involute spline (internal) 3

[rosie2277]

can anyone help me please, im having trouble using this site as ive seen this question answered on here but cant comment on it! - im wondering if anyone can translate my info into a dxf file please?

INVOLUTE SPLINE DATA, FLAT ROOT, SIDE FIT, INTERNAL.
NO OF TEETH - 24
PITCH - 16/32
PRESSURE ANGLE - 30
BASE DIAMETER - 1.2990 IN
PITCH DIAMETER - 1.5000 IN
MAJOR DIAMETER - 1.5625 IN
FORM DIAMETER - 1.5500 IN
MINOR DIAMETER - 1.4375 IN
CIRCULAR TOOTH THICKNESS
MAX ACTUAL 0.1011 IN
MIN EFFECTIVE 0.0982 IN

 

[EnergyMix]

Welcome to Eng-Tips. You might want to read through the site policies found in FAQ731-376.

To answer your questions: The reason you probably couldn't post on the other thread was becuase it was old, but that's probably a good thing as you should start a new question unless you're answering the original posters question.

The site doesn't give out contact information for any members. However, gearguru is pretty active, so he might read this thread (or he might not.

However, when it comes to someone putting your information into a dxf file ... ummm that sounds periously close to your asking someone to doing your work for you for free. I suggest that, as a first post, it doesn't make a good impression. Perhaps you should explain what you've done yourself so far and why you can't put it in a dxf file yourself (as I presume you're being paid to do). Then if someone decides they want to help you, they will.


Want to know the do's and don'ts of Eng-Tips? Read FAQ731-376.
English not your native language? Looking for some help in getting your question across to others or understanding their answers? Go to forum1529.

 

[rosie2277]

CAN ANYONE TELL ME SOFTWARE I CAN USE TO DRAW UP AN INVOLUTE SPLINE I HAVE ALPHACAM BUT IT ONLY DRAWS AN INVOLUTE CURVE, AND IVE TRIED LOADS OF WAYS BUT ALL THE SIZES DONT MATCH AND IM STILL UNCERTAIN IF IT WOULD MATCH THE MATING PART AND HAVE NO WAY OF CHECKING AGAINST IT.
THANKS FOR THE REPLY

 

[dinjin]

The curve for an involute spline is the same as for an involute gear.
Your problem might simply be to know how to rotate this curve to have
1/2 the circular thickness to the right and 1/2 the circular thickness
to the right about the vertical centerline. The same applies to circular
space instead of circular tooth thickness for an internal spline.
If you can draw an external spline, you can draw an internal splince
by using the tooth circular space instead of the tooth circular thickness.
Reverse also the values of the addendum and dedendum.

 

[rosie2277]

GOT IT THANKS, IT WAS ACHIEVING THE CORRECT CIRCULAR THICKNESS THAT I WAS STRUGGLING WITH!

 

[mfgenggear]

rosie

what are trying to do with the DXF file. Wire EDM ? or just simply know to do it?



Mfgenggear
if it can be built it can be calculated.
if it can be calculated it can be built.

 

[gearguru]

Better late than never... I only now found this thread.
If you know how to draw an involute the rest is a piece of cake.
I can't help you with the dxf file (no CAD - retired years ago), but if you have some specific questions - ask.
And yes - let us know for what you need that dxf ?
Just two warnings:
Be sure that the circular tooth thickness is measured AS A LENGTH OF AN ARC.
And be sure that you use the appropriate part of that involute.
gearguru

 

[Occupant]

Rosie, are you still there? Probably not, but I had to find out for myself.

 

[rosie2277]

thanks for the reply's everyone!
i only have one problem now, when i draw and internal and external side fit spline then place them on top of each other there is clearance on the minor and major but the splines are touching, no clearance, the circular tooth thickness on both drawings is different so there should be clearance, is there a calculation to get circular tooth thickness into an angular size? or even a linear size? - i could easily offset lines allowing my parts to fit together but these parts have to be compatable with competetor parts.
this was a prototype part and ive made one fine but i now have the fun of making around 30 different size involute splines in batch quantities, i will be wiring some and getting horn inserts groung for otheres, either way once i can draw them succsefully on my cad i can output programs for any machine or wire or send drawings to horn to get some inserts made.

