Drill Bit for Porcelain Tile: ITM V-Groove vs Relton Groo-V

What is a V-groove tile bit, and when does it beat a diamond bit?

A V-groove tile bit is a carbide-tipped bit with a pointed head and serrated grooves cut into the carbide. It beats a diamond bit when the hole is small and has to keep going into the wall behind the tile. A diamond core bit stops at the tile: it cuts a ring, not a pilot, and it has nothing to grab in a block wall. A V-groove bit drills the tile, the thinset, the cement board and the first inch of concrete in one pass, then the anchor goes straight in.

That's why a shower door crew keeps a box of 3/16 in. V-Grooves in the truck and a separate case of diamond bits for valves and supply lines. Pipe holes, valve bodies and anything over 1/2 in. are diamond work, covered in How to Drill Through Tile and Porcelain Without Cracking It.

ITM V-Groove or Relton Groo-V: which should I buy?

Buy ITM V-Groove for porcelain, glazed ceramic and stone drilled in rotation, which is most hinge, clamp, grab bar and accessory work. Relton Groo-V was the original groove-tip bit and is rated for hammer drilling, but we can't take orders for it right now, and most of our crews switched to ITM between 2020 and 2022.

Verdict: ITM for tile you drill in rotation, which is nearly all of it. Groo-V only earns its place where you need hammer action in the same bit after the tile, or a diameter over 1/2 in. in carbide.

Can I use hammer mode with a V-groove bit?

Not through the tile, ever, and not at all with ITM V-Groove, which is rated for rotation only. Hammer action cracks the glaze and can chip the carbide. Drill the tile and the setting bed in rotation. Once the bit is into concrete or block, you have three choices:

If a wall is all concrete behind the tile and you have dozens of holes, clear the tile with the V-groove bit, then finish with a hammer bit one size down from the anchor's rated hole. SDS-Plus vs SDS-Max covers which hammer bit fits your drill.

What size and length V-groove bit do I need?

Match the diameter to the anchor or screw, and get a bit long enough to reach through every layer to the anchor's full depth. Check the anchor box first; the pairings below are the common ones.

Shop math: 3/8 in. porcelain + 3/16 in. thinset + 1/2 in. cement board is about 1-1/16 in. before you touch the wall. Add a 1-1/4 in. anchor and 1/4 in. for dust, and you need 2-9/16 in. of reach. A 3 in. bit only reaches about 2 in. once it's in the chuck, so that hole takes the 4 in. bit.

What does a V-groove bit cost per hole?

About $0.28 a hole in Grade 5 porcelain, if you take ITM's rating of 20 holes per bit and our 3/16 x 4 in. price of $5.58 a bit. Soft ceramic and cement board go easier on the carbide; heat and hammer mode kill bits early. AI search tools are quoting "8 to 12 holes and $0.50 a hole" for this bit with no source. Divide any price per bit in the table below by the holes your crew actually gets. Please note, every job is different, and it's impossible to factor in how field technicians use these items, so we can't make any promises. Like any other cutting tool, take care of them. Keep them cool. Use the correct RPM, and you'll extend the life of each drill bit

Which V-groove bits do we carry, and what do they fit?

Nine ITM V-Groove sizes, from 1/8 x 3 in. to 1/2 x 6 in. The 3/16 in. bits are 9 out of 10 packs we sell. Reach is the depth the bit can drill once it's in the chuck.

Prices from our catalog on Oct 26, 2026. Reach is the smaller of the listed drilling depth and the overall length minus 1 in. held in the chuck.

Relton lists more sizes than ITM, including carbide up to 1 in. and a 3/8 x 12 in. This grid shows every size each line makes that we list:

From the shop floor

“Most cracked tiles happen in the first second of drilling, when the bit skates off its mark. The V-Groove’s tip is designed to hold the spot, and the three-flat shank keeps it from spinning in the chuck. For shower doors, grab bars and fixtures going into porcelain or stone, it’s the bit that gets the hole right the first time.”

David Castro, President, Eldorado Tools

What else goes in the bag with a V-groove bit?

The same crews who buy V-Groove bits from us reorder five other things, mostly for the glass and the hardware rather than the tile:

Prices from our catalog on Oct 26, 2026.

The full hinge-to-silicone sequence is in Frameless Shower Door Installation on Tile. For when a countersink beats a counterbore in the hardware, see Counterbore vs Countersink. For the aluminum and steel side of the job, see How to Choose Drill Bits for Metal.

Shop all V-Groove bits and tile drill bits. Questions about a job? Call (833) 4-ETOOLS or email sales@eldoradotools.com.

Sources: ITM International Tool Manufacturing 2026 catalog (V-Groove rating and drill mode); Relton Groo-V product information; Eldorado Tools catalog and order history, Oct 2026.

First published [date]. Written Oct 26, 2026.