Speeds and feeds calculator enhancement #96
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Interesting. Feeds and speeds are a bit of magic and a bit of calculation. Tool material is a large part of this, carbide generally needs 3x the sfm that hss does. Chip load is the next limiter, which relates to rpm because if you are cutting Al with a 4 flute .125" bit turning 10000 rpm, your machine can't move quick enough to clear the chips, instead of chewing them up again rubbing against your newly cut path. Can you doodle up a sketch of what you think this might look like? Tool material, material to be cut, tool diameter, # of flutes, output should be suggested feed rate and spindle rpm. And no, I won't be suggesting that anyone go out and buy a commercial grade machine. If you had the need and the money you would not be using Grbl/whatever GUI in the first place. Plus you would be losing out on the journey and experiential learning on the road to your machining goals :-) |
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I too went through this process and agree with Gerrit. The biggest problems
I had was using a low powered spindle. The Shapeoko 2 I purchased came with
a want to be mototool. I quickly moved to the 400W Quiet cut spindle and
burnt that out. Now I use the Dewalt Router and it has 1.25hp. Where I use
to have problems making cuts and would blame the power of the stepper
motors. Now I can make a .25" deep pass and the nema 17 motors don't even
have a problem with that. So don't underestimate the power of the spindle.
…On Thu, Feb 23, 2017 at 7:47 AM, Gerrit Visser ***@***.***> wrote:
Interesting. Feeds and speeds are a bit of magic and a bit of calculation.
Tool material is a large part of this, carbide generally needs 3x the sfm
that hss does. Chip load is the next limiter, which relates to rpm because
if you are cutting Al with a 4 flute .125" bit turning 10000 rpm, your
machine can't move quick enough to clear the chips, instead of chewing them
up again rubbing against your newly cut path.
And then there is machine rigidity.
I play with FSM Wizard on my tablet but it is not really relevant to home
machining.
I only have a manual horizontal mill at present so I go by sound feedback
to set the feed rate :-) That is why so many Grbl users were asking for
Overrirdes, you can adjust on the fly to get optimum rates for your
situation without re-doing the Gcode.
Can you doodle up a sketch of what you think this might look like? Tool
material, material to be cut, tool diameter, # of flutes, output should be
suggested feed rate and spindle rpm.
And no, I won't be suggesting that anyone go out and buy a commercial
grade machine. If you had the need and the money you would not be using
Grbl/whatever GUI in the first place. Plus you would be losing out on the
journey and experiential learning on the road to your machining goals :-)
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Hi guys, this is the closest i have got to meaningful values.
the excel data and formulas have come from a number of sources, as for a
GUI/dropdown i quite like the one from
http://www.custompartnet.com/calculator/milling-speed-and-feed which is on
my excel sheet as an idea of layout for a gui. The spindle excel sheet is
the one I borrowed the formula from. cant remember where i found it off
hand.
If you can open a local web instance from GrblPanel then the custompartnet
widget html code can be copied to it. however it wont have the material
chips & feeds table.
over the last week ive tried loads of formulas and got some really weird
feeds and speeds - its the old imperial mix up most of the time. I also
discovered that loads of online calculators are available but not
common/free anymore, even the tool manufacturers are making it harder.
Why i have no idea.
John Saunders at NYCCNC posted a video about working out chip loads/feeds
and speeds
https://www.youtube.com/watch?v=KNwAHE73SHk
again fantastic if you have tormach and buy tools from manufacturers and
not Ebay or third party suppliers like cutwell, RS etc who don't give you
the data tables but tend to be the source of most hobby machinists tools.
GUI design wise i was thinking of a popup windows form and a dropdown list
which would populate the FSM info into the relevant boxes when a material
was selected, the user would then enter the tool size and no. of flutes -
perhaps this should be done first so that the chip load was selected with
the material selection ? If someone is good and programming and math and
can create two sliders or even just entering values into rpm or feed boxes
which recalculated the other values in the entry boxes then that would be
really neat. Say for example we were to mill Alu SFM of 800 and a very
likely RPM output of 7500 for argument sake, my machine only produces 3600
rpm so i could enter that into the rpm box even though it currently has the
original calculated value in it. Inserting the new value adjusts the
feedrate to compensate.
Im not concerned about precision same as the human ear
calculators/operators out there and given that a tool will work over a wide
range of feeds and speeds, calculating a rough gestimate should help in
reducing the number of tool purchases and holes in the garage wall.
The only other problem will be guessing what type of material you have with
brass coming as hard or soft which is great if you have a bit of both side
by side on the bench, of what type of steel have you just pulled out of
your scrap box with SFM's ranging from 80 to 500, For a bit of structural
steel of free machining steel. I think i could spot bright and obviously
the difference between carbon and stainless but grades ummm.
Mach3 had the edge for hobby machines due to the wizards and their attempt
to build the GUI like a Pro GUI it fails miserably for two reasons, firstly
the parallel Port output/interface with the machine, i think the last PC i
had with one of those was a 386. Secondly the GUI actually looks like a
child drew it with crayons.
I like GRBLPanel, its clear, straight forward and well laid out Its a
credit to you Gerrit.
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I forgot to mention depth and width of cut.
for refference
My usual tool selection goes something like,
look in the box and get out what looks like an appropriate size
is it sharp
how many flutes
what speeds etc to run it at - then put it back in the box and give up.
Its two of the simplest equations ever why is it so confusing?
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@MeJasonT Did you mean to attach an Excel file? |
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Yes i did intend to send 2 excel files, although they loaded it looks like the have not gone through. |
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and try number 2 |
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Are you looking for a job on the side regrinding tools, you will be inundated with customers for that fantastic machine. |
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Just to show Im not anti United Trump of America here is a great link to a good old slide rule, well worth a look. http://solo.dc3.com/VirtRule/md-speed-feed/virtual-md-speed-feed.html |
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I really like the slide rules etc. I have a few for things such as SHCS details. So much quicker than flipping through Machinery's Handbook or Mechanical and Metal Trades Handbook (EU). I think when I implement this tool it will need to have a way to enter your materials and SFM/SMM's yourself. That way you control the results a bit more to your liking/machine's liking. |
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I agree, the tables were just rule of info i found from other sources. Having said that most of the tables i found gave similar information for SFM's |
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Are you going to be kind and offer both imperial and metric conversions. |
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btw my account picture was my old ship in the Royal Navy HMS Danae |
Hi gerritv,
I have spent days trying to figure out how to calculate feeds and speeds for my milling machine and relate it to GRBL.
I have the following known values Max rpm =3600 X and Y setting is $110=450 (x max rate, mm/min)
$111=450 (y max rate, mm/min) $112=500.000 (z max rate, mm/min). The biggest pain in the butt is nearly all the formulas you find on the web are American imperial measurements. you then have to convert to mm and end up with really odd feed rates like 350000 what! - i figure i just enter F450 S3600 as that's as far as i can go. It great for John at NYCCNC on youtube showing us how to zigzag the feeds and rpm's to get the best out of our tools but some of us cant peddle fast enough to reach Tormach speeds.
So a calculator on the GUI which takes into account the settings we use in GRBLPanel would be a very nice toy to have. Just in case you were tempted. At some point you will turn round to us and say why don't you just go and buy an industrial CNC VMC instead of turning my Gerritv Gui into top end software. You cant blame us for being enthusiastic about your enthusiasm lol.
I've just learnt today that i can use a macro to run quick test code from the GUI instead of importing a text/nc file, feels really professional now.
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