Yeah, I broke the insert. And yes, it was a cheapo chinese insert. As delivered, the holder body was not well made and the bottom of the slot for the tool was tapered, causing a tilt in the cutoff blade of about 3 degrees or so. Imagine that from an ebay seller! So I put it in the the vise and milled the slot more parallel, which corrected the vertical angle of the cutoff blade, mostly. I tried to minimize stick-out but still got too much chatter. Part isn't that far out from the 4-jaw, but a tailstock center might've helped on chatter.
This is on a piece of 1.5" steel rod I got left from a construction project, no idea what alloy. Maybe I have the wrong speed going and need to crank it up for carbide cutting. Heard people say many home lathes struggle to spin fast enough for carbide but that seems unlikely. Haven't tested higher revs yet, wanted to get your thoughts.
I saw a youtube video this morning where a guy made a little foot from a piece of CRS that he bolted through his tool holder that sits on the top of the cross slide to keep it from bending down which seems interesting, but not sure if I could do that or not on my lathe.
|
Re: Breaking carbide inserts parting off?
??? ??? Yea , looks like it can be cut down some . These folks
sell the drawings separate so a guy/gal can make their own with
what they have . I don't see why it really has to be made from CI?
but maybe someone else here can school me/us on that matter . the
plans are only $ 6.00 for the tool post or the cross slide . I
thought I had read somewhere at one time that if you bought the
plans & then bought the casting later they would credit you on
the plans when purchasing the casting ?
??? ??? IIRC OKC Bill bought a crossslide kit from a guy that
bought it & never made it .
??? ??? animal
On 4/21/2023 1:29 PM, Andrei wrote:
toggle quoted message
Show quoted text
Looks like that rear parting tool is designed for 12 inch and
bigger lathes. You can probably shave down the casting and alter
the dovetails to make it work on your Sheldon.?
Andrei
??? ??? They have a rear mounted parting tool tool post they
also sell .? I should buy the crossslide & just have it
here for when I'm ready to make one . I need to learn
dovetails first .
??? ??? Rear Tool Post
??? ??? animal
On 4/21/2023 12:20 PM, Nick
Andrews wrote:
This is on my 11" Sheldon lathe.? No, haven't tried
snugging the gibs but did lock the saddle.? I guess if I
am taking the time to make something, tweaking the gibs
shouldn't seem like such a chore...
Interesting casting.? Do you then just bolt your tool
post on directly somehow?
On Fri, Apr 21, 2023 at
1:49?PM mike allen < animal@...> wrote:
??? ??? I've seen some of those parting tool supports
that folks make on youtube in the past . Folks seem to
like them ,? but then again its the guy that made it
that says its bitchin . These folks make a longer
crossslide casting that you machine to finish that
allows you to put a tool post behind the work so your
parting tool is mounted upside down , some folks say
this is a huge improvement when parting . This is one
of my projects on my list to make sometime . Are you
locking the saddle & tightening the crossslide
& compound gibs? when parting ?
??? ???
??? ??? animal
On 4/21/2023 11:25 AM, Nick Andrews wrote:
Now I know that for some folks parting off in
the lathe is routine, but for some of us it's a
real PITA.? Or can be.? I've tried using a nice
HSS blade in a holder with lots of oil and
freshly-ground tip and still got it pulling to one
side, and now a 1-inch tall steel blade with
carbide insert for the first time last night.?
Yeah, I broke the insert.? And yes, it was a
cheapo chinese insert.? As delivered, the holder
body was not well made and the bottom of the slot
for the tool was tapered, causing a tilt in the
cutoff blade of about 3 degrees or so.? Imagine
that from an ebay seller!? So I put it in the the
vise and milled the slot more parallel, which
corrected the vertical angle of the cutoff blade,
mostly.? I tried to minimize stick-out but still
got too much chatter.? Part isn't that far out
from the 4-jaw, but a tailstock center might've
helped on chatter.
This is on a piece of 1.5" steel rod I got left
from a construction project, no idea what alloy.?
Maybe I have the wrong speed going and need to
crank it up for carbide cutting.? Heard people say
many home lathes struggle to spin fast enough for
carbide but that seems unlikely.? Haven't tested
higher revs yet, wanted to get your thoughts.
