Common practices for reviewing drawings

I was wondering what others in simular situations do to assure themselves that they have not missed any corrections on drawings sent to customers or engineers who recieve them? I find that I commonly sometimes miss simple things like spelling errors or forget to add a revision comments. Sometimes I find that certain things have been missed but it is after it has been submited to customer for approval. I unfortunatly dont have a engineer that can give me a second set of eyes to look at the print. Once in a while The engineers will look at it but they dont spend time with it besides a quick glance and off it goes. I guess I'm looking for a guidline for an easy way to go through the drawing before giving it out. I should be going through the drawing and redmarking it dimension by dimension & note by note but I dont always do this. What are the common practices of some of the experienced designers out there?

Larry Jedik

I try to mentally work through making the parts and assemblies. Start with the overall size, yep, it's there. Do I have enough info for this hole? Yep. Does the hole match the mating part? Etc.

What I do is go through the BOM and mark off each item and it's corresponding balloon for assy's. For parts, each hole, slot, etc. feature should have x/y dimensions or locations. Check all notes for references to item numbers as they aren't yet interactive as the BOM order changes. These are the main things.

WT

Sometimes on more complex parts, I will go through and highlight each feature, with a highlighter, that is fully constrained to make sure dimensions aren't missing. Any corrections have a circle placed next to them. When I have updated the drawing, I put a checkmark in the circle to close out the edit.

Larry, as you know this is an age-old and common problem. Speaking from experience in setting up and maintaining engineering standards, there are three basic approaches, each with varying success.

The first, which is what you're doing, is to try to check all of your own prints. Pressure to get on to the next task and tunnel vision leads to small things being missed. Sometimes larger things get missed too but usually the small things that you pointed out.

The second approach is what I would call round-robin checking where each person in the group gets to check everyone else's prints on a rotational basis. The good news is that because it's a process which gets adopted by the group at least everything gets looked at. The problem, which you also mention, is that sometimes it's just a quick look. And many of the group don't want to do it to begin with so they are too quick about it. You can attempt to improve each of the groups checking skills but it's still "human nature times the number of people in the group".

The third, which is the most successful for improving the quality of drawings is also the most difficult to justify to management because it sounds like big change. And their reaction is often "that's not what I'm paying that person for." It involves a dedicated checker with a trained set of checking skills. Everyone in the group should be trained in drawing checking but the checker is the final word for what level of drawing quality gets signed off. In a smaller group this is just one person chosen for their skills and their impact on project time, with time set aside every few days or aligned with a release schedule, to check and redline drawings. The drawings don't get released until the checker signs off. Then presumably, the checker's boss, etc. At each step above the checker, like manager approval, the sign off process takes less time because the checker spent the good time ensuring drawing quality and manufacturability. Repeat, I am not suggesting this is a full-time job, although in some instances it can be :)

As an example, at one company I implemented a dedicated checker for a group of about 12 engineers. This checker had other job functions too but based on a release schedule, they would check drawings. Always the same person, always the same quality. Prior to the dedicated checker, everyone would try to check their own drawings or have a neighbor "look" at them, similar to what it sounds like you're doing. Engineering changes after release were reduced over 50% with the dedicated checker. In contrast, I let their sister company with a smaller group implement round robin checking and the quality of the drawings changed as often as the assigned checker. Some of the engineers were meticulous, some missed small things, and some missed larger things. Overall drawing quality improved but it was sporadic. There was another downside too, if there was a problem with a drawing going back to the checker wasn't always an option because the person who checked it may be involved in something and not have the time to go back and help investigate. It was a mess compared to a real checker.

If it's only just you and you're going to be the "dedicated checker" then set aside a few hours every week to do nothing but check and use the good methodology suggestions from the other postings. You'll likely have to justify the time slot(s) to your bosses but it's easy to do given what an engineering change costs. It's better to have someone else check your work but we don't always have the luxury.

Good luck!

- Eddy

By the way, more to your point... when I was checking drawings here was my process (similar to the other postings)...

• if there's six people standing in your office, wait until they leave.

• check title block; material, finish, p.n, description, project info, next assy, where used, etc.

• check notes and make them live to a standard. Vendors really appreciate this.

• check bom descriptions, p.n.'s, qty, etc. and balloon status, then compare against balloons

• check each view, cross checking to other views, and ensure that enough views are depicted. On a very complicated drawing, the quadrant method helps focus on a given view.

• ensure presence of each dimension required and that no rules are broken

• when part has mating features, like holes, to other parts, compare tolerances on those drawings. If those drawings aren't available yet, make a note for yourself to go back and verify when those drawings do come across.

• check revision history for status and flags, check that each flag is present

- Eddy

Eddy: Coming from a small engineering team I was constantly checking and releasing my own drawings. All of the above techniques are great and should be employed. After doing all that I still would have errors. you become tunneled by looking at the same stuff for hours. I used to finish the drawings and checking. That package would sit on my desk for 2 days. After that time, I would revisit the package and catch the errors with a clean head. It was not the most efficient way but it was the only way I could distance myself enought to see the errors.

HTH, Steve

Yipes. Spoken like a manager :)

I've had the same thing said to me numerous times from engineering directors who weren't engineers "if you're using cad then everything must be correct, right?"

- Eddy

In message , Eddy Hicks writes

Can these guys still be found. When I worked in contract offices he was always 'Billy No-Mates' in the corner as everyone eventually fell out with him over the interpretation of a note or standard. Justifying a dedicated checker must be difficult these days, after all as a client said to me when I explained there was an error in the drawings 'how can there be your using solid models'.

In a small engineering office, I have to second this method. It's the only one that works consistently. Instead of laying the job aside though, I go to another section of the project, or nearing the end of the project, to the start of the project and work on it for a while. I'm always working on the project, just a different portion of it. As mentioned by someone else, you get a form of tunnel vision and can't see the trees for the forest. If you can back away, by dealing with a different section or by laying the project down for a couple of days, your mind clears and you get a fresh perspective on it. R. Wink

I was a Design/Drafting checker for about 5 years at a company which had 10 drafters/designers. My job was to "proofread" their dwgs to make sure that they made sense and followed any applicable drafting standards. It was not my responsibility to change the functional design of the parts/assemblies but to make sure that what was being committed to paper/computer was correct. By the way, it was not something that I was simply hired into doing - I had worked for years with my work being checked the same way.

About 2 companies ago, it became apparent that this function was being seen as "redundant" by many companies. This is a flat-out wrong approach to take. A person should be free of prejudicial experiences in order to objectively find errors. A person can not check their own work with large accuracy. I'm positive that there a large number of errors being left to be discovered either in pre-production testing or worse, in production itself.

In short, get another pair of eyes to review everything that is important. Hopefully those eyes will be dedicated to that job alone.

The following was sent to me yesterday and it's a good illustration of why some one else should check ones work. Unfortunately many of us have no choice.

Aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it deosn't mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht the frist and lsat ltteer be at the rghit pclae. The rset can be a total mses and you can sitll raed it wouthit porbelm.Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe.