Thomas Aquinas, part 2: sawing

Thomas Aquinas, part 2: sawing. Two large sandstone blocks

1. Two large sandstone blocks of Udelfanger sandstone: 1 for the statue of Thomas Aquinas, 1 for Serge's angel

Two large blocks

The work on the on copy of the statue of Thomas Aquinas has finally started. I had received two large blocks of Udelfanger sandstone some time earlier: one destined to make two angels out of it and one block from which I had to carve the two parts of the statue of St. Thomas from St John's Cathedral in Den Bosch and fit them together. So the first step was to divide both blocks into two with the diamond chainsaw.

Thomas. Aquinas, part 2: sawing.  I halved the block with the diamond chainsaw

2. The block is cut in half with the chainsaw

Thomas Aquinas, part 2: sawing. Presawing the lower body

3. Sawing the lower body

Presawing Thomas

After that I put one block on my copying saw and started presawing Thomas' lower half. The dividing line of the two parts was meant to be near the line of his hood, so that it will be almost invisible. Reminder: in an earlier post I wrote that the old statue was made from a single piece of stone, in which the layers run vertically. Because it's more desirable that the layers run through the statue horizontally (in that case, there's less chance that an entire big slice comes falling down at once, after weathering) it will be different in this copy. But the quarry has no banks in which the stone is higher than 120 cms. Therefore, the head was to be made from a separate piece.

Because of the large color differences between separate blocks of Udelfanger sandstone I was sent a very large block from which I had to cut the two parts. From this I made the body and the head of Thomas.

Thomas Aquinas, part 2: sawing. Upper body presawed.

4. The upper body was cut from the second half

Thomas Aquinas, part 2: sawing. Rough carving the head and body

5. The head and the body are roughly carved

Fitting together of the two parts

Then, the two pre-sawn parts of the head and body had to be made to fit to each other snugly. That wasn't so easy, because the dividing line doesn't run straight. It follows the wavy line of the hood and needs to be higher at the right hand, because otherwise the joint seam would run through the knuckles. These inclined faces need to fit together well. For this, it should first be clear what will be located where, and for that I needed to rough carve the two parts for quite a ways. I carved the upper body and the lower body so that I could see where it all would be going, and I could see where the dividing line was to run. Then I could find the joint surfaces.

Thomas Aquinas, part 2: sawing. Making both planes fit

6. The joint surfaces are being made to fit

Thomas. Aquinas, part 2: sawing. The head and body are bonded.

7. the two parts are bonded together

Joint surface

Because I made this joint line visible on both pieces, I could demarcate the joint surface and carve away the excess stone. By keeping on fitting the pieces together and scribing the excess stone, I could ultimately achieve a tight seam. When the fit was tight enough, I scribed off where I wanted to put the stainless steel pins and drilled four holes. Two holes in each piece, so I could adhere both parts with strong epoxy glue and two thick threaded rods. Also, the joint plane itself was bonded with a suitable breathable mortar. You should actually never make a horizontally extending closed off gluing surface on a statue sitting outside. The stone above such a dense glue layer can't lose its moisture and will start to rot right above the glue seam.

Serge's angel

Copying an angel for St. John's Cathedral

The other block was halved as well. From the one half this angel was presawn for Serge

My colleague Serge had an commission in Udelfanger sandstone as well for St. John's Cathedral in Den Bosch. He was asked to copy this angel. He had previously made one and asked me if I wanted to saw this one as well. So, here goes.

Read more soon about the continuation of this project. is the blog of Koen van Velzen, sculptor in stone and bronze. Look up my website as well:

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Which diamond chainsaw for which job?

My diamond chainsaw

I recently cut up a blue block of sodalite with my diamond chainsaw. Because it's quite an expensive material, I could save quite a large chunk by this method. If I'd made this sculpture in the normal way with the angle grinder, lump hammer and point chisel, I would have had some wheelbarrows full of expensive rubble for the dumpster. So in this case my chainsaw came in handy. But I actually rarely cut up or spalt large stone blocks. I actually bought this saw to remove blocks from historic buildings, or to cut loose heavily anchored statues from their foundation.

The diamond saw I chose in 2015 chose was a Cardi Coccodrillo35. But what types are there actually, what kind of job do you use them for, and which one is the best for which job?

Petrol engines

rough block of stone for Aachen Cathedral. Made a piercing cut with the diamond chainsaw

deep cuts in tight corners

The first type diamond chain saw for stone and concrete was made by the American company ICS. The older types ran on an extra greasy oil mixture, were heavy and noisy, and often choked because of a wet air filter, caused by the water spray thrown up by the chain. I hope that they have solved this now. ICS has also developed the first diamond chain, and now makes it for a lot of other manufacturers as well. ICS has several petrol versions on offer and make different kinds of chains.

Then also Husqvarna came with their own machine. They obviously have been making gasoline engines for chain saws and also for power cutters since a long time , so it fitted in well with their own range of machines. I know no further details. The price is around 3400 euros.

So their competitor Stihl could of course not lag behind. They have also developed their own version, plus their own chain with twice as many diamond bits on it.

Hydraulically driven

Now a gasoline engine makes a lot of noise and stench, and the torque at low revs is not great. That's why ICS soon developed a hydraulically powered version in the beginning, in three types. Hydraulic power is supplied by a separate hydraulic drive. This hydrostation of course also needs power supply, and this may be either via a gasoline engine (yet again noise and stench) or with an electric motor on 400 Volts (and then you'll need a 400 Volt power supply). The oil pressure goes to the chainsaw through two thick heavy hydraulic ducts. These are quite rigid and make the operation very difficult because they continually work against the operator.

Electric chainsaws

Then since the last few years there are also electric diamond chainsaws. I happen to own the machine shown above, the Cardi Coccodrillo35, by the Italian brand that also makes diamond drills and wall saws. It works on 230 volts at 3420 Watt.

But the German brand Dr. Schulze (if it says Herr Doktor in front of it, then it must be good!) has created a competitor to it that runs on both 230 Volt and on 400 volt. For the latter, you'll need a separate frequency converter, but then it suddenly consumes 6500 Watt, so it's a lot stronger on 3-phase power. Dr. Schulze uses the same motor for both their cutter and their ring saw as well. It is striking that this machine also has a kind of quick-tensioning knob, and a handle that can be adjusted in a variety of positions. Electric diamond chainsaws are a lot quieter, but not necessarily lighter than gasoline versions.

Pneumatic concrete chainsaw

For applications where sparks are absolutely undesirable because of fire hazard, an air powered version is also available. ICS provides one of those, for use in places where for example many utility lines are running.

Advantages and- disadvantages of the various types

Strong and light

sculptor Koen van Velzen cutting the statue of Moses from Lambertus church in Veghel with a concrete chainsaw / diamond chainsaw

cutting statues free with the chainsaw

I do not pretend that I know all about the different types of diamond chainsaw. I worked in the past with hydraulic chainsaws from ICS, with older petrol versions from ICS which kept choking and were very noisy and smelly, and now with my own 230Volt saw. But in short: gasoline saws are very flexible to use because they only require a water supply. This can already be done with a tank and a pump, though the pump will need to be powered by a generator or gasoline motor. It gets a lot easier if a water supply is simply available. Drawback therefore is their noise and stench. For the latter, you can adjust the fuel, that makes a bit of a difference already. But if, just a when I was working in Nijmegen at the Stevens Church, you need to cut for hours on end in a densely populated area, then it just wouldn't be right to start chainsawing right in the middle of city centre. Stihl would be my choice if I ever wanted a gasoline powered saw, because I've worked a lot with Stihl (chainsaw for wood, hedge trimmers and brushcutters), and was impressed by their quality. In addition, it's also fairly lightweight.

