Sending drawings out to the fabricator

[drawoh]

Our old blueprint machine is on its last legs. At least it was on its last legs last week. A repairman is coming.

All of our fabrication is subcontracted. We need to think about how we send drawings out.

I still prefer to send out scale drawings on paper, complete with signatures on the originals to indicate that everything is official. As the designer/drafter, I need to know how the end user is going to receive my stuff so that I can communicate clearly. I am routinely asked by fabricators for DXF files and other CAD formats. I send these too, as I am confident that these provide reliable scale information. I am not absolutely confident that a DXF file created by my CAD software will come up on the recipient's CAD softare exacly the way I saved it.

How do people here send drawings out to the shop, and ensure that this is the latest, official drawing?

JHG

 

[TheTick]

Before creating a DXF for vendor use, I temporarily alter the source drawing (SolidWorks) with an expiration date stamp.

DXF is a pretty reliable means of transmitting 2D geometry. I wouldn't worry too much. Also, there are lots of viewers and translators and other applications that read DXF that can be used to recheck your output.

 

[drawoh]

TheTick,

I agree that DXF is a reliable resource for transmitting scale models. I am less confident about the information ont the drawing. If you have a complex part with all sorts of GD&T symbols all over the place, you are up against the other CAD software's fonts and scaling.

JHG

 

[TheTick]

This is where Adobe Acrobat comes in real handy. You can make a PDF out of anything you an print (I highly recommend PDF995, available at <

http://www.pdf995.com>).

Since the Acrobat reader is readily available to anyone at no cost, it is a great way to ensure text information is preserved. The downside (maybe upside, if security is a concern) is that PDF files aren't useful for manipulating geometry (i.e. measuring, CAM export, etc.), so you may still need DXF.

Due to illness, the part of The Tick will be played by... The Tick.

http://www.EsoxRepublic.com

 

[EdDanzer]

We prefer 8 ½ X 11 drawings. Much easier to handle in the shop, and can be destroyed when done. That way revisions don’t get mixed up.

 

[Mandrake22]

Ed,
Do you issue magnifying glasses with these prints?!

 

[FredGarvin]

I double Tick's comments about PDF995. I use it myself when I have to send something to an outside source. I feel much better about having a completely non-alterable format of a drawing going out the door. Plus, it will do any size that your cad will do. I routinely make pdf's of C size drawings. You can not tell the difference in print quality either.

 

[lurker]

It seems DXF is a standard format, but I agree with drawoh in that sometimes the CAD system on the other end isn't as compatible as initially thought... symbols, fonts, etc. can be distorted, misplaced, or even missing.

PDF is a good format also (and we do use the official Adobe Acrobat software to generate them) but as someone said, measurements can not normally be taken from them.

I work with our shops and vendors in almost an iterative process to ensure they have the everything they need. If I send DXF, I followup with a phone call to make sure they can open it, see it, and do what they need to do. Same when sending 3-D bodies (usually IGES). It's just a hassle for both parties when the part comes in and it's wrong because the models or the drawings were messed up on their screen...

- lurker

 

[EdDanzer]

Mandrake22,
If the intent when creating the drawings is to help the shop people, a magnifying glass is not required. It usually requires more than one sheet for larger items. I have received large drawings that are harder to read than 8 ½ X 11 on white paper.

 

[drawoh]

TheTick,

I use Ghostview to generate PDFs from the CAD printer files. I like PDF, but I have not tried sending it out to fabricators. I like generating fabrication drawings at 1:1 scale. This means that big, complicated things end up on E-sized sheets.

If you use 1/8" (3mm) lettering on B and C sized sheets, A-sized PDFs are quite readable. If you use 5/32" (4mm) lettering on D-sized sheets, these are fairly readable at A-size, especially for young people with good eyesight.

Documenting a large machined part on A-sized paper, even with multiple sheets, sounds like a challenge.

JHG

 

[dangnm]

You have an ISO problem, not an engineering one.

To control this, in general I do not permit machine shops to keep prints after the job is done. They are required to send the original print back to me with the quality control audit. True, a shop can photocopy the print but it would be their loss when another job uses a print, not necessarily the one they used before. Most machinist do collect prints, typically this is the responsibility of the shop and they do have policies in place. Other smaller shops do not, and that's fine. The entire assembly is NEVER handed over to one machine shop, but farmed out across the industry so everyone does something different. This way you maintain control of the design.

On the other hand, larger engineering firms have product lines that date many decades. In this case, it is up to purchasing to utilize the quality control program to ensure vendors listed and authorized to do particular work, have the latest and most recent drawing. What I like to do is scan in a print that is signed and stamped with the Professional Engineering stamp as well as the company Permit to Practice stamp. The scan therefore is electronically transferrable and storable. Our purchasing department works under the guidelines of ISO 9001 to ensure the inspectors are looking at the right piece relative to the latest revision of the drawing.

There are other systems which offer better or worse opportunities than these, but essentially this is a quality issue handled by various departments. Keep an updated log of vendors who you have supplied prints with the current revision. There are many canned programs which can do this for you, I wrote my own for flexibility and additional information I had found useful, experience wise.

Hope this helps you out somewhat.

 

[Reggie1968]

When I use customers drawings, I like to get them in a DXF file. A lot of the time I find there is a dimension that I need that is not allready marked. It saves time calling the customer when you can get your own information. On a PDF file you cannot get your own dimensions. You need to be able to count on the fabrication shop to do their job.

 

[friartuck]

I add a scale line to all my drawings. It shows typically 0-5 metres (i dont do macjhine drawings as you have already guessed). Then there can be no mistake when the drawing is imported as to what the actual acale is. In other words, they cant print it at the wrong scale without noticing it.
Also, all our drawings have revisions and dates in the drawing and the DXF file name. A drawing issue sheet goes with the drawing so they know what revision we are at.

When the drawing is printed on our plotter, we also have the file name printed on the bottom LHS to let us know when it was plotted etc.

Friar Tuck of Sherwood

 

[drawoh]

(),

Here is a star! This is way closer to the question I originally asked. How to I get the right documents out to the shop in a readable format? Being able to prove I got the right documents out there gives me a shot at ISO certification.

Our shops like to hang onto prints, so that when we revise stuff, they can compare it with the old drawing and revise their CAM programs. We mark the revision number explicitly on the purchase order. I prefer to send out a complete drawing package with each purchase order, ensuring the shop has a copy of the latest drawings. I suspect that a few other people here assume that the shop already has something.

I know people who like to send out the assembly, but I do not. My drawings are clear enough, and if they are not, I want to be called and asked. The same goes with DXF files. DXF provides the dimension, not the tolerance.

Very rarely do we send out drawings with a PE stamp, but it would be nice to get signatures onto things.

What graphic format do your scanned drawings go out in?

JHG

 

[Boathouse]

Just a question to Reggie1968. If you extract a dimension by measuring off of the blue print and do not get the drawing updated, what do you inspect the part to?? In my experience, unless the drawing is a non-dimensioned full size one (known as a lofted part, or flat pattern - which will have grid lines at a predetermined and measurable spacing) then there has always been a note on the face of the drawing stating something like "DO NOT SCALE".

If the part requires a dimension measured from the face of the drawing then it is inadequately defined and should be corrected.

Just my two 'penneth - cheers!