Gear Review: DMT Aligner ProKit and DuoSharp 10″ Bench Stone

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It is possible to put a great edge onto a knife with very basic equipment and a lot of time. However, with the ever harder and more abrasion resistant steels, diamond stones make it much easier and faster to achieve that edge. DMT are one of the best, if not the best, makers of diamond sharpening stones. If you have checked my ‘Recommended’ page you will have seen that DMT was actually already my favourite diamond sharpener brand, with a pair of DiaFolds (Coarse/Extra Coarse and Fine/Extra Fine) always with me for field maintenance.

In this review I’m looking at two very different sharpeners, a large bench stone (Duo Sharp 10″ Bench Stone) and a guided precision sharpening system (Aligner ProKit).

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“Getting your EDGE back”:

There are so many variations in knife design, size and purpose, and I shall continue to try and review as many as I can, but the one thing that they all have in common is a cutting edge, and it is that edge which makes a knife into a tool. When you buy a knife, the factory put an edge on the blade, but this can vary considerably in quality even from good manufacturers. Relying on the factory edge is like buying a car and only driving it as far as the original tank of fuel will take you. You can transform the performance of a knife, so it is worth investing in quality sharpening equipment.

Actually this section title uses the name of a sharpening service I offer to neighbours (100% going to charity), and is absolutely appropriate for anyone who wants to have the best performance from their cutting tools.

I’ve used just about every method of sharpening, both manual methods and powered. These range from the humble carborundum bench-stone to high-end guided sharpening systems, as well as various wet/dry grinders and belt sanders. Manual sharpening does take longer, but gives you greater control and removes less metal. Where Diamond sharpeners really stand out is the speed they cut, and a quality diamond stone can cut 6-10 times faster than other stones. That is a lot fewer strokes you need to make.

There are many diamond stones to choose from with very different prices. DMT claim the flattest sharpening surfaces with the highest quality of diamond particle and density of coating. I can’t examine this to confirm or deny their claim, but what I can say is that where other diamond stones have let me down and worn out quickly, the DMT stones I have, have worked very very hard and are still going strong.

A few more details of the Aligner ProKit:

The Aligner ProKit comes in a storage/carry case.
 photo 01 DMT Aligner Box P1180054.jpg

For this review DMT have also included the Extra-Extra-Fine stone (pink colour) so this is not normally in the ProKit pack. What is included are the three grits Coarse, Fine and Extra Fine, the stone holder/guide-rod, the Aligner adjustable clamp and guide, a tapered serration sharpening diamond coated rod plus the instructions.
 photo 02 DMT Aligner Box open P1180056.jpg

Laying everything out, this is what is in the box (remember the pink stone is not part of the ProKit).
 photo 03 DMT Aligner Box contents P1180061.jpg

As it can’t be fitted into the stone holder, the tapered rod has its own guide rod which screws into the widest end.
 photo 04 DMT Aligner serration rod thread P1180063.jpg

I don’t have a microscope to really go in ultra-close to the different grit stones, but this series of images at the same scale give an indication of the different grits.
First up is the Extra-Extra-Fine where the surface appears almost as if there were no particles in it.
 photo 05 DMT Aligner extra fine P1180066.jpg

Moving up to Extra-Fine and the surface is starting to take on a textured appearance.
 photo 06 DMT Aligner fine P1180067.jpg

With Fine you can see the grainy surface.
 photo 07 DMT Aligner medium P1180068.jpg

Finally with Coarse there is a distinct texture to the surface of the stone.
 photo 08 DMT Aligner coarse P1180069.jpg

Each of the different grit stones are fitted into the holder for use.
 photo 09 DMT Aligner holder P1180071.jpg

The stone is pressed into the pocket in the holder.
 photo 10 DMT Aligner holder P1180073.jpg

Then the lock at the end of the holder is turned to hold the stone securely in place.
 photo 11 DMT Aligner holder P1180074.jpg

A closer look at the rotating lock. Initially the fit of the stones into the holder is snug enough to not need the lock, but as you use it more they loosen up slightly and you do need to use the lock.
 photo 12 DMT Aligner holder lock P1180075.jpg

Being a portable kit, the stone holder has a folding guide rod. Here it is folded over the stone.
 photo 13 DMT Aligner holder folded rod P1180078.jpg

The rod hinges round and locks into place in the open position.
 photo 14 DMT Aligner holder rod hinge P1180079.jpg

Then we have the crucial part of a guided system, the guide itself. This is a clamp which fits onto the blade spine and has adjustable guide rings for the guide rods to run in.
 photo 15 DMT Aligner clamp P1180082.jpg

Looking in close at the clamp jaws. There is a brass screw for adjusting the width of the jaws.
 photo 16 DMT Aligner clamp jaws P1180084.jpg

