Large Drop Point Twistmaster from Cold Steel

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

The review consists of :

• specifications
• stock evaluations
• general work : food
• edge retention
• ease of sharpening
• grip
• overview
• comments and references

Specifications

The Twistmaster is ground from 1/8" thick Carbon V, hardened to a uniform 59 HRC. The knife has a distal taper with a full flat primary grind of about 2.1 (2) degrees. The sharpened edge starts only 1.5 centimeters in front of the index finger, thus the leverage disadvantage is almost minimal. This is a large folding knife, 27.5 centimeters long when open, and 15 centimeters when folded. The edge is 11.5 cm long and gains another centimeter in working length because of the curvature which produces a sweep of about 10 degrees down from the choil and up towards the tip. In spite of its size the knife only weighs 120 grams.

The edge grind varies along the blade, about 16 degrees per side near the choil sweeping to 13 degrees near the middle and then back up to about 18 degrees as it runs towards the tip. Behind the edge the blade is 0.022" thick near the choil, towards the middle 0.12", and near the tip it thickens again to 0.21" . The profile thus gives maximum cutting ability across the middle of the blade with the tip and the base of the blade reinforced for heavy cutting. The handle is made from plastic with a very aggressive texture. It is swelled well in both axis, with a 0.5 centimeter taper across the back, and a lighter taper vertically. It fits well in hand, though the blade cut outs in the handle have very sharp edges.

Stock testing

The edge came highly polished and could push shave hair readily, and push cut photocopy paper. Light thread push cutting required 110 (13) g, and slicing 1/4" poly with a 500 g load required 3.1 (4) cm of edge, and under a 1000 g load the blade needed a minimal 0.50 (5) centimeters of edge.

Slicing one inch points on a basswood dowel through six points on average 12.2 +/- 0.8 cuts were needed.

Using a rocking push cut on 3/8" poly, the Twistmaster made a complete cut requiring only 37.0 +/- 0.9 lbs of force. On the same rope, a a 52100 Allen Blade / Ed Caffrey MEUK took 41 +/- 2 lbs, and a custom from Ed Schott custom 30 +/-1 lbs. Ed's blade does so well as the edge grind is 12 degrees. The MEUK has a much more obtuse edge, about 20 degrees per side, but is very thin, ~0.005" thick behind but the edge.

After the rope and hardwood cutting, the Twistmaster was slightly dulled, in the region of most use, 147 (15) g was needed on the thread, and 1.3 (2) centimeters of edge were required for the poly (1000 g load). It was stropped on leather loaded with 0.5 micron CrO buffing compound. Twenty passes were made alongside both sides of the blade. The blade now cut the 1/4" poly under the 1000 g load with 0.30 (5) centimeters of edge, sightly better than the NIB performance.

The tip on the Twistmaster is thin though wide and gets 159 +/- 6 pages of penetration into a phone book under 50 lbs of force. Hard stabs were not attempted due to possible lock failure, and 2x4 digging was not performed as it would lead to obvious point failure.

Kitchen use

Any knife can be used in the kitchen, however few are efficient, and some of the normal cutting tasks are near impossible with some blades. Take a turnip for example and attempt to slice it up with a thick tactical knife. Kitchen use frequently calls for very deep cutting on materials that exert very high binding forces on blades and thus the only knives that can do it well in general have a very high level of cutting ability. The Twistmaster excels at preparing vegetables and meats and will even handle crusty bread if the edge with a coarse finish. The blade will however patina quickly, and will develop rust spots without frequent flushing with fresh water and drying.

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.

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 :

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 about 500%. The biggest difference is seen on the force required to cut the slice, after 126 cuts, with the DMT finish the Twistmaster edge is cutting at about the same level as just after 6 cuts with the edge having a high polish, showing an increase in cutting edge lifetime of over 20 times. 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 profile of the Twistmaster was modified with use of a belt sandel, to about 10-12 degrees per side. With another fine DMT finish with a 22 degree micro-bevel the cutting on hemp was repeated :

The rate of edge degredation is significantly lower than before which was confirmed with other steels and infered to be due to the effect of the cutting board. As an interesting note, with the newer profile which has a much higher level of cutting ability the Twistmaster can match the performance of the VG-10 Deerhunter where it was outperformed radically with the stock profile when both had the same 22 degree fine diamond microbevel.

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

The edge retention increases by about 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

This steel has little issues with sharpening, it is a simple low alloy carbon steel and grinds easy with minimal burr formation easily accepting a either coarse or high polishes easily and is capable of very low edge angles.

Lock

The action of the blade is very stiff, it takes about 14.8 +/- 0.5 in.lbs of torque to actually pivot the blade out of the handle. Closing it is a little easier, it only requires 7 in.lbs of torque. The locking ring is also difficult to turn. It is also possible to jam if over tightened. On the positive, the locking ring has an angled cutout which should act as a mechanism to counter act wear, it could be cut similar on the bottom to lock the blade in the handle.

The lock is very secure and has no problems with spine whacks, white knuckling or torquing. The only possible accidental release would be the hand ramped up on the handle and then the knife was torqued so as to moving the locking ring. Given how difficult the locking ring is to move, this isn't likely. However in regards to raw strength, the locking ring is only 0.02" thick and would thus readily be compacted. The back stop of the blade also rests against just the plastic handle and thus it would also get damaged if the blade was to see impacts. In regards to lateral stress, again it is just plastic holding the blade in place.

One of the initial reasons for buying this knife was to check its batoning ability, as this has been an issue with other knives such as the X-Ray Vision. However the lock does not have the level of strength and durability needed for such work, and is easily damaged by batoning.

Grip

The grip is swelled in the right places and fills out the hand well. Aside from the two sharp cutouts in the center of the handle, the only issue is the aggressive texture of the handle. For really heavy impact work this is an excellent idea, but this knife isn't going to stand up to that kind of use. For most extended light to medium cutting the handle can be abrasive. However it does give good security with a grip slippery from working with oils, fats or viscera.

Overall

The knife has a large carbon steel blade of decent thickness with a lock that sacrifices ease of opening and closing for security and strength. However the very low strength of the lock and the fact that the main strength of the body depends on just hard plastic makes it unsuitable for really heavy use. The blade and edge geometry are also optimized for high cutting performance and with the stock edge it will easily out cut most production folders. Is is also one of the few modern folders without a stainless steel blade.

Comments and references

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

• Initial impressions : Cold Steel large drop point Twistmaster

More information can also be found on the Cold Steel website.