Tape Strip Holders

[GaryM]

I'm located in New Zealand, and involved in small scale audio manufacture, and have been for many years. Typically any of the suppliers here that do sheet metal work will have laser cutters these days, often extremely sophisticated ones. If they do sheet metal work they will have the capability to press fit studs or threaded inserts of various types. We are batch manufacturing with regular order sizes of 10 units of various parts: complex chassis with many holes and inserts down to simple folded metal heatsinks. The costs are quite modest for the simple parts even in small qtys. 2mm or 3mm steel would not a problem to these places. Europe has a much bigger manufacturing base so I would be surprised if you can't find cost effective suppliers there. Don't be afraid of asking for pricing from the Chinese source I posted, I obtained a cost for a part from them earlier this year and they were very approachable, good with communication and quick to quote. We didn't go ahead as we found a local supplier at slightly lower cost, but the exercise was worthwhile.

[JohnSL]

Let's say the top plate is 2mm, bottom plate is 3mm. Then you would need an M3x4.5mm thumb screw to fix the top plate. There is no such thing so you will also need a custom made thumb screw. Or add many washers.

I'm not sure why 4.5 mm instead of 5 mm (possibly with a washer). I found some thumb wheels that press onto a cap head screw: https://www.mcmaster.com/#91175a061/=159vvhb. So these could be used with a 5 mm screw.

2mm or 3mm steel would not a problem to these places.

I've been doing some research on press-fit screws, and I'm not really sure what to search for. Here is one link I found: http://pkprecision.com/std-02.htm. That particular one looks like it needs a minimum of 3 mm thick material. I also found another type, such as these http://www.pemnet.com/fastening-product ... -and-pins/ that appear to require a custom punch and anvil. But they can work just as well with 2 mm thick material.

I've changed the design to have a 3 mm lower plate and a 2 mm upper plate. This required increasing the height of the holder by another 1 mm, so the table to the top of the tape is now 23 mm. I also made the "legs" on the holders 3.2 mm high so the top plate can push down on them a little to allow them to be held in place more firmly. I need to do some testing to ensure there aren't other changes I have to make as well:

Hold Down Bar 3.PNG (51.39 KiB) Viewed 21861 times

I'm going to do one last test with 3D-printed parts. But unless I find any issues, I think it's ready to start the manufacturing process. Earlier I sent the files to my local injection molding company. However, they said they're very busy at the moment, so I'm not sure how long it will take to get a quote back for the mold (or molds).

Also can I offer a link to a company that may be of use to you for the manufacture? I have had some interaction with them, and they are quite professional. Based in China but owned and operated by westerners... I have no connection to the company, I just have them bookmarked for some possible projects for my own business. http://www.star-prototype.com/

Do you know anything more about them? I've only worked with one company in China--Seeed Studios, and they were really great to work with, and very honest and ethical. I just want to check before sending them design files for a quote. I think I'll reach out to them and start a dialog before I send the files.

[vonnieda]

Also can I offer a link to a company that may be of use to you for the manufacture? I have had some interaction with them, and they are quite professional. Based in China but owned and operated by westerners... I have no connection to the company, I just have them bookmarked for some possible projects for my own business. http://www.star-prototype.com/

Do you know anything more about them? I've only worked with one company in China--Seeed Studios, and they were really great to work with, and very honest and ethical. I just want to check before sending them design files for a quote. I think I'll reach out to them and start a dialog before I send the files.

I visited Star Prototype during my time in China in 2015. They are a very high end prototyping and small to medium manufacturing company with the ability to do basically everything in house. I was completely impressed with their capabilities but they are at the very top end of that type of business and are very expensive.

[GaryM]

Also can I offer a link to a company that may be of use to you for the manufacture? I have had some interaction with them, and they are quite professional. Based in China but owned and operated by westerners... I have no connection to the company, I just have them bookmarked for some possible projects for my own business. http://www.star-prototype.com/

Do you know anything more about them? I've only worked with one company in China--Seeed Studios, and they were really great to work with, and very honest and ethical. I just want to check before sending them design files for a quote. I think I'll reach out to them and start a dialog before I send the files.[/quote]

The guy you will be talking too is a Brit so communication is easy. It costs nothing to ask for a price. What quantity would you be looking at ordering? Perhaps you might want to start cautiously with your idea of the screw from below, and then when you are up and running with the design and it is proven you could then move to press fitted studs. Pemnet is the supplier that is almost universal for these pressed in components.

In our case in small quantities a CNC machined part was quoted at NZ$33 from them and was NZ$29 here locally. Because of the small price and also the freight difference we went local. I still think that there will be many suppliers capable of this work in small numbers in Europe.

[GaryM]

Thumb nuts...

http://www.ebay.com/itm/Good-use-M3M4M5 ... 33IdJTe46w

http://www.ebay.com/itm/Alloyed-Red-M3- ... 3R8ztBk7bA

[JohnSL]

Thumb nuts...

Thanks for those links!

Then you would need an M3x4.5mm thumb screw to fix the top plate. There is no such thing

I just stumbled on this link http://www.ebay.com/itm/M3-x-4-5mm-Phil ... DXEWfkQzwA. So they do exist.

[JuKu]

I talked with my supplier, where I buy laser cut steel plates. Threads can be tapped with ease. Thread and countersink requires a thick plate. Press-fit screws exist, but they don't work with them. So, for production reasons, if the holder is made here, it uses thumb screws, not thumb nuts.

The problem with thumb screws is to find right length, most are too long. But Misumi (I buy there all the time, a very good supplier) has 4mm long M4 thumb screw and 5mm long M3's. If top plate is 2mm, bottom plate is 3mm and the mount requires some push down (0.x mm), both would work. Almost 2mm in M4 is stronger than you can tighten a thumb screw, almost 3mm to 3mm plate assumes clean hole.

http://www.misumi-europe.com/en/catalog ... s2products

http://www.misumi-europe.com/en/catalog ... s2products

Latter is much cheaper.

[mrandt]

There is no such thing.

I just stumbled on this link http://www.ebay.com/itm/M3-x-4-5mm-Phil ... DXEWfkQzwA. So they do exist.

Woah. I guess one should never say never Let me put it another way: M3x4.5 is not a standard size

I'm not sure why 4.5 mm instead of 5 mm (possibly with a washer).

Simply to avoid the washer. You don't want any screw to hit the end of a blindhole; so blindhole needs to be a bit deeper than the screw size. Assuming the top plate is 2mm and bottom plate 3mm, M3x5 might be just a bit too long.

Press-fit screws exist, but they don't work with them. So, for production reasons, if the holder is made here, it uses thumb screws, not thumb nuts.

Fair enough. Let's not overcomplicate the design. We could always change for press fit bolts and thumb nuts later; but for now thumb screw and tapped hole sounds like the easiest and probably cheapest solution to me.

Even if we needed a washer to fit the M3x5 that wouldn't worry me too much.

I think the more interesting parts are the feeders - and those look fabulous

[JohnSL]

I've done some more looking and it seems like M3 x 6 is easy to find. M3 x 4.5 is not quite as easy to find. And M3 x 5 is harder to find. So I'm thinking we should go with M3 x 6 plus some washers. If we use wide washers, that will also help spread out the load a little (although I'm not sure that would matter much with steel). Also, the screw holes will be tapped all the way through, so we don't need to worry about the threads near the bottom, as they'll be just as good as the threads at the top.

Juha, do you want to choose a thumb screw? It seems like we have two general options. One is to have a large knob on the head so you have enough leverage to tighten it by hand. The other option is to use smaller ones that allow tightening with a screw driver.

Sloted Head 8 mm in diameter: http://www.misumi-europe.com/en/catalog ... s2products

The "resin" thrumb screws are 11 mm in diameter: http://www.misumi-europe.com/en/catalog ... s2products

So the plastic thrumb screw isn't that much larger in diameter than the slotted one. Yes, it's cheaper, at about 1/3 the price of the slotted version. The other option is to order these screws from China. I'm currently leaning toward the 6 mm long slotted as you can get them tighter than finger tight.

-- John

[JuKu]

I would think that hand tightening would be tight enough considering the application. It would be more convenient if a tool is not required. And finally, I prefer a European source over a Chinese one, if the price is acceptable. From China, the shipping is either expensive or slow without any idea when the stuff arrives.

This is not a big issue. Even a regular screw would be just fine: a slight twist on a couple of screws and slide the top plate aside (nice idea, btw!) is easy enough. But as I said, I'd start with the resin one.