CNC Machining Centers
Horizontal Boring Mills
Pilot Hole Preparation
On a non-conventional gundrill machine a pilot hole is required prior to gundrilling to hold the gundrill steady and accurate during the entry. This is usually prepared with a drill and reamed hole .0005” (.0127mm) larger than the gundrill and one to two times diameter in depth and a flat bottom is preferred.
Turning the gundrill 25 RPM in a counter clockwise direction while entering the pilot and stopping about .100” (2.54mm) before the bottom is recommended in case if any misalignment between the spindle, holder, and drill it which case the heal of the drill will guide the tool into the pilot hole.
Once inside the pilot hole the coolant is turned on to the applicable PSI, the RPM is started in a clockwise direction and the feed is started. A gundrill is fed with a steady feed rate and no pecking. Once the desired depth is obtained the gundrill is immediately retracted to the start position in the pilot hole and the RPM and coolant is turned off at which time the drill can be removed from the part.
Drill Masters – Eldorado single flute gundrills are available in diameters from .039” (1.0mm) to 3.0” (76.2mm). Included in this range are over 800 sizes and lengths in stock for same-day delivery. We also offer an expedited service for non-stock gundrills to satisfy your urgent requests. In addition to the single flute design, we offer solid carbide single flute tip and shank, for maximum rigidly in small diameter applications. All with either round coolant orifice, kidney shaped coolant orifice and dual coolant orifices depending on the diameter specified.
In addition to the single flute we offer two-flute gundrills for increased feed rates in non-ferrous materials. Reamers/gunbores are also available for tighter ID tolerances.
Specify your application upon ordering to obtain the correct tool for your process.
Single Flute - (Crimped Tube)
Single flute gundrills are the most commonly used tool due to it’s versatility to produce an exact to print precision hole in any type material in a single pass. Standard single flute gundrills are a three piece construction tool with a solid carbide head brazed on a heat treated aircraft grade tube with a chip channel (vee) formed down the length and brazed into a driver. Every gundrill is flow checked at a specified PSI and is aligned to straightness as low as .002” (.05mm) OAL.
Single flute gundrills have no length to diameter ratios therefore depending on diameter, lengths are available from 3” (76.2mm) to 20+’ (6.1m)
All tools may be re-tipped when maximum carbide usage is reached.
New clear picture needed.
Single Flute - (Solid Carbide)
Single flute solid carbide gundrills are constructed of a single piece of carbide with no braze joint at the head and tube transition. Solid carbide gundrills will yield greater tool life, more strength, rigidly, 2-3 times faster feed rates, and maximize your productivity. Due to its rigidity this tool enables much faster SFM without the whip factor therefore enabling increased feed rates.
Stock diameters are available from .055” (1.397mm) to .070” (1.778mm) in lengths to 6.0” (152.4mm) Special diameters and lengths are available from .039” (1.0mm) - .1875” (4.762mm) in lengths up to 10” (254mm). Delivery is 2-3 weeks depending on carbide availability.
New clear picture needed.
Single Flute - (Multi-Diameter – Step)
There are many applications when two to three diameters are needed in a single bore. Multi-diameter step drills may be the solution to entering the bore in two to three passes and obtaining the precise print tolerances in a single pass. There are some limitations to this process due to carbide lengths, diameter ranges, and coolant hole locations. Send us a print and see if we can cut some time of you process.
New clear picture needed.
Two Flutes - (Crimped Tube)
The two flute gundrill design incorporates two cutting edges, which reduces the chip load and increases penetration rates up to 100% over single flute drills in various non-ferrous applications. They can be used in conventional gundrilling machines and in CNC lathes, machining centers, boring mills, etc.
Due to the tube design of the two flute the chip channel (flute) it’s only crimped to center and not deeper as the single flute. Therefore two flutes can only evacuate smaller more fine chips and is limited to non ferrous type materials. It is recommended to increase the coolant pressure by 20% over the recommended single flute PSI to evacuate chips more efficiently.
Two flutes are available in diameters from .1875” (4.7625mm) to 1.25” (31.75mm) and lengths to 84” (2133mm). All tools may be re-tipped when maximum carbide usage is reached.
Drill Masters - Eldorado Tool has recently procured equipment unique to the industry which allows our company to manufacture Solid Carbide Gundrills without the need for centerless grinding. This method allows perfectly straight head and tube configurations with virtually no deviation in wall thickness from one end to the other. This guarantees the most rigid tools available in the industry today. This process also allows the fastest lead times normally 2-3 weeks. Matched with the finest European carbide grades the feedback from our customers has a proven track record of a far more superior drill than ever before.
Drills are manufactured form .040" (1mm) to .1875" (4.762mm) and lengths to 10" (254mm)
Ideally, gundrill oils with a minimum of 2 ½% sulfur and 4 ½% chlorine are desired and can be optimized to 6% sulfur and 10% chlorine for best results.
CNC machines are not capable of using oils and therefore water soluble, synthetics, and semi-synthetic coolants are used. These types of coolants are suitable but result in about 30% - 40% less tool life from oil based coolants.
There are a vast number of non-oil coolant manufacturers and most work well but keep in mind that 10% - 12% concentration is vital to the success of this type of tool.
Always keep in mind that 5-20 micron filtration depending on the diameter of the drill being used is an important factor to the success of the process function properly.
Another is the temperature of the coolant, it should never reach 100F – 110F or a chiller is highly recommended.
Advancing Manufacturing, Tomorrow and Today
A drilling solution improves the production of a component that is critical for correcting spinal disorders. Meanwhile, an apprenticeship program ensures that improvements like this one can continue into the future.