External involute spline - MC 9.1

[Mct010]

Sence I have the demo version of mc9.1 I was wondering if I could get someone to draft the spline for me and post in on the ftp sight.

 

I just need one tooth that goes into the shaft and can rotate it around the outside myself i just need the shape.

 

Data :

 

Number of teeth 27

Dia Pitch 8/16

presure angle 30 deg

 

circular tooth thinkness at pitch dia

max Eff. .1953

min actual .1918

 

Base Dia. 2.9228357 ref.

measure over pins 2x.21600 - 3.6664/3.668

 

3.250 form dia max

3.209 min dia

3.375 pitch dia ref

 

Now I don't know what all this means but its on the print.

I tried to figure the spline out myself but It seems that the Machinist handbook didn't have all the formulas that I was looking for,

Like how to figure the radius on the side of the spine for example. If I could have figured it out I wouldn't have bothered you all but I don't know everything

 

If more info is needed, let me know

Mike

[chris m]

I actually have a part running in my gear shapers right now that has a very similar spline in it, though ours has a 3.750 pitch diameter. How are you going to cut your spline? I will forward your post to one of our mechanical guys and see if they can help you out.

 

C

[Don Trust]

Below is the output of our gear program. (in-house written)

 

I see that the MOW doesn't match what your data shows (using the mean CTT.

 

The radii listed at the end can be drawn and trimmed off to get a tooth wall.

 

 

C:gears27TEETH using version 4.2

 

Number of Teeth.......... 27

Pressure Angle........... 30.000

Diametral Pitch.......... 8.00000

OD....................... 3.25000 Standard OD = 3.62500

Root..................... 3.20900 Standard Root= 3.06250

Wire Diameter............ 0.21600 Standard Wire= .2160

MOW...................... 3.66930

CTT...................... 0.19360 Standard CTT = .19634

Pitch Diameter........... 3.37500

Base Circle.............. 2.92284

Beta Prime............... 0.3003

Fillet Radius............ 0.00000 Standard Fillet = .0375

Tip Radius............... 0.0000

Change Factor............ 1.620 : 1

Tooth Spacing............ 13.33333°

1/2 Tooth Spacing........ 6.66667°

 

POINTS ON THE INVOLUTE

 

Points #1 - 12 Points # 13 to 26

 

X 0.007659003 Y 1.461397799 X 0.028062068 Y 1.546225952

X 0.008107096 Y 1.467938767 X 0.030494269 Y 1.552724450

X 0.008900855 Y 1.474477574 X 0.033022903 Y 1.559217488

X 0.009922557 Y 1.481014485 X 0.035645592 Y 1.565704723

X 0.011130811 Y 1.487549366 X 0.038360210 Y 1.572185807

X 0.012501998 Y 1.494081990 X 0.041164841 Y 1.578660391

X 0.014020377 Y 1.500612085 X 0.044057749 Y 1.585128126

X 0.015674532 Y 1.507139359 X 0.047037352 Y 1.591588661

X 0.017455723 Y 1.513663504 X 0.050102202 Y 1.598041644

X 0.019356999 Y 1.520184202 X 0.053250970 Y 1.604486720

X 0.021372679 Y 1.526701128 X 0.056482426 Y 1.610923536

X 0.023498016 Y 1.533213952 X 0.059795436 Y 1.617351738

X 0.025728971 Y 1.539722340 X 0.063188942 Y 1.623770968

 

Chords - Maximum of 4

 

0.32477

0.66486

1.00494

1.34503

 

6 Circles make up the Involute

 

X Location Y Location Radius

------------------------------------------------

0.185043613980,1.451154956128 0.177680094641

0.343205522169,1.420943036695 0.338688672307

0.441861743480,1.393264352622 0.441153517401

0.520897192060,1.365616551612 0.524885122786

0.588550465102,1.337814956132 0.598028047031

0.648440102647,1.309809647218 0.664142064017

[Mct010]

quote:

---

How are you going to cut your spline? I will forward your post to one of our mechanical guys and see if they can help you out.

---

Well, I just want to draw it up, not doing any G-code for it, the company I work for does it on a machine, with a Hub (not sure of the spelling) But I just want to make the part into a solid and cut the spline with the sweep function on MC

I have drawn up much of the part with the drafting version and MC and saved the file, and make it into a solid when I call it up in demo version, but I just can't do the drafting of the spline

 

Mike

[Mct010]

Don Trust

 

You lost me lol

 

Mike

[Don Trust]

Mike,

 

Sorry. Been doing gears so long using that program I forgot that it may not make sense to someone else.

 

An easier way would be to just use the

GEAR C-hook in MC.

 

ALT-C --> choose GEAR.dll

 

You can put in all the gear parameters you have and MC will draw the entire gear for you, all teeth or just one. Then you can make whatever toolpath you want on it.

[Don Trust]

Mike,

 

On the FTP site, in the Ver 9 directory, there is a file called 27tooth.mc9.

 

See if that is what you are looking for. I created it using the GEAR C-Hook I mentioned above.

 

You can trim the OD and ROOT to what you need.

[Mct010]

Don,

 

Not really, the one you made is to pointy

 

The print shows more of a flat on top and bottom

and I only need just 1 tooth so can can sweep it . it leaves the part with a rad at end of the spline

 

If you know what I mean

 

Let me try scanning it and sending it to your email address if that will work better for you.

 

MIke

[chris m]

Its a hob that they're using to cut it

 

I read your post too quickly; the one we're making is an internal spline

 

My design guys said that we used to have software that would create a solid using just the parameters you have in your table, but we don't have it any more. They are pretty swamped over there or I'd ask one of the boys to model it for you

 

Sorry about that

 

C

[Don Trust]

Mike,

 

Yes, the one I drew has just standard OD & Root that would be for a standard gear. An Involute spline just has those clipped off. Involute is the same, you're just looking at a particular portion of it.

 

The tooth form wouldn't change if you change OD or ROOT. You can just create the circle you want for the OD (major ø) and the ROOT (minorø) and trim off the part of the involute that falls outside those circles.

 

On a gear, the OD and Root have nothing to do with the involute. (tooth sidewall) There are standards for the OD & ROOT, but a majority of gears are altered from those standards. I just made it that way so you could trim it to what you needed.

 

The Involute is controlled by the Pitch ø, number of teeth, and either CTT or MOW. The CTT is altered plus or minus for clearance, based on the gear it is to mate with. There are a number of other considerations, but there are large books devoted to that.

 

One thing to note for your parameters is that the MOW in your original post doesn't work with the CTT. Those two things are intimately tied together. One HAS to match proportionally with the other. You will want to check on that.

 

Hope this helps.

 

Don

 

p.s. you can certainly email me the scan and I'll take a look at it.

[Mct010]

Don, you have mail

 

Mike

[Don Trust]

Mike,

 

Back at cha. You have mail.

 

Don

[Mct010]

Don,

 

Looks great

Thank you very much for your time.

 

Mike

[Don Trust]

Glad to help.

 

For the future...

 

If you get into gears more, there is a great little book that will help a lot.

 

From "The Van Keuren Co."

 

It's called Precision MEasuring Tools - Handbook #36 - Section II.

 

I don't know whether it is still in print. Ours is so old the price listed in the book is $2.00

[John Summers]

Stock Drive Products will send you a FREE gear handbook.