Dieter Schmid's Fine Tools
Spiral Cutters

Spiral Cutter Router Bits

Spiral Cutter Bits are used to make grooves and notches in almost any kind of wood, including tropical hardwoods and various kinds of wood products. The advantage with spiral cutters over normal straight cutter router bits is that the spiral form of the cutter helps to produce a smoother and more regular groove, and clears the chips far better. All this produces a better cut and allows the spiral cutter bits to work better longer. The spiral form also tends to reduce vibrations, because the spiral bits do not, like straight cutter bits “beat” the wood over their full width with every turn, but rather continuously slice the wood out!

Spiral Cutter Router Bits are also very well adapted to plunge drilling and routing. In general the word on them is “quick and clean.” A disadvantage is that they are more expensive than regular straight cutter bits, and for technical manufacturing reasons, the heads cannot be made wider than the shaft. So the choice of bit sizes is limited. There are also no ball bearing pilot rings for these bits, but one can use a copy ring to get a similar result if needed. Sharpening these bits should only be done by a professional sharpening shop.

The Spiral Cutters by Sistemi Klein are made of solid tungsten carbide metal. All of the bits we offer are designed to be used in right- or standard-turning routers.

Recommended speed: These spiral cutters are made for a max. speed of 24000 rpm. The recommended speed depends on other facts such as type of material, depth of cut in one run, quality of the router and precision of the chuck. We recommend to start with 18000 rpm and adjust speed step by step.

Spiral Cutters Up Cut (twist to the right)
With spiral cutter bits with a right-oriented spiral, the chips are gathered up and ejected from the groove. When speed is important, this is the bit for the job, because the bit cuts clean and the chips do not clog up the groove. This makes for a very sharply cut and clean bottom of the groove. But, depending on the wood’s grain structure, one can sometimes have problems with tear-out and chipping at the top of the groove, as the spiral tends to tear up on the wood as it cuts.
Advice: Make sure the wood is firmly clamped to the work surface, as the right-oriented spiral flutes on the bit can tend to pick up the wood. It is best to use this bit with the router mounted on a router table.

Dia-
meter
D
Cutting
length
B
Total
length
L
Shank
diameter
S
CodePrice
3 mm 12 mm 60 mm 6 mm
Code 362400CartPrice € 22.50
4 mm 14 mm 60 mm 6 mm
Code 362402CartPrice € 23.90
5 mm 17 mm 60 mm 6 mm
Code 362404CartPrice € 23.80
3 mm 12 mm 60 mm 8 mm
Code 362420CartPrice € 24.90
4 mm 14 mm 60 mm 8 mm
Code 362421CartPrice € 24.90
5 mm 17 mm 60 mm 8 mm
Code 362422CartPrice € 25.90
6 mm 22 mm 70 mm 8 mm
Code 362423CartPrice € 26.90
7 mm 32 mm 80 mm 8 mm
Code 362424CartPrice € 31.30
8 mm 35 mm 80 mm 8 mm
Code 362425CartPrice € 31.50
Spiral Cutters Down Cut (twist to the left)
The left-twist spiral cutters work with a pulling cut, which has the effect of leaving the top edges of the groove very sharp and clean. This is important when the edges will be visible in the finished work. The chips, unlike with the right-twist bits, are not pulled up and ejected from the slot, but rather tend to stay in the groove or be pressed down into the cut. With this left, negative twist cut the work goes somewhat slower than with the right, positive cut. The bottom of the groove is also not as clean and sharp as with the right-twist bits.
Advice: This bit is also only for right-turning machines.
Advice: One must keep an unusually firm hold on the router when using this bit, as the spiral will tend to want to launch the bit out of the workpiece!! This bit is best used with the machine mounted in a router table.
Dia-
meter
D
Cutting
length
B
Total
length
L
Shank
diameter
S
CodePrice
3 mm 12 mm 60 mm 6 mm
Code 362410CartPrice € 23.50
4 mm 14 mm 60 mm 6 mm
Code 362412CartPrice € 22.50
5 mm 17 mm 60 mm 6 mm
Code 362414CartPrice € 23.50
3 mm 12 mm 60 mm 8 mm
Code 362430CartPrice € 24.90
4 mm 14 mm 60 mm 8 mm
Code 362431CartPrice € 23.90
5 mm 17 mm 60 mm 8 mm
Code 362432CartPrice € 25.90
6 mm 22 mm 70 mm 8 mm
Code 362433CartPrice € 26.90
7 mm 32 mm 80 mm 8 mm
Code 362434CartPrice € 31.50
8 mm 35 mm 80 mm 8 mm
Code 362435CartPrice € 32.90
Compression Cutters
Up Cut (twist to the right) on tip side
Downcut (twist to the left) on shank side

Spiral cutter router bits with alternating axis angles are used where both edges of the workpiece must be cleanly cut, for example in the various kinds of wood laminates. That means though, that the chips are channeled into the middle of the cut. So you might wonder how the chips are cleared. In fact the cutting edges are offset by 90 ° - this is provides for proper chip removal. Because of this it always appears in photos of these cutters that the point is thinner than the rest of the bit, but this is not so. You can click on the photo, to see the same cutter from three different perspectives.
Advice: these cutters are, because of the offset cutting edges, trickier to control than other kinds of router bits. Using them in a hand-held router means a higher risk of breakout. So work very carefully and absolutely avoid climb cutting or backing up the router. If possible, using these bits with a table-mounted router is by far the best option.
The length of the right-hand twist cutting edge at the tip of 8 mm shaft bits is 6 - 7 mm, and with the 12 mm shaft bits it is 11 - 12 mm.
Dia-
meter
D
Cutting
length
B
Total
length
L
Shank
diameter
S
CodePrice
8 mm 22 mm 80 mm 8 mm
Code 362380CartPrice € 43.20
8 mm 32 mm 80 mm 8 mm
Code 362381CartPrice € 44.90
12 mm 42 mm 100 mm 12 mm
Code 362384CartPrice € 79.80
12 mm 52 mm 110 mm 12 mm
Code 362385CartPrice € 95.90
Spiral Cutters Up Cut Roughing Style (twist to the right)
The cutters of this spiral bit are interrupted in order to increase the speed of the chip removal. So this bit is used where the speed of the cut is more important than a perfectly clean and consistant cut, and in work pieces where there will be no visible joints. Fundamentally the bit works in more or less the same way as the right twist bit described above. This bit must be used only in a stationary machine, such as a router mounted on a router table.
Dia-
meter
D
Cutting
length
B
Total
length
L
Shank
diameter
S
CodePrice
8 mm 35 mm 80 mm 8 mm
Code 362440CartPrice € 49.50
10 mm 35 mm 80 mm 10 mm
Code 362441CartPrice € 52.50
12 mm 35 mm 80 mm 12 mm
Code 362442CartPrice € 66.50
12 mm 45 mm 80 mm 12 mm
Code 362443CartPrice € 99.90
Spiral Cutters Down Cut Roughing Style (twist to the left)
The cutters of this spiral bit are interrupted to increase the speed of chip removal. So they are used where the speed of the cut is more important than a clean and consistent cut, and also in pieces where the joints will not be visible. In principle the bit is used in a similar way to the left-twist bit described above. This bit must be used only in a stationary machine, such as a router mounted on a router table.
Dia-
meter
D
Cutting
length
B
Total
length
L
Shank
diameter
S
CodePrice
8 mm 35 mm 80 mm 8 mm
Code 362450CartPrice € 49.90
10 mm 35 mm 80 mm 10 mm
Code 362451CartPrice € 52.50
12 mm 35 mm 80 mm 12 mm
Code 362452CartPrice € 69.00
You are here::   Homepage   →   Router Bits   →   Spiral Cutters