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Splitting Component Drawings - Is It Normal?

02/04/2009 10:04 PM

My production manager wants each component drawing split up into individual drawings to suit each stage of machining. So the person drilling holes only gets the details & dimensions suited to their task. The person shaping the outside radius gets a drawing to suit their task and the last person (polishing) gets their drawing brief on how the part looks after polishing. Its a foreseeable nightmare when you consider revisions and QC. His point is to give machinists ONLY the information they need. When does engineering take responsibility for work instructions?

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#1

Re: Splitting Component Drawings - is it normal?

02/05/2009 12:09 AM

He's the production manager - the say is his. It is his job to establish procedures that he believes will efficiently lead to quality results. It is your job to follow the procedures he establishes without complaint. If you can show documented reason why his procedures lead to inefficiencies and poor quality, present them to him in a professional manner. But at the end of the day, it is still his call.

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#2

Re: Splitting Component Drawings - is it normal?

02/05/2009 12:41 AM

If the design and drawings are done perfectly and the people doing the jobs do it properly, I don't see a problem. If I drill a hole while someone else turns a shaft that goes into that hole just so, as long as we both do our jobs to the letter, it will fit.

The downside of that is that if someone makes a mistake with the drawings and dimensions, we won't know about it until assembly time. If I had the complete set of drawings, I might be able to catch that. If I have only the drawings I need, I certainly won't catch it.

So the burden of getting first things right falls on the guy making the drawings and the guy making the design (by providing the dimensions to the draftsman). They have to make sure that everything's correct before distributing the drawings.

I've disagreed with my boss countless times. The thing is I explain my objections and he gives his reasons for his. A lot of times, I see the error of my ways and agree to his line of thinking. Sometimes, I get my way. At times, I still disagree, but his decision is final. Just put your misgivings aside and do your best.

regards,

Vulcan

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#3

Re: Splitting Component Drawings - is it normal?

02/05/2009 12:57 AM

Thanks for the responses. I come from an engineering community. Normally we'd make a final drawing and send it out to a supplier. How they make the part is their business.

I suppose we are in a country where the skills are a bit lacking and the workers need to be 'supervised' to a finer degree. While it makes their task into the most basic read, it increases the engineering task 6 fold. More resources are needed and the possibility of mistakes increases.

The decission does come from above (even if they have a background in bakery) but due to my culture, I'm not a 'yes man' to easily accept ideas that could be better thought out.

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#4
In reply to #3

Re: Splitting Component Drawings - is it normal?

02/05/2009 1:47 AM

we are in a country where the skills are a bit lacking and the workers need to be 'supervised' to a finer degree

We are in the same situation with some of our fabricators. We've managed to weed out the bad ones by not giving them any business and giving it only to those who do a good job. It's taken time and a lot of frayed nerves but it has been sorted out.

Contracting jobs out to other companies is something that's happening everywhere. If they set up a fabrication shop, they have to buy the equipment and hire skilled people, pay for the electricity and materials and everything to keep it running. Sending the job out somewhere else makes economic sense to them.

Another reason to not give the entire set of drawings is secrecy. If I get a drawing for a set of gears, I won't know what it's for unless I get the whole set.

Why not ask your production manager for his reasons?

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#5

Re: Splitting Component Drawings - is it normal?

02/05/2009 2:03 AM

In our organisation it is usually single drawing for a component with some variations. TThe drawings are split between sheets

a) Fabrication/ casting drawing, Finish machined drawing

b) Sometimes rough machining drawing too

These two are used when the part above is either off-loaded or done in a different facility.

c) When the drawing is too large or complex and can not be accommodated in a single sheet of A0 size (we do not have A(-1) or A(-2) so we proceed toll A0 and then split if required )

However splitting of drawings create one problem and that is applicable in all the three cases.

When you modify your drawing (which you will be in a dynamic design) - yiou must remember to touch up each sheet else you have a problem. In ACAD when you change a dimension, you know a drilled hole will go in air or a keyway slot will become un-balanced, but in the split drawings unless all the drawings are touched, you never know, and in case of problem, you have to re-trace steps in each sheet (We have faced this problem few times despite these not being split as extensively as you want)

So to facilitate a production, you are more-likely to hamper it.

What we do is a better way- The Work Instructions are translated from drawings. In-fact, when we do for vendor audit and surveys, his is one aspect that carries a good amount of marks in the technical competence as well as quality parameters - Preparation of work instructions (Technical), Clarity (Tech), Availability at work place (Quality), Understanding by the line operator (Q) , Correlatability with the product (Q) and various other details.

