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Calculating machining cycle time
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Neil
Mon, 14 Aug 06 05:39:23 +0000
Hi all,

I am trying to estimate (doesn't have to be too precise) how long my machining
time would be for various parts on different CNC lathes (and perhaps mills as
well). Is there a formula or software app that does this easily? I know the
dimensions of the raw material, and of the finished part, but what other info
would I need -- spindle speed? Rapids? Material type? Etc?

Alternatively, can it be estimated by the quantity (weight or volume) of metal
that is removed?

The purpose is that I am looking into the purchase of a commercial CNC lathe,
and trying to estimate what my realistic costs would be, other the the
machine and raw material. The next largest costs would be the operator time
(hence the calcs above) and the tool bits.

Thanks,
-Neil.

15 replies folowing
John Dammeyer
Mon, 14 Aug 06 07:03:12 +0000
There's a book I bought from Lindsey Press called "Milling and Milling
Machines" published originally by Cincinnati Milling Machine Co.

In this book there are detailed explanations on how to work out cycle time
for manufacturing parts. It takes into account things like running a tool
at full speed verses a slower speed based on how long it takes to replace or
regrind the tool. For example, if you cut at 50 ipm with a specific depth
of cut you may get only 10,000 inches before the cutter needs resharpening.
Running at 40 ipm would mean longer tool life. Depending on the price of the
tool and the speed at which you replace and recalibrate it may be less
expensive both in time and cost to run slower even though intuitively it may
appear to be better to do the opposite.

John Dammeyer






Subject: [DIY-CNC] Re: Calculating machining/cycle time?

>
>
>
> > Hi all,
> >
> > I am trying to estimate (doesn't have to be too precise)
> how long my machining
> > time would be for various parts on different CNC lathes
> (and perhaps mills as
> > well). Is there a formula or software app that does this
> easily? I know the
> > dimensions of the raw material, and of the finished part,
> but what other info
> > would I need -- spindle speed? Rapids? Material type? Etc?
> >
> > Alternatively, can it be estimated by the quantity (weight
> or volume) of metal
> > that is removed?
> >
> > The purpose is that I am looking into the purchase of a
> commercial CNC lathe,
> > and trying to estimate what my realistic costs would be,
> other the the
> > machine and raw material. The next largest costs would be
> the operator time
> > (hence the calcs above) and the tool bits.
> >
> > Thanks,
> > -Neil.
> >
> >
> A decent CAD program like Dolphin will give you quite
> accurate machinig times.
>
> John S.
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>
>
>


dicsEE
Mon, 14 Aug 06 18:00:56 +0000
 
Richard Garnish
Mon, 14 Aug 06 18:00:56 +0000
The other posters in this thread have addressed the actual question
better than I could, but one observation I should make is that with a
CNC machine you don't pay your operator to stand and watch the machine
run its cycle, so the actual cycle time shouldn't be the primary way of
determining staff costs. The operator needs to load stock (less often
if you have a bar feeder, for instance), maintain tooling, do initial
checks on output, carry out finishing operations which cannot be done
automatically, etc.; but all the time the machine is working, the
operator is better employed doing something else.

Richard

On Mon, 2006-08-14 at 06:39, Neil wrote:

> The purpose is that I am looking into the purchase of a commercial CNC lathe,
> and trying to estimate what my realistic costs would be, other the the
> machine and raw material. The next largest costs would be the operator time
> (hence the calcs above) and the tool bits.
>
> Thanks,
> -Neil.
>
>
>
> Yahoo! Groups Links
>
>
>
>
>



hooya10_4
Mon, 14 Aug 06 23:58:38 +0000
Sometime in the late eighties - early nineties, multiple machine
running by a single operator really came into vogue...perhaps pushed
by the approach of just-in-time manufacture...dunno. I can't tell you
the number of shop owners I've seen who see the cycle time on the
monitor, do a little quick simplistic math, and then run for their
air conditioned office while fuming at their "lazy" employees. The
previous poster is absolutely right about other variables, like
preliminary part inspection, workpiece change, carbide insert or
broken tooling change, offset change...cutting into real cycle time.
If your part run is large (1000's) with short cycle times, every
second counts...on small runs you can relax a bit. My advice? ...run
it as fast as you can balancing cutting edge life against
quality, ie. if a critical dia. has to be frequently adjusted because
the
finisher insert is wearing out too quickly, you're losing money every
time an offset change has to be made, so reduce the SFM. The single,
overall MOST important aspect...is the part a
good one? If the parts you're racing through are out-of-tolerance
scrap...you may as well have them made in China.

--- In DIY-CNC@yahoogroups.com, Richard Garnish wrote:

> you don't pay your operator to stand and watch the machine
> run its cycle


...and that warm amber glow inside the lathe is your $250 Komet
insert drill breaking & reducing itself to a melted candle
puddle...followed by the sequential failure of the next boring bar,
ID groove tool, etc. LOL. Make sure your operator is ALWAYS close
enough to hear & investigate any tool failure noises before they
become a shop-wide rumble. Overloading an operator with other
distractive tasks can have catastrophic consequences. - John







Andy Wander
Tue, 15 Aug 06 12:41:10 +0000
Mach3 software has a "simulate" function which will show you how long the run would take.

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Verrex Corporation
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-----Original Message-----
From: DIY-CNC@yahoogroups.com [mailto:DIY-CNC@yahoogroups.com] On Behalf Of Neil
Sent: Tuesday, August 15, 2006 9:38 AM
To: DIY-CNC@yahoogroups.com
Subject: Re: [SPAM] Re: [DIY-CNC] Calculating machining/cycle time?

On Monday 14 August 2006 00:34, Keith Green wrote:

> The cycle times will depend a lot on individual programmers and
> operators. The 'givens' are; what material are you cutting? this leads
> to what speed and feed you will cut that material at which can give you
> an estimate of time.
> Other factors will include the toolpaths you choose and how good
> ...
> I guess the short answer is that there isn't really a 'formula' per
> ...


Sure, but there's no way to get a ballpark if I have/get this info? I was
hoping that if I get the CAD/CAM software, it could give me an estimate of
tool path distance, then I'd use that with the spindle speed and tool-travels
speeds (I assume this is the "rapids"), and I could come up with an estimate.


> ...
> There is an online machine shop which you can check out for an
> example of a quoting formula in action. You fill in an online form with
> ...



I've been using the emachineshop software for some time, but never actually
had them do anything since they're ridiculously expensive, compared to other
shops that I've had work done at, and it has a lot of software bugs. The
software is great for quickly visualizing what a part would look like, or for
getting a 3D image so I can pass to a shop to see. But I see no way to get
machining/cycle time off this software.


> About the best I can say is that you should just dive in there and
> work at it. ....


There in lies the problem. I am not a machinist. But I am considering the
purchase of a CNC lathe to bring the machining portion of a product in-house.
Reason is that I'm sick and tired of getting screwed around by shops. I've
dealt with some reliable shops in the past, but for this product price is
critical and those shops don't come anywhere near to the target. So at this
point I am evaluating what it would cost me to bring the machining in house.
All I need is an estimate -- sort of like business planning. I can figure
out what the machine would cost me, and not concerned about my time to learn
and program the machine for these few parts. I can calculate the cost of the
material easily. Then I need to know how much time it would take for each
part, so I can estimate how long I need an operator at the machine. Fudge in
a small factor for maintenance, electricity, etc, and this will all
eventually lead to a cost estimate and a decision as to whether I should do
this or not. I expect volumes to get better over time, so even it it costs
me a bit more now, I'd be willing to take the plunge to stop dealing with
shops.

The key is that I was to know this *before* buying the machine.

-Neil.



Yahoo! Groups Links








This communication including any attachments, are intended
for the exclusive use of the addressee(s) and contains
confidential or copyrighted materials. Duplication,
distribution or reproduction is strictly prohibited by law
without written permission of Verrex

Neil
Tue, 15 Aug 06 13:38:29 +0000
On Monday 14 August 2006 00:34, Keith Green wrote:
> The cycle times will depend a lot on individual programmers and
> operators. The 'givens' are; what material are you cutting? this leads
> to what speed and feed you will cut that material at which can give you
> an estimate of time.
> Other factors will include the toolpaths you choose and how good
> ...
> I guess the short answer is that there isn't really a 'formula' per
> ...


Sure, but there's no way to get a ballpark if I have/get this info? I was
hoping that if I get the CAD/CAM software, it could give me an estimate of
tool path distance, then I'd use that with the spindle speed and tool-travels
speeds (I assume this is the "rapids"), and I could come up with an estimate.


> ...
> There is an online machine shop which you can check out for an
> example of a quoting formula in action. You fill in an online form with
> ...



I've been using the emachineshop software for some time, but never actually
had them do anything since they're ridiculously expensive, compared to other
shops that I've had work done at, and it has a lot of software bugs. The
software is great for quickly visualizing what a part would look like, or for
getting a 3D image so I can pass to a shop to see. But I see no way to get
machining/cycle time off this software.


> About the best I can say is that you should just dive in there and
> work at it. ....


There in lies the problem. I am not a machinist. But I am considering the
purchase of a CNC lathe to bring the machining portion of a product in-house.
Reason is that I'm sick and tired of getting screwed around by shops. I've
dealt with some reliable shops in the past, but for this product price is
critical and those shops don't come anywhere near to the target. So at this
point I am evaluating what it would cost me to bring the machining in house.
All I need is an estimate -- sort of like business planning. I can figure
out what the machine would cost me, and not concerned about my time to learn
and program the machine for these few parts. I can calculate the cost of the
material easily. Then I need to know how much time it would take for each
part, so I can estimate how long I need an operator at the machine. Fudge in
a small factor for maintenance, electricity, etc, and this will all
eventually lead to a cost estimate and a decision as to whether I should do
this or not. I expect volumes to get better over time, so even it it costs
me a bit more now, I'd be willing to take the plunge to stop dealing with
shops.

The key is that I was to know this *before* buying the machine.

-Neil.
Neil
Tue, 15 Aug 06 14:04:43 +0000
Just found this. Hmmm... any lower cost options? Can turboCNC do this?
-Neil.



On Monday 14 August 2006 01:49, John Stevenson wrote:

> > Hi all,
> >
> > I am trying to estimate (doesn't have to be too precise) how long my
> > ...
>
> A decent CAD program like Dolphin will give you quite accurate machinig
> times.
>
> John S.

Keith Green
Tue, 15 Aug 06 15:08:13 +0000
If you're not a machinist, how are you going to choose proper
toolpaths, inserts, tools, speeds and feeds?
What you're asking is doable with most CAM software. I use OneCNC
and the cycle time prediction can be very accurate. This depends totally
on how true your program is to the finished one, how long your machine
takes to change a tool and how many times it has to do that during the
run. The software is usually programmable for rapid rates of different
machines, but usually not for tool change time. The rapid time usually
covers only those moves you've programmed, so if the home and tool
change positions are far away from the part, you lose a lot of time.
I also run and program Mazak machines with their conversational
control. These things, for me, are the best value out there as regards
setup and programming time. Typical program on a lathe takes about 15
minutes and it gets proved out during the first couple parts most of the
time. You can program another part while the first one runs out so the
only programming time you pay for is really the first one of the day (if
you start every day with a new program). You can adjust the speeds and
feeds on the fly by using the % keys/dials as there is a 'verify change'
key on the control that changes values in the program based on what is
set at the control panel. Changes come into effect at the end of the
cutting cycle and will be in the program the next time you run it. No
need to stop and make changes or make notes for changes to be made on
the next cycle. If your runs and/or cycle times are long enough, 1 guy
CAN run 2 machines. Our two lathes are placed face to face with about
8-10' between so either one is only a step away. On parts where the
programs are rock solid and I know that there are rarely any problems,
I'll work on the mill 20' away and just keep an ear open. For anything
but really complex curvy shapes, programming and running these is much
nicer than dealing with a CAM-crutch. The mill is pretty good too, but
due to the funny shapes you often deal with in those machines, you may
end up using the crutch anyway. G-code programs can run side by side
and in conjunction with ones you've hand-coded with the Mazatrol. There
is practically no g-code to be seen in a Mazatrol program; it all runs
on macro's built into the system. We bought CAM software several years
ago now but have yet to use it on the Mazak lathes. Occasionally we use
it for the mill, but it's often quicker and easier to deal with if you
use the CAD portion of the software to pick off intersection points in a
2D profile and hand-code using that. 3D you're better off with the CAM.
The simulations give a decent approximation of run time in this control,
though I think the simulations are pretty limited in scope if you run
g-code in there.

Bottom line is, I think what you're going to get is a
sometimes-accurate approximation of the run-time of the program, not an
estimation of cycle time. Cycle time to me is the chip-to-chip time; how
long it is from the time I press "cycle-start" on one piece, to when I
press "cycle-start" on the next. The time in between will be filled with
everything you need to include; loading, deburring, rapids, toolchanges,
general handling, etc.

