Guide · Clamps, T-track and inserts
CNC hold-down clamps: top, toe, low-profile and stops
Top clamps, edge and low-profile clamps, toe clamps, stops and dovetail clamps for CNC: materials, threads and where each fits, per the makers.
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Short answer
Use a clamp that matches your table's thread or slot and leaves the toolpath clear. Top clamps press down on the stock's face; edge, toe and low-profile clamps push from the side or sit low so more of the face can be cut. No clamp keeps the bit away by itself: plan every toolpath around the clamps.
Why clamping matters
OSHA's router guidance lists poorly fixed stock among the causes of kickback and advises securing the stock.[2] CCOHS also advises checking stock for staples, nails, screws or other foreign objects before routing.[1]
Top clamps
A top clamp presses down on the stock's top face near the edge. It is simple and works for most through-cuts where the edge is waste.
Carbide 3D's Essential Clamps are injection molded from glass-filled nylon.[3] Its clamp steps sit under the foot of its Essential or Aluminum Gator Tooth clamps to keep the clamp near level and to extend the range of stock thickness the clamps can hold.[4]
Edge and low-profile clamps
Edge clamps push sideways against the stock, so the top face stays open.
- Crush-It Essential: glass-filled nylon clamps used with M6 hardware, with metal inserts and stainless steel hardware.[5] Each is 25 mm wide and, per Carbide 3D, sits as low as 11 mm above the table when seated in a Hybrid Table slot.[5] Carbide 3D lists 2 mm of jaw travel at a 45-degree angle.[5] The set lists 4 Crush-It clamps with serrated jaws, 4 replacement flat jaws, 4 Crush-It stops, 4 Essential Clamps and 1 Nutz 'n Bolts kit.[5] Extra jaws come with the set but are not sold separately.[5]
- Crush-It Pro: 6061 aluminum.[6] The package lists 2 clamps, 2 serrated jaws, 2 flat jaws and 2 hard stops.[6]
- Tiger Claw: Carbide 3D announced it as low-profile quick clamps for fixtures and setups where clamping the top face is not an option.[7] Its current workholding collection does not list it, so check availability with Carbide 3D. In the announcement thread, one beta tester said they avoid using the clamps for through-cuts near the material edge because the sideways pressure could bend the slot; that is one user's report, not a Carbide 3D statement.[7]
Toe clamps
A toe clamp is a low block with a sliding jaw that pushes against the stock's edge. Genmitsu's low-profile aluminum toe clamp (101-63-VC) uses M6 screws and nuts and measures 106 x 22 x 15 mm.[8]
Picks that fit2 products
For M6 holes or T-track: choose the 101-63-VC toe clamp (106 x 22 x 15 mm) for larger stock, or the 101-63-MVC mini vise clamp (56 x 22 x 21 mm per SainSmart) for small parts, each in a 2- or 4-piece pack.
More on choosing
Both use M6 hardware; not for 1/4-20 holes.
Smaller M6 clamp for small machines
Genmitsu Mini Vise Clamps for CNC routers (101‑63‑MVC), 2 or 4 pieces
Stops
A stop does not clamp; it gives the stock a fixed edge to push against. Carbide 3D's Lock Stops are low-profile stainless steel stops with a serrated face, sold in sets of 2 and 4; a set includes two M6 x 16 mm button head cap screws.[9] Carbide 3D says they work on Nomad and Shapeoko machines alongside its Tiger Claw or Gator Tooth clamps.[9]
Dovetail-track clamps
Some tables use a routed dovetail groove instead of a threaded hole. MICROJIG's MATCHFIT dovetail clamp fits a 1/2 inch x 14-degree dovetail groove routed 3/8 inch deep.[10] Its MATCHFIT Ramp Clamp rides in the same 1/2 inch x 14-degree track with a low-profile, rotating head, and MICROJIG lists CNC among its uses.[11] No bolt thread is involved, but the groove must match that profile.
Picks that fit2 products
Choose the DVC-538K2 two-pack only if your spoilboard or fixture plate has (or will have) a 1/2 in x 14-degree dovetail groove routed 3/8 in deep.
More on choosing
Choose the CN-P3K2 Ramp Clamp two-pack for a low-profile, rotating head in the same 1/2 in x 14-degree track. If buying on Amazon, check that Ships from / Sold by is Amazon.com or MICROJIG.
Dovetail-groove clamps, no thread needed
Low-profile dovetail-track clamps
| Clamp | Material (maker) | Thread or slot | Where the maker says it fits |
|---|---|---|---|
| Carbide 3D Essential | Glass-filled nylon | M6 supplied; 1/4 in hardware on your own track or inserts | Hybrid Table, Teez-Nutz, your own track |
| Crush-It Essential | Glass-filled nylon, metal inserts | M6 | Hybrid Table or an M6 fixture plate; not Shapeoko 3 |
| Crush-It Pro | 6061 aluminum | Not stated | Not stated on the page |
| Genmitsu 101-63-VC | Aluminum and stainless steel | M6 | T-track, hybrid tables, M6 spoilboards; Genmitsu 4030 and larger |
| Carbide 3D Lock Stops | Stainless steel | M6 x 16 mm screws | Nomad and Shapeoko |
| MICROJIG MATCHFIT | Steel | 1/2 in x 14-degree dovetail, 3/8 in deep | Any matching groove |
Next
Questions
Which clamps keep the bit away from the clamp?
None guarantees it. Low-profile and edge clamps sit lower or off the top face, but you still have to plan toolpaths around every clamp and check the clearance before you run the job.
Top clamp or edge clamp for sign work?
If you are carving the whole top face, a top clamp sits in the way, so edge or low-profile clamps make sense; Carbide 3D announced its Tiger Claw for setups where clamping the top face is not an option. For through-cuts and parts with spare margin, top clamps outside the cut area work.[7]
Are nylon clamps safe to hit with a bit?
No maker claim we found says so, and you should not rely on it. Plan toolpaths so the bit never reaches any clamp.
Can a person hold the work instead of a clamp?
No. CCOHS advises never relying on yourself or a second person to hold the material being routed, and OSHA lists poorly fixed stock among causes of kickback.[1][2]
Can I buy extra Crush-It jaws?
Carbide 3D says extra jaws come with the Crush-It Essential set but are not sold separately.[5]