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Remove tap drill size from hole callout on drawing
Asa_Eckert_Erdheim
Member Posts: 3 ✭✭
in Drawings
Is there any way to remove the drill size from a tapped hole callout on a drawing? I don't see any way to edit the default callout.
1
Comments
I agree this should be added. Currently if you want callouts not to feature it you have to dimension it with a note and type everything manually.
Yes, @onshape, please remove tap drill size from threaded hole callout on Drawings, or make it something that can be toggled.
probably needs to be entered as an improvement request
From an educator - I'm seeing that things dimensioned means things inspected. We can't inspect a tap drill size.
I can understand the reasoning stated here. However, I hope that Onshape does not just remove this but gives us the option. There are times I would want to show this on drawings.
I also like to show this on drawings, some engineers I work with like to see all the info in the drawing
@kate_leipold_rit Absolutely right that a tap hole can't be inspected in the final part, but it could be an in process inspection. What might make more sense is to make the display optional, and possibly make it a reference dimension.
The overall plans are to make these things optional with hole callouts and likely at the company level - since these sorts of things are usually corporate norms. Hole callouts show up in other places besides just drawings - for example in the hole table in the part studio. Resulting tap drill sizes can be inspected in some cases - for example when a tap drill is used through the entire part but the thread is some depth that is not through the entire part. In a good amount of threads, the tap drill diameter is actually the minor diameter of an internal thread - and it can indeed still be inspected (gauge pins are one easier method of approaching that). Of course there are differences with materials and thread forming types (cutting versus thread forming), so the devil is in the details as usual.
Typically the minor diameter of an internal thread is not all that consequential to an adequately strong and well functioning thread since most of the strength of the thread is from the root area of the cantilevered beam when we look at it that way. All that being said there is not one single standard/preference for what to show and not show on callouts and Onshape needs more flexibility for companies/users to decide what their callouts should be showing.
Most of the drawings I produce are manufacturing instructions first. It's the engineer's job to understand how a part will be manufactured. In my experience, best practice is to have both manufacturing and inspection drawings.
Having the tap drill size on there saves someone a bit of time going to look it up.
Also all the other things others have mentioned above.
I agree with @PeteYodis. Yes, pin gauges can be used to inspect minors. And yes, the thread's "drill" size can change based a few things that I can think of: 1. Using oversize taps/drills to compensate for plating and 2. using roll taps instead of cut taps as Pete pointed out. In these 2 cases the minor might not be the drill size. I misspoke when I asked to remove the drill size, as it is actually the minor that is being listed on the drawing. :-D
Listing the theoretical minor and/or drill size of a thread on a print seems superfluous and is not a practice I have seen in all my years (unless its a partially threaded hole). Yes, the theoretical minor for an M6x1 should be 5mm, but this doesn't need to be called out on the print, and seems to just add clutter. If the engineer or machinist doesn't know what minor to measure to, or perhaps which drill size to use for a tapped hole; then I suggest referencing the Machinery's Handbook rather than trying to add all this information on a print. However, I do agree that it should be optional. :-)
As far as a partially threaded hole, including the drill hole size and depths are necessary, though again this might not be the actual drill size needed to make the tapped hole, eg: the untapped portion is just a vent hole. Cheers.
I too think it is not necessary information. It's like calling out the final diameter of a turned part, while instructing the machinist to take 3 passes to get there. That's not the designer's responsibility.
I worked in a machine shop for a few years and the machinists just want the final thread callout, and the class of fit if its a specialized thread. How they make the thread is up to them.
If it's a one off or a prototype sure. In a production environment you don't want variability in manufacturing methods. It can lead to quality and product issues that are very difficult to track down.
Ideally the production drawings are created with some input from everyone who's going to use them. If someone then has a better way to do something you need to do it through change management to make sure it's logged and communicated to everyone else.