i have a newbie question. can i find the tangent point of rad to angle using a chord calc.? or is this 2 different things?

i have a R.1 nose to a 45 i can draw it in cam and get the #'s for the lathe but i like to double check my #'s. think i got myself mixed up.

is this what you are looking for

that is what i was talking about. how do i use this to get correct #'s or is this something different.

i get different #'s with smart cam. and now im real "cornfuzed". lol

any info would be great i thank u.

TURN ME,
What you really need is called trigonometry.

any info would be great i thank u.
here you go try this link http://www-gap.dcs.st-and.ac.uk/~history/HistTopics/Trigonometric_functions.html

TurnMe
What info do you have and which figure do you require?
Give us the figures off your CAD drawing or post a pic.

THANKS FOR ALL THE INPUT.
raduis .1
end angle 45
x.14142 z-.02929 here are the #'s i got and used.
i was given start point radius and angle.
still foggy on the chords but im reading and like a sponge i 'll soak it up lol.
im learning on a little okuma lathe w/live tooling.
so any wizdom on turning would be awsome.

what are you looking for a cord for?

TurnMe
Check if this is what you need. Is the angle taken from the correct points.
As Mike said, is the X figure really what you require?

this looks like it will work. thank u kiwi
this should work for any radius to angle as long as i add the dia. to the x=value right?
if the radius is not a nose.
did u make that program kiwi?

im not sure what a cord is i did use much math in my other job.
i am reading the machinist handbook all the time.
i also read alot of post on here and pick up some tips.
what would the formula look like for this to figure the x and z values?
and how did u get a pic of machine mate?

TurnMe
Yes I wrote the Visual Basic program, Its about as simple as they come.
I drew the drawing with CAD and then "Print Screen" and added to program to make it clear how the figures fitted the sketch.
The cord of a circle is the figure you are calling X
I've had nothing to do with CNC Lathe only Mill, but I'm still confused why you need this figure. I would have thought you would only want half of that figure. Centre Line to tangent Point. Check this out and advise. No problem to change.
The formula for Z is: R - (R * Cos(Angle))
.1 - (.1 * Cos(45)) = 0.02929
I'll show you the X once you confirm which number you require.

it is programed in dia. if that helps with why that x #.
i was thinking i could use that program to figure any of my radius to angle problems by adding the dist. from center line to the start point *2 ?
would this be correct?
did u learn vb in school or ur self?

Kiwi,
so the cord would be the tangent point were rad meet ang?
would u say it is the tangent point or the intersection point?
i have a guy that works on the mill next to me he thinks he knows everything and he is realy confuzing me.
so i realy thank u for ur time and info

TurnMe
Can you give me a picture of the tool path. I'm not conversant with Lathe programs.
Somebody else will need to give some input.
I'm sure what you want can be done but I need to understand.
When I went to school, electronic calculators weren't invented. Just self taught.

Kiwi,
so the cord would be the tangent point were rad meet ang?
would u say it is the tangent point or the intersection point?
i have a guy that works on the mill next to me he thinks he knows everything and he is realy confuzing me.
so i realy thank u for ur time and info

Can you post a geometry file (iges, step, dwg, 3dm, sldprt)? I program lathes and would like to help you. If you post a file drawing we can better understand what it is that your trying to do.

Remember that the X axis is always *2 of the Z axis movement when doing angles, chamfers, and radii.

Example:

G0 X0. Z0.1
G1 Z0. F0.015
X0.75 (START POINT OF .125 CHAMFER)
X1. Z-0.125(END OF CHAMFER)
Z-0.5(START POINT 3/8 RADIUS)
G2 X1.75 Z-0.875 R0.375(END POINT OF RADIUS)
G1 X1.8(START POINT OF .1 RADIUS)
G3 X2. Z-0.975 R0.1(END POINT OF RADIUS)
G1 Z-1.125

As a note if your using Tool nose Radius Compensation you have to designate a Tool Tip something like the jpeg screen shot.

simple lathe geometry DXF File with X * 2 because X 0.0 is the center line of the part.


simple lathe geometry 2 dxf

This short PGM has a Chord R.1 at 90 Degrees Included Angle

G42 G0 X0. Z0.1
G1 Z0. F.01
X0.1414
Z-0.1293
G3 X0.2 Z-0.2 R0.1 (0-90 degrees of the arc)
X0.1414 Z-0.2707 R0.1(90-180 degrees of the arc)
G1 Z-0.4707

TurnMe
The chord is the green line in the pic.
I would say the tangent point and the intersection point are the same but I'm not familiar with Lathe programing.
Are you able to draw the tool point and the part in CAD and supply a picture.

ok here is a dxf of it.
hope it helps.
i think ur program will give me the #'s i need.
do u think it will after u look at this file?

