Having trouble figuring how to create dimension

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areyouthere89
Posts: 16
Joined: Tue Mar 05, 2019 1:15 am

Having trouble figuring how to create dimension

Postby areyouthere89 » Tue Mar 05, 2019 2:16 am

I'm new to CAD but im learning (slowly) on my own, so bear with me. I am working on a part and cant figure out how to make a certain dimension on on it. I have a hub that will have a .97" radius lip (extrusion) raised .2" based off the center. Unfortunately a 4x1.0" - 1/4-20 bolt pattern intersects it. the bolt pattern also requires a .2" radius counterbore. I have spent the last week on/off trying to figure out how to create this (8 hours total). I know i am doing something wrong in the way im going about creating it which i why i am posting. I have attached my last attempt that sorted worked to a point but only raised the outer edge/line. also at attached is the before file so if anyone wants to shown me how its done they have a fresh start.

my second to last attempt was : merging a .97 radius circle sketch with a .2" radius 4x1" pattern sketch then attempting to trim the intersecting lines to create the needed shape but i wasnt able to pad that due to constraint conflicts, when i tried to remove them, the sketch "fell into pieces"

My last attempt was: creating the circle, using the bolt pattern as a reference and making 4 arcs based off center then trimming out the circle.

I'm very well aware there may be several ways of going about making this. For right now, id just like to know how to easily making it in sketcher or in part design unless that is what my problem is.

OS: Windows 7
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.13541 (Git)
Build type: Release
Branch: releases/FreeCAD-0-17
Hash: 9948ee4f1570df9216862a79705afb367b2c6ffb
Python version: 2.7.14
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.2.0
Locale: English/UnitedStates (en_US)
Attachments
Rotor Hub Adptr V1.1.FCStd
Last attempt
(34.57 KiB) Downloaded 13 times
Rotor Hub Adptr V1.0.FCStd
Fresh start
(37.86 KiB) Downloaded 12 times
chrisb
Posts: 19562
Joined: Tue Mar 17, 2015 9:14 am

Re: Having trouble figuring how to create dimension

Postby chrisb » Tue Mar 05, 2019 6:37 am

Hi areyouthere, welcome. As you say, there are several ways. One of them is to change the sequence of steps: Create the hub first and the holes later. All it requires is to increase the length of the counterbore.

I just want to remark that attaching sketches to faces makes the model prone to fail if you have to change something in an earlier step.
You find more about this in the wiki about creating stable models.
Bildschirmfoto 2019-03-05 um 07.36.08.png
Bildschirmfoto 2019-03-05 um 07.36.08.png (20.53 KiB) Viewed 319 times
Attachments
Rotor Hub Adptr V1.1_cb.FCStd
(39.24 KiB) Downloaded 14 times
chrisb
Posts: 19562
Joined: Tue Mar 17, 2015 9:14 am

Re: Having trouble figuring how to create dimension

Postby chrisb » Tue Mar 05, 2019 6:55 am

I deleted your double post.
freedman
Posts: 1023
Joined: Thu Mar 22, 2018 3:02 am
Location: Washington State, USA

Re: Having trouble figuring how to create dimension

Postby freedman » Tue Mar 05, 2019 4:04 pm

For best results on a object like this where it can be built from the XY plane:
In the tree; click Origin, and select XY plane, now create your sketches.
areyouthere89
Posts: 16
Joined: Tue Mar 05, 2019 1:15 am

Re: Having trouble figuring how to create dimension

Postby areyouthere89 » Wed Mar 06, 2019 1:12 am

chrisb wrote:
Tue Mar 05, 2019 6:55 am
I deleted your double post.
its okay, i wasnt 100% sure if the original got posted or not, so i tried again. then after rechecking a few hours later and not seeing the second, i reread the sticky thread a second time and realized my error in impatience.
areyouthere89
Posts: 16
Joined: Tue Mar 05, 2019 1:15 am

Re: Having trouble figuring how to create dimension

Postby areyouthere89 » Wed Mar 06, 2019 1:42 am

chrisb wrote:
Tue Mar 05, 2019 6:37 am
Hi areyouthere, welcome. As you say, there are several ways. One of them is to change the sequence of steps: Create the hub first and the holes later. All it requires is to increase the length of the counterbore.

I just want to remark that attaching sketches to faces makes the model prone to fail if you have to change something in an earlier step.
You find more about this in the wiki about creating stable models.

Bildschirmfoto 2019-03-05 um 07.36.08.png
Ill review this article asap. Thank you very much for the helpful advice. Your solution was going to be one of the very last attempts if i wasnt able to find clear help on here. And please correct me if i am wrong, but you basically cleared the board, remade the hub portion with .2" thicker then pocketed the area outside the 1.94" diameter down to create the lip, then did all the bolt patterns and added .2" to the original counterbore depth. Reason being the hole can only be mapped to "the main face" and not the added extrusion. The jist of it all is, "stacking sketches" is less sturdy than "editing one padded sketch several times" so to speak.... ?

i've put alot of time in to this hub; its going to be a real physical part at some point. hence why i was saving starting over completely for last. Other than that one example, how else could i have done that? i have a feeling that i may not be using some functions in a correct sense and getting stuck like i did was because of it. Just asking for some key steps that i could expand upon.

I will say i do not have any kind of formal engineering software education, much less engineering in the college level education sense. But i do work in the machine trades as a service technician and im hoping that learning how to use this tool will help give me knowledge that ill be able to apply towards other aspects in my profession since im not just tasked with fixing broken machines.
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craig9
Posts: 20
Joined: Thu Mar 22, 2018 10:45 pm
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Re: Having trouble figuring how to create dimension

Postby craig9 » Wed Mar 06, 2019 3:44 am

areyouthere89 wrote:
Wed Mar 06, 2019 1:42 am
... Other than that one example, how else could i have done that? i have a feeling that i may not be using some functions in a correct sense and getting stuck like i did was because of it. Just asking for some key steps that i could expand upon.
I read your follow-up question as: "How could I have fixed my model without starting from scratch?", so here's a short video showing how I would fix the issue without starting again:

https://youtu.be/nbCNo31wpyc

I believe the way I have attached the sketch to the pad's face isn't best practise, and that probably a datum plane should be used, but I don't fully understand those, so this is my best effort until I have a better understanding. I suggest you watch some of Ha Gei's youtube videos to learn more about datum planes, and I will do the same! :)

Cheers,
Craig
areyouthere89
Posts: 16
Joined: Tue Mar 05, 2019 1:15 am

Re: Having trouble figuring how to create dimension

Postby areyouthere89 » Sat Mar 09, 2019 6:33 pm

Awesome! thanks!
Let the learning begin