Much power and deep cutting

The hydraulic version is already a lot quieter. You can hear it clearly, but it's not deafening. The hydraulic power unit on gasoline makes a bit more noise. This machine is actually particularly suited to work in a well-organized construction site. You can cut very deep with the hydraulic version and have a lot of torque, but with that big power pack for the oil pressure it's just not as easy to move. Especially if you work on 3-phase power. I've always hated these machines because those heavy hydraulic hoses make using them so exhausting. I was always searching for places that I could hang them up on with a length of rope or I had them slung over my shoulder. But it's a very reliable machine; not much to get damaged on it. It can take a beating and can even do its work under water just fine.

No sparks

I'm not familiar with the pneumatic version of the diamond chainsaw, but judging from all air powered equipment, it seems to me that these don't have much torque left at low rpms. Added to that, a large air consumption always leads to a cooling effect, So I wonder how this would work at lower ambient temperatures. Maybe then you'll need to have an air dryer as well. Plus, you'll need to rent a large diesel compressor. I expect this one would also make a pretty loud howling noise.

No odor and flexible

My electric version was the solution for me. It's obviously not silent, but generates much less noise than a petrol engine. You can't cut as fast as some gasoline- and hydraulic saws, because you've got less power. The version of Dr.. Schulze promises several options for chains and sword. However, an electric motor of 3500 Watts is no light thing, so it is as heavy or heavier than a gasoline engine.

Chains and quick release

At Stihl they have developed their own sword and chain, though I do hear that a chain with diamonds on each link is not always convenient: Sometimes the chain itself wears out faster than the diamonds do, so that would unecessarily raise the costs. For example if you're cutting sandstone or brick. That is why ICS is sporting various different chains, for example, for brick, fresh concrete, hard concrete, granite and an economic version.

Now a diamond chain stretches out really fast. While cutting, you're continually checking to ensure that the tension is still right. A too tight chain pulls the blade sideways and thus gets stuck in the kerf, and a too loose chain get unrailed and starts to 'wander about’ inside the kerf. It should hang loosely so that the links at the bottom of the blade just clear the rails. Once the engine starts pulling it will be just right. Tensioning is a tedious job: you always keep unscrewing the two nuts again that you just tightened up, then tightening a difficult to reach nut behind the chain and finally tightening the two lock nuts again . At Mito they have since found a solution: a quick release on top of the diamond chainsaw. This machine is by Chicago Diamond Supply and works on hydraulics, but I think there will be many more to follow suit soon.

Dr. Schulze has also something like that, as I think I noticed. Unfortunately no videos of how this thing works.

Applications for the diamond chainsaw

I use my diamond chain for cutting loose statues and stone blocks, in case I want to cut any deeper than the 7 cm from my angle grinder. In recent times I've done for example deep cuts in stone finials, cutting smaller some old tufa side flowers, cutting behind the back of Noah, en cutting Moses and Aaron free from their walls, en removing a pedestal.

In restoration these machines are used for removing large blocks from a facade with minimal damage to the surroundings. In construction they use it for all kinds of modifications to existing buildings, though large circular saws and wire saws are much in use there as well.


Table of diamond chainsaws

-Click on the image for the file in pdf (Sorry, it's in Dutch only)-

Update 2 april 2019: Apparently it's all a lot cheaper if you go shopping in Germany (for example, the Cardi Coccodrillo costs € 1988,45 there, incl VAT, and they'll put in an extra chain!) is the blog of Koen van Velzen, sculptor in stone and bronze. Look up my website as well:

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Sculpture 'The Night’ for St. Eusebius Church Tower

Last phase of the tower

Work on the tower of St. Eusebius's Church is nearing completion. Actually, the sculptres of The Day and The Night are the last two pieces that the builders are urgently waiting for. So I think a deep sigh of relief must have come from the scaffolds of the church when I completed The Night this week. For the tower, and part of the church, need to be free of scaffolding when a commemoration of the Battle of Arnhem