The Bernardo MD 3550 VD variable speed (Variable Drive) magnetic core drill offers core drilling capacity up to Ø 35 mm with a maximum depth of 50 mm, twist drill capacity up to Ø 13 mm, drill head stroke of 155 mm, continuous speed adjustment from 100 – 830 rpm to adapt to core drilling, reaming, boring, universal Weldon 19 mm shank for standard core drills, automatic internal lubrication with integrated tank, electromagnet with adhesion force of 14,800 N, 1550 W motor at 230V single-phase. Weight 11 kg, machine dimensions 150 × 280 × 430 mm. Suitable for metal fabrication, machine construction, automotive industry, construction sites and workshops. Manufactured in Austria, distributed in Italy by Krollit as an official Bernardo distributor since 2007.
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Core drilling capacity: Ø 35 mm × 50 mm depth
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Max twist drill: Ø 13 mm
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Head stroke: 155 mm
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Spindle speed: 100 – 830 rpm
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Magnet adhesion force: 14,800 N
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Motor: 1550 W – 230V single-phase
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Weight: approx. 11 kg
Who uses the MD 3550 VD and for what
The Bernardo MD 3550 VD is a portable magnetic core drill sized for mechanical workshops, metal fabrication shops, and construction sites. Continuously variable speed 100 – 830 rpm: the 'VD' in the name indicates 'Variable Drive', the electronic system that allows selecting the optimal speed for each tool-material combination. For hard steels, low speeds (100-200 rpm), for standard steels 300-500 rpm, for soft materials higher speeds. A useful feature in workshops with a variety of operations and materials. The electromagnet with 14,800 N adhesion force ensures secure fastening to steel structures even in vertical or overhead positions, with a safety belt/chain supplied as standard. The automatic internal lubrication system delivers coolant directly to the tool through the spindle, significantly extending the life of core drills (expensive consumables) and improving hole quality. Its 11 kg weight and compact dimensions (150 × 280 × 430 mm) make it transportable to construction sites in a case or plastic container, without the need for a pallet jack or crane. In Krollit customer labs, the MD 3550 VD is chosen by metal fabricators, automotive workshops, steel structure manufacturers, industrial maintainers, and on-site installers.
Its place in the Bernardo range
The Bernardo magnetic core drill range is organized by core drilling capacity (max diameter and depth) and drive type. The range includes 10 models divided into 3 families:
E family (fixed speed): MD 3550 E (Ø 35 mm), MD 3850 (Ø 38 mm), MD 4055 (Ø 40 mm), MD 5050 E (Ø 50 mm). Suitable for workshops with repetitive standard operations on known materials.
VD family (Digital Variable Speed): MD 3550 VD (Ø 35 mm), MD 5050 VD (Ø 50 mm), MD 6050 VD (Ø 60 mm), MD 9875 VD (Ø 98 mm). Continuously adjustable speed for adaptation to material, suitable for workshops with a variety of operations.
M family (multi-gear/multifunction): MD 5075 with 2 gears (Ø 50 mm × 75 mm depth), TPC 1000 multifunction with tapping up to M18.
VD version of the MD 3550 E: same geometric capacities (Ø 35 mm × 50 mm depth) but with electronic variable speed. Practical difference: the 3550 E has a fixed 810 rpm (standard steels); the 3550 VD allows 100-830 rpm to optimize for different materials.
Krollit logistics and support
Bernardo shipping in 5-9 working days (7 days to the South). Weighing 11 kg, it is shipped in a case/plastic container and easily handled by one person, even on a construction site. Weldon 19 mm core drills, mandrels, adapters, and original Bernardo spare parts available from stock with 3-5 working day shipping. Customer support available in Italian.
Who is the MD 3550 VD for
| Profile |
Compatibility |
Reason |
| Passionate hobbyist |
Suitable |
For advanced use on variable materials. The VD costs more than the E version but handles more types of processing. |
| Workshop with a variety of materials |
Recommended |
Variable speed 100 – 830 rpm allows finding the optimal value for each material (soft steels, hardened steels, aluminum, special alloys). |
| Industrial maintenance / installer |
Recommended |
Suitable for contexts where the processing material changes frequently. Fine speed adjustment significantly extends the life of core drills. |
Not suitable for: core drilling beyond Ø 35 mm (upgrade to MD 5050, MD 5075, MD 6050 VD or MD 9875 VD models); deep core drilling beyond 50 mm (the MD 5075 with 75 mm depth or MD 9875 VD with 75 mm depth are correctly sized); tapping operations (the TPC 1000 multifunction is the correctly sized choice); non-magnetic structures (aluminum, non-magnetic stainless steel): the electromagnet does not adhere; continuous industrial use at high frequency (magnetic core drills are sized for intermittent use).
Working capacity
| Specification |
Value |
| Max core drilling diameter |
Ø 35 mm |
| Max core drilling depth |
50 mm |
| Max twist drill diameter |
Ø 13 mm |
| Drill head stroke |
155 mm |
Speed and tool holder
| Specification |
Value |
| Spindle speed |
100 – 830 rpm |
| Weldon shank |
19 mm |
| Distance Weldon - base |
160 mm |
Magnetic base
| Specification |
Value |
| Magnetic adhesion force |
14,800 N |
| Magnetic base dimensions |
165 × 80 × 50 mm |
Motor and power supply
| Specification |
Value |
| Motor power |
1550 W |
| Voltage |
230V |
| Power supply |
Single-phase |
Dimensions and weight
| Specification |
Value |
| Machine dimensions (L × W × H) |
150 × 280 × 430 mm |
| Weight |
approx. 11 kg |
Compliance
| Specification |
Value |
| Marking |
CE |
Standard equipment
- Bernardo MD 3550 VD magnetic core drill
- Plastic carrying case
- Coolant tank
- 1.5 – 13 mm keyless drill chuck with 1/2'' – 20 UNF / Weldon 19 mm adapter
- Bubble level
- Safety belt/chain for vertical and overhead use
- User manual in Italian
- Service tool kit
Frequently Asked Questions
What materials does the MD 3550 VD electromagnet work on?
Only on magnetic ferrous materials: structural steel, iron, carbon steels. It does not work on aluminum, non-magnetic stainless steel, non-ferrous materials.
The electromagnet creates the magnetic field that fixes the machine to the structure: without ferrous material, fixing is impossible. For working on aluminum or non-magnetic stainless steel, fixed column drills or dedicated mechanical clamping systems are required. For most standard metal structures (fabrication, frames, profiles), the electromagnet is the fastest and most reliable clamping system.
Can I use the core drill in a vertical or overhead position?
Yes, with the included safety belt/chain. The 14,800 N magnetic force is dimensioned for clamping in any position, but safety always requires an additional mechanical restraint.
The electromagnet holds the machine even during a momentary power interruption for the seconds necessary to prevent falls, but in the event of a prolonged interruption (torn cable, blackout), the safety belt/chain is the only reliable system. Standard safety procedures ALWAYS include mechanical restraint in addition to the electric magnet, regardless of the nominal adhesion force.
How does the automatic internal lubrication system work?
The coolant (oil-water emulsion or dedicated metalworking oil) starts from an integrated tank and is delivered directly to the center of the tool through an internal channel. It works in any position (even overhead) via gravity or pressure.
Internal lubrication significantly extends the life of core drills (expensive consumables) by reducing friction and dissipating heat. Without lubrication, drills last 30-50 holes; with internal lubrication, 100-200 holes. The coolant fluid is not included and is available from standard industrial suppliers.
Is the Weldon 19 mm shank a universal standard?
Yes. The Weldon 19 mm is the international standard for core drills: most commercial drills (Karnasch, Magbohrer, Rotabroach, BDS, etc.) use this shank. The drills all have a Weldon 19 mm pin for quick fastening via a side set screw.
For workshops with drills from other brands or other standards, adapters can be used. For future investments, the Weldon 19 mm is the most common choice with the widest market offering. Original Bernardo drills have a Weldon 19 mm shank and are available from stock with 3-5 working day shipping.
How much power does the motor consume in intermittent use?
The 1550 W motor typically absorbs 1.6-1.8 kWh per actual hour of work. In intermittent artisanal use (1-2 minutes per hole, pauses between holes), the average consumption is 0.3-0.5 kWh/hour.
The motor only runs during hole cutting: it is off between holes. For workshops with significant electricity costs, consumption is negligible. The core drill is an electrically efficient machine: nominal power is only engaged during actual processing minutes. For intensive continuous use, a standard industrial meter is recommended.