With the jaws adjusted to the right size, a locking screw is used to tighten the jaws onto the blade.
 photo 17 DMT Aligner clamp lock screw P1180085.jpg

Each of the two guides have a number of positions they can be set to. Each of these positions has a groove moulded into the guide arm.
 photo 18 DMT Aligner clamp guide adjuster P1180087.jpg

Here we have the clamp fitted onto a blade and the guides set to position 3.
 photo 19 DMT Aligner clamp fitted P1180095.jpg

A few more details of the DuoSharp Bench Stone:

The box was shown earlier along with the Aligner ProKit. Inside the box you get the DuoSharp, a sharpening guide (showing other DMT products) and a set of rubber feet.
 photo 01 DMT Benchstone contents P1180008.jpg

There are eight feet which need to be fitted to the eight pegs (two in each corner).
 photo 02 DMT Benchstone feet P1180012.jpg

While the bench stone is upside-down one of its stand-out features can be seen – a handle. This is part of the DuoBase design.
 photo 03 DMT Benchstone handle P1180014.jpg

The handle means that you can take the stone to the blade instead of the blade to the stone. For larger blades this is ideal and makes the DMT benchstone pretty unique. Later on I show an example of exactly this with a ham knife.
 photo 04 DMT Benchstone handle P1180017.jpg

The Diamond stone slab is double-sided, so for the other grit you need to flip it over. It is held onto the base with two plastic clamps. Turning the base over you can see the two tabs that click into place. (you can also see the positions these can be put for the smaller 8″ stone.)
 photo 05 DMT Benchstone clamp P1180021.jpg

Simply pinch these together to release the stone clamp.
 photo 06 DMT Benchstone clamp release P1180023.jpg

You only need to remove one of the clamps to allow the stone to come free.
 photo 07 DMT Benchstone off P1180024.jpg

Fitting in with the colour coding across the DMT range the Red dot represents the Fine grit. The smaller blue dot shows what grit the other side of the stone has – in this case Blue/Coarse.
 photo 08 DMT Benchstone grit indicator P1180028.jpg

The DuoSharp 10″ benchstone has an ‘interrupted’ surface which helps clear the filings produced during use. There are a couple of pin marks into the plastic which probably relate to location pins used during the moulding of the plastic part.
 photo 10 DMT Benchstone holes P1180033.jpg

You can see how the diamond surface has been moulded into a plastic base-plate. One end has the elongated tab, only part of which fits under the stone clamp.
 photo 11 DMT Benchstone corner P1180036.jpg

The other end has a smaller tab for the stone clamp to hold.
 photo 12 DMT Benchstone other end P1180037.jpg

Flipping the stone over you can see the Blue grit indicator spot, this time with the smaller Red dot for the other side’s grit.
 photo 13 DMT Benchstone other grit P1180041.jpg

Fixing the stone back onto the base, first slide the tab under one stone clamp.
 photo 14 DMT Benchstone fitting P1180044.jpg

Then fit the second stone clamp.
 photo 15 DMT Benchstone fitting P1180047.jpg

Press the clamp down until it clicks into place.
 photo 16 DMT Benchstone fitting P1180049.jpg

For an idea of scale, here is the stone next to a Fällkniven F1. At 10″, this is a good sized stone.
 photo 17 DMT Benchstone size P1180050.jpg

What are they like to use?

Firstly, the Aligner fully packed in its box is not only compact, but is also light weight. This makes it a great kit to take with you on trips, to keep in the car, or to use to sharpen friends/relatives knives. With DMT diamond stones being used dry you also don’t need to carry any oils or lubricants, so overall it is very convenient.

Clamp based sharpening systems are limited by the capacity of the clamp. The Aligner’s clamp has a 6.5mm capacity if the adjustment screw is fully removed and reinserted one half turn. I’d prefer more than half a turn, so I think a 6mm blade thickness is a more realistic maximum.

It is best to have an ‘approach’ to keep your results consistent. In this case what I’m referring to is the clamp position. Moving this along the blade will change the angle the stone runs on the edge. So far my approach has been to fit the clamp in the centre of the cutting edge of the blade on every blade I sharpen. Working in this way, in future you will put the clamp into the same position for subsequent sharpening sessions.

As with this type of guided sharpening, once the clamp is fitted to the blade spine and locked on, sliding the guide rod into the guide ring you can now move the stone across the knife edge at a consistent angle.

