Genmitsu MC40A 40pc End Mill Set Review: Specs, Fit & Feeds (2026)
The default first bit purchase for anyone on a 1/8-inch machine. Forty cutters means you can afford to snap a few while you learn what a chip load actually feels like, which you will.
As a set, this is a breadth purchase rather than a depth one: it exists to cover a range of jobs while you find out which two or three geometries your work actually needs. That is the right first purchase and the wrong second one - once you know what you reach for, buying that geometry in quantity costs less per cut and removes the reluctance to push a cutter that leads to burning.
What you get
It spans 2-flute flat nose, ball nose, nano blue coat, titanium coat. Mixed-geometry sets are useful precisely because they let you compare finishes on the same material without buying four separate cutters first.
What a set like this will not include is a spare of the size you break most, or a collet to match if the shank differs from what your spindle currently holds. Both are worth ordering at the same time rather than discovering mid-project.
Specifications
| Shank mm | 3.175 |
|---|---|
| Pieces | 40 |
| Types | 2-flute flat nose, ball nose, nano blue coat, titanium coat |
| Cutting length mm | 17 |
| Overall length mm | 38 |
| Carbide | 0.2um ultra-fine tungsten carbide |
| Shank | 1/8 |
Machines this fits
Matched by collet and shank size.
What the specifications mean in use
- A 1/8-inch shank is the fragile one
- A 1/8-inch shank deflects noticeably more than a 1/4-inch one under the same side load - bending stiffness falls off sharply with diameter. In practice that means shallower passes and more of them, and it is the reason a cut that starts square can finish slightly bowed on a light machine. Keep the stickout as short as the job allows; the length hanging out of the collet matters as much as the diameter.
- Cutting length is your depth ceiling
- The flutes run 17mm, and that is the hard limit on how deep a single pass can go - beyond it the shank is rubbing rather than cutting, which burns the wall and can seize the tool. It is also not a target. Depth of cut past roughly one cutter diameter starts loading the tool disproportionately, so on most work the practical pass is a fraction of the available flute length, taken repeatedly.
- Overall length is about stickout, not reach
- At 38mm overall there is material to grip beyond the flutes, which is what you want - but resist the temptation to use the extra length as reach. Deflection rises with the cube of stickout, so an extra 10mm hanging out of the collet costs far more accuracy than it sounds like it should. Seat the cutter as deep as the collet allows and lower the spindle instead.
- What the coating does and does not do
- Coatings buy edge life and lower friction; they do not make a blunt geometry cut well or rescue a wrong feed rate. On wood and plastics the gain is modest, because the failure mode is usually heat from an under-fed cut rather than abrasion. Where a coating genuinely pays is in abrasive material - MDF, and anything with glass fibre in it - where the binder wears carbide down fast enough that the extra hardness shows up as real hours.
- Carbide grade: 0.2um ultra-fine tungsten carbide
- Grain size is the trade-off nobody puts on the box. Finer-grain carbide takes and holds a sharper edge, which is what you want for a clean cut in wood and plastics; coarser grain is tougher and survives interrupted cuts and crashes better. A fine-grain cutter run at the right chip load will outlast a tough one run badly, so the grade matters less than the feed you give it.
- 40 pieces - coverage, not quantity
- An assortment this size is a breadth purchase: expect to use a handful heavily and leave most in the case. That is not waste, it is how you find out which geometries your work actually needs before committing to buying them in quantity.
When to reach for it - and when not
- General profiling, pocketing and through-cuts across wood, plastics and sheet goods.
- Work where chips need to leave the cut and a little top-face fuzz is acceptable or will be sanded.
- Learning feeds and speeds, because this is the geometry every published chip-load chart assumes.
- Finished top surfaces that will not be sanded - an upcut lifts fibres as it clears chips.
- Melamine and veneered board, where a compression bit is the only geometry that keeps both faces clean.
- Running at a feed meant for a different flute count, which is the fastest way to burn an edge.
Starting feeds and speeds for this cutter
Starting points for a 3.18mm cutter with 2 flutes, taking a 1.59mm pass at the mid-point of each material's usual spindle range. These are computed by the same engine as the feed and speed calculator, not copied from a chart.
| Material | Spindle | Chip load | Feed rate |
|---|---|---|---|
| Hardwood | 16,500 RPM | 0.1016 mm | 3,353 mm/min · 132 IPM |
| Plywood | 17,000 RPM | 0.1320 mm | 4,488 mm/min · 176.7 IPM |
| MDF | 17,000 RPM | 0.1524 mm | 5,182 mm/min · 204 IPM |
| Acrylic | 14,000 RPM | 0.1016 mm | 2,845 mm/min · 112 IPM |
Cutting diameter is not published for this product, so these assume a cutter the same diameter as the shank. If yours is narrower - a common combination is a small cutting diameter on a stout shank - put the real figure into the calculator, because the chip-load range moves with cutter diameter rather than shank.
What wears it out
Cutters do not announce that they are blunt. The edge wears round rather than chipping, so the first symptom is usually a fuzzy edge or a burn on a job that was cutting cleanly an hour earlier - and the instinctive response, slowing the feed, makes it worse by thinning the chip further.
Abrasive material sets the pace. MDF and composites consume edges several times faster than hardwood at identical settings, because the binder and the glass are harder than the wood fibre around them. Budget cutters as a running cost on those materials rather than as a one-off purchase, and keep a spare of whatever geometry you use daily so you are never tempted to nurse a dull one through one more part.
Getting the settings right
Before the first cut, put this cutter's diameter and flute count into the calculator with your material and spindle speed. Swapping to a bit with a different flute count at an unchanged feed rate is the most common way a working setup starts producing burnt edges.
Chip-load ranges for the materials this suits:
What else to consider
Genmitsu 5pc 4-Flute Carbide End Mill Set
This listing was out of stock at the last check. The link is kept so you can see whether it has returned.
Common questions
- What shank size is the Genmitsu MC40A 40pc End Mill Set?
- 1/8-inch. Shank size is decided by the collet in your spindle rather than by preference - check the collet before ordering, because no adapter runs from a larger shank into a smaller collet.
- What feed rate should I use with these bits?
- It depends on the material, the cutter diameter and the flute count together - feed rate alone tells you nothing. Put those three plus your spindle speed into the feed and speed calculator, which returns a feed rate and shows whether the resulting chip load sits inside the published range for the material.
- Is a bit set better than buying individually?
- As a first purchase, yes - it is the cheapest way to find out which geometries your work needs. After that, buying the two or three you actually use in quantity works out cheaper per cut and means you stop nursing dull cutters.