Tag Archives: v-block

Jig or Weld Fixture Design — Holes 101

By | |
Leave a comment

In machine design there are fundamental rules to follow when locating fasteners.  I remember taking drafting classes but I was taught the basics of holes and hole locating only after I started working for Rentapen many years ago.

Mr. Iyer commented on the blog last time that I didn’t talk about construction holes for locating the angled cut on the v-block. He is right! So this video talks construction holes. I just want to add that in the video I put in .313″ construction hole. Looking back at it, a .25″ would have been better for this small part.

Also the video today talks about a major rule of thumb for locating mounting holes.

Mr. Iyer’s comment talked about using a plane that goes from the construction hole to the dowel hole that was zero/zero in the other surface. If this helps, where should I locate the other zero that is normal to that one. Also at the original surface dowel?

Remember, nothing is written in stone here. So if you know a better way or your company does it differently, share that with us in the comment section below!   Are there other rules of thumb you can share?

MORE TO LEARN!

A reader of this blog, Marvin Davis, has shared with us some links to other free education.  It doesn’t appear that any of them are on machine design, but some are on computers and math and so might be of interest to you.  I am sharing the list below.  But before you leave us to surf and learn, be sure to sign up for Rentapen news and updates on the right side of this page.  Then you will be notified of the next Weld Fixture Design 101 blog.

 

The Really Free Schools are Onlinehttp://www.independent.co.uk/life-style/gadgets-and-tech/features/the-really-free-schools-are-online-2353052.html

 

Berkeley Webcasts

http://webcast.berkeley.edu/series#c,s

 

CERN Document Server

http://cdsweb.cern.ch/

 

Harvard Open Learning Initiative

http://www.extension.harvard.edu/open-learning-initiative

 

Houston – University of Houston

http://www.youtube.com/user/UHouston#g/c/4F8EC29025F10C20

 

Indiana Multimedia Distribution System

http://www.imds.iu.edu

 

iTunes U

http://www.apple.com/education/itunes-u/

 

Khan Academy

http://www.khanacademy.org/

 

Math On Line – University of Colorado Colorado Springs

http://www.uccs.edu/~math/vidarchive.html

 

Mathematical Sciences Research Institute

http://www.msri.org/web/msri/home

 

MIT Open Course Ware

http://ocw.mit.edu

 

McGill Courses On Line

http://cool.mcgill.ca/

 

nanoHUB

http://nanohub.org/

 

Open Learn – the Open University

http://www.open.ac.uk/openlearn/

 

Oxford Podcasts

http://podcasts.ox.ac.uk/

 

RSA Animate

http://comment.rsablogs.org.uk/videos/

 

Scribd – Social Publishing

http://www.scribd.com/

 

Stanford Engineering Everywhere

http://see.stanford.edu/see/courses.aspx

 

Video Lectures

http://videolectures.net/

 

Yale – Open Courses

http://oyc.yale.edu

 

YouTube – Education

http://www.youtube.com/education

 

 

 

Three Ways to Detail a V-Block – Jig or Weld Fixture Design 101

By | |
Leave a comment

The Art and Science of Detailing a V-block

Now that we have talked about how to hold a round tube with a V-Block and how to create a V-Block in Pro/E 4.0 (Pro/Engineer), now it is time to talk about detailing. How do you make a drawing of a V-Block so that the machinist can understand it, and create it as quickly and accurately as possible.

A Word About Detail Standards

I keep saying that Machine Design is both Science and Art.

When you work for an existing company, they most likely have standards that you will follow for dimensioning.

If you don’t have standards or are confused about how to dimension a part, it is helpful to spend some time getting to know how your parts will be made. When you take a break from the computer, if you can go out and visit the shop and talk to the people who make the parts that you design, it will be time well spent. A helpful CNC operator, or an angry one, can teach you a lot about designing and detailing.

