I am completing a old Brass Car Sides Bi-Level commuter car and need some advice to continue.
I am trying to drill very small holes into the end cap of the cab car to install grab and wipers irons near the windows for the crew. Currently the metal seems very tough and breaking the #80 drill bits and bee’s wax. The shavings from the holes I have started is fine power like. I am using a pin vice and have the metal clamped to the table to minimize any movement. I have a photo depicting the project. I am open to any advice.
I have one suggestion that may reduce the breakage. That is to chuck your bit so very little of it is sticking out of the pin vice, maybe 1/4" or less. This reduces the tendancy for the bit to flex sideways, which is what breaks the bit.
I also find that I have a nasty habit of pushing the bit harder as the hole progresses. That is a sure recipe for breaking the bit.
If your bit is only producing fine filings it may be that the bit isn’t ground correctly. I have found a lot of variation in the cutting ability of different bits, even from the same manufacturer. In fact, I find it rather rare when I get a bit that will actually cut decently. You could try re-grinding the tips but that almost requires a microscope to see what you are doing, and besides I could never get the proper angles when I tried anyhow, even on much larger bits. I buy a bunch of the same sized bits and if one doesn’t bite in it goes in the garbage.
You could also use slightly larger bits, like a #78. They seem to be more forgiving according to several posts on the subject in the past, and in my own experience. The excess space around the grab iron will be filled by whatever you are using to secure the grab.
One other suggestion I would make is to put a dimple in the brass where you want to make the hole. You can use a sharp scratch awl or something similar. The dimple will keep your bit from wandering off center. In your picture it appears that the two holes you have drilled are not at exactly the same height. The grab will be crooked when you put it in. You can compensate by using a pair of pliers to twist the grab into alignment once it is installed, or you can drill a larger hole, fill it with solder, and then redrill at the proper height.
Try using motor oil instead of the wax. You want the bit to cut, not slip. The oil will act like a coolant and extend the bit life.
Also try going up to a 78 drill bit. The extra size is only a few thousands. A #80 is 0.0135 vs the #78 at 0.0160. Paint or solder will fill in the tiny excess in the hole diameter.
And follow Dave’s advice about limiting the length of the bit.
Check with a local machine shop to see what the best cutting oil would be for the material. I had a friend once tell me that different metals cut better with different types of oil. I changed the one for the job I was doing and it made a big difference. I was a long way from sheet brass and numbered drills, but what a difference it made to use the recommended cutting oil. My drills lasted much longer and drilled much faster.
I’ve drilled lots of tiny holes on brass engines to add / change details parts. I just chuck the drill in my variable spped Dremel set low and drill away. … and yes, there are collets that step down tight enough to hold a #80 bit.
a miniature drill press might help, but that is a 200 dollar solution to a 2 dollar problem. i bought one from micromark years ago before they got to be so proud of them.
you have already gotten some good input from others.
for my part, i would not be opposed to using a slightly larger size. wire grabs that small are almost invisible to me and i personally prefer something a bit bigger.
I have never had much luck drilling any kind of metal with a hand held device.
I often will drill ovesize holes into hard metals with whatever I have handy, (#68 or larger), then fill the holes with epoxy (JB Weld) or CA and then redrill them with the appropriate size bit.
I also always go about 2 sizes larger than the hole I need. #78 for a #80, #76 for a #78, etc. The CA I use to glue the part will fill in the hole and will completely disapear once it’s painted or touched up.
Might be easier as the others have said about a larger hole and fill it with solder and then drill the smaller size thru the solder. It can be filed or sanded to the thickness of the brass, worked for me a few times. Jim.
Hello,