Large Drop Point Twistmaster from Cold Steel


A shot of the Twistmaster alongside a large Opinel for reference :

twistmaster and opinel

The review consists of :

Specifications

Basic specifications :

The edge is sharp but fairly inconsistent in angle :

The edge thickness also varies significantly as well :

Stock testing

The edge came highly polished and could push shave hair readily, and push cut photocopy paper. The edge retention stock cutting results were also solid showing medium to high sharpness :

A few stock tests of cutting ability :

The tip shows high penetration getting 159 (6) pages of penetration into a phone book under 50 lbs of force.

Use

The Twistmaster is a folder that does not sacrifice the common attributes that folders do to increase ease of carrying :

As a result the knife ends up being among the highest performing of the large folders being only slightly behind an Opinel and far ahead of not only tactical knives such as the XM-18 but also both utility folders such as the Delica simply because of the :

The knife can also be held right next to the blade to remove any leverage disadvantage and increase ease of precision.

In the kitchen it excels, again for a folding knife :

And due to the size and raw length it has the ability to work on :

For utility work, the tip is very thin, excellent penetration but not something to use to pry the lip off of a paint can or dig in hardwoods - however the ability for fine work is very high. The only downside is that the large size makes it a bit awkward. In general the blade excels at slicing and draw cuts due to the full blade curvature and when left with a decently aggressive edge finish it absolutely shreds ropes, cardboards, webbing and fabrics.

Edge retention

The Twistmaster was used to slice through 3/8" thick manilla hemp, with cuts done through a two inch section of blade with the rope on a plastic cutting board. The cutting ability was determined by the amount of force used to cut the hemp and the sharpness checked using light thread and poly under a 1000 g load. The cutting was initially performed with a fine polish from a ceramic rod with microbevels set at 22 degrees. Three runs were made (separate rolls of hemp) including a completely sharpening to remove and reset the micro-bevels.

3/8" hemp sliced with a Twistmaster from Cold Steel : fine ceramic finish
# hemp cuts Thread Poly Hemp
grams cm lbs
  0115 (11)0.60 (5) 
  2185 (  8)0.88 (6)22 (1)
  6255 (  9)1.8   (1)26 (2)
14 323 (15)3.0   (3)30 (2)
30 330 (16)4.5   (3)35 (3)
62403 (18) 36 (3)

The blunting is nonlinear as is common, after slicing through about 30 pieces of hemp with a fine ceramic finish, the Twistmaster has a significant lack of aggression and is just barely able to cut the poly and sliding a lot on the hemp. Dulling is evident by a visual inspection as light can be seen reflecting from the edge. Some work with a smooth steel restores the knife back to within a few percent of optimal performance showing that the main cause of the blunting was edge roll, some wear can be seen under twenty times magnification. The edge retention is fair with the fine ceramic finish. With the edge left more coarse the cutting ability and edge retention were much improved :

Hemp cutting with the Twistmaster : fine DMT (600 grit) finish
# hemp cuts Thread Poly Hemp
  grams cm lbs
    0210 +/-   60.75 +/- 0.05N/A
    2253 +/-   30.92 +/- 0.0814 +/- 2
    6270 +/-   91.42 +/- 0.0816 +/- 1
  14288 +/- 121.75 +/- 0.1519 +/- 1
  30343 +/- 232.20 +/- 0.1120 +/- 2
  62365 +/- 192.87 +/- 0.1623 +/- 4
126415 +/- 204.60 +/- 0.2724 +/- 3

The huge change in aggression is immediately obvious even by feel and the thread and poly numbers show a huge change, the poly results showing an increase of 3-4 times the edge life. The performance is the same as found on the Becker CU/7 once the edge had been reprofiled to a similar level of cutting ability by adjusting the angle which makes sense as they are the same steel. Comparing it to other steels, it is significantly behind higher and harder alloy steels which makes sense as well.

The edge was then reground with use of a belt sander, to about 10-12 degrees per side. With another fine DMT finish with a 22 degree micro-bevel the cutting on hemp was repeated :

Reprofiled hemp cutting with the Twistmaster: fine DMT finish
# hemp cuts Thread Poly Hemp
  grams cm lbs
    0 143 +/- 130.75 +/- 0.05N/A
    2 185 +/- 150.85 +/- 0.0811.8 +/- 0.9
    6 208 +/- 121.08 +/- 0.0813.0 +/- 0.8
  14 220 +/- 161.23 +/- 0.0413.5 +/- 0.8
  30 263 +/- 161.63 +/- 0.1714.8 +/- 0.4
  62 285 +/- 162.35 +/- 0.0716.5 +/- 0.4
126 360 +/- 173.35 +/- 0.0818.3 +/- 0.6
254 420 +/- 234.80 +/- 0.1319.0 +/- 0.7

The rate of edge degradation was significantly lower than before which was confirmed with other steels and infered to be due to the effect of the cutting board as lower forces in the cutting mean lower forces on the cutting board.

