Best 1/8 Downcut CNC Bit (2026): 5 Picks Compared
Five 1/8 in downcut CNC bits compared by cut length, overall length, coating and pack count, with scores for each pick here.
On this page
Top picks at a glance
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- 1
Best OverallEANOSIC 1/8 Downcut 3 in9.7/10View on Amazon - 2
Best 3-PackSHARPRO 1/8 Downcut 3PCS9.6/10View on Amazon - 3
Best for AcrylicSHARPRO Coated 12mm 3PCS9.6/10View on Amazon - 4
Best Value 5-PackSpeTool 5PCS Downcut Set9.6/10View on Amazon - 5
Best Single BitSpeTool 1/8 Downcut Bit9.5/10View on Amazon - 6
SpeTool 1/8 Inch Spiral Downcut Router Bit 1/4 Inch ShankView on Amazon - 7
1/4 Inch Downcut Spiral CNC Router Bit for WoodView on Amazon - 8
CNC Spoilboard Surfacing Router Bit 1/4 Inch ShankView on Amazon - 9
1/4" Shank CNC Spoilboard Surfacing Router Bit 1-3/8" CuttingView on Amazon - 10
CNC Spoilboard Surfacing Router Bit 1/4" ShanView on Amazon
Clean top edges on plywood signs and inlay pockets are what a downcut bit is for. The best 1/8 downcut cnc bit pushes chips down into the cut instead of lifting the surface, and we compared five of them on cut length, overall length, coating, pack count and the materials and warranties each listing states.
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Quick picks
- Best Overall EANOSIC 1/8 Downcut 3 in: 1 in cut length on a 3 in bit, nano blue coating, rates for metals too Check price on Amazon
- Best 3-Pack SHARPRO 1/8 Downcut 3PCS: Three 1 in cut bits with 140-degree edges and plastic cases Check price on Amazon
- Best for Acrylic SHARPRO Coated 12mm 3PCS: Coated 12mm cut bit rated for acrylic and aluminum, three pack Check price on Amazon
- Best Value 5-Pack SpeTool 5PCS Downcut Set: Five 1/8 in downcut bits with 1/2 in cutting length Check price on Amazon
- Best Single Bit SpeTool 1/8 Downcut Bit: Solid carbide 1/8 in downcut bit with 1/2 in cut length Check price on Amazon
Machines on the list
EANOSIC Downcut Spiral Router Bit 1/4 inch Shank
A 1/8 in downcut bit with a 1/4 in shank, 1 in of cut length and 3 in overall, in solid carbide with a nano blue coating.
Pros
- 1 in cutting length, the longest here
- Nano blue coating for hardness and heat resistance
- Listing rates it for carbon steel, tool steel, cast iron and aluminum alloy
- Extra long 3 in total length
Cons
- No warranty term is stated
- Bullets say the bits can upcut grooves, a strange line on a downcut bit
- Only a single bit in the box
- No safety statement in the listing
1/8 Router Bits 1/4 Shank
A 3-pack of 1/8 in downcut bits with 1/4 in shanks, 1 in cut length and 3 in overall, in solid carbide.
Pros
- Three bits in the box
- 1 in cut length with a 140-degree end cutting edge
- Surface roughness below Ra 0.8um stated
- Each bit ships in a plastic case with compression holder and rubber cap
Cons
- No warranty term is stated
- Wood-only materials list, no acrylic or metal claim
- Sustainability claims are marketing, not specs
- No coating stated, unlike the coated picks
1/8 Downcut Spiral CNC Router Bits 1/4 Shank
A 3-pack of coated 1/8 in downcut bits with 1/4 in shanks, 12mm of cut length and 55mm overall.
Pros
- Coating stated on the carbide
- Rated for acrylic and aluminum as well as wood
- 12mm cut length on a 55mm bit
- Serial code tracking stated for quality control
Cons
- No warranty term is stated
- Spec table says 1/2 in CL while the title says 12mm, a small mismatch
- 3 bits, no single-bit option
- No feed or speed guidance stated
SpeTool 5PCS Down Cut Spiral Router Bit Set 1/4"
A 5-pack of 1/8 in downcut bits with 1/4 in shanks, 1/2 in of cut length and 2 in overall, in solid carbide.
Pros
- Five bits, the largest pack here
- 1/2 in cut length, 2 in total length
- Solid carbide, 2 flutes
- Works with CNC routers and handheld routers
Cons
- Spec table says cutting length 0.05 in, which conflicts with the 1/2 in in the bullets
- No warranty term is stated
- No coating stated
- Item diameter 0.25 in in the spec table conflicts with the 1/8 in cutting diameter
SpeTool Spiral Router Bits with DownCut 1/8 inch
A single 1/8 in downcut bit with a 1/4 in shank, 1/2 in of cut length and 2 in overall, in solid carbide.
Pros
- Solid carbide with 2 flutes
- 1/4 in shank fits 1/4 in collets
- Rated for plywood, laminate, oak and MDF
- 2 in total length suits standard collets
Cons
- Single bit, no multi-pack
- 1/2 in cutting length is the shortest here
- No warranty term is stated
- Spec table lists cutting diameter as 0.13 in vs the 1/8 in title
Other machines to compare
SpeTool 1/8 Inch Spiral Downcut Router Bit 1/4 Inch ShankCheck price on Amazon
1/4 Inch Downcut Spiral CNC Router Bit for WoodCheck price on Amazon
CNC Spoilboard Surfacing Router Bit 1/4 Inch ShankCheck price on Amazon
1/4" Shank CNC Spoilboard Surfacing Router Bit 1-3/8" CuttingCheck price on Amazon
CNC Spoilboard Surfacing Router Bit 1/4" ShanCheck price on Amazon
Specs compared
| Bit | HQ Score | Cut length | Overall length | Coating | Pack |
|---|---|---|---|---|---|
| EANOSIC 1/8 Downcut 3 in | 9.7/10 | 1 in | 3 in | Nano blue | 1 |
| SHARPRO 1/8 Downcut 3PCS | 9.6/10 | 1 in | 3 in | Not stated | 3 |
| SHARPRO Coated 12mm 3PCS | 9.6/10 | 12 mm | 55 mm | Stated | 3 |
| SpeTool 5PCS Downcut Set | 9.6/10 | 1/2 in | 2 in | Not stated | 5 |
| SpeTool 1/8 Downcut Bit | 9.5/10 | 1/2 in | 2 in | Not stated | 1 |
Specifications are manufacturer rated, as published on each listing and collected 23 October 2026.
What the listings tell you, and what they leave out
We read five downcut bit listings for this guide. Every one states a 1/8 in cutting diameter, a 1/4 in shank, 2 flutes and solid carbide. None states a warranty term, and none states a safety rating. Two listings contradict their own spec tables: the SpeTool 5-pack bullets say 1/2 in cutting length while its table says 0.05 in, and the SHARPRO 55mm title says 12mm of cut length while its table says 1/2 in. We trusted the titles and bullets in both cases, and we point out every mismatch in the reviews below.
Buying guide: choosing the best 1/8 downcut cnc bit
Downcut vs upcut
A downcut spiral pushes chips down into the cut, which the listings tie to clean edges and a clean top surface on grooves, slots, mortises and dados. The trade-off is chip clearing at the bottom of the cut: the SpeTool listings mention efficient chip removal with 2 flutes, and the SHARPRO listings note a 140-degree edge for rapid chip evacuation. If you also cut aluminum parts, the end mill for metal picks are worth a look.
Cut length and overall length
Cut length decides how deep a pass can go: 1 in on the EANOSIC and SHARPRO 3 in bits, 12mm on the SHARPRO 55mm bit, and 1/2 in on the two SpeTool bits. Overall length decides how far the bit reaches past the collet: 3 in on the long pair, 55mm and 2 in on the rest. Match cut length to your deepest single pass, not to the stock thickness you wish you could cut.
Coating
Two picks state a coating: the EANOSIC nano blue coating, which the listing ties to hardness and heat resistance, and the SHARPRO coated bit. The other three state plain solid carbide. No listing gives a hardness figure, so treat coating as the maker’s claim rather than a measured advantage.
Pack count
Single, 3 and 5 packs cover different habits. The SpeTool 5-pack and the two SHARPRO 3-packs suit shops that swap bits often, while the single SpeTool bit suits one job. For plywood dadoes in particular, see our best dado bit for plywood guide.
Router bits throw chips at high speed, and MDF dust needs extraction. Wear eye protection, keep hands clear of the cut path, and follow the CNC maker’s feed, speed and depth guidance for the bit size. Never cut PVC or vinyl on a CNC router: the fumes are hazardous.
Project Match
- Plywood signs and dadoes: SpeTool 5PCS, SHARPRO 3PCS, SpeTool single (listings state plywood and MDF)
- Inlay and mortising: SHARPRO 3PCS (states inlay and grooving), EANOSIC (states mortises and dados)
- Acrylic and aluminum: SHARPRO Coated 12mm, EANOSIC (listings rate these materials)
- Deep slots in one pass: EANOSIC 3 in (1 in cut length)
How the scores add up
Each bit is scored on performance, build, value, safety and warranty, with the weights published on our How We Pick page. A spec the listing does not publish scores nothing. None of the five listings states a warranty term or a safety statement, so the safety and warranty scores are zero across the board.
| Product | HQ Score | Perf. /35 | Build /25 | Value /25 | Safety /10 | Warranty /5 |
|---|---|---|---|---|---|---|
| EANOSIC 1/8 Downcut 3 in | 9.7 | 32 | 21 | 21 | n/a | 0 |
| SHARPRO 1/8 Downcut 3PCS | 9.6 | 30 | 21 | 20 | n/a | 0 |
| SHARPRO Coated 12mm 3PCS | 9.6 | 29 | 20 | 20 | n/a | 0 |
| SpeTool 5PCS Downcut Set | 9.6 | 28 | 20 | 20 | n/a | 0 |
| SpeTool 1/8 Downcut Bit | 9.5 | 28 | 20 | 19 | n/a | 0 |
Scores run from 9.2 to 9.8: each product’s point total is placed on that range, so more points always means a higher score. Safety counts only for powered gear or where the listing states safety features; where it does not apply, the score is taken over the remaining 90 points.
FAQ: lasers and CNC
What does downcut mean on a CNC bit?
The spiral pushes chips down into the cut, which the listings tie to clean edges and a clean top surface on grooves, slots and dados.
What collet do 1/8 in downcut bits use?
All five bits here have a 1/4 in shank and fit 1/4 in collets on CNC and handheld routers.
Can a 1/8 in downcut bit cut aluminum?
The SHARPRO Coated listing rates acrylic and aluminum, and the EANOSIC listing names aluminum alloy, carbon steel and tool steel. Treat these as the makers’ claims.
Which bit cuts the deepest?
The EANOSIC and SHARPRO 3 in bits list 1 in of cut length, the longest here. The SHARPRO Coated lists 12mm and the SpeTool bits 1/2 in.
Do any listings state a warranty?
No. None of the five listings states a warranty term, so every warranty score here is zero.
Related: the cnc tooling hub. Also see our best dado bit for plywood. Also see our best v bit for brass engraving. Also see our end mill for metal.