The wirk instructions can be language, sketch etc anything and can be converted from your ACAD drg by the methods engineer and have the drg no, rev no, order no etc as the correlation data.

This as far our experience goes is the best way and not messing up with a higher level document (drawings).

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#6

Re: Splitting Component Drawings - Is It Normal?

02/05/2009 8:50 PM

I am not a big fan of this idea. As a machinist I prefer to have ALL the information available to me - not at some one else's discretion.

It could also prove to be inefficient. Lets say I do not have the final finish call outs. I can rough a piece on down to size leaving a much rougher finish than is called for in final and as a result double or even triple the polishing teams work time. In comparison if I just assume that I should shoot for a 64 on everything (never assume) then I may be spending much too much time and tooling to achieve this.

Also, there have been many occasions where I or some one has caught an error in the drawings only after they hit the shop floor and all have reviewed.

I would much rather pull hair out by training a group of less than optimaly skilled folks how to do the job right and the interdependent nature of multiple processes than try and keep up with the paper nightmare short-cutting your PM is trying. But I am on the WAY outside looking in. Just an opinion, and barely that.

As stated it is his call (I am a production manager too). If you feel that it is a problem waiting to happen I offer this advice: Discuss it in full, respectfully and professionally. Monitor the situation through reliable metrics (sequence efficiency, rework and rejection rates, customer satisfaction etc.) and agree to revisit in some reasonable period of time. But do not appear to have an axe to grind - even if you do.

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#10
In reply to #6

Re: Splitting Component Drawings - Is It Normal?

02/06/2009 12:32 AM

correct... the PM needs to know how much extra pain he is creating, so he can properly and professionally assess the cost/benefit of such decisions. You don't have to second guess his reasons, and the best value you can provide is an accurate estimate of the expected increase in workload. For this type of situation, the old "Think like a CEO" is applicable.. just get the answers, but don't fight with him/her. Present it as professionally as possible, and make sure he knows you are 'on the team, and on the ball' Engineering will Always be seen as support for production. you are providing a service, and that service must adapt to meet the needs of your 'customer'. but the customer has to know the price is different when they ask for more. There are ways to improve and minimize the workload, and increase efficiency.. it might be a positive thing in the long run.

Chris

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#7

Re: Splitting Component Drawings - Is It Normal?

02/05/2009 10:46 PM

Normally this is the responsibility of the production department to sort out, not engineering. Engineering provides production with documentation of what the part is to be. It is up to production to figure out how to achieve that end. If they think they can make a cylindrical hole that is positioned within .005 and is held to within .005 of size with a hand chisel and a mill bastard file, that is their concern, not yours. You do not generally care if the hole is drilled, bored, honed, reamed, chiseled, or EDM'd, just as long as it is on size and properly located. You are right that by breaking the drawings up into pieces you are compounding the risks of revisions not being carried forward properly. You do this at your own peril.

I suspect the Production Manager's problem is geared toward preventing someone from stealing the design. This is a somewhat common practice among defense systems manufacturers working on classified equipment.No one vendor or machinist has enough information to completely reverse engineer the system or part. This is part of the reason why government projects cost so much. Tthe bureaucracy required to keep up with all of that BS is a nightmare.

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#8

Re: Splitting Component Drawings - Is It Normal?

02/05/2009 11:05 PM

Its not wrong for him to ask for it. He should realize the amount of extra effort he his asking for, and that is your job to assess. If you end up having to make multiple drawings, for each process, then essentially, you have to make him aware that he has multiplied the time and energy required to make them, and simply ask for more resources.

However, if all your drawing is done in AutoCAD, or an application that uses layers, you can still engineer your product concurrently, but create a layer for each work station, so only those operations go on that layer, and you can print each layer separately, while still having the ability to view them collectively, and keep their relationships intact.

This all presumes that you are manually machining, and not having each operator create CNC programming from the individual drawings, as that would definitely be inefficient. there are definitely better ways, especially if you are using solidworks, which can be translated to CNC toolpath files.

If you aren't using computers for drawings.. get one, and a simple cad program that can do layers. put a copy of the title block on each layer, for each view orientation. (if 2D)

Chris

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#9

Re: Splitting Component Drawings - Is It Normal?

02/06/2009 12:06 AM

Hello Bangkok-Watches:

I assume by the name you are in watch making? Forgive if not OK? But, whatever you are in, it is more and more crucial that the competition should not get hold of any ideas and, or drawings, dimensions etc.

The Production Manager has to do what he thinks best when all things are considered. I am sure, Apple, Samsung, Nike etc, all do what amounts to similar things to stop or prevent copying. It should not be looked upon as a kind of back-handed insult to the Engineers making the parts!