If you are not used to working with this can be a little awkward. The instructions say to hold the knife handle in one hand and the stone holder in the other; personally I find it easier to hold the clamp in my left hand (I’m right handed) with the blade sitting on my hand. The feel is the same for both sides of the blade. If you have to hold the knife handle it means swapping round an moving the stone with your non-handed hand as well.
 photo 20 DMT Aligner sharpening P1180096.jpg

For narrow blades you should check for clearance (keeping the stone from wearing into the clamp). In this case there is plenty of room, but the blade is not narrow.
 photo 21 DMT Aligner sharpening P1180097.jpg

To select the right angle you can use the ‘Sharpie’ method (using a marker pen to blacken the edge bevel and check where the stone is cutting) and if necessary adjust the position of the guide rings. If you are using different settings for different blades, you will want to keep a note of the positions used for each blade to allow you to sharpen it properly next time without changing the bevel angle.
 photo 22 DMT Aligner sharpening P1180103.jpg

Once you are done, I find it best to leave the clamp on the blade when you test the edge in case you need to work on the edge a little more.
 photo 23 DMT Aligner done P1180105.jpg

Overall the Aligner is light and efficient, and the DMT diamond stones cut very well.

Update 20 Jan 2017
Following some discussions on the clamp being liable to flex as it is plastic, I wanted to show more clearly how I use the Aligner and similar guided sharpeners. In the instructions for the Aligner it show the stone being held under the knife and the knife being moved over the stone in a similar way to using a bench stone. This means you are holding the knife by its handle and pressing down onto the stone. Like this there is maximum room for flexing. However I have always used this type of guide differently.

I hold the clamp and allow the handle to rest onto my wrist for this side of the blade.
 photo 32 Aligner holding P1250263.jpg

And for the other side I again hold the clamp and support the handle (or blade depending on the blade length) with my third and fourth finger. This way round the blade also sits onto the pad of my thumb.
 photo 33 Aligner holding P1250265.jpg

In this way it is possible to support where the clamp holds onto the blade while you bring the stone to the blade.
 photo 30 Aligner holding and using P1250260.jpg

And the other way. Hopefully this show clearly why I haven’t had any actual issue with flexing from the plastic clamp.
 photo 31 Aligner holding and using P1250258.jpg

End of Update 20 Jan 2017

Now we move onto the DuoSharp Bench stone and the technique requiring most user skill. However due to its wide flat surface and diamond cutting efficiency it certainly seems to make sharpening this way much easier than on the carborundum stones I learnt on.
 photo 18 DMT Benchstone kitchen P1220149.jpg

The kitchen knives being sharpened are slightly magnetised due to being stored on a magnetic rack. The filings stand themselves up like this due to being magnetic themselves. A wipe over with a damp rag clears these off nicely.
 photo 19 DMT Benchstone kitchen filings P1220161.jpg

A few of the knives this stone breezed through.
 photo 20 DMT Benchstone kitchen knives P1220169.jpg

Now onto something a little more challenging, a 16″ ham knife. Ham knives are super flexible and thin, so are not easy to work onto a stone with.
 photo 21 DMT Benchstone ham knife P1230617.jpg

This blade had seen some abuse in the past and the edge was a bit wavy. I wanted to tidy it up and put together a very simple jig to keep the blade straight. A couple of stop-screws on a wooden base and some masking tape to keep it in place. To the right you can see an angle guide I setup for reference to help me stay on track.
 photo 22 DMT Benchstone ham knife jig P1230623.jpg

Using the handle on the back of the base I then used the bench stone hand-held. Working on the long and flexible blade in this way was so much easier and resulted in a corrected and hair-splitting edge (after a final strop).
 photo 23 DMT Benchstone ham knife sharpen P1230634.jpg

The only real limitation with a large flat bench stone like this is with the recurve section of some blades. Those concave recurve sections just won’t get to touch the diamonds, but that is always the difficulty of a recurve blade.

Being able to hand hold the DuoSharp bench stone was an unexpected benefit of the DMT design and makes it much more versatile.

Review Summary

The views expressed in this summary table are from the point of view of the reviewer’s personal use. I am not a member of the armed forces and cannot comment on its use beyond a cutting tool or field/hunting knife.

Something that might be a ‘pro’ for one user can be a ‘con’ for another, so the comments are categorised based on my requirements. You should consider all points and if they could be beneficial to you.

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Things I like What doesn’t work so well for me
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Aligner package is lightweight for easy transport. Aligner guide clamp will only fit blades up to 6-6.5mm thick.
Aligner ensures you maintain a consistent angle. Aligner – One side of the blade is more awkward to work on than the other.
Aligner – Easy swapping of grits. Aligner – Clamp needs to be fitted tightly and can flex if pressing too hard.
Bench Stone – Large flat surface. Bench Stone – Large surface prevents recurve blades being sharpened.
Bench Stone – Handle included to allow hand-held use. Bench Stone – Rubber feet can fall off.
Bench Stone – Easily identifiable grits.
DMT stones can be used dry.
DMT diamond surface cuts very well.

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