I also run a big lathe with a GE 2000 control on it (now obsolete,
though very powerful) and am learning on a big vertical boring mill with
brand new Fanuc 18i control. The Mazatrol is still far and away my
favourite. Since we bought those G-code machines, the office staff have
had to add a new sequence to the computerized time-clock we use:
"Programming". Deburring parts from those machines takes extra time as
well. The Mazatrol makes it very easy to produce a burr-free part. It
takes too much programming time in the CAM system to draw in all those
tiny radii and chamfers and stuff. I especially like it (the Mazak) for
any type of grooving. Those processes are probably some of the hardest
lathe operations to program because you're guessing all the time on a
lot of variables. In the Mazatrol, if a program change is required
(often is with grooving patterns) it takes only a minute or two, most of
the time. A complete rewrite of a 'lengthy' grooving sequence would only
take 5 or 10. Changes like this are faster because they're done right at
the machine, hands-on, by the operator who knows what he wants to do and
how he wants to do it. He'll run that first draft program and make
changes based on direct observation. Most of these type of changes don't
ever get made when you're dealing with a CAM program and g-code as the
time it takes to make a change can be excessive.

Ah crap. This has turned into somewhat of a rant again...
OK. As I said earlier, i think you're going to find estimates of
run-time for a given program, but not the actual cycle time. Cycle times
will be based on way to many pretty well unpredictable factors in a
normal shop environment. I highly automated shops and such, cycle times
are more predictable, but I think such palces don't have the flexibility
you would want in your place.



Keith





Neil wrote:

>
> On Monday 14 August 2006 00:34, Keith Green wrote:
> > The cycle times will depend a lot on individual programmers and
> > operators. The 'givens' are; what material are you cutting? this leads
> > to what speed and feed you will cut that material at which can give you
> > an estimate of time.
> > Other factors will include the toolpaths you choose and how good
> > ...
> > I guess the short answer is that there isn't really a 'formula' per
> > ...
>
> Sure, but there's no way to get a ballpark if I have/get this info? I was
> hoping that if I get the CAD/CAM software, it could give me an
> estimate of
> tool path distance, then I'd use that with the spindle speed and
> tool-travels
> speeds (I assume this is the "rapids"), and I could come up with an
> estimate.
>
> > ...
> > There is an online machine shop which you can check out for an
> > example of a quoting formula in action. You fill in an online form with
> > ...
>
> I've been using the emachineshop software for some time, but never
> actually
> had them do anything since they're ridiculously expensive, compared to
> other
> shops that I've had work done at, and it has a lot of software bugs. The
> software is great for quickly visualizing what a part would look like,
> or for
> getting a 3D image so I can pass to a shop to see. But I see no way to
> get
> machining/cycle time off this software.
>
> > About the best I can say is that you should just dive in there and
> > work at it. ....
>
> There in lies the problem. I am not a machinist. But I am considering the
> purchase of a CNC lathe to bring the machining portion of a product
> in-house.
> Reason is that I'm sick and tired of getting screwed around by shops.
> I've
> dealt with some reliable shops in the past, but for this product price is
> critical and those shops don't come anywhere near to the target. So at
> this
> point I am evaluating what it would cost me to bring the machining in
> house.
> All I need is an estimate -- sort of like business planning. I can figure
> out what the machine would cost me, and not concerned about my time to
> learn
> and program the machine for these few parts. I can calculate the cost
> of the
> material easily. Then I need to know how much time it would take for each
> part, so I can estimate how long I need an operator at the machine.
> Fudge in
> a small factor for maintenance, electricity, etc, and this will all
> eventually lead to a cost estimate and a decision as to whether I
> should do
> this or not. I expect volumes to get better over time, so even it it
> costs
> me a bit more now, I'd be willing to take the plunge to stop dealing with
> shops.
>
> The key is that I was to know this *before* buying the machine.
>
> -Neil.
>
>
> ------------------------------------------------------------------------
>
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.1.405 / Virus Database: 268.10.10/418 - Release Date: 8/14/2006
>


nanmol
Tue, 15 Aug 06 15:39:50 +0000
--- In DIY-CNC@yahoogroups.com, Neil wrote:
>
> Hi all,
>
> I am trying to estimate (doesn't have to be too precise) how long my

machining

> time would be for various parts on different CNC lathes (and perhaps

mills as

> well).


SYNERGY does this automatically for you. See www.webersys.com



delmar1192005
Tue, 15 Aug 06 16:50:40 +0000
Neil,

If you are looking at new machine, why not give the drawings to the
manufacturer and ask them. I'm sure they would be happy to take your
drawings and code them, set them up and do a test run. That way you
get to see the quality, and have an exact time.

Del



--- In DIY-CNC@yahoogroups.com, Neil wrote:

>
> Hi all,
>
> I am trying to estimate (doesn't have to be too precise) how long

my machining

> time would be for various parts on different CNC lathes (and

perhaps mills as

> well). Is there a formula or software app that does this easily?

I know the

> dimensions of the raw material, and of the finished part, but what

other info

> would I need -- spindle speed? Rapids? Material type? Etc?
>
> Alternatively, can it be estimated by the quantity (weight or

volume) of metal

> that is removed?
>
> The purpose is that I am looking into the purchase of a commercial

CNC lathe,

> and trying to estimate what my realistic costs would be, other the

the

> machine and raw material. The next largest costs would be the

operator time

> (hence the calcs above) and the tool bits.
>
> Thanks,
> -Neil.
>








Neil
Wed, 16 Aug 06 05:27:33 +0000
Does it cover lathes/turning? Other than the math, is the book useful for
newbies? Also, I just googled for Lindsey press and got a ton of results to
Lindsay Lohan and the press. Geez. Any links?

Thanks,
-Neil.



On Monday 14 August 2006 02:03, John Dammeyer wrote:

> There's a book I bought from Lindsey Press called "Milling and Milling
> Machines" published originally by Cincinnati Milling Machine Co.
>
> In this book there are detailed explanations on how to work out cycle time
> for manufacturing parts. It takes into account things like running a tool
> at full speed verses a slower speed based on how long it takes to replace
> or regrind the tool. For example, if you cut at 50 ipm with a specific
> depth of cut you may get only 10,000 inches before the cutter needs
> resharpening. Running at 40 ipm would mean longer tool life. Depending on
> the price of the tool and the speed at which you replace and recalibrate it
> may be less expensive both in time and cost to run slower even though
> intuitively it may appear to be better to do the opposite.
>
> John Dammeyer
>
>
>
>
>
>
> Subject: [DIY-CNC] Re: Calculating machining/cycle time?
>
> > > Hi all,
> > >
> > > I am trying to estimate (doesn't have to be too precise)
> >
> > how long my machining
> >
> > > time would be for various parts on different CNC lathes
> >
> > (and perhaps mills as
> >
> > > well). Is there a formula or software app that does this
> >
> > easily? I know the
> >
> > > dimensions of the raw material, and of the finished part,
> >
> > but what other info
> >
> > > would I need -- spindle speed? Rapids? Material type? Etc?
> > >
> > > Alternatively, can it be estimated by the quantity (weight
> >
> > or volume) of metal
> >
> > > that is removed?
> > >
> > > The purpose is that I am looking into the purchase of a
> >
> > commercial CNC lathe,
> >
> > > and trying to estimate what my realistic costs would be,
> >
> > other the the
> >
> > > machine and raw material. The next largest costs would be
> >
> > the operator time
> >
> > > (hence the calcs above) and the tool bits.
> > >
> > > Thanks,
> > > -Neil.
> >
> > A decent CAD program like Dolphin will give you quite
> > accurate machinig times.
> >
> > John S.
> >
> >
> >
> >
> > Yahoo! Groups Links

Neil
Wed, 16 Aug 06 05:35:40 +0000



On Monday 14 August 2006 00:34, Jon Elson wrote:

> All of the above and more come into it. If you make small parts, then a
> low spindle speed
> could greatly limit throughput. If the parts are large, then rapid feed
> might be a limit,
> as it sets the minimum time to get from one end to the other. If the
> machine is not
> rigid enough to take a lot of material off a piece in big bites, or to
> take reasonable
> cuts on really hard stuff, then that will slow you down. You don't
> describe the pieces you
> intend to make, so I am totally shooting in the dark here, and many of
> these comments
> may not apply. Will this be an automated job? Will you be using a bar
> feeder and bar
> puller? Or, will you be hand inserting each piece and removing the
> finished parts?


Parts are small, and will be made from aluminum tubing (to minimize
machining). The tubing is over 2" dia and a bit over 1" length. There will
be some cutting on the inside and outside of the tubing. I actually figure
that if I can mount two inserts on a tool bit in opposing directions, then I
should not even need to change tools.

Parts will be made individually, or maybe 2-3 from a each piece of metal. I
can estimate chucking time.


> Have you made these parts manually? A CNC can do it a bit quicker than
> a manual
> machinist, as it doesn't have to squint at dials and look at prints for
> the right dimension,
> but it may not be a whole lot faster. A turret lathe or automatic screw
> machine can often
> make simple parts FASTER than CNC, but the setup time is longer, and the
> change-over
> time is where CNC really shows a plus. The SECOND time you make a part
> by CNC, it
> can often be setup in minutes.


No, have not made it manually, as I do not have a capable-enough lathe yet.


> >Alternatively, can it be estimated by the quantity (weight or volume) of
> > metal that is removed?
>
> Yes, there are calculators that can estimate, given machine type,
> spindle Hp and material
> type, what volume or weight of material can be removed per minute.


Where do I find this handy-dandy calculator?

Thanks,
-Neil.



> For example, machining aluminum alloy, the "power factor" is 3.0 on my
> machining "slide
> rule" calculator. That means that a 1 Hp spindle should be able to
> remove 3 Cu In per
> minute. This number may only be correct for milling, but I suspect that
> it is pretty close
> for turning, too.
>
> >The purpose is that I am looking into the purchase of a commercial CNC
> > lathe, and trying to estimate what my realistic costs would be, other the
> > the machine and raw material. The next largest costs would be the
> > operator time (hence the calcs above) and the tool bits.
>
> Jon

Neil
Wed, 16 Aug 06 05:38:56 +0000
Unfortunately with these parts, there is relatively a very little bit of
machining to be done, and with a manual (non bar-fed) machine, there will be
(I expect) minimal time to do anything useful otherwise between each part, so
the operator will be there for most of it. But volume is very low, so I
expect this to happen one day a week or so.

-Neil.



On Monday 14 August 2006 13:00, Richard Garnish wrote:

> The other posters in this thread have addressed the actual question
> better than I could, but one observation I should make is that with a
> CNC machine you don't pay your operator to stand and watch the machine
> run its cycle, so the actual cycle time shouldn't be the primary way of
> determining staff costs. The operator needs to load stock (less often
> if you have a bar feeder, for instance), maintain tooling, do initial
> checks on output, carry out finishing operations which cannot be done
> automatically, etc.; but all the time the machine is working, the
> operator is better employed doing something else.
>
> Richard
>
> On Mon, 2006-08-14 at 06:39, Neil wrote:
> > The purpose is that I am looking into the purchase of a commercial CNC
> > lathe, and trying to estimate what my realistic costs would be, other the
> > the machine and raw material. The next largest costs would be the
> > operator time (hence the calcs above) and the tool bits.
> >
> > Thanks,
> > -Neil.
> >
> >
> >
> > Yahoo! Groups Links

Neil
Wed, 16 Aug 06 05:55:52 +0000
On Tuesday 15 August 2006 10:08, Keith Green wrote:
> If you're not a machinist, how are you going to choose proper
> toolpaths, inserts, tools, speeds and feeds?


Two ways -- I plan to hire a consultant to me started and will have a
part-time operator to run things eventually. Also, I've spoken with a number
of used-CNC dealers and a few new-CNC dealers, and they've seen my parts
(there are only a few), and they all agree it's very simple and some would be
willing to create the program for me at no extra cost. I have no problem
learning any of this stuff when the time comes, but for now I just want to
figure out for sure that this is worth my time/money.


> What you're asking is doable with most CAM software. I use OneCNC
> and the cycle time prediction can be very accurate. This depends totally
> on how true your program is to the finished one, how long your machine
> takes to change a tool and how many times it has to do that during the
> run. The software is usually programmable for rapid rates of different
> machines, but usually not for tool change time. The rapid time usually
> covers only those moves you've programmed, so if the home and tool
> change positions are far away from the part, you lose a lot of time.


I posted about this just now, but I think I may be able to get away with one
tool only ... no changes.


> I also run and program Mazak machines with their conversational
> control. These things, for me, are the best value out there as regards
> setup and programming time. Typical program on a lathe takes about 15
> minutes and it gets proved out during the first couple parts most of the
> time. You can program another part while the first one runs out so the
> only programming time you pay for is really the first one of the day (if
> you start every day with a new program).


I have just a few parts and will be repeating these for years. I have no
problems learning G-code or any programming language -- it's the machining I
scratch my head at. But for that I will hire the correct person.


> You can adjust the speeds and
> feeds on the fly by using the % keys/dials as there is a 'verify change'
> key on the control that changes values in the program based on what is
> set at the control panel. Changes come into effect at the end of the
> cutting cycle and will be in the program the next time you run it. No
> need to stop and make changes or make notes for changes to be made on
> the next cycle. If your runs and/or cycle times are long enough, 1 guy
> CAN run 2 machines. Our two lathes are placed face to face with about
> 8-10' between so either one is only a step away. On parts where the
> programs are rock solid and I know that there are rarely any problems,
> I'll work on the mill 20' away and just keep an ear open. For anything
> but really complex curvy shapes, programming and running these is much
> nicer than dealing with a CAM-crutch. The mill is pretty good too, but
> due to the funny shapes you often deal with in those machines, you may
> end up using the crutch anyway. G-code programs can run side by side
> and in conjunction with ones you've hand-coded with the Mazatrol. There
> is practically no g-code to be seen in a Mazatrol program; it all runs
> on macro's built into the system. We bought CAM software several years
> ago now but have yet to use it on the Mazak lathes. Occasionally we use
> it for the mill, but it's often quicker and easier to deal with if you
> use the CAD portion of the software to pick off intersection points in a
> 2D profile and hand-code using that. 3D you're better off with the CAM.
> The simulations give a decent approximation of run time in this control,
> though I think the simulations are pretty limited in scope if you run
> g-code in there.
>
> Bottom line is, I think what you're going to get is a
> sometimes-accurate approximation of the run-time of the program, not an
> estimation of cycle time. Cycle time to me is the chip-to-chip time; how
> long it is from the time I press "cycle-start" on one piece, to when I
> press "cycle-start" on the next. The time in between will be filled with
> everything you need to include; loading, deburring, rapids, toolchanges,
> general handling, etc.


Ahhh.. thanks for the clarification. The machine run time is what I'm trying
to calculate then. All else I can estimate fairly.


> I also run a big lathe with a GE 2000 control on it (now obsolete,
> though very powerful) and am learning on a big vertical boring mill with
> brand new Fanuc 18i control. The Mazatrol is still far and away my
> favourite. Since we bought those G-code machines, the office staff have
> had to add a new sequence to the computerized time-clock we use:
> "Programming". Deburring parts from those machines takes extra time as
> well. The Mazatrol makes it very easy to produce a burr-free part. It
> takes too much programming time in the CAM system to draw in all those
> tiny radii and chamfers and stuff. I especially like it (the Mazak) for
> any type of grooving. Those processes are probably some of the hardest
> lathe operations to program because you're guessing all the time on a
> lot of variables. In the Mazatrol, if a program change is required
> (often is with grooving patterns) it takes only a minute or two, most of
> the time. A complete rewrite of a 'lengthy' grooving sequence would only
> take 5 or 10. Changes like this are faster because they're done right at
> the machine, hands-on, by the operator who knows what he wants to do and
> how he wants to do it. He'll run that first draft program and make
> changes based on direct observation. Most of these type of changes don't
> ever get made when you're dealing with a CAM program and g-code as the
> time it takes to make a change can be excessive.
>
> Ah crap. This has turned into somewhat of a rant again...
> OK. As I said earlier, i think you're going to find estimates of
> run-time for a given program, but not the actual cycle time. Cycle times
> will be based on way to many pretty well unpredictable factors in a
> normal shop environment. I highly automated shops and such, cycle times
> are more predictable, but I think such palces don't have the flexibility
> you would want in your place.


Thanks,
-Neil.


>
>
>
> Keith
>
> Neil wrote:
> > On Monday 14 August 2006 00:34, Keith Green wrote:
> > > The cycle times will depend a lot on individual programmers and
> > > operators. The 'givens' are; what material are you cutting? this leads
> > > to what speed and feed you will cut that material at which can give you
> > > an estimate of time.
> > > Other factors will include the toolpaths you choose and how good
> > > ...
> > > I guess the short answer is that there isn't really a 'formula' per
> > > ...
> >
> > Sure, but there's no way to get a ballpark if I have/get this info? I was
> > hoping that if I get the CAD/CAM software, it could give me an
> > estimate of
> > tool path distance, then I'd use that with the spindle speed and
> > tool-travels
> > speeds (I assume this is the "rapids"), and I could come up with an
> > estimate.
> >
> > > ...
> > > There is an online machine shop which you can check out for an
> > > example of a quoting formula in action. You fill in an online form with
> > > ...
> >
> > I've been using the emachineshop software for some time, but never
> > actually
> > had them do anything since they're ridiculously expensive, compared to
> > other
> > shops that I've had work done at, and it has a lot of software bugs. The
> > software is great for quickly visualizing what a part would look like,
> > or for
> > getting a 3D image so I can pass to a shop to see. But I see no way to
> > get
> > machining/cycle time off this software.
> >
> > > About the best I can say is that you should just dive in there and
> > > work at it. ....
> >
> > There in lies the problem. I am not a machinist. But I am considering the
> > purchase of a CNC lathe to bring the machining portion of a product
> > in-house.
> > Reason is that I'm sick and tired of getting screwed around by shops.
> > I've
> > dealt with some reliable shops in the past, but for this product price is
> > critical and those shops don't come anywhere near to the target. So at
> > this
> > point I am evaluating what it would cost me to bring the machining in
> > house.
> > All I need is an estimate -- sort of like business planning. I can figure
> > out what the machine would cost me, and not concerned about my time to
> > learn
> > and program the machine for these few parts. I can calculate the cost
> > of the
> > material easily. Then I need to know how much time it would take for each
> > part, so I can estimate how long I need an operator at the machine.
> > Fudge in
> > a small factor for maintenance, electricity, etc, and this will all
> > eventually lead to a cost estimate and a decision as to whether I
> > should do
> > this or not. I expect volumes to get better over time, so even it it
> > costs
> > me a bit more now, I'd be willing to take the plunge to stop dealing with
> > shops.
> >
> > The key is that I was to know this *before* buying the machine.
> >
> > -Neil.
> >
> >
> > ------------------------------------------------------------------------
> >
> > No virus found in this incoming message.
> > Checked by AVG Free Edition.
> > Version: 7.1.405 / Virus Database: 268.10.10/418 - Release Date:
> > 8/14/2006

Neil
Wed, 16 Aug 06 05:57:24 +0000
Correct, and even some used machine dealers have offered this, considering how
simple my parts are. But I really think the programming part will not be my
issue.

Cheers,
-Neil.



On Tuesday 15 August 2006 11:50, delmar1192005 wrote:

> Neil,
>
> If you are looking at new machine, why not give the drawings to the
> manufacturer and ask them. I'm sure they would be happy to take your
> drawings and code them, set them up and do a test run. That way you
> get to see the quality, and have an exact time.
>
> Del
>
> --- In DIY-CNC@yahoogroups.com, Neil wrote:
> > Hi all,
> >
> > I am trying to estimate (doesn't have to be too precise) how long
>
> my machining
>
> > time would be for various parts on different CNC lathes (and
>
> perhaps mills as
>
> > well). Is there a formula or software app that does this easily?
>
> I know the
>
> > dimensions of the raw material, and of the finished part, but what
>
> other info
>
> > would I need -- spindle speed? Rapids? Material type? Etc?
> >
> > Alternatively, can it be estimated by the quantity (weight or
>
> volume) of metal
>
> > that is removed?
> >
> > The purpose is that I am looking into the purchase of a commercial
>
> CNC lathe,
>
> > and trying to estimate what my realistic costs would be, other the
>
> the
>
> > machine and raw material. The next largest costs would be the
>
> operator time
>
> > (hence the calcs above) and the tool bits.
> >
> > Thanks,
> > -Neil.

Roy J. Tellason
Wed, 16 Aug 06 16:08:17 +0000
On Wednesday 16 August 2006 01:27 am, Neil wrote:
> Also, I just googled for Lindsey press and got a ton of results
> to Lindsay Lohan and the press. Geez. Any links?


Somebody just pointed me to this link last night:

http://www.lindsaybks.com/

Could that be what you're looking for? Lots of interesting stuff there, too
bad my book-buying budget is basically zero for the near-term...

Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin