Buyer’s Guide · Core Drilling Rigs

Core Drilling Rig for Sale: A Buyer’s Specification Guide

By Windrilling Technical Team · September 2026 · 11 min read

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In February a junior exploration company sent me the same request I get almost every week. “Quote us a core drilling rig for sale, 400 metres, NQ.” So we quoted a WD-C1000 package — rig, rods, core barrel, water pump, spares. Two weeks later they forwarded a competing offer. Same words on the header. The machine inside was nothing like it.

The cheaper offer had a mechanical transmission, a 3 metre feed stroke, no wireline winch and a hoist rated for half the rod string. On a 400 metre NQ hole that rig would spend more time tripping rods than cutting core. The price was lower because the work was smaller. Nobody lied. The specification simply never said what it was.

That is why I never quote a core rig from a depth number alone. Depth is a claim. The components behind it are the product. Below is the exact order I check a specification in before we release a quote — and the same order I would follow if I were the buyer.

1. What a Core Rig Is Actually Built to Do

A core rig does not make a hole. It recovers a sample. Everything on the machine exists to bring an intact cylinder of rock to surface without grinding it into dust.

That single purpose explains the whole design. Rotation has to be smooth and controlled rather than simply powerful. The feed has to hold a constant weight on a diamond core bit that cuts by abrasion, not by impact. Flush pressure has to be high enough to cool the bit and clear cuttings, and low enough not to wash the core away. When a rig is wrong for exploration, it usually fails in one of those three places rather than in the engine bay.

The other decision that shapes the machine is how the core leaves the hole. A conventional setup pulls the entire rod string every run, core barrel attached. A wireline setup drops an overshot down the inside of the rods, retrieves just the inner tube, and never breaks the string. On a 400 metre hole with 3 metre rods that is the difference between 130 round trips and one.

If your core recovery rate is what the client is paying for — and in exploration it is — the wireline system is not an upgrade. It is the baseline. Our wireline core drilling field guide walks through the full process if you are new to the system.

2. NQ, HQ and PQ: The Letters That Set Your Depth

Buyers say “NQ” the way they would say “two inch pipe”. It means something more specific. The letter tells you the hole diameter, the core diameter and, indirectly, how deep a given rig can push that string.

Size	Hole diameter	Core diameter	Where it is normally used
PQ	~122.6 mm	~85 mm	Shallow holes, large sample for grade and geotech work
HQ	~96.0 mm	~63.5 mm	The working middle: cleaner samples, heavier string, less depth per rig
NQ	~75.7 mm	~47.6 mm	Deep holes, lowest rod weight per metre, the exploration default
BQ	~60.0 mm	~36.5 mm	Mining definition, tight budgets, small diameter targets

Here is the trade in one sentence: smaller core reaches further, and gives your geologist less rock to look at. PQ produces a sample a field geologist can log comfortably. NQ produces a sample that has to be handled carefully — and lets a mid-size rig reach 800 metres or more.

Most exploration programmes solve this by drilling a PQ or HQ collar and then reducing. That is why the phrase “400 metres NQ” hides a second question the seller must answer: 400 metres of what, from which hole diameter, from what rod size? A rig quoted for 400 m NQ is a smaller machine than one quoted for 400 m HQ, and the two are not interchangeable.

3. The Five Numbers Behind Every Depth Claim

When a supplier writes “400 m capacity”, four other numbers decide whether that is achievable at a profit or only on the best day of the year.

• Hoist capacity. A 400 m NQ string of rods, core barrel and overshot has real weight. If the winch cannot lift the full string with margin, the rig cannot recover a stuck rod — and the stuck rod becomes a lost hole. Ask for the hoist rating at first layer, not the marketing number.
• Feed stroke. Short strokes mean more chuck repositioning per rod, more time, more bit wear at each restart. A long-stroke mast feed pays for itself in daily metres on deep holes.
• Rotation torque and speed range. Diamond bits need high rotation with low weight in hard rock, and slower rotation with higher weight in soft formations. A narrow speed band forces the driller to compromise on both.
• Rod handling. Manual rod handling on a 400 m hole costs you a helper and a back injury. A rod holder, breakout wrench and hydraulic rod rack are not luxuries at that depth.
• Power unit and pump. The flushing pump must deliver the pressure and volume the bit and formation demand. Undersized pumps are the most common hidden cost in low quotes: the rig drills, but the core recovery is poor and the metre rate collapses.

A practical test I give buyers: ask the supplier to send a video of the rig during a real rod pull and a real core recovery, with the depth shown on the driller’s panel. Quoted numbers survive the sales email. They rarely survive video.

4. Matching Rig Class to Hole Depth

Core rigs are sold in classes, and the class is set by the rod string the machine can lift and rotate all day — not by the biggest number in the brochure. The table below is the way we group the market before we ever open a price list.

Class	Typical work	Normal rod size	Mounting
Light / portable	Geotech, soil investigation, shallow mineral holes, work where access is the problem	BQ, NQ	Skid, trailer, small crawler
Medium hydraulic	The exploration mainstream: multi-hole programmes, HQ collars reduced to NQ	NQ, HQ	Crawler or truck
Heavy / deep hole	Deep mineral exploration, large programmes, long shifts where trip time decides the contract	NQ, HQ, PQ	Full crawler, high-capacity mast

Two practical notes about this table. First, every class has a depth ceiling that changes with rod size: the same rig that reaches a deep NQ hole in good conditions will reach far less with PQ in broken ground. Second, conditions move the ceiling more than the spec sheet does. Fractured rock, swelling clay, high water inflow and abrasive quartz all shorten what a rig can realistically do in a shift.

So when you compare a WD-C800 against a WD-C2000, do not compare the depth column. Compare the hoist, the stroke, the torque band and the pump. Those four decide which of the two actually finishes your programme on schedule.

5. What Really Drives the Price of a Core Rig

Two core drilling rigs quoted for sale at the same depth can differ in price by more than double. In my experience the gap comes from six items, roughly in this order of impact.

• Transmission and controls. A fully hydraulic rig with a variable-speed motor, hydraulic chuck and joystick control costs more than a mechanical rotary table — and drills more metres per shift, in more formations, with fewer rod failures.
• Winch and mast. Long-stroke masts, hydraulic rod racks and high-capacity main hoists are the single biggest step-up between the light and heavy classes.
• The string you actually need. On a deep hole, rods, core barrel, overshot and diamond bits can approach the price of the rig itself. A quote that includes a full string is not expensive next to one that does not. See our drilling tools range for the consumables that travel with every core rig.
• Engine and hydraulic components. Known-brand engines and pumps cost more at purchase and far less at year three, when a repair means an airfreighted part and a stopped site.
• Mobility and mounting. Crawler-mounted machines that walk themselves between pads cost more than skid mounts and save mobilisation weeks on a multi-hole programme.
• Documentation and support. Operating and maintenance manuals in your language, spare parts lists with part numbers, factory test records and training. Cheap on the invoice, decisive when the rig stops at kilometre 300.

6. New, Used or Refurbished

A used core rig can be the right answer for a short programme. It is almost never the right answer for a contracted multi-year campaign, because the risk is not the purchase price — it is the unplanned stop.

• New. Rated capacity you can plan against, warranty, factory test records and a parts channel. Highest capital cost, lowest operational surprise.
• Refurbished. Worth it only when the seller documents what was replaced — winch, pumps, chuck, bearings, hoses — and can evidence it. “Refurbished” without a parts list means “cleaned”.
• Used. Judge the string, not the paint. Check the box threads for deformation, the mast pins for oval wear, the hydraulic oil for metal, and the hoist brake under load. Then ask why it is for sale.

One rule has held up in my fifteen years of shipping: the rig is usually the cheapest part of the decision. The programme schedule is the part that costs money when you get it wrong.

7. Six Checks Before You Sign

1. Ask for the depth claim in writing with the rod size attached. “400 m NQ” is a specification. “400 m” is a slogan.
2. Request the component list, not just the machine list. Hoist, chuck, pumps, engine, control valves — brand and model.
3. Watch a factory test video at your hole diameter. If the supplier cannot produce one, ask what happens instead.
4. Get the spare parts list with part numbers before shipping. Hydraulic and rotation parts, not just filters and hoses.
5. Confirm the package: rods, core barrel, overshot, bits, water pump, tools. A rig without a string is a deposit on a future argument — check the drilling tools list line by line against the quote.
6. Agree training and manual language in the contract. One day of commissioning training saves weeks of improvised repairs.

If you are still deciding between drill systems rather than rig size, the full hydraulic DTH guide covers the impact side of the market, and our geothermal rig selection guide works through a similar specification logic for another sector. And if the question is where to buy rather than what to buy, read the five mistakes buyers make sourcing rigs from China first.

FAQ

How much does a core drilling rig cost?

A complete mobile core drilling package with rods, core barrel, overshot and bits moves in a wide band that is set mainly by depth class, hydraulic specification and what is included in the string. Because two rigs quoted at the same depth can differ by more than double, a useful number only exists once the rod size, depth and package list are fixed. Send us those three items and we will price the machine and the string together.

Is a crawler mount worth the extra cost for core drilling?

On a multi-hole programme, usually yes. A crawler rig walks itself between pads on the same site, so mobilisation becomes hours instead of days. On a single isolated hole with good road access, a trailer or truck mount can be the cheaper and simpler choice.

Can one core rig drill both HQ and NQ?

Yes, within the same rod family — that is normal practice. You drill an HQ collar for sample quality, then reduce to NQ to reach depth. What the rig has to be sized for is the heavier string, because the HQ section sets the hoist and torque requirement. A rig chosen only for NQ depth may not lift the HQ string comfortably at the top of the hole. The models we build for both are listed in our core drilling rig range.