 

[rosie2277]

occupant
i cant open that file till i get back to work monday, ill have a look thou thanks

 

[dinjin]

Circular thickness is an arc length on the pitch radius.
The math is basic. Are you a student?

 

[rosie2277]

dinjin

no im not a student just hopless at maths

 

[rosie2277]

occupant
i opened your file and its identical to my 1st attempt, if i draw an internal and external the same they dont fit together, yours measures the same as mine? and i think the tooth thickness needs to be reduced. it measures 0.098 linear??????

 

[rosie2277]

rite i think ive nearlly got it! - since dinji pointed out im stupid i went on some maths site and sussed the maths out, i can get circular tooth thickness into degrees, wahoo.
so only 1 question left - what size do i use for circular tooth thickness, is it in the middle of max effective and min actual (internal spline), or (external spline) in the middle of min effective and max actual?

 

[rosie2277]

im going to clarify my last comment -
i have the drawings for mating splines and on the external spline the circular tooth thickness is given as max effective = 0.0982 and min actual = 0.0953.
then on the internal spline its givin as max actual = 0.1011 and min effective = 0.0982.
what size do use when calculating?
also this mite be obvious but i need to check, on an external spline its the tooth im measuring but on in internal its the gap?

 

[Occupant]

The tooth thickness/gap on my drawing is 0.5*Pitch which, in the standard, is listed as the minimum and the maximum in your case would be 0.100103 (calculated). This applies to the internal spline and for the external spline the minimum actual would be 0.09381 and the maximum effective 0.096675 - the rest is up to you. One thing I don't get, though, you have the *.dxf - and in my case I know, the involute is correct -, so how are you going to fabricate this? E.g. if you wire cut the intenal, the programmer would have to offset the cut by half the wire diameter anyway - if it were 0.014", the offset would be 0.007". Increasing or varying this offset a little would really not be a big deal for him.

 

[rosie2277]

I need to be certain im drawing these things correctly, if im wiring these yes ill be using compensation i.e G41-G42 on my wires, and yes i can just alter the wire comp size till it fits but checking these things is going to be difficult and chances are ill be using the OD ind ID to check its cutting size so the involute has to be in the correct position, when i draw the one you did i get the angle to be 7.3898 degrees yet yours measures 7.5 degrees and i know its not much but its enough to get the parts interfiering with each other?

 

[Occupant]

They will definitely interfere. But how did you come up with 7.3898 deg.? It is 360/(2*24)=7.5 deg for half a tooth. If your angle for the arc is different, then you made a mistake.

 

[rosie2277]

at 1st i was just going 360 divided by teeth and geting 7.5, but realising that this would cause interferance between internal and external i realised that the tooth thickness had to goveren the width and the only way i could draw it was to convert the circular tooth thickness into an angle so i could rotate the involute curves to the rite position to achieve the correct tooth thickness, i did however rotate my finished tooth 7.5 degrees times 24 to achieve the rite spline, my question is what is the correct size or mid size for the circular tooth thickness?
everything on your drawing is correct except the circluar tooth thickness

 

[mfgenggear]

Rosie

Just as a helpful suggestion.

if you are wire cutting these splines just because it is drawn correctly does not mean it will automatically be machined correctly.
The choices are it must be either verified with plug or ring gages, or verify each attribute independently like MBW, MOW, Totally Index Error. Involute. lead, & runout. whoever is cutting the parts, it is whole lot easier to maintain tolerances, if there are a set of gages to verify the go & nogo size.
therefore maintaining compliance. without gages it will be more difficult.

if these are blind holes it has now more difficult because now electrodes have to be machined. there are more issues with taper & size.


Mfgenggear
if it can be built it can be calculated.
if it can be calculated it can be built.