As a visual overview of the hemp cutting, the above three edge retention trials graphically :

Image hosting by Photobucket

The edge retention increases by about 3-4:1 with the switch from the fine ceramic to the fine diamond, and further another 2:1 when the edge angle is reduced which minimizes the wear of the edge against the cutting board, showing that the cutting board is causing a significant amount of the blunting, which is similar for kitchen cutting.

The increase seen in slicing edge retention from going from a high polish to a fine DMT rod, can be extended even further with an more coarse finish such as seen in the review of the Becker CU/7. The downside to really coarse finishes is reduced cutting ability and a low edge lifetime during push cutting.

Sharpening

The Twistmaster has a blade made from Carbon V which is one of the most used knives steels of its time in the cutlery industry though it very rarely is called the same thing twice. 1095 cro-van, 1095CV, Carbon V, 0170-6, are all the same steel - AISI 50-100B which is a fairly simple steel :

It is basically 1095 modified with minimal elements to increase ease of manufacturing; the chromium prevents the difficulty in quenching 1095 which has an extremely small time before pearlite formation and the small amount of Vanadium helps prevent the grain from growing in austenization.

Practically as there are no high alloy carbides it grinds very easily and can be shaped even on a fairly inexpensive benchstone. The image at the right is off of the rough side of a cheap benchstone. It shows the very rough edge which would be expected given the rough grit of the stone and the low edge angle of 8-10 degrees per side.

At this stage the edge is very sharp :

It will also push cut newsprint if the edge is at a slight angle and is cut relatively close to the point of hold, 1" or less. However this edge is really biased towards slicing only and has poor push cutting performance, especially in regards to durability.

The image at the right is off of the fine side of the stone which is similar to fine India (BRICO). The edge angle was also increased to 12-14 dps which also refines polish as well as the finer grit of the stone. In general, very general, this is a very nice grit for a general purpose finish as it combines a very decent level of slicing aggression and edge retention without becoming too fragile for push cutting outside of chopping. With this geometry and sharpness the cutting ability on 3/8" hemp was very high :

In general though, for significant work where the edge was damaged and a decent amount of material had to be removed a decent stone would be preferred as the steel is a bit harder to grind due to the combination of cementite and hardness of the blade. It can be done with cheaper and natural stones but unlike the very easy to grind blades (Mainstays Santoku) a benefit will be seen here if the more aggressive cutting stones are used.

Lock

The Twistmaster has as the name would expect, the same twist action lock ring found on the Opinel, the inspiration for this design. The only differences are :

Both locks have angled intersections/mating surfaces so they are designed to handle wear in use.

This lock is an example of extreme security with relatively low strength as it is next to impossible to unlock by accident as it ignores many of the actions which can unlock liner locks such as :

However the ultimate strength of the lock is set by the "stop pin" which is just the polypropylene handle reinforced by a very thin locking ring and thus it could not hope to achieve the very high break points of many modern locks - but it also is extremely difficult, if not impossible to unlock by accident.

The action of the blade is very stiff, though this is dependent on many things including lubrication used around the blade/pivot. As boxed it takes about 15 (1) in.lbs of torque to pivot the blade out of the handle and 7 (1) in.lbs of torque to close. to turn.

Grip

Thw Twistmaster makes no allowance for a clip or pocket carry and thus the handle is optimized for comfort and security without any compromises :

It also has an aggressive texture which however isn't in general abrasive as the handle fills the hand well and cuts so well that the forces in hand are in general fairly low.

The handle even has an end swell (in both planes) to enhance security and even allow a two finger leuko style grip for light chopping. The only downsides are :

In regards to durability and general issues :

Overall

In short :

The downsides are (compared to modern folders) :

Comments and references

Comments can be sent to : cliffstamp[REMOVE]@gmail.com or by posting to :

All of the pictures can be seen in the PhotoBucket website.


Last updated : 11/01/2013
Originally written : 10/30/2001
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