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Frequently Asked Questions

The carbide knives are placed along the helical grooves either at a slight angle or parallel to the centerline of the cutter blocks. In order to distinguish, we call the first type spiral cutterhead, the second helical cutterheads.

The working edges of the carbide knives on spiral cutterhead are angled not square to the feeding of the board. When the edges approach a board, only a very short fraction of the edges cut. This is shear cut action. Helical cutterhead comes with carbide knives with straight edges. When the knives contact the boards, the whole edge of a few carbide knives cut straight on the board. Everybody knows that shear cut is better than straight cut. 

 Below is the comparison.

Descriptions
Spiral Cutterhead
Helical Cutterhead
Cutter Edge
Round (Ours is R150)
Straight
Angle to Centerline
10° to 15°
Zero
Cut type
Shear
Straight
Chips
Thinner and Shorter
Good
Surface Finish
Better
Good
Dust Extraction
Better
Good

 

Heavy duty helical cutterheads are installed with two-edge carbide inserts at sizes of 30x12x1.5mm. The inserts are securely clamped in the pockets with wedges, which allows heavy cutting up to 8 to 10mm one pass. Our unique design put all the carbide inserts at a slight angle to the feeding, which generate a shear-cut as well. All the four corners are slightly chamfered, which helps to make smooth surface finish.

 

 

 

If your machine is well maintained, you can still use your old bearings provided you pull them off intact with bearing or pulley puller. Most of the bearing are pressed onto the shaft for tight-fit. It often happens that the bearings end up getting damaged. Therefore, we recommend that you replace old the bearings. The bearings we provided are greased, sealed with cover for life use. Add the bearings before you fill the shopping cart. 
This is not necessary. As spiral cutterheads have some carbide inserts keep constant contact to the materials, the start-current of the motor may be a little more than old style cutterhead can bring. But when the spiral cutterheads are in operation, less power is required as spiral cutterheads cut in a staggered way.
Our spiral cutterheads are dynamically balanced to the industrial grade and can run at the maximum speed of your planer or jointer allows. The dynamic balanced is completed with all the carbide inserts preinstalled.
The inserts are angled for shear-cut design. The screws are positioned in the taper holes for secured locking. When tightening the screws, keep the wrench square to the screw head face.
Old style cutterhead with long straight blade hammers wood in the full length at once. It makes an annoying and loud noise. Your beloved ones and neighbors may complain or have to tolerate the sound. With the spiral cutterheads, only a few carbide inserts cut in continuous intervals, this creates weaker sounds. Sound test proves that 15 to 20 decibels can be dropped after Sheartak spiral cutterheads are installed. Noise reduction is one of the prenominal changes of our cutterheads.

 Are more knives on the spiral cutterhead worth the extra $$$?  It depends.

When you compare the prices of the spiral cutterheads from different suppliers, take the quantities of the carbide knives on the cutterheads into your consideration. Don’t be misled by quantities of the spirals or helical grooves.

Tools are different to human being. One knife on the spiral cutterhead is as efficient and productive as another. One plus one always equals two. More knives on the spirals mean more value, more productivity. But how many knives are good for you depends how often you operate your jointer or planer, how great your project is. For instance, we can make the spiral cutterhead 4 spirals, 5 spirals, 6 spirals, 8 spiral, 9 spirals, 12 spirals for the same planer with 120mm diameter cutterhead and each spiral has the same quantity of carbide knives. So the bet is the dollars vs the performance. If woodworking is just your hobby, have a spiral cutterhead with knives that merely enough. If you operate a mill and run the machines over a couple of hours daily, more knives is the best bet.

Contact us and we can help you make the proper choice.  

