I am modifying stainless screws with a Dremel and files, and after destroying a couple of files have sort of figured out with Google's help that "work hardening" can be reduced by working at low speeds rather than high. Or at least that seems to help. Then there's the fact that stainless is kind of sticky, and tends to clog files that are not chalked or oiled. Any other tips? Also, any recommendations on what kinds of files to use, even specific brands? Thanks.
Mike
Hi Mike. How are you trying to modify the screws. Length or the head?? I've found that if your trying to mod the heads I've used a bench grinder with a cordless drill. If that's the case then make sure the chucked screw in the drill is turning the opposite direction of the grinder wheel.
Use canola oil for cutting oil, it's cheep and works better than the ozone safe garbage they sell today. Make sure you clean it up though, it turns into a tough to remove varnish.
If you are grinding, its important to control the heat you are putting into the part. There are specialized grinding compounds that work wonderfully on stainless, but its typically outside of the scope of the hobbyist. So stick with name brands, and if it starts changing color, you are heating it too much.
Stainless in its natural state is not very hard, but it is very tough and gummy. It work hardens though, which can make working with it difficult. Avoiding work hardening should be your number one priority when doing any cutting, drilling, or machining on stainless. Keep the speed down, and use plenty of pressure.
Sharp cutting tools are imperative. Quality matters here, cobalt steel drills do very well on stainless, but HSS should be considered a minimum. Carbon steel loses its temper with heat, and dulls quickly on stainless. Dull bits further promote work hardening because they cant cut the material easily. Use cutting fluid, and do not let the cutter get too hot. I like Pro tap, and Union Butterfield tapping fluid is amazing, and rather expensive.
Files should not have any difficulty with stainless, as long as they are good quality. I use only Nicholson files, most are made in mexico now and are very high quality. Not much more expensive than the store brand, made in china crap. Ill never buy a chinese file.
At the shop I work at, about 80% of the parts we make are stainless. It is not that stainless is difficult to work with, its just different, and has a specific set of conditions where it cuts well. But once you get out of that narrow envelope, it creates difficulties.
I chucked the screw in a Dremel on speed 1 & did my grinding on a Diamond Wet Stone. I had no problem.
Mike
Thanks for the replies.
bmitch (Bob?), I'm turning down heads at the moment, which requires removing a good amount of metal. A bench grinder might be a good alternative, but what I've got is a Dremel and files. I've also got a good hand-held drill with a whole lot more low end torque than the Dremel. Maybe I should try to rig something to hold it steady on the bench.
Lee, I will definitely try the canola.
Adam, I've bookmarked your post as something to refer to repeatedly. Great stuff.
Mike, does the Dremel set on low speed produce enough torque to be useful? I will experiment. Diamond files are pretty inexpensive and should work also, no?
Again, thanks.
Mike
I prefer a bench sander over a grinder for what I do. I'll try to get a photo of mine.
Mike1010
I'm only doing screw heads. It works for me but I'm retired with no where to go. Yes it does work. I bought the Chinese Stones from the same place as the Files. I use the Course one. I have another set of screws to do one of these days for a 99. When you live in an apartment with no work shop you learn new ways.
Mike
I use a drill, grinder, drill press, drill and grinder, and lots of lubricant to keep things cool.
I got a cheap set of diamond files for turning down the heads of screws chucked in a dremel on its lowest speed, as bluefish69 Mike suggested above. You can't apply much force to the files, or they will start shedding diamonds. That's okay, because the dremel doesn't generate enough torque to allow strong pressure anyway. The combination works well, and work hardening is not an issue.
Quote from: mike1010 on March 02, 2015, 10:03:02 PM
I got a cheap set of diamond files for turning down the heads of screws chucked in a dremel on its lowest speed, as bluefish69 Mike suggested above. You can't apply much force to the files, or they will start shedding diamonds. That's okay, because the dremel doesn't generate enough torque to allow strong pressure anyway. The combination works well, and work hardening is not an issue.
Diamond is slow, but it does a good job on stainless without work hardening being an issue. The diamond cuts it just as well hardened as annealed.
Quote from: bluefish69 on February 24, 2015, 03:49:51 PM
When you live in an apartment with no work shop you learn new ways.
In my apartment days, I tried to get a 2 bedroom and covered the floor of the spare bedroom with Masonite, duct taped the edges and made a workshop. The Masonite was a hold over from the way we protected floors at work. Sweeps up easily and protects the carpet.
I currently only use cobalt drills and blades when working with stainless. Cobalt is better than TCT as it doesn't suffer heat degradion so easily. Slow and heavy (pressure or feed) is the golden rule with stainless - you need to be cutting new material all the time - if your not cutting you're 'polishing' and stainless will work harden. Use cutting oil - high temp vegeatable oil (rapeseed/canola oil) is pretty good and cheap. Cobalt also does a good job with aluminium and brass (and plastic, micarta etc.).