Part Layout Hacks/Tools/Techniques

[Mross506]

Doing this blindly is a bad idea. There are two separate issues that are often conflated: how you write the dimension and what the tolerance is. Building equipment in-house, you are in a good position to make your design and manufacturing processes work together. Don't throw that away.

The answer to your question is that it depends on how oversized the holes are. If it's a 1/8" hole, it's probably for a #4 (.112") or M3 (.118") screw. If you actually change it to 1/16" rounding, your error can be half that, or 1/32" (.03125"). It's obvious here that it might not work.

Now, you might say, "I'm not going to round to the nearest 16th, I'm just going to truncate to 2 decimal places, surely nothing bad could happen". Now your sensor has 4x M3s on an 87mm (3.4252") square. Your new setup truncates the decimal to 3.43". Assuming the .125" holes aren't undersized, your new tolerance band, if you want a symmetric tolerance band, on the 3.42" dimension is +-.002". This is now a more expensive part, rather than an easy +-.005 part.

There isn't usually a good reason, in my opinion, to not show three decimal places if you're laying things out with a CNC or DRO. It minimizes rounding errors and says nothing about requiring a tight tolerance. If your welders can't figure out that both 0.19 and 0.188 are 3/16, you have bigger problems. That being said, if you actually do drawings with fractions, those can be great for fab shop drawings, you're just putting the onus on the designer to ensure that what they have on the drawing is what they want to get. Blindly truncating dimensions is not the answer.

I'm not even going to get into how Solidworks handles explicit tolerancing of holes/bores and how truncation can screw you up there.

There is no alternative to your engineers actually thinking about tolerances, tolerance stackups, and how the part is being manufactured and assembled.

All of the above make sense. The engineers are more than willing to make changes that help us on the floor so it is just a matter of educating them on the details that are important to us....Thank you for the feedback!

 

[Freedommachine]

Well, I can confidently say that I will never share a drawing on PM...

As for part layout tools; Check out Sharpie industrial markers. They are good up to 500°F, they are also much more resistant to coolant than a standard marker.

https://www.amazon.com/Sharpie-13601-Industrial-Permanent-12-Count/dp/B00006IFEO

 

[DDoug]

All of the above make sense. The engineers are more than willing to make changes that help us on the floor so it is just a matter of educating them on the details that are important to us....Thank you for the feedback!

The problem is the mindset.
You can't just fix all your problems with freebie suggestions here and there.

 

[Mross506]

The problem is the mindset.
You can't just fix all your problems with freebie suggestions here and there.

And what mindset is that?

We may not be able to fix ALL of our problems with freebie suggestions but I wouldn't hesitate to say that the little time I have invested into this post has more than been worth it..... An old mentor told me once: "If you ever want to become an expert at anything, there are only 2 ways to achieve it. You dive in and spend 30 years learning lessons as they come while finding someone that has already spent 30 years learning those lessons and ask them as many good questions as you can..."

PM has the most experienced members of any other single location in the world and I can access that knowledge without it costing a dime. Why would I not take advantage of that? The responses we have rec'd have created great conversations within our team and have opened our eyes to how we can approach the tasks differently. We don't have the luxury of already having years of fabrication layout experience so you gain information where you can.

If you have any recommendations on how to fix all of our problems please share!

Thanks for the feedback!

 

[Mross506]

Well, I can confidently say that I will never share a drawing on PM...

As for part layout tools; Check out Sharpie industrial markers. They are good up to 500°F, they are also much more resistant to coolant than a standard marker.

https://www.amazon.com/Sharpie-13601-Industrial-Permanent-12-Count/dp/B00006IFEO

I asked for the feedback and feedback is what I rec'd!

I just put a box of the markers on order to try! We just ordered some of the long neck layout markers, too. The jury is still out on them.

 

[DDoug]

And what mindset is that?

We may not be able to fix ALL of our problems with freebie suggestions but I wouldn't hesitate to say that the little time I have invested into this post has more than been worth it..... An old mentor told me once: "If you ever want to become an expert at anything, there are only 2 ways to achieve it. You dive in and spend 30 years learning lessons as they come while finding someone that has already spent 30 years learning those lessons and ask them as many good questions as you can..."

PM has the most experienced members of any other single location in the world and I can access that knowledge without it costing a dime. Why would I not take advantage of that? The responses we have rec'd have created great conversations within our team and have opened our eyes to how we can approach the tasks differently. We don't have the luxury of already having years of fabrication layout experience so you gain information where you can.

If you have any recommendations on how to fix all of our problems please share!

Thanks for the feedback!

I've read most of all your postings, and I thought about a PM, I could consult for you, come in and give your designers some pointers, fix your fixturing problems, it's what I do.

But after the last few postings, I see you want it all for free, and thus wouldn't pay me for my time. And your push back on some really good suggestions is not conducive to change.

You get what you pay for, sometimes less.

 

[Mross506]

I've read most of all your postings, and I thought about a PM, I could consult for you, come in and give your designers some pointers, fix your fixturing problems, it's what I do.

But after the last few postings, I see you want it all for free, and thus wouldn't pay me for my time. And your push back on some really good suggestions is not conducive to change.

You get what you pay for, sometimes less.

Please elaborate on where I have made either of these statements? I think I have been pretty open and very appreciative of the great feedback.

I am definitely not against bringing in consultants if there is value to be had. We partner with vendors on a daily basis. Perhaps you should have led with an offer to share you knowledge as a consultant instead of insulting me...

As always, I appreciate the feedback.

 

[LatheLover91106]

I got covered with Dykem steel blue layout dye today.....its a gray RedKap shirt.....any way to get the dye out of my shirt...its stained blue for right now...plz help

 

[jmkasunich]

We are going to immediately remove 3 digit dimensions...When rounding to a 1/16", is that accurate enough to allow a sensor with 4 threaded 1/8" holes line up properly? There is alot of areas that we could automatically change to a 1/16" rounding. The question is whether I could do it for everything and not see too many issues from it.

For that scenario you have tight tolerances between the four small holes and a much looser tolerance for the overall location of the 4-hole pattern. I'd suggest making a template/jig for that sensor (and any other small items that you use a lot of). Dimension the first hole to the nearest 1/16" or whatever makes sense. Pop that hole, then drop your jig in place and drill the other three using the jig. If you use more than a few of that sensor it could be worthwhile to make the jig with a locating pin that drops into the first hole and drill bushings for the other three. Or make it with four drill bushings and clamp it in place before you drill.

The key point is to recognize that you aren't drilling four independent holes all measured from the end of the tube, you are drilling a single hole pattern. So the holes in the pattern should be referenced to each other. A jig does that.

 

[metalmagpie]

Great advice above. But you can go a long ways with a cheap 24x36" granite plate and 24" height gage. Clamp part upright to an angle plate. Quickly scribe all the height dimensions, rotate the part and scribe the rest. Centerpunch everything. Then use a pointed spud in the chuck of the mag drill to grab one punch mark at a time, then energize the magnet and drill. Way more brute-force than the elegant solutions above, but valid nonetheless.

 

[jmkasunich]

Great advice above. But you can go a long ways with a cheap 24x36" granite plate and 24" height gage. Clamp part upright to an angle plate. Quickly scribe all the height dimensions, rotate the part and scribe the rest. Centerpunch everything. Then use a pointed spud in the chuck of the mag drill to grab one punch mark at a time, then energize the magnet and drill. Way more brute-force than the elegant solutions above, but valid nonetheless.

OP uses a bridgeport (presumably with a DRO) for parts that will fit on the table. The mag drill is for longer parts, he gave an example that is 54" long. You aren't going to be laying that out with a height gage.

 

[pat pounden]

These tapping aids have been very helpful doing big plates and weldments. We liked the little one so much I made a larger model for 3/4 npt taps and such. I also made an adapter for a pipe threader for big taps after you get them started straight.

We made a long travel drill press with DRO for long tubes and plates. Repurposed a mag base drill and it works really well. Sure beats skipping a 20ft bar down a Bridgeport table.

both of those are GREAT ideas!!

 

[Mross506]

You guys have provided some INVALUABLE advice and education for me that has really kickstarted the thought process of how we should be approaching our original question regarding layout tips and tricks. Here is an update of what has come from these conversations:

• Whenever the part will fit in a Bridgeport, we are using the BP.
  • To help facilitate this we set up a sequence of training modules at our local community college. One of which is 40 hours of Bridgeport Mill training. This will make ALL of the techs on the floor comfortable using it to at least its base capacity which will provide them a building block for their future development
  • We are setting up a set of stands that will allow us to handle larger pieces when necessary
    • Ultimately, we want to set up a drill press with stops like a couple of you have recommended. A homemade Tigerstop system basically
• Whenever we are able to use a DRO, the part dimensions will stay 3 digit. When they can't, one of two courses of action will happen
  • When the part is a multiple piece production, we will order a laser cut template. This would work for alot of our mounting holes even if we just have a hole pattern on the template that we then have to locate dimensionally on a long piece of tubing. It would make sure all the holes are in proper relation to each other and only allow the error to be in the exact location the hole pattern is placed.
  • When it isn't something we want to spend the time or money waiting on a pattern to be made, we will do our best to convert the dimensions to something easily replicable on the fab floor. No more trying to convert 3 decimals to the nearest fraction.
• There were also some guys that were taking short cuts and referencing each hole off of the hole before it (even though the drawing always references from X) We have done some retraining that has helped!
• We are ordering a tapping arm
• Reviewing all drawing dimensions with the ENG team before release
  • They are also reviewing their process and making some changes with our ease of completion in mind. Alot of this was created because they just didn't know any better and the ENG's with more experience have moved on to bigger jobs and aren't involved in alot of the layout work. They are going to spend some time training on their side.

I am sure I am forgetting things but we are moving in the right direction for sure! Thanks everyone!