# question about drilling soft metal



## SE18 (Feb 21, 2008)

I guess this could also apply to white metal castings, but I made some train castings in a lead/solder mix.

When I try to drill thru the metal the bit melts the metal and slides around. I did make a starter hole using a punch but there still was some bit wandering.


Do I just need more practice, drilling a little at a time and backing out and repeating? Any tricks.

The thickness of the metal is about 3/8"

Thanks

Dave Vergun


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## xo18thfa (Jan 2, 2008)

Posted By SE18 on 17 Feb 2010 11:41 AM 
I guess this could also apply to white metal castings, but I made some train castings in a lead/solder mix.

When I try to drill thru the metal the bit melts the metal and slides around. I did make a starter hole using a punch but there still was some bit wandering.


Do I just need more practice, drilling a little at a time and backing out and repeating? Any tricks.

The thickness of the metal is about 3/8"

Thanks

Dave Vergun 




Hi Dave: Softer metals are hard to drill sometimes. They like to gum-up the bits, soft metal likes to grab too. Very sharp bits, somewhat lower speed on the drill, somewhat slower feed, oil seem to help. Yes and for some reason, they like to wander. Choke up the drill bit in the chuck to make it more rigid. Maybe start the hole with machinist's centering bit first, then switch to regular drill.


This is what I mean by a center drill. They are very rigid and intended to start a hole on a rough metal surface:










Bob


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## SE18 (Feb 21, 2008)

thanks, I'm always amazed at the variety of bits out there that I never even knew about


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## Greg Elmassian (Jan 3, 2008)

Drill a lot more slowly 
Use a sharp bit 
lube the bit with beeswax (helps keep the metal from sticking to the bit) 
Drill a bit and back out to clear shavings 

You did not mention the diameter of the hole you are drilling... 

Regards, Greg


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## SE18 (Feb 21, 2008)

Thanks. diameter is 3/16. 

BTW, I did notice a fair amount of shavings coming off the bit. 

Best part of screwing it up is I can reheat and repour; can't say that about resin castings; also, no expiration date


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## Trains West (Oct 4, 2008)

drill very slowly like under 100 rpm


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## Robby D (Oct 15, 2009)

Use a Screw Machine Length Parabolic drill with a tin coating.


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## Totalwrecker (Feb 26, 2009)

Drill a pilot hole with a hand held pin vise, around 1/16th will do. Wax or dipping the bit in light oil and slow speed. Don't let the lead pull the bit, you'll feel it. 

A drill press that can be spun by hand can help with the fnal hole, if you have one, otherwise slow speed and light pressure, lube and a sharp bit....


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## Jack - Freshwater Models (Feb 17, 2008)

I made some train castings in a lead/solder mix.





Dave,

Part of the problem is the alloy! I spin-cast Britannia metal (AKA white metal) parts. I have drilled more then my share of holes in them and I try to avoid drilling when possible. Your lead tin and who knows what else alloy probably isn't going to drill well. Most common white metal alloys are not easy to drill but they are probably a lot easier to drill than what you have. These alloys have antimony and other metals like copper that make them harder than solder. The alloy I cast is 92% tin 7.75% antimony and .25% copper. It drills ok but is no picanick! First try to avoid drilling by "coring" the holes. This can be done using rubber or teflon rod. If you must drill, use a SHARP, short drill, like a screw machine drill, turning at low speed if possible and lubricate the drill while drilling the hole. It is relally better to cast the hole rather than drill the hole! I know from unhappy experience of drilling many holes in cast parts.

Jack


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## coyote97 (Apr 5, 2009)

drilling is generally one of the hardest problems when working with metal.
(LOL-im a professional deep-hole driller....we have experiences from aluminium over brass, steel, steel implants, titan and highspeed-steel. But whitemetal, we didnt had in 15 Years now!!!) 

the main problem is the temperature, that highly concentrated in a small volume. Drilling can make with NO problem temperatures over 800 degrees celsius.