I never worked in that kind of industry where the products were potentially very valuable. I suppose you can take the view it makes the Engineers no more than robots. But is that true? I think if robots could do the work with the necessary skill required, they would be doing it already and, there would be no need for hardly any workforce at all!. I suppose they get to see the finished product though? It is not vital for this to happen but, it would inspire the workers to try harder and accept the 'rules' or working conditions, or, perhaps they will be out of a job in a very short time. As if any 'details', crucial word that, were to get out, they would be out of a job anyway as the item your company make will be made elsewhere, probably China or an island around the fer-east?

Would you not rather like to get round and, find a workable solution to, in your words "a nightmare"? Sooner that than the alternative of not doing a job I am sure they may be proud of? Particularly given the perceived importance of the actual details of the product, what ever it be?

Take care and take a more positive attitude.................They are not out to get you honest!

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#11

Re: Splitting Component Drawings - Is It Normal?

02/06/2009 3:10 AM

I prefer the full-detailed drawings. I prefer to know not only what to do but also why to do it. Military environment: it's a different story...

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#12

Re: Splitting Component Drawings - Is It Normal?

02/06/2009 3:48 AM

If you are working with AutoCAD or TurboCAD, consider placing different information of the object in "model space" on different layers, and then turning on the required layers for each machining step on separate "paper spaces". That way, the information stays on the one drawing and there is no redundancy of information.

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#26
In reply to #12

Re: Splitting Component Drawings - Is It Normal?

02/06/2009 11:28 AM

Thats exactly what I said in #8

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#13

Re: Splitting Component Drawings - Is It Normal?

02/06/2009 5:13 AM

Your production manager is asking you to take a useful step in the direction of better control of your manufacturing process. We'll assume here that he has picked the best method to do this to fit the organization's situation. (there are a number of things that are often done to improve manufacturing process control. Detailed process instructions are just one of them).

The most important issue here is whether he wants to impose this extra drawing creation effort on the people who design and develop the product (product design engineering) or on the people who are charged with providing engineering support direct to production. (production or manufacturing engineering.)

In most Western manufacturing organizations concerned with making hardware according to design engineer produced drawings and specifications the inclusion of specific manufacturing process directions with design drawings and specifications is strongly discouraged for the following reasons:

1. Manufacturing specifications on design drawings constrain the ability of production to pick the best process without the design engineer's approval.

2. The work required to "draw" and maintain the "drawing" is increased by the additional content.

3. The probability of duplicate or conflicting dimensions on the drawing is increased.

4. The engineering change control process can be heavily burdened by the increased activity to meet production needs to maintain and improve their process control. This can be painful when design engineering drawing activity takes a back seat to urgent production requirements. Failure of timely engineering changes can result in increased production and warranty costs, missed market opportunities, slow response to product quality problems and even legal problems due to slowly resolved safety and environmental issues.

5. Slowing down the engineering change control process can be a genuine enterprise destroyer.

6. Design engineers and drafters often do not have the skill sets to produce manufacturing process instructions without detailed input from production engineers.

The most common practice in USA manufacturing companies is for a design engineering group organizationally detached from Manufacturing designs a product and formally releases drawings, specifications and parts lists to Manufacturing under a change or revision control protocol. Typically there is a production or manufacturing engineering group that reports to Manufacturing management. This group is responsible for development and related engineering duties associated with the manufacturing process. These guys take the newly released drawings and use them to create the process for manufacturing. The tangible results of their work usually consists of manufacturing process instructions, tool and fixture designs, procurement specs for purchased production machinery, CNC programming and project management where the new drawing changes need to be coordinated with other manufacturing groups like production control, quality control, production departments, facilities management and the industrial safety department.

It is very typical for manufacturing engineers to use parts of engineering drawings, both text and images, in the creation of their manufacturing process instruction documents. Solid model images can be especially helpful in this area in the hands of a good instruction writer.

A manufacturing engineering department will usually have its own change control system for the process instructions and CNC software. Such systems are usually less formal than the design department's Engineering Change control process and are organizationally separate. In smaller organizations they can be under the control of individual manufacturing engineers, each for those instructions in his particular area of responsibility.

Occasionally manufacturing companies will experiment with putting the design engineering department under production management. This is usually a company reorganization tactic in which there had to be a political loser, typically the design engineering manager who was insensitive to the needs of manufacturing. This abnormal situation generally doesn't continue for long as the CEO sees his market share suffer from the lack of new products due to the subjugation of design engineering priorities to the imperatives of making each month's production targets.

Bottom line here is that it is not a good idea to ask design engineers to be responsible for the routine activities involved in control of manufacturing processes.