TurnMe
I've looked at your profile and (if I'm reading your drawing correctly) I find the start point is 0,0 and the tool radius is the same as the first curve radius which makes a number of figures the same value and don't help when explaining which number we are talking about.
I've attached a diagram on how I see it. I may be way off and I hope Toby puts me right.
I would think the tool path is the tip of the tool marked with red circle.
I think the angle should be read off the part..red arc line.
I would think the red numbers should be (added for Z : subtracted for X) to the green numbers which equal the blue numbers.
Can somebody please confirm if this is correct.

This will be your G-Code for this part.

G0G40G99M5
G50S2000M41
G96S750M3
T101M8
G40G0X.4Z1.0
G42G0X0.Z0.1
G1Z0.F.006
G3X0.1414Z-0.0293R0.1
G1X0.375Z-0.1461
Z-0.5
X.4
G0Z.1
G40G0Z1.0

I have no idea what canned cycles you have on an Okuma so this is just the finish geometry
:cheers:

TurnMe,

Going by Toby's program my diagram is a load of old rubbish.
I've been thinking you needed to know where the radiused tool tip touched the part and this needed to be calculated to write the tool path.
I'm now thinking you need the point where the angled path line tangents an arc. Looks like you believe you need to know the chord length (2 * triangle side) because the X figure is doubled (Tobys post #2?) which I think is converted to a diameter figure.
Looks like the blind leading the blind here.
I still think the program is giving you the figures you need as long as you add/subtract to the correct figures. I do have concern where the 45deg is taken from and the correct angle being used in the program. That is why in the diagram on the program I used 40deg. Can you confirm the figures shown in the pic are correct? You will need to do a CAD drawing but draw the angled line at 40deg. as your draftsman would.

TurnMe,

Going by Toby's program my diagram is a load of old rubbish.

I am unable to help until I have a better understanding of what is required.


Kiwi,

That's not Rubbish, it's Trig ;) Should we make this a Beer Post now? :D
:cheers:

wow i figured out what i was doing wrong with the chord calulator. lol
ur going to laugh at this. :)
when it ask for angle i was putting in 45deg. when what it was asking for was the included angle witch would be 90 damn im a noob lol.
i cant get my print screen to work or i would send a pic. but i think u will get it pretty quick . to bad i didnt.
lol

so i was looking for a chord lenth, and chord hieght.
man i got confuzed lol thanks for ur help.
u guys have been awsome.

TurnMe
I'm not sure I understand what's going on. You shouldn't be entering 90deg.
If you enter the radius as .1 and the angle as 40 deg. you get the same figures as the picture. Are these the correct figures that you require for R.1 Deg.40 ???

i was looking for R.1 45deg.
i got #'s from cad then used a chord calculator, and instead of putting in the angle i put my #,s in for chord length c=x=.1414 and chord hieght h=z=-.02929
and the included angle in this ex. 45*2=90deg.
i was putting in 45deg. and it would give me different #'s thats how i got confuzed. and thought a chord must be something different.

a chord calculator should be able to produce #'s for a radius to angle on a dia.?
or will u have to divid the chord length /2 ?

i was looking for R.1 45deg.
i got #'s from cad then used a chord calculator, and instead of putting in the angle i put my #,s in for chord length c=x=.1414 and chord hieght h=z=-.02929
and the included angle in this ex. 45*2=90deg.
i was putting in 45deg. and it would give me different #'s thats how i got confuzed. and thought a chord must be something different.

a chord calculator should be able to produce #'s for a radius to angle on a dia.?
or will u have to divid the chord length /2 ?


Turm Me,

If you are using CAD why are you using a calculator? Take all of your Y=(X) values and multiply by 2. All the X=(Z) values will remain the same. On your drawing plot points at all the intersecting lines like so.


I am sending your drawing back with points at the intersections. Out of curiosity what CAD Software are you using?

TurnMe
I'm sorry but I want to make sure the program I sent you is producing the correct figures. I don't want you to take it for granted that they are correct and get the programs wrong.
I realize your request was for 45deg but because 45deg is half a 90deg arc it is not possible to confirm the formula used is correct. This is why I'm asking for you to check 40deg as there is not any confusion.
I'm not sure why you need to know a chord length, I can understand you may need to know the distance from the centre of the tool to the tangent point and the X figure may need to be doubled to convert to dia. (This is my understanding) This figure may be the same as the chord length of a circle with the same radius but calling this figure the chord is confusing the issue.
Can you please draw the arc R 0.1 with a line at 40deg as your drawings would show, and advise if the tangent point figures are the same as the program I sent you shows.
I'm trying to confirm the formula is correct.

