drilling/tapping into metal

I am building a custom wrist watch. I am using Shapeways to prototype the case. I need to drill and tap tiny screw holes into the case (which will be made of metal). I am looking for feedback about how diffucult it will be to drill/tap into stainless steel, alumide or silver.

Hello,
I have worked with stainless steel for many years and have had a lot of experience tapping as small as 1mm metric threads into stainless. At such a small size it becomes quite tricky not to snap the tap off in the hole. Although i have not tried tapping the 3D printed stainless i have drilled it and found it to be much tougher than normal 316 stainless. You should have no issues with Silver but the alumide my be prone to threading at smaller sizes. Let me know how you go if you go ahead with your project andGood luck.

PS, i have tapped the Strong white and Flexible material with a 3mm tap and found it quit good.

Thanks for this information. It is very helpful. I am curious, do you normally use a drill press to drill the holes into stainless steel? I may decide to buy an inexpensive one, unless a cheap one wont cut it. Also, what kind of drill bits do you use? I am anticipating the need to buy special ones from a watch supply so I can get ones small enough. Also, did you use a hand tool to tap the tiny holes or did you have some kind of tapping machine?

The 3d printed stainless steel is hard and a bit brittle.

Some force at thin points will likely lead to breakage.

So make sure the part where the holes will be tapped are well supported.

I have not yet tried drilling it, but if you like I could see if I have some scraps I can drill. But I do not have drills below 1 mm.

A drill press is always handy to have around and probably a must for this work. The cheaper ones tend to have and develop more play which might be troublesome with tiny drills and accuracy.

For this work a decent micro drill press should do.

It could be useful to implement the hole in the model itself, or at least a dimple so your drill will be nicely centered.

The sterling silver is the most accurate and might prove good result with printing of the holes.

The Alumide might be a bit allergenic. And it is also a more brittle materials.

Cheers.

virtox is right, a dimple if not a hole smaller than the tap drill size is very smart. I use a drill press every time if suitable, i drill holes using a jewelers hand drill if a tricky vantage point is needed. A dremel is not as nimble but can still be used if your steady. I use normal high speed steel drills but some are better quality than others. Special jeweler drills are available that will fit into a hand drill with a flexible shaft or a dremal but are quite expensive, they do however come in a good range of sizes under 1 mm. When drilling stainless steel it is very wise to use some oil for cooling, this will help and keep the drill sharper for longer.

The SS print material is composed of alloy 420 stainless, this is a tool steel grade alloy and nothing like alloy 316. Yes it is a booger to drill and tap. During the last several months the furnace profiles for processing SS prints have been adjusted to produce a somewhat more ductile and machinable material but it remains a tough and abrasive material. Care must be taken to use slower than normal cutting speeds and feeds and definitely use a machining fluid designed for steels.
Trying to drill holes, especially tiny ones, without using a drill press equipped with a vice is not a good idea! Many broken bits and/or scarred fingers is a likely scenario if attempting to hand drill parts made from this material. The good news is that where expensive carbide tooling was once the only hope for drilling and tapping this material, now you can get good results with standard hi-speed alloy drills and taps.

-G

Thanks for this information. I always planned to make the watch case out of stainless because that is very common. Probably because it is strong and resistant to scratching...or? However, after reading this I am starting to lean more toward silver. But is silver more likely to scratch? Besides the difference in price, is there anything else I should know about silver? Pros and cons?

Silver is MUCH softer than SS. Yes it will definitely scratch more easily than the SS. It is also more likely to bend or deform. You will need to account for this in your design. Even so, over time a watch case of silver would acquire a nice natural satin patina due to abrasion. This could look very nice unless you want shiny chrome like surface.

Also, how does SS and silver compare to the white, strong and polished material? I would guess even silver is much harder, or? And how do they compare in terms of accuracy (how well do the details print)?

Silver is much more durable than any printed plastic. You ought to post your design so people can get a sense of what it looks like and what is most appropriate material.

No problem. Here is how it might look when done (3D rendering in 3DStudio Max).

Here is how the case looked before I painted it. White, strong, polished plastic.

Here it is with a fresh coat of hobby paint.

Finally, here it is with some test artwork, a crystal which fits nice and snug, lying on a leather band.

Cool! Should be a fine design done in silver or stainless. A small mill or lathe would ceratinly help get precision fits. But anything is possible with clever hands.

-g