 

For regular cutting, our customers told us that our carbide inserts last average 10 times longer than the standard straight HSS blades. For the square inserts, there are four indexable edges and the set of carbide inserts is worthy of 40 to 50 fresh HSS blades.
We install carbide inserts of standard sizes. They can be easily acquired online at reasonable prices. We keep them in stock all year round for prompt delivery as well. We include 5 extra 5 inserts and 5 screws free as spare parts. But we recommend adding one or a few boxes for your future replacements. You have to pay fair amount of shipping cost for these inexpensive inserts.
Our carbide inserts are made of tungsten Grade C3++. For different applications and materials, we do have carbide inserts with different grades, different cutting angles. Contact us if you have any question or concern.
All the surfaces of the pockets on our spiral cutterheads are fine milled with mirror finish. This ensures the cutterhead accuracy and most reliable interchangeability of the inserts.

Thicknessers, jointers and combination planers by their functions are made simple to operate but substantial in construction so, cast-iron, machined steel components , heavy duty bearings and powerful motors are utilised with the view to longevity and reliability, especially the old machines. They don't wear out and are still in good shape. 

The straight knife cutter block has always been the limiting factor by noise creation, sharpening maintenance and time required by skilled technicians for accurate alignment. Even if the machine is new, the straight blades become dull very quickly. 

Spiral cutters and tungsten inserts remedy this situation. Quality cut surface finish, reduced noise, no sharpening, easy setting up, long blade longevity, easy chip extraction, three quarter afterward sanding reduction and many more...

If you come across an old machine in good condition at good machines, don't hesitate to buy it. Install a Sheartak spiral cutterhead. It will be better than a brand new machine but still with long straight HSS blades.

 

What is the most efficient configuration and number of inserts you need to make a cutting head work best?

This is one of the most frequently asked questions because there are some machines on the market that appear to skimp when it comes to inserts. The number one advantage is that the spiral cutterhead shears in a staggered way. Instead of removing the whole length as the long straight blade does, each insert on a Sheartak spiral cutterhead cuts only a part of its 15mm length at a time (12.5mm). Most of the European cutterheads have straight edge inserts which cut the whole length of the inserts, e.g, 14mm or 15mm and do not cut in a shearing action.

Below is some simple maths about the number of carbide inserts you need to produce an efficient cutterhead. Take the spiral cutterhead fitting DW735 for example. Our standard configuration is 40 carbide inserts. So, the total cutting length is about 48x12.5=600mm. The straight blade length of the old style cutterhead is 330mm. 600/330=1.82. This means that 40 carbide inserts take up 2/1.82=110% of the workload.

There are similar helical cutterhead which come only 30 carbide inserts or even fewer inserts. Their total effective cutting length is about 30/40x1.82=1.365 straight blade. The 30-insert helical cutterhead takes up 2/1.365=147% of the workload. The fewer insert design will make more noise and produce a less smooth surface finish, bring more pressure to the bearings as well. 

It’s easy to understand why more spirals with more carbide inserts are better. But how many inserts are good? It totally depends how often customers operate their machines. For industrial use and heavy cutting, more spirals are recommended. If it’s just for hobby, four spirals are okay. DW735 is our best seller, the cutting diameter is around 50mm. We install 40 carbide inserts on four spirals. We can make it 26 carbide inserts. Will this work? The answer is yes. Can this 26-insert version be the same as the 40 carbide inserts? Never.

The cutterblock is made of GB/T 40Cr  structural alloy steel grade, equivelent to ASTM grade 5140, AISI 5140, SAE 5140, DIN 41Cr4, BS 41Cr4, JIS SCr440, EN 41Cr4.

Main composition: C:0.37-0.44%, Si: 0.17-0.37%, Mn: 0.50-0.80%, Cr: 0.80-1.10%. 

Physical Properties:

Tensile strength: 115-234σb/MPa

Yield Strength: 2σ 0.2 ≥/MPa

Elongation: 65 δ5≥ (%)

HBS: 123-321

HRC: 30

This alloy steel widely used in low and moderately stressed parts for vehicles, engines and machines. 

Dynamic balance is one of the key parameter for reducing and elimination vibration during the helical cutterheads are in action. Drillign holes is for this purpose. All our cuttrheads are dynamically balanced to Grade G2.5 ISO1940 with the blades preinstalled. In case the blade(s) break off, replace with new blades(s) promptly. 

dynamic balance

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