The metal used in recent LaBelle kit castings is very much harder that that in my ‘heritage’ kits. I am having difficulty drilling holes for handrails etc. without breaking bits. Does anyone have advice about bits, techiques, or ??
Ken Ziebarth
Talk to you dentist and see if he or she will give you some of their used bits. They’re stronger than most anything you’ll buy for modeling.
Ray
Use a lubricant such as WD40, kerosene, bees wax, a light oil.
I have some carbide drills that are hard but cannot be flexed at all or they break.
I drill using a pin vise.
Rich
You are talking about using number sized bits, say #60 down thru #80 to drill into pot metal or Zamac castings?
I always drill by hand with a pin vise. Power drilling with a Dremel is an invitation to break the drill. Always center punch to get the hole going in the right place. Lubricate the drill, 3 in in oil is good. Drilling soft metal the flutes of the drill tend to dig in too deep and lock the drill. When you feel resistance to rotation building up, stop, and rotate the drill in reverse to free the flutes from the work. Then continue forward to drill some more. Keep the flutes clear of shavings, back the drill out of the hole periodically to clear them.
Drilling metal castings should be done at high speed, with the drill-bit lubricated with oil, and small dips intro the hole before backing out to clear chips. Never try to punch through all at once. If possible, use high-speed steel drills, they are harder than carbide drills. Use a drill press whenever possible, as a hand-held drill may get “out-of-line” and break the drill-bit as it bends.
A. Wallace,
I agree with everything you’ve said above except for what’s underscored. Carbide is actually harder than high speed steel (HSS) but is also more brittle. With that being the case, HSS will “flex” better than carbide. However, in most instances, I’d rather go with the hardness and durability of carbide and take my time drilling into the piece.
Also, while HSS does need lubrication to keep the bit cool so that it extends the life of the drill, carbide can actually be run either wet or dry. Just make sure you plunge in small increments and clear the hole frequently, as you have already suggested.
And, as a general rule, the smaller the drill bit, the faster the drill bit (rotational) speed needs to be.
Tom
For my flagmen I use small drills too. I did never think about those material Preiser use. It’s very drill consuming!!
Wolfgang
I have lost more bits using a small drill press than using a pin vise. I doubt anyone other than a good machinist can do this.
Please make a video of drilling at high speed with a drill press into a small metal part using the 60 to 80 drill bits. I and others have to see this. [:D]
Rich