Model 252/253 Drill Units

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Pneumatic Stroke/Self-Feeding

The model 250, 252, & 253 drill units are self-feeding drills which can be actuated with air or oil. They are capable of producing thrusts of up to 182 lbs. with 100 psi air pressure and 364 lbs. with 200 psi oil pressure. These units are usually used for drilling, reaming, boring and light milling applications, but can also be used whenever simultaneous rotary and linear motions are required. It can be mounted in any position, horizontal, vertical etc. As illustrated, it is supplied without a motor, but can be easily powered by an electric or air motor up to 1/2 hp. A simple pneumatic, or hydraulic control system is required to achieve forward and reverse stroke control. This can be purchased separately from Blackalloy™. See our Drill Unit Components reference page for a description of the customization options available.

Description

Drill Unit Options:

The series 250 drill units can be equipped with the following options:

No Feed Control - Model 250
Feed Control - Model 252
Deep Hole (Peck) Drilling - Model 253
Self-Reversing Tapping Head Attachment - 3250 Tapping Heads
Multiple Spindle Heads with Adjustable or Fixed Spacing

Depth Control:

The stroke length of model 250, 252, & 253 series drill units can be controlled by a stop screw dial and nut which is fully adjustable from zero to the entire stroke range as ordered (1-1/2", 2", 3", 4", 6", & 8" Stroke Lengths). Depth control is achieved to within about .001" to .002" inch.

Lubrication:

The internal seals of the drill unit must be lubricated with a light spindle oil to reduce friction and wear. A filter regulator and lubricator can be purchased from Blackalloy™. Although the spindle and spline bushing are generously lubricated at the factory with grease, continuous use and hostile environments may require manual lubrication on a frequent, scheduled basis.

Drive Motors:

Drill units are usually powered by electric or air motors up to 1/2 HP and are usually belt driven through pulleys or driven directly through a flexible shaft coupling. The rear bearings are adequately sized to withstand normal pulley belt loads. However, over-tight belt tension may cause over loaded bearings and reduce bearing life.

Recommended Spare Parts:

Normal wear items that may require replacement depending on length of service and operating conditions are all bearings and seals. These can be purchased as kits to keep on hand to reduce down time. For critical installations where down time must be minimized, a complete spare drill unit should be kept on hand.

Installation:

Unit may be mounted in any attitude, i.e., horizontal, vertical or inclined as long as a sturdy and very flat support for both end blocks is provided, so as not to strain or distort the assembly. Three 1/4”-20 tapped holes are provided for mounting the unit, and a 1/4" dowel hole and 1/4" keyway are located in-line with the spindle, to facilitate line up and to insure exact repositioning. Flush out all chips and debris from air or oil lines before connecting to unit.

Diagrams

Model 252 Drill Units with Feed Control Cylinders
Series 152/252 Diagram

Model Drill Units Stroke
"A"
Model 252
"B" "C" "Y" "Z"
252-1.5 1.5 9.56 3.03 5.62 4.06
252-2 2 10.56 3.03 6.13 4.56
252-3 3 12.56 3.03 7.13 5.56
252-4 4 14.56 3.03 8.13 6.56
252-6 6 18.56 3.03 10.12 8.56
252-8 8 22.56 3.03 12.12 10.56
Dimensions in Inches

Specifications

Stroke Lengths: 1-1/2", 2", 3", 4", 6", & 8"
Feed Control Lengths: 1", 2", 3", 4", & 6"
Spindle Extensions: #2 Jacobs Taper
Ø17mm (Ø.669") Round
5/8-16 External Thread
7/16-14 Internal Thread
Max Drill Size: Ø3/8" in Steel
Ø5/8" in Aluminum
Ø7/8" in Wood & Plastic
Recommended Maximum RPM: 3,600 RPM (5,000 w/ High Speed Bearings)
Recommended Maximum HP: 1/2 HP
Maximum Operating Pressure: 200 PSI
Minimum Operating Pressure: 20 PSI
Cylinder Bore: Ø1.75"
Spindle Runout: .0002" - .0003"
Effective Stroke Area - Forward: 1.82 in.²
Effective Stroke Area - Reverse: 1.19 in.²
Thrust @ 100 PSI: 182 lbs.
Port Size: 1/8" NPT
Standard Pulley P.D. (Ø.750" Bore): 1.75" ('3L' Belt)
Maximum Ambient Temperature: 150°F (65°C)
BE IN TOUCH

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