There is one important exception here. That is where a part or assembly cannot be economically measured by its maker to insure it meets all required specifications. This is where it becomes desirable for design engineers to specify elements of the manufacturing process. In this case the best approach is to create a separate engineering specification under change control with nothing more than a note on the part or assembly drawing referring to the number of that specification.

Ed Weldon

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#14
In reply to #13

Re: Splitting Component Drawings - Is It Normal?

02/06/2009 8:14 AM

Ed is right, but there is another aspect that may come into play too. You may also cause tolerance stack up issues by doing this. Generally speaking part features that are related to each other are dimensioned to each other in order to control the tolerance stack up of the location and size of those features. often, parts of those features may be made by a different manufacturing processes. by splitting the drawing up by manufacturing processes, those features that are important reference points disappear. I would strongly suggest that this is a very dangerous practice and can lead to severe manufacturing problems.

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#28
In reply to #14

Re: Splitting Component Drawings - Is It Normal?

02/06/2009 11:31 AM

excellent point. GA

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#20
In reply to #13

Re: Splitting Component Drawings - Is It Normal?

02/06/2009 9:17 AM

Ed, Very good and thorough answer.

When a department or area of responsibility is lost (or mismanaged) so is the inherent value. It was always a pain in the butt in project meetings when the process guys would say "we can't build that". Mainly because that is what they always said. But I appreciated the value of their attitude because it was a starting point to a solution. And in turn a good product and process.

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#27
In reply to #13

Re: Splitting Component Drawings - Is It Normal?

02/06/2009 11:30 AM

well thought out Ed

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#15

Re: Splitting Component Drawings - Is It Normal?

02/06/2009 8:14 AM

This isn't necessarily a bad idea provided everyone is aware of the added time/cost to do it.

Most good CAD programs can accomplish it by smart use of layering and assigning attributes.

If the manager is insistant on individual drawings for each componant, then the only smart way to manage the drawings is with high quality PDM (Product Data Management). One thing to keep in mind is that the methodology of individual drawings, leans toward drawing centric production rather than componant centric. In other words, over time, the drawing(s) become more important than the parts.

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#16

Re: Splitting Component Drawings - Is It Normal?

02/06/2009 8:27 AM

It looks like people are really getting into this topic. I don't usually see this many long, multi-paragraph comments. Anyway I just wanted to explan the way we do things where I work to add another version. In some cases, especially for parts that will be made in house, we create a drawing and part number for the raw material. Then we create a drawing and part number for the finished part and structure a bill of material calling the raw material as the only component. Some old drawings skipped the BOM step and just called out the other part number in the material block. You could make each part as a component of the last and be forced to trace back when one is revised.

Another option is to make a multi page drawing with one part number and a separate page for each "step". That way when they are printed the PM can figure out how to distribute them.

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#17

Re: Splitting Component Drawings - Is It Normal?

02/06/2009 9:04 AM

I've experienced this before. And the #1 value that is lost is design intent. A complete component drawing communicates this through the relationship of features and relative dimensions and tolerances. When an issue arises it is very difficult to diagnose the problem when the design is dissected like this.

A set of work instructions with technical sketches is more useful and user friendly in an instance like this. Separate from the engineering drawings these would be under the control and revision of the production department. Usually these documents are listed in an engineering change to flag a change (or not) for production. But they are not the responsibility of engineering.

If a person is of such a low skill set that they need a drawing with two holes in it, then they shouldn't be working to a drawing. And they should not be asked to do so.

There is a HUGE value in supplying the complete design to the machine operator. Typically these people really know their stuff. And many times they will return your print with suggestions, notations or even corrections. It's a value I appreciate as a designer!!

All of this said, I've had to do this. But it didn't last. It doesn't take long before the realization that it is a waste of time and resources surfaces.

You may have to endure simply because some people will not understand what you take as common sense. Good luck.

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#18
In reply to #17

Re: Splitting Component Drawings - Is It Normal?

02/06/2009 9:06 AM

WOW! I really taxed the server when I spell checked that post. Not a good morning.

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#19
In reply to #17

Re: Splitting Component Drawings - Is It Normal?

02/06/2009 9:10 AM

Agreed! that was what I was trying to say in my #14, you have said it better however.

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#29
In reply to #17

Re: Splitting Component Drawings - Is It Normal?

02/06/2009 11:33 AM

well said.. GA

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#21

Re: Splitting Component Drawings - Is It Normal?

02/06/2009 9:51 AM

ANSI Y14.5M 1994

1.4 Fundamental Rules

Dimensioning and tolerancing shall clearly define engineering intent and shall conform to the following:

(c) Each necessary dimension of an end product shall be shown. No more dimensions than those necessary for complete definition shall be given. The use of reference dimensions on a drawing should be minimized.

(e) The drawing should define a part without specifying manufacturing methods. Thus, only the diameter of a hole is given without indicating whether it is to be drilled, reamed, punched, or made by any other operation. However, in those instances where manufacturing, processing, quality assurance, or environmental information is essential to the definition of engineering requirements, it shall be specified on the drawing or in a document referenced on the drawing.

..... so even when manufacturing notes are on the drawing, it is intended for engineering requirements not process.

A confusion occurs when there is the assumption that engineering drawings are for more than engineering. Process, purchasing, shipping, inventory..... these are all different entities. And all are very fluid which make them not a good match for an engineering change process. Todays process may not match tomorrows technology or available products.

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#22
In reply to #21

Re: Splitting Component Drawings - Is It Normal?

02/06/2009 10:00 AM

Additionally, being engineers, we may not be intimately familiar with the capabilities and processes of purchasing, manufacturing and the like. we should not presume such knowledge by trying to dictate the processes involved to those who know more than we how to do their jobs.

The next time I see a drawing calling for a such and such sized drill, I swear I will KILL the drafter and hang his or her entrails on the the flagpole as a warning to the rest of them.

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#23
In reply to #22

Re: Splitting Component Drawings - Is It Normal?

02/06/2009 10:08 AM

Thanks for the Friday laugh.....

I agree totally!!

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#30
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Re: Splitting Component Drawings - Is It Normal?

02/06/2009 11:35 AM

GA for finding that nugget

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#24

Re: Splitting Component Drawings - Is It Normal?

02/06/2009 10:21 AM

I agree with the Guest comment, it is the production manager's call.

My first thought to this thread is "Is the production manager new?"

It is also the production manager's responsibility to watch costs.

I see it as unnecessary usage of paper. It is hard enough in the engineering department to conserve paper as it is.

Furthermore, it's a lot of excessive labor spent creating drawings for each specific task when one drawing will suffice.

I do disagree with Guest in his comment that you're just supposed to do as you're told and like it.

It doesn't hurt to point out these concerns to your production manager. I work for a production manager that is open and listens respectfully to whom ever is speaking with him. I know there are managers out there that think they are less of a man if they should actually stop, listen and consider someone else's input.

All the same. It is your company that you're working for and it is every bit as much your concern to help control costs.

Labor is probably the biggest cost factor in your situation and it is primarily the higher dollar labor that it directly affects because I'm only assuming that you and your fellow engineers are getting paid more then the boys in the machine shop.

If he's not considering the labor costs, then he's missing his mark as to his function as a manager.

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#25

Re: Splitting Component Drawings - Is It Normal?

02/06/2009 11:18 AM

I seem to have come to this post a bit late but one point a can't see here is that, by splitting the drawings this way you are dictating how the part is made. If this all takes place in house, fair enough, but if the work is subbed out you might create extra expense because say, the firm that shapes the outside could also drill the holes in the same operation on a CNC machining centre.

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#31

Re: Splitting Component Drawings - Is It Normal?

02/06/2009 11:43 AM

I do not really see how the production manager has an effect on final decisions unless there is no engineering manager or design manager, it seems you are in the discussion phase prior to this "split up" implementation.

There may be 100 different reasons why. You should be able to ask the manager (carefully) - "why" - without offending him, consider that a potential recent problem has caused his decision or suggestion to be made, and he had been asked to come up with a solution. Then the pacifiers has been provided.

As to the CAD comments I have seen, a high end 3D cad program which is parametrically based has cause and effect to all created drawings from the main model, an update affects all drawings automatically. If the respective parts are created with proper drawing intend, and in a similar fashion as to the manufacturing process, it would be fairly simple to create detail drawings for each task, for the task you described unnecessary, as placing holes and rads on a manual machine are likely done by the same person, although maybe in different operations on a milling machine. CNC of course would do all operations on one, perhaps except for polishing, the 3D model would be used, not the drawing, except perhaps for tolerances or GD&T.

As to the tolerances on various surfaces, etc. they are easily specified for each step. Besides we were talking about hole placements and Rads.

I agree it creates more work - is it beneficial? That depends for who, perhaps you are truly needed, or need to understand all the tasks involved in more detail. Enough speculation - just ask - don`t forget to share his answer with us.

Generally a tool-room also has a manager directing the proper production, it would be beneficial if at least he did have all the info.

By a remote possibility - perhaps there is not enough work to go around, but he really does not want to loose you!

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