When your company is reviewing their detail standards, be sure to invite some machine operators onto the standards committee. They will bring a perspective that could save the company time and improve the quality of the parts that are made. A couple things you have to keep in mind is that this part might be made again in the future. If so, you want to detail it so not just your current machinists can read it, but future machinists as well.

So. enough about that!

I have detailed the V-Block in three different ways. Let’s take a look.

So there you have it, three ways to detail a V-Block. I am sure there are other ways that I have not covered here.

Do you do it differently? Please tell me by adding your comments below. This is our chance to learn from each other.
To follow this ongoing conversation on Jig or Weld Fixture Design, just sign up for future Education and Updates on the right of this page.

Keep learning,

The Queen

Jig or Weld Fixture Design — Five Items to Consider in V-Block Design

By | |
Leave a comment

Five items to consider when designing your V-block

In our last Jig or Weld Fixture Design blog we talked about different ways to locate a round rod or tube.   One of the more common ways is with a v-block.

Today we will discuss some of the questions that help you decide the material, modeling method using Pro/E  4.0, and fastener locations.

1)      MATERIAL  —

First decide what material you will need the v-block to be.

How much will the fixture be used?    That means knowing what the product is made of because we need the v-block to be strong enough not to wear down too quickly.  We want to be able to produce lots of product before we have to replace any of the parts in the fixture.    The more the fixture is going to be used the harder you need to make the v-block relative to the product tube or rod.

Do you need to plan for weld splatter?

If the v-block is located near the weld joint, you will need to consider using a metal that the weld splatter will not stick to as easily, or using a weld splatter shield.  Remember that like metals stick better.  So if you are welding steel, you may want your v-block to be Ampco 18 bronze or a hardened steel such as 4140 PH or A2.   If you are welding aluminum, hardened steel may work just fine.

2)      TOLERANCING –

Is the location of the rod or tube critical?

If the tube or rod needs to be located in just the right spot in order to work or assemble easily to the rest of the product parts, then you will want to design in adjustability with shim packs.  You will need to look at the product drawing and also know your customer’s preferences.

At Rentapen we design for many different customers.  So we have to consider the standards and preferences of each customer when we design.  Some of them love to shim every locator in a fixture.  Some of them don’t like to shim at all.   If you are a CAD drafter, you may be working under more than one designer.  Each designer may have their own preferences.  But it is up to you to look at the product drawing and then advise them when you think shims will be needed to meet the tolerances of the product drawing.   Then do what they say, they are your customer.

If it is a rough location, you may be able to use a purchased V-block from somewhere.  Do you have a favorite model or brand you would like to share?

3)      FASTENERS –

Once you have decided if your v-block will have shims to fine-tune its location before going into production, you can decide about the location of the fasteners.  If the tube or rod location is critical, you will need to use dowels to lock in the location.  If it is rough, you can just fasten the v-block directly to the base plate with screws.

4)      MODELING —

Locating the Vee in the v-block.

Here is how I model in the Vee cut.  Click on the video to see my method using Pro/E  Wildfire 4.0.

In this video I dimensioned the construction hole from the BOTTOM of the block.  However, the v-cut may fail if I make an adjustment too big in one direction or the other.  Some of the project engineers I have worked with prefer that the dimension for the V-cut be from the TOP surface of the block.  That way you can change the size of the block without having problems with the cut.

Some like to create planes that intersect at the center where the the construction circle will be located.  These planes are created before you start the sketch to cut the Vee.  I think your preference depends on your experience and how your brain works when making adjustments to parts while in the assembly.

5)      CLAMPING —

Clamping is a whole topic by itself that we will address in a future blog.  I just wanted to note that it is something that you need to think about.  We always clamp down our parts in weld fixtures, even if it is a table mounted fixture and gravity does its work.  You want to be sure that tube doesn’t move when the heat of the weld hits it.

 

And now I would like to share a couple of things with you.

First, Rentapen’s Holiday Greeting to our customers, vendors, students, and friends.

Second, we are in the news!  Check out the latest news at Rentapen by clicking here.

Till next time!

Susan Straley

The Queen of Lean Machine Design