So the white-metal alloys are arround 350 or 400 melting, u should avoid every overdone friction and for the bad sability of those metals as less mechanical pressure or power as possible.


so, the tips were quite right:

stay down with rpm
use a good lubrication
take time to drill
work with less feed.


Frank


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## SE18 (Feb 21, 2008)

thanks, pretty much everyone agrees with what Frank summed up in 4 points. 

Jack, casting the hole is good advice, thanks. I'm not clear on how or what a rubber or teflon rod would do, I'm assuming you mean to place the rod where the hole will be and then pour around it. 

Cheers 

Dave Vergun


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## Jack - Freshwater Models (Feb 17, 2008)

Dave, 

A core is a separate part that fits in a molds core print and creates a hole or feature in a casting. There are a number of reasons why a core may be used. An example of a simple and common core would be to make a cast tube. The pattern would be the tube with a rod runing through it and sticking out at both ends. The two bits sticking out at both ends will create the core print in the mold. The core can be a teflon rod the same diameter as the hole but longer. You set the core in the core print in the mold, close up the mold, and pour the metal. Open the mold, pull out the cast part and remove the core. Generally speaking the core has to run parallel to the parting line in the mold. 

To learn more just look for information regarding patternmaking/foundry. Though the info you find will be about big castings, it can be applied to small stuff also. Teflon is a suitable core material for white metal. White metal can be cast in either suitable RTV rubber or jewelers fine grained oil bonded casting sand. 

I hope this helps. 

Jack


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## SE18 (Feb 21, 2008)

thanks, I'm still a novice at this. Sounds like there are a few tricks to learn


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## SE18 (Feb 21, 2008)

thanks, all, I followed your advice and successfully drilled and then tapped my homemade curly spoked wheels. A nail serves as axle, which I died both ends to screw into the wheel

I noticed that the act of tapping the wheel and even screwing in the nail, can cause puddling of the soft material so I had to proceed slowly so as not to build up too much heat


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## Jack - Freshwater Models (Feb 17, 2008)

Cool wheels!!!! Great picture! 

Those wheels have a lot of character. An axle hole would be tough to cast in place since the hole runs perpendicular to the parting plane. Something like that I would drill a small hole and bore using a tiny boring bar. What is the mold material? 

Jack


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## Totalwrecker (Feb 26, 2009)

Jack, 
The rod can be cast perpendicular, but I would use a polished steel rod. 
I did it all the time when I was making jewelry molds for lost wax cating, a shot of silicon spray before and a twist to remove. Just make the pin longer so the ends are held in the rubber. 
John


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## SE18 (Feb 21, 2008)

thanks: 1:3 solder/lead in that ratio. You can try to bend the wheels but they won't bend; sturdy

I'd like to see how you did the perpindicular process; photo or sketch. But after reading over what you wrote, I can visualize the process. I'm still learning. Thanks

each axle (axle + 2 wheels is 93 grams, btw. I could use a thicker nail and widen the tires to achieve even more weight if need be as it's 7/8 scale 


incidentally, I made a resin wheel off a Bachmann wheel, then milled the wheel using a drill and files as I have no mill or lathe 


Dave


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## Totalwrecker (Feb 26, 2009)

Dave, 
I was making vulcanised rubber molds, if your wheel is about 1/4" thick I'd use a mold 3/4" thick and the pin would be 1/2". I cut my molds so they would hinge at one end, open the mold and insert the pin. The pin also helps align the two halves, easier to avoid parting lines than fix them after... At the corner of each mold make cuts to leave a block on one half, cutting it out leaves the matching depression on the other, these line up to help with parting lines... 

Sorry no pics... that was 10 years ago and I can't draw clearly enough on the PC... 

John


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## SE18 (Feb 21, 2008)

thanks, I'm using RTV mold; in fact I've used it multiple times; it stands up well to hot, low-temp metals. Very robust. Amazing stuff; you get about 3 seconds to press it before it cools; forgot to mention


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## Ray Dunakin (Jan 6, 2008)

Nice looking wheels!


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