Dowel Pins as Locating Features - Ep. 1: What are they good for?

[@yuvalbarakmechanicaldesign5045]

Can't wait for the following video! Great and interesting content.

[@gdtguychuck]

Thanks, Yuval - glad you like it. There are 7 more in the queue, scheduled to drop on Tuesdays and Fridays!

[@deplorablesecuritydevices]

Thanks for sharing, just starting to machine some castings and Im new to all of this.

[@Fun_Dealer]

What’s the benefit of using the pins over just the 4 screws? Is precisely locating the plate important?

[@mrcoolabhishek123]

Great video. Thanks.

[@gdtguychuck]

Here's that link again if it didn't come across: mountaintopdevice.com/gdt-guy-dowel-pins

[@sgonzalz]

The brilliance of GD&T lies not in allowing to find a way to make a bad design work, but in allowing to find a way to make a bad design good. The two dowel pin plus plane design is a bad design because it has Competing Datum Features. Each pin individually and the plane are trying to control the same 2 rotational degrees of freedom and that is causing the tolerance stack-up to exist. The way to make it a good design is by replacing the two dowel pins with two tooling balls (spheres), pairing one ball to a countersink cylinder to control position and the other ball to a chamfered slot radially aligned to the cylinder to control rotation. This will eliminate the tolerance stack-up (therefore making it inherently more precise) and will also make it quite easy to assemble due to the elimination of the Competing Datum Features plus the addition of the ease of assembly features.

[@PaulBinun]

Chuck, You may remember me from the GA days. I remember you. Fantastc video and great effort! Just want to say regarding laser alignment, is not all black and white. The question is what kind of error of laser beam on aperture can you tolerate vs the cost. I suspect that those will be addressed in your next video and I look forward to it. Cheers.

[@gdtguychuck]

Hi Paul! Glad to hear from you, and I'm really glad you liked the video! I may have opened myself up to critique by bringing up laser alignment, especially by providing such a simple example of a problem. I'm not sure what is your exact criticism, but for one thing there are certainly occasions where a fixed mirror is appropriate. My major point with the mirrors is that it is easy to make a CAD design that is reliant on parts being manufactured absolutely perfectly. The higher state of consciousness for the designer is to accept that machined parts are not perfect, and that there may be ways to adjust designs to allow for more manufacturable parts. Stay tuned, and by all means DM me if you think there is something specific I should cover! CS

[@PaulBinun]

@@gdtguychuck Hi Chuck, There is no criticism. Your video makes a great point with the laser beam. I will DM you and we can talk more.

[@recepates5091]

i completely lost my trust in dowel pins thank you

[@gdtguychuck]

Awww, come on now. That is not the desired effect. My point is that you should know what you're getting into.

[@recepates5091]

@@gdtguychuck hahaha no no, my faith in pins were misplaced and information you gave made my designs much better. Love your vids and thank you very much🙏