Tapped holes

[Jim at Gentex]

I was wondering if there is an industry standard for showing tapped holes on a cad model.

 

Every model I've ever seen just shows the tap drill sized hole w/o the threads. We've always relied upon secondary instruction from our designers and / or engineers to be sure we know which holes are to be tapped and which aren't, but that system isn't foolproof by any means! I sent two small parts out this week that each had a .213 diameter hole that should have been tapped 1/4"-28, but nobody told me until after the parts were shipped!

 

Luckily, the customer was cool about it, but things like this shouldn't happen in the first place!

 

Is there a formal way to designate this on a model? If not, I would like it if the designer would simply put a drafting note on the model to designate tapped holes. This would avoid situations like the one we had this week!

 

Any input on this would be appreciated.

[robk]

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I was wondering if there is an industry standard for showing tapped holes on a cad model.

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I wish!!!!

We request a bill of materials with every job that comes through the door.

[cunder_1999]

I most always have a print with the details on it concerning the part.

 

Charles.

[mayday]

most of our customers are setup with standards.

taped holes are at tap drill dia with a chamfer. dowels are extruded at actual size ei pf/sf. bores are the same but they usually attach a tolerance sheet if needed. some have a color code for tolerancing but we have to bring them in as surfaces to get the colors

[Jim at Gentex]

Thanks for the replies.

 

Welcome to the forum, Charles, and thanks for your input.

 

I like the idea of modeling the tapped hole with a chamfer. I am going to pass that up the chain here and see what happens. I also think it wouldn't kill the designer / engineer to pop in a drafting note with a leader to point to the tapped holes or just to give any out-of-the-ordinary information.

[Tom Szelag]

No standard for the actual solid model.

 

Shouldn't all that good stuff...thread callouts, tolerances, etc, be on the drawing?

[Jim at Gentex]

Yes, Tom, you're absolutely right.

 

But the company I work for does 99.9% of all in-house work via electronic means. As a result, I seldom get anything more than a work request from engineering, and the name and location of the appropriate model on the network. I seldom if ever see a proper drawing, so I need to rely on the model itself and input from the requestor for all my data. Also, much of the R&D stuff I do doesn't even have a formalized drawing until they are ready, for example, to contract it out to a vendor for production. This usually only happens after the development stage when the design is finalized. Up to that point, cad models are all we have.

[Paul McGarr]

I model the drill diameter including tip angle going to full depth, then I have the tap diameter with no tip angle going to the depth I want the hole tapped to. Thats how the hole wizard in solidworks does it too. When you see a hole like that in a model, you know without question that its a tapped hole.

 

That being said, your company should address this problem. I'll bet YOU took the heat for the mistake right?

 

Paul

[Tom Szelag]

Thats nuts man. No tolerancing. Around here its "no drawing, no part." And 99.9% of the stuff we do is also in house, sent over by engineering. Make it to the print and there's no way they can nail us for the part not working of it meets spec.

[CAM-mando]

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Thats nuts man. No tolerancing.

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It is becoming more common. Boeing provides Model Based Definition only on new designs. We pull the Catia model and a seperate "Engineering Notes" File directly out of their PDM over the web.

 

All block tolerance stufff is described with a series of general notes. Close tolerance features have the tolerance hung on the model in model space.

 

Jim, I prefer hanging a note on the model with thread size. What CAD system do your engineers use ?

[HevyMetl]

ProE creates a surface represnting the tapped threads around the holes at tap drill size. It also places a 3-d note in the model stating tap size. Very handy in Pro, but when you IGES or STEP the files into mastercam all of that neat stuff goes away, unless you specify it in the translation.

[robk]

We deal with customers files all the time... Different customers mean different files. One man shop makes his files a lot different than a big company. With 3 to 5 days delivery quotes we have to learn components that go into the mold frame. In our business you have to know that, for example; bubblers use fine threads, Manner (brand) is metric as well as Husky, etc... You mostly work with assembly prints. It's up to the programmer/operator to figure out what is pressed and what is slipped and how a mold works. IMO, there never will be an industry standard. Too many designers with no machining experience using different software brands. Your inhouse standard is not necessarily another shop's standard.

[Jim at Gentex]

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Make it to the print and there's no way they can nail us for the part not working of it meets spec.

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Yes, That's the norm. But in R&D there often is no spec...at least not yet. It's a catch-22 situation all the way around. (i.e. damned if you and damned if you don't)

 

We often make one-off prototypes for engineers to use for mockup purposes where they are simply looking at the conceptual stage of a part and usually aren't worried too much about detail at that moment in time. The engineers will not spend the time to develop a full blown, fully detailed drawing of something they are just conceptualizing. These are usually just a model with some verbal instruction from the engineer. He or she will always specify verbally if there is any critical or close tolerance dimension we will need to hold. Otherwise, it's pretty much +/- .005 on all measurable linear dimensions as taken from the model. The problem is that when we shift from 'mockup prototype' to 'fully functional prototype' to 'customer deliverable prototype' we are still using the same system of cad model with verbal instructions.

 

Only when we move out of the prototype realm into the actual production article will we usually ever see a full blown detailed drawing. Then we will be held responsible to meet drawing specs and to provide things like manufacturing history sheets, and material certification records. I've been here for 14 years and have been dealing with this same system from day one!

 

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What CAD system do your engineers use ?

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That's another issue here.

A better question may be which system DON'T they use!

As of now, I believe we have Catia, Solid Works, Pro-E, Autodesk, and of course Mastercam. One of the recent engineering management goals here is to finally consolidate into ONE cad system for ALL. This is why I have been asking questions here in the forum about Catia Mill...because that's the way they seem to be leaning.

 

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Thats how the hole wizard in solidworks does it too.

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Thanks, Paul. Yes, I like that style too...It's getting them to USE it that seems to be the problem.

 

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I'll bet YOU took the heat for the mistake right?

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Yes, I am quite familiar with the role of 'whipping boy'.

[chopsley]

I feel your pain Rob,

The shop I'm working at now does a lot of business with a well known customer. I'm appalled at the sloppy way they maintain their prints. I get a Rev. "A" with missing dimensions. I point this out to our ME. A day or so later a new print appears with the missing dimensions. It is still Rev. "A". I could, of course, just program it to the model but what is the machinist and inspector to do? More phone calls and wasted time. Oh well...