Great advise from all! I saved this thread to my favorites for refering to again. Dan
WayneI wish I had thought of that before drilling the 40 #75 holes in my Cary E7 body. I only used three bits but your way would have been so much easier and probably five times faster.I’ll remember that but I think that the E7 body will be my last.Mel My Model Railroad http://melvineperry.blogspot.com/ Bakersfield, California Turned 84 in July, aging is definitely not for wimps.
I've found that drilling holes in cast metal (zinc/zamac) boilers is a fast way to dull many of those smaller drill bits.Instead, for adding details, I use a regular drill bit (1/16" or larger, depending on the size of the detail being added), then use a slightly larger diameter piece of styrene rod, dipped several times into MEK, in order to soften the exterior of the plastic.The rod is then forced into the hole and snipped-off. Once the plastic has rehardened, the excess is removed and filed or sanded smooth. I then use an appropriately-sized drill bit, in a pin vise, to make a hole in the styrene that will accept the mounting pin of the detail to be added, securing it with ca.
This saves ruining those expensive smaller drill bits, and once the item is painted, the styrene plug becomes invisible, whether it's covered by a water pump or fully visible accommodating only a piece of wire used as piping.I recently purchased some small drill bits from a local tool supplier, paying $1.36 for a #52 HSS drill bit, and a package of 12 #79 HSS bits for $47.40...just a tad under four bucks apiece. These bits, with care, have an extremely good lifespan, whether used in a pin vise or chucked into my DeWalt battery-powered drill, which is capable of very low speeds.
I formerly bought small drill bits from a now long-gone hobby shop, at fairly reasonable prices, but one day made the mistake of buying Walthers bits at a much better price, only to discover that none of them, regardless of size, was capable of drilling a hole in any material, without either breaking or becoming dull before the hole was deep enough...lesson learned - you get what you payed for.
I generally get very good lifespans from those #79 bits, especially when used in a pin vise while working with styrene.Some time ago, I was re-working some True-Line (now part of Atlas) Dominion-Fowler boxcars, which were fairly nicely-done, but used overly thick free-standing plastic grabirons.I removed them, then plugged the mounting holes using styrene rod, then drilled new holes using a #79 drill bit in a pin vise...each car required 78 holes.
I was working on the seventh car, when the drill bit finally quit, just 3 holes short of 500.
Wayne
Got it! Thanks Mel and Randy.
When working with tiny drill bits they normally grab the material and break. The advantage of high speed drilling is the bits don’t break as often but the high speed dulls them quickly.
Mel My Model Railroad http://melvineperry.blogspot.com/ Bakersfield, California Turned 84 in July, aging is definitely not for wimps.
Mel, do you break them or do they get dull?
I have have had good luck sharpening them on a sanding disk in a Dremel tool.
I do an eBay search and go with a US vender, usually around $6 for a pack of 10 free shipping. My last order was #75 for $7 back in October.I just ran a search and it came back the same as October.https://www.ebay.com/sch/i.html?_from=R40&_nkw=%2375+10pc+Mini+HSS+Wire+Gauge+Twist+Drill&_sacat=0&_sop=15Prices have really increased over the last year.
I have better luck drilling at 250 to 500 RPM even though they are high speed bits. I normally get about 8 holes in Cary metal bodies and 10 to 12 in K&S Brass.
I'll be doing some drilling into metal with #72 or #70 into zinc locomotives, and K&S brass plate for handrails. I recon I'll need a supply of these tiny drill bits, I don't expect they'll last real long.
I see Micro mark sells them in packets of 6. Is that as good a deal to be found out there as far as quality and price are concerned? Any advice for drilling these metals? Dan