Problem with Gear Teeth in the side of a simple cylindere

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SupDoc
Posts: 59
Joined: Sun Oct 27, 2019 12:05 am

Problem with Gear Teeth in the side of a simple cylindere

Postby SupDoc » Fri Nov 15, 2019 5:03 pm

I have had so much trouble trying to get gear pattern (Knob grooves) with Ha Gei's Knob tutorial: https://www.youtube.com/watch?v=H9qPMf3pxxo that I have simplified the pattern to a rectangle that when rotated around the z-axis becomes a simple cylinder.

Following each step in his tutorial carefully (except using a cylinder instead of Ha Gei's knob) I click on the original sketch, and I get something quite different from what he gets. I am showing both images here. When I click on the original sketch, I get a return of my original square used to make the rotation to a cylinder, with the widget showing right and the coordinates showing we are in the YZ-plane with the X-axis pointing down. In the tutorial we see the knob in white outline form capable of allowing rotation of the object. Since I cannot achieve equivalence I cannot proceed.

Can someone get me past this point, please?

I am using: Windows 10 64bit and FreeCAD 0.18.4
Attachments
MyGrooveTest.PNG
MyGrooveTest.PNG (168.47 KiB) Viewed 378 times
HaGeiKnob.PNG
HaGeiKnob.PNG (387.58 KiB) Viewed 378 times
SupDoc
Posts: 59
Joined: Sun Oct 27, 2019 12:05 am

Re: Problem with Gear Teeth in the side of a simple cylindere

Postby SupDoc » Sat Nov 16, 2019 2:55 pm

I'm not getting any response here - please, someone help me here!!

OS: Windows 10
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.4 (GitTag)
Build type: Release
Branch: releases/FreeCAD-0-18
Hash: 980bf9060e28555fecd9e3462f68ca74007b70f8
Python version: 3.6.6
Qt version: 5.6.2
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/UnitedStates (en_US)
un1corn
Posts: 161
Joined: Sat Dec 26, 2015 2:06 pm

Re: Problem with Gear Teeth in the side of a simple cylindere

Postby un1corn » Sat Nov 16, 2019 3:27 pm

Not sure if this is what you are trying to achieve.
If not please be a little more specific.
Attachments
Knob_gear_test.FCStd
(47.13 KiB) Downloaded 4 times
Knob_gear_test.JPG
Knob_gear_test.JPG (192.37 KiB) Viewed 334 times
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papyblaise
Posts: 3094
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Location: France

Re: Problem with Gear Teeth in the side of a simple cylindere

Postby papyblaise » Sat Nov 16, 2019 3:38 pm

Hello , don't wary , be happy :?:
the video was made in V.16 , and a bit mush hesitation
if you need folow the same path , use sketch and PartWb
I make the profil whithout constraintes except vertice and horizontal in XY plane, I rotate it around the Y axis
Faced to the top face , I draw the profil of the teeth , Pad it and for the fun I do filet at the end
In Draft Wb I do a polar array around the Y axis (12 occurs) , and soustraction booleen
Attachments
knob.FCStd
(63.68 KiB) Downloaded 4 times
knob.PNG
knob.PNG (53.58 KiB) Viewed 330 times
SupDoc
Posts: 59
Joined: Sun Oct 27, 2019 12:05 am

Re: Problem with Gear Teeth in the side of a simple cylindere

Postby SupDoc » Sat Nov 16, 2019 7:16 pm

Dear Unicorn,
You asked for details, so here are two files showing exactly what I am trying to accomplish. The first is a pictorial view of the object. What I want to do is to put 8 symetrically spaced grooves (semi circles radius = 0.82) into the dished face of the top of the object shown in the pictorial.

I thought if I could get the gear teeth pattern of the knob to work, maybe I could figure out how to do them at right angles on my object. I'll settle for either a gear tooth pattern or prefer semicircles.

In case you may be interested, sucking on the bottom end with a small vacuum pump, I would place a thin rubber sheet over the top dished-face. Holding it down with the vacuum I could trim it with scissors to the outside diameter of the cylinder, apply glue to the far edges, and stick it down over a pressure transducer.
Attachments
Bladder_Holder.FCStd
(6.47 KiB) Downloaded 5 times
Bladder_Holder.PNG
Bladder_Holder.PNG (194.12 KiB) Viewed 310 times
chrisb
Posts: 32181
Joined: Tue Mar 17, 2015 9:14 am

Re: Problem with Gear Teeth in the side of a simple cylindere

Postby chrisb » Sat Nov 16, 2019 9:32 pm

You can do this in one step by using a sketch containing 8 (semi-) circles for a pocket or by making one pocket plus a polar pattern. I will now go for the latter:
- revolve the sketch so that you get what you have shown in the picture above
- create a sketch in the XY plane
- while in Sketcher switch to the Model tab at the left and hide the Revolution and show the Sketch
- in 3D view: hold the Alt-key and tilt 3D view like so:
Snip macro screenshot-b0fdb9.png
Snip macro screenshot-b0fdb9.png (1.84 KiB) Viewed 298 times
- click the tool "Create an edge linked to external geometry" Image
- click the vertical line shown left in the image. Note that the line is not marked directly, you see a projection in the sketch plane instead.
Snip macro screenshot-778350.png
Snip macro screenshot-778350.png (3.38 KiB) Viewed 298 times
- return to normal view by clicking "view sketch perpendicular to sketch plane Image
- Draw a circle with the center coincident with the upper end of the line and constrain the radius:
Snip macro screenshot-edaf78.png
Snip macro screenshot-edaf78.png (4.43 KiB) Viewed 298 times
- close the Sketcher
- Select the new sketch and create a pocket "Through all"
- Hide Sketch and you should see something like this:
Snip macro screenshot-c014be.png
Snip macro screenshot-c014be.png (18.78 KiB) Viewed 298 times
- Select Pocket and click the Polar pattern tool Image
- Leave axis "Normal to sketch" and change only the number of occurrences to 8
Snip macro screenshot-01a111.png
Snip macro screenshot-01a111.png (51.42 KiB) Viewed 298 times
- Confirm and you are done
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
SupDoc
Posts: 59
Joined: Sun Oct 27, 2019 12:05 am

Re: Problem with Gear Teeth in the side of a simple cylindere

Postby SupDoc » Sun Nov 17, 2019 1:02 am

Opps!

I wanted the 8 semicircles at right angle to what you have shown, so they are lying within the curved face. So it would look lie the spokes of a wheel.

Sorry I wasn't more clear in my explanation.
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papyblaise
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Location: France

Re: Problem with Gear Teeth in the side of a simple cylindere

Postby papyblaise » Sun Nov 17, 2019 7:39 am

Draw your sketch on the YZ plane :!:
Attachments
knob1.PNG
knob1.PNG (28.9 KiB) Viewed 266 times
un1corn
Posts: 161
Joined: Sat Dec 26, 2015 2:06 pm

Re: Problem with Gear Teeth in the side of a simple cylindere

Postby un1corn » Sun Nov 17, 2019 8:58 am

Hi Supdoc, looks like Papybalaise has you covered.
chrisb
Posts: 32181
Joined: Tue Mar 17, 2015 9:14 am

Re: Problem with Gear Teeth in the side of a simple cylindere

Postby chrisb » Sun Nov 17, 2019 9:38 am

SupDoc wrote:
Sun Nov 17, 2019 1:02 am
I wanted the 8 semicircles at right angle to what you have shown, so they are lying within the curved face. So it would look lie the spokes of a wheel.
It's the same procedure, only the plane to attach the sketch is different. Take it as an exercise!
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.