TurnMe
This is a drawing of the R0.1 and 40deg angle. Is the angle drawn correctly??????
Are the figures marked in RED the ones you need.
These are not what the program will give you. If you advise I will modify and send you a new copy.

ok kiwi
hope this is what u need see dxf.
R.1 40deg. angle
start point x0 z0
center point x0 z-.1
end point x.1285 z-.0233
angle 40deg.

toby,
im trying out caps turn right now
i program alot with IGF but its on the machine would like to try okuma's admac software.
i cant get IGF to produce the correct #'s for the questoin at hand (r.1 45deg)
so i use smart cam at work to get #'s for the lathe.
i would like to have other ways to check the #'s before i run and im trying to get a better understanding of what i do.

ok kiwi
hope this is what u need see dxf.
R.1 40deg. angle
start point x0 z0
center point x0 z-.1
end point x.1285 z-.0233
angle 40deg.

toby,
im trying out caps turn right now
i program alot with IGF but its on the machine would like to try okuma's admac software.
i cant get IGF to produce the correct #'s for the questoin at hand (r.1 45deg)
so i use smart cam at work to get #'s for the lathe.
i would like to have other ways to check the #'s before i run and im trying to get a better understanding of what i do.



NCPlot is a nice back plotter that even simulates some of the Canned Cycles for Fanuc Based Controls www.ncplot.com

:cheers:

thanks for the link. toby
what sofware do u use?
and do u like it?

i run alot of 4140 and A-2 im trying to get a very smothe bore any tips?
bore is 3" deep and need to use .75 bar get close but feels kinda dry not slick.
using coolant think i might be leaving to much stock for finish but any less and i get harmonics. i know there is alot to consider in this so any tips would help.

TurnMe
Thats what I needed. Now that I see where the angle goes, the program needs modifying.
My no.1 PC has crashed so I need to install VB on a old backup machine and rewrite your program. Wont be ready until tomorrow.

thanks for the link. toby
what sofware do u use?
and do u like it?


BobCAD-CAM V21 and yes, for $500 with Full 3D Solid Functionality for Milled Parts and Lathe Geometry, yes, I do like it.

As for achieving a Nice finish in 4140, try Cermet Inserts (Seco Carboloy FF1 grade)(www.carboloy.com) with the Largest TNR that can be applied to your application. A2 is a PITA and I avoid that stuff ;)

that will be great kiwi but dont go to any troble ok.
i think i can use this machinist calculator program.
it should do the same thing?

TurnMe
New program attached.
I've added extra text boxes so you can add figures which can be added or subtracted.
Checkout and advise. You may want the X addin figure to be doubled???

thats the same file u sent the first time kiwi.
u must have picked the wrong one during upload.

You are right, sorry about that.
I've removed the file. I want to make a small change so I'll alter and repost.

BTW. The first program is OK to use, it is virtually the same as your chord calculator except you enter the correct angle.

This time. Let me know if this is what you require.

kiwi,
that is it. it works good.
would it be hard to have the picture and the formulas at the bottom to change with the entered data?
if thats too much or if i can help in some way let me know.
i realy thank u for ur work and time.

TurnMe
Having the figures changing in the drawing can be done. Without a lot of trouble I can't get the angle line correct. I will have a look but will be a day or two.
Is the extra add/subtract of any use and could it be improved?

kiwi,
add/subtract is good might want to add muiltply\divid.
if i can help let me know. :)

TurnMe
I'm a little confused which numbers you would want to multiply and divide.
I'm not conversant with lathe programing but I added the add/subtract because I asumed the figures you required would sometimes be either added or subtracted from another set of numbers. My thought was if you entered these other numbers into the boxes, you can then add/subtract, then copy and paste into your program. No need to put in a calculator where there is room for errors.
Can you explain a little what you do with the numbers you require?

KIWI,
i thought it would help me to get figures for this. see file
but it is all i need add/sub will do fine.

Here is your 30 degree angle with a 1/8 radius bmp and dxf

TurnMe
Latest version, check and report.

thats cool **** kiwi (ur program) i thank u.
it inspires me to learn how to program.
i will try it as soon as i get back to work off for holidays.

thank u too toby

Your welcome:wave: