Plastic Nuts for Wood From Mercedes Dealers

[Pawel66]

I thought I would share, when I was doing my homework before work on wood, I sensed there were availability issues of the plastic nuts from MB. They are there, quite decent, not blue.

Price is, of course, ridiculous, $17 per piece vs. , e.g. $6.70 at Authentic Classic or about EUR 1 at SLS (just those from SLS are a bit worse by looks).

[wwheeler]

Seems like back when I was reinstalling the dash wood, these new MB nuts were a bit tight. Made me nervous and reused the old blue ones. Anybody else had that experience?

[ja17]

For that kind of money they should be able to supply the correct color. The scarce original blue plastic nuts were used on some sedans of the era also. The W108, W109, W114 and W115 cars used two of them below the rear windscreen, they hold a trim strip on the flat shelf. They can be removed from the trunk (boot) of the car. I always salvage these when parting an old sedan.

[wwheeler]

Those plastic dash nuts would be a perfect piece for the new 3D printing method. I would think getting a blue color wouldn't be all that hard either. 

[Jonny B]

You would just need someone to put together the file (that is the model) in a file for the 3D printing process. Don't know if you can scan the original is some way. I would assume that is possible.

 There are a number of different plastics that can be used, and colors too. This would also be an application where the lines from the printing don't really matter. The lines in the part are from the filament that is used to form the part. Not all 3D printing uses that, but that is what we had from the company that did the battery caps/bases.

[mrfatboy]

You would just need someone to put together the file (that is the model) in a file for the 3D printing process.

If someone can give me the dimensions of the nut I can attempt the model. Shouldn’t be too difficult. 👍

[Pawel66]

I think this is a very good idea.

We just need dimensions of the original blue one or statement that the new one is the same, just different colour- then I would just take mine for scanning.

[wwheeler]

They are not exactly the same. See page from SLS -  https://www.sls-hh-shop.de/main/en/mercedes-230-280sl-w113-/67-windscreen-230sl-250sl-280sl/fastener-for-window-frame-p-5901/waehrung/Pfund

Pretty sure I have both and could send to someone who can handle this.

Wallace

[Pawel66]

You are right, certainly not the same...

I know one gentleman who is fluent in this

I will be fixing my wood back in about a month...

[mrfatboy]

@wallace

If you can provide a picture or hand sketch with the dimensions I will attempt a model.

[wwheeler]

I can do that. I designed rubber tooling for years, so this will be easy. I assume you want the original design (blue), not the newer white version?

[mrfatboy]

I think the vote is for original blue👍

[ja17]

If you need an original blue one I can donate it to the cause.

[mrfatboy]

Ja17,

That might better if you have a spare. If will be easier to see all the little detail and will save Wallace the work of marking all the dimensions.

I will pm my address to you👍

[Pawel66]

Ok, so this is rolling, great!

I will help any way I can.

[WRe]

Hi,
you can buy these flanged Polyamid-Nuts (e.g. white, grey, black) in specialized shops for 50 cents.
...WRe

[Pawel66]

WRe, thank you, but the point is:
1. To have fun
2. To have even more fun
3. To have a nut that looks like original that everyone can print

[wwheeler]

I will finish this tomorrow and put the dimensions on it. Complicated little nut and unbelievable how much time they spent designing this with the little knubs on the side. They could have made it much simpler, but when has Mercedes ever done that!

[66andBlue]

Here is a small monkey wrench for the 3D printing project.
There are actually two types of blue nuts as shown in the photos.
I believe the longer one is the one that was used for the wood in Pagodas. It has an M5 thread whereas the shorter one has a smaller thread, M3 or M4?
Perhaps Joe (JA17) has the answer for that.

[ja17]

Yes, only the larger thread is correct for Pagodas. The smaller thread blue nut is used to hold dash pieces on w111 and w110 Mercedes sedans of the era. I possibly may have sent you the wrong one some time ago. Do you need the correct one?

[Pawel66]

Having seen how threads come out of the 3D printing, let me perhaps have a small suggestion to mrfatboy and wwheeler - perhaps the design for 3D printer does not have to be with the thread? perhaps it would be easier to print the nut with a hole so that we can thread it ourselves?

I am happy to test the printing when the files are ready - with and without thread and see how it goes.

[mrfatboy]

Wallace and I have already had a discussion regarding the threading and came to the same conclusion.   I will be making two versions. One version with M5 threads and the other with a hole that you can tap yourself.

You would definitely need a high quality 3D printer for the threaded version to work. We will just have to see.

[wwheeler]

FYI, the larger thread and taller nut is what came off the wood on my W111 coupe. That is the one I used to make a print of. It is for sure 5mm. Mine is an early ‘68. Maybe earlier W111 cars were different?

Maybe the smaller one is for the W108 cars and the wood on the rear window like Joe had mentioned earlier?

I just sent Col a PM asking him if he can measure both his Pagoda and his W111 dash wood studs.

[wwheeler]

I agree on the threads. Depending on how it comes out, the pilot hole size may need to be adjusted to account for this being plastic. Won’t know until you try it on parts.

Also, is there any shrinkage on this part when it is printed? If so, the dimensions may need to be adjusted. About the only critical dimension is the flats on the nut. They cannot be too tight for a wrench or like wise too lose. Everything else is just for looks.

[ja17]

The smaller threads are used to secure dash face panels on W110 and W111 sedans not coupes and cabs. The nuts that hold the dash top wood on pagodas and probably the coupes and cabs, like yours Wallace, used the larger hole blue nuts.

[wwheeler]

Ok sorry. I didn’t see sedan in your description. That makes sense. Thanks for the clarification.

[Pawel66]

Wallace and I have already had a discussion regarding the threading and came to the same conclusion.   I will be making two versions. One version with M5 threads and the other with a hole that you can tap yourself.

You would definitely need a high quality 3D printer for the threaded version to work. We will just have to see.

No hole at all - trouble to make a centered hole. Any hole - can be drilled to proper diameter for the thread to be made.

Again, the drawing should be in high resolution. I am happy to test print.

[mrfatboy]

Here is my first attempt at creating the nut in 3D. I'm just a beginner at CAD drawing and some of the geometry was difficult to replicate.

Special thanks goes out to Wallace, 66andblue, and ja17 for sketches and providing a nut for analysis.   

I do not have a 3D printer and who knows how this will turn out. 

The original nut has a 5 mm hole at the bottom(unthreaded) that goes up 4.5mm. Then the rest of the hole is 5mm threaded.  Instead of trying to make 5mm threads I just reduced down to 4mm. Someone can just tap or force make the threads with a 5mm bolt.  We will just have to see how it works.

I will send Pawel the 3D file to test print. When everything checks out and we are happy with it I can post the file in the tech manual for others to print.

Cross your fingers

[Pawel66]

Great!

We make the threads not with the bolt, but with the thread maker (do not know the English name), you can buy (most likely) M5x0.75mm everywhere.

I will just probably need to work out the resolution dispute with the printing house.

Got your file on mail, thank you. I will take it with the printing guy.

[Benzgirl]

Better deal at Niemoller for sure but then shipping cost must be high....

[Garry]

Better deal at Niemoller for sure but then shipping cost must be high....

It is probably cheaper to get from Germany as the US postage has skyrocketed in price recently and is certainly quicker as next to nothing is getting into or out of the USA at the moment due to Covid flight restrictions.

[Pawel66]

I think they sell the same type of nuts at Niemoeller as they sell in SLS. It is a really cheap looking one...

[wwheeler]

The tool you need is called a tap and will cut threads into the ID of the nut. You need a 5mm - .80 tap. BTW, a die is the tool used to make threads on the OD.

The specs call for the ID hole to be 4.2mm to make correct 5mm threads. So you will need to drill the 4mm hole to 4.2mm or just try it the way it is. Cutting threads in plastic is different than in metal, so who knows what will work the best.

Don’t use a regular screw to cut threads and won’t work well. They do make special thread cutting screws but only create so-so quality threads. You will want the threads in the nut to be smooth so that you do not dislodge the studs in the wood.

[mrfatboy]

Inside the nut the threads start out to be 5mm and toward the top they get smaller slightly for a interference fit.  I measured a 4mm hole at the top in the sample nut I had. If necessary I can enlarge the upper part of the hole to 4.2nm

I would be surprised if I got this perfect on the first try so I will wait Pawel’s comments for version 2 if necessary.

[wwheeler]

I would leave it as is for now. Who knows what the hole diameter will need to be in the end. It is more close enough for now.

Nice job on the CAD. I did that some when it came out years ago. But I found that I spent more time figuring out how to get the program to do what I wanted and less time actually creating the part.

[66andBlue]

Great!
We make the threads not with the bolt, but with the thread maker (do not know the English name), you can buy (most likely) M5x0.75mm everywhere.
I will just probably need to work out the resolution dispute with the printing house.
Got your file on mail, thank you. I will take it with the printing guy.

Pawel,
to tap hard plastic it will help if you don't use only the final dimension thread cutter but go in stages, coarse to final. Unfortunately, few sets include this feature. And if the taps are tapered then you can stop and not go all the way through to the largest diameter. As Wallace wrote, it should be a M5x0.8mm, not M5x0.75mm.
I have found this one very convenient. Even Joe A. likes it. 

[Pawel66]

Alfred, yes, thank you I was thinking of cutting the thread in stages. I do not think I will have an issue finding any of the cutters here, some of them I probably have in the garage.

I am not sure about the 0.75 or 0.8mm thread. I believe what you are saying that it is originally 0.8mm, but some of us may have the studs replaced and if anybody did it, they did it with standard M5 bolts. I am not sure what is the most common standard - 0.75 or 0.8. Anyhow if the "raw" nuts are produced, anybody can thread them as they need.

Thank you for your kind attention and the tip!

[mrfatboy]

If anybody is interested I have attached a photo how I started the CAD drawing.  First, I drew it out as a 2D shape looking down on it.  From there, I just push/pulled the geometry to make the basic nut.

Once I got the basic shape I had to do a lot of detail work.  As Wallace said, it can become frustrating to get the App to do what you want.    I had to start over many times.  You really need to think the whole project through before you even start.

I used Google Sketchup.

[DaveB]

you are a super-tinkerer!

[wwheeler]

Alfred,

I have never seen a tap set like that. That makes prefect sense because the standard taps usually create threads that are a bit too loose. You can get adjustable dies, but never seen a way to make better internal threads. I know they have the tapered, plug and bottoming taps with different ends. Very interesting.

[Pawel66]

Alfred and Wallace were right as for the M5 thread cutter (not a surprise, actually). The standard is M5x0.8mm.

Example of the set under the link, can be Google translated.

https://allegro.pl/oferta/gwintownik-gwintowniki-m5-m6-m8-m10-uchwyt-zestaw-6280691090

[wwheeler]

I can't seem to find these in the US and also with inch sized taps. Maybe just in Europe and metric?

[Pawel66]

We have fabricated the 3D printed nuts - description is under separate thread "Blue Plastic Nuts For Wood Self Fabricated".