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Deep Hole Drilling equipment suggestions


Oct 26, 2012
griffin, ga
Hello guys,

I'm currently working on a equipment list for the company I work for. We are a rubber molding facility that makes some of our tooling in-house, mainly prototypes and spare parts. They are wanting to expand our capabilities to do everything in-house. I've got a general idea of all the equipment we are needing and we have purchased some of the must have stuff already. The one thing I'm struggling with is what equipment do I need for the deep drilled holes.

The holes we will be drilling are mainly for cartridge heater platens and cold deck water channels. The holes are generally 1/2" diameter x 12" deep. We may get into some smaller holes, let's say 1/4" to 5/8" diameter would be a good size range and 12" to 16" deep. The material is 4140, Royalloy, and Ramax.

All the old timers tell me that if you're gonna do heater holes we would need a Gun drill machine. I'm not opposed to a Gun drill machine, but it seems like a lot of shop space for something we will only use to drill 4 to 8 holes a month tops. I'm thinking a Bigger CNC mill would be capable of most of our needs.

So, What do you guy's think would be the best machine to get for what I'm doing? A gun drilling machine or a Bigger CNC mill and I would like to maybe hear some success stories of people doing these type of holes in their CNC mill.


Cast Iron
Dec 29, 2014
A CNC machine with through spindle coolant and the correct drills is all you need. You may get by with longer twist drills at those depths but will need TSC regardless. The smaller the hole the higher the pressure you'll need. For those sizes 400psi should suffice though going for 1k may not be a poor idea incase you need more later.


Sep 23, 2014
I agree with above any mill with 1000psi through spindle coolant should be capable of doing it. If you use water based coolant the gun drills won’t last as long but it is probably cheaper to just replace the drills more often than to have a machine dedicated to drilling a few holes.


Jun 7, 2012
I don't know how expensive gun drilling machines are, but if all you're going to do is drill deep holes, I'd get a used cnc.
500psi coolant minimum,1000psi preferred.
Make sure you're able to go to the depths you need before you buy the machine.
I'm partial to verticals, but horizontals would work also.