I saw a youtube video this morning? where a guy
made a little foot from a piece of CRS that he
bolted through his tool holder that sits on the
top of the cross slide to keep it from bending
down which seems interesting, but not sure if I
could do that or not on my lathe.??
|
Re: Breaking carbide inserts parting off?
Looks like that rear parting tool is designed for 12 inch and bigger lathes. You can probably shave down the casting and alter the dovetails to make it work on your Sheldon.?
Andrei
toggle quoted message
Show quoted text
??? ??? They have a rear mounted parting tool tool post they also sell .? I should buy the crossslide & just have it here for when I'm ready to make one . I need to learn dovetails first .
??? ??? Rear Tool Post
??? ??? animal
On 4/21/2023 12:20 PM, Nick Andrews wrote:
This is on my 11" Sheldon lathe.? No, haven't tried snugging the gibs but did lock the saddle.? I guess if I am taking the time to make something, tweaking the gibs shouldn't seem like such a chore...
Interesting casting.? Do you then just bolt your tool post on directly somehow?
On Fri, Apr 21, 2023 at 1:49?PM mike allen < animal@...> wrote:
??? ??? I've seen some of those parting tool supports that folks make on youtube in the past . Folks seem to like them ,? but then again its the guy that made it that says its bitchin . These folks make a longer crossslide casting that you machine to finish
that allows you to put a tool post behind the work so your parting tool is mounted upside down , some folks say this is a huge improvement when parting . This is one of my projects on my list to make sometime . Are you locking the saddle & tightening the crossslide
& compound gibs? when parting ?
??? ???
??? ??? animal
On 4/21/2023 11:25 AM, Nick Andrews wrote:
Now I know that for some folks parting off in the lathe is routine, but for some of us it's a real PITA.? Or can be.? I've tried using a nice HSS blade in a holder with lots of oil and freshly-ground tip and still got it pulling to one side, and now a
1-inch tall steel blade with carbide insert for the first time last night.? Yeah, I broke the insert.? And yes, it was a cheapo chinese insert.? As delivered, the holder body was not well made and the bottom of the slot for the tool was tapered, causing a
tilt in the cutoff blade of about 3 degrees or so.? Imagine that from an ebay seller!? So I put it in the the vise and milled the slot more parallel, which corrected the vertical angle of the cutoff blade, mostly.? I tried to minimize stick-out but still got
too much chatter.? Part isn't that far out from the 4-jaw, but a tailstock center might've helped on chatter.
This is on a piece of 1.5" steel rod I got left from a construction project, no idea what alloy.? Maybe I have the wrong speed going and need to crank it up for carbide cutting.? Heard people say many home lathes struggle to spin fast enough for carbide
but that seems unlikely.? Haven't tested higher revs yet, wanted to get your thoughts.
I saw a youtube video this morning? where a guy made a little foot from a piece of CRS that he bolted through his tool holder that sits on the top of the cross slide to keep it from bending down which seems interesting, but not sure if I could do that
or not on my lathe.??
|
Re: Breaking carbide inserts parting off?
??? ??? They have a rear mounted parting tool tool post they also
sell .? I should buy the crossslide & just have it here for
when I'm ready to make one . I need to learn dovetails first .
??? ??? Rear Tool Post
??? ??? animal
On 4/21/2023 12:20 PM, Nick Andrews
wrote:
toggle quoted message
Show quoted text
This is on my 11" Sheldon lathe.? No, haven't tried
snugging the gibs but did lock the saddle.? I guess if I am
taking the time to make something, tweaking the gibs shouldn't
seem like such a chore...
Interesting casting.? Do you then just bolt your tool post
on directly somehow?
On Fri, Apr 21, 2023 at
1:49?PM mike allen < animal@...>
wrote:
??? ??? I've seen some of those parting tool supports
that folks make on youtube in the past . Folks seem to
like them ,? but then again its the guy that made it that
says its bitchin . These folks make a longer crossslide
casting that you machine to finish that allows you to put
a tool post behind the work so your parting tool is
mounted upside down , some folks say this is a huge
improvement when parting . This is one of my projects on
my list to make sometime . Are you locking the saddle
& tightening the crossslide & compound gibs? when
parting ?
??? ???
??? ??? animal
On 4/21/2023 11:25 AM, Nick Andrews wrote:
Now I know that for some folks parting off in the
lathe is routine, but for some of us it's a real
PITA.? Or can be.? I've tried using a nice HSS blade
in a holder with lots of oil and freshly-ground tip
and still got it pulling to one side, and now a 1-inch
tall steel blade with carbide insert for the first
time last night.? Yeah, I broke the insert.? And yes,
it was a cheapo chinese insert.? As delivered, the
holder body was not well made and the bottom of the
slot for the tool was tapered, causing a tilt in the
cutoff blade of about 3 degrees or so.? Imagine that
from an ebay seller!? So I put it in the the vise and
milled the slot more parallel, which corrected the
vertical angle of the cutoff blade, mostly.? I tried
to minimize stick-out but still got too much chatter.?
Part isn't that far out from the 4-jaw, but a
tailstock center might've helped on chatter.
This is on a piece of 1.5" steel rod I got left
from a construction project, no idea what alloy.?
Maybe I have the wrong speed going and need to crank
it up for carbide cutting.? Heard people say many home
lathes struggle to spin fast enough for carbide but
that seems unlikely.? Haven't tested higher revs yet,
wanted to get your thoughts.
I saw a youtube video this morning? where a guy
made a little foot from a piece of CRS that he bolted
through his tool holder that sits on the top of the
cross slide to keep it from bending down which seems
interesting, but not sure if I could do that or not on
my lathe.??
|
Re: Breaking carbide inserts parting off?
This is on my 11" Sheldon lathe.? No, haven't tried snugging the gibs but did lock the saddle.? I guess if I am taking the time to make something, tweaking the gibs shouldn't seem like such a chore...
Interesting casting.? Do you then just bolt your tool post on directly somehow?
On Fri, Apr 21, 2023 at 1:49?PM mike allen < animal@...> wrote:
??? ??? I've seen some of those parting tool supports that folks
make on youtube in the past . Folks seem to like them ,? but then
again its the guy that made it that says its bitchin . These folks
make a longer crossslide casting that you machine to finish that
allows you to put a tool post behind the work so your parting tool
is mounted upside down , some folks say this is a huge improvement
when parting . This is one of my projects on my list to make
sometime . Are you locking the saddle & tightening the
crossslide & compound gibs? when parting ?
??? ???
??? ??? animal
On 4/21/2023 11:25 AM, Nick Andrews
wrote:
Now I know that for some folks parting off in the lathe is
routine, but for some of us it's a real PITA.? Or can be.?
I've tried using a nice HSS blade in a holder with lots of oil
and freshly-ground tip and still got it pulling to one side,
and now a 1-inch tall steel blade with carbide insert for the
first time last night.? Yeah, I broke the insert.? And yes, it
was a cheapo chinese insert.? As delivered, the holder body
was not well made and the bottom of the slot for the tool was
tapered, causing a tilt in the cutoff blade of about 3 degrees
or so.? Imagine that from an ebay seller!? So I put it in the
the vise and milled the slot more parallel, which corrected
the vertical angle of the cutoff blade, mostly.? I tried to
minimize stick-out but still got too much chatter.? Part isn't
that far out from the 4-jaw, but a tailstock center might've
helped on chatter.
This is on a piece of 1.5" steel rod I got left from a
construction project, no idea what alloy.? Maybe I have the
wrong speed going and need to crank it up for carbide
cutting.? Heard people say many home lathes struggle to spin
fast enough for carbide but that seems unlikely.? Haven't
tested higher revs yet, wanted to get your thoughts.
I saw a youtube video this morning? where a guy made a
little foot from a piece of CRS that he bolted through his
tool holder that sits on the top of the cross slide to keep it
from bending down which seems interesting, but not sure if I
could do that or not on my lathe.??
|
Re: Breaking carbide inserts parting off?
For some truly amazing parting tool action check out Robin Renzetti: |
Nick Andrews
Carl Bukowsky
Rick Swineford
Mark Z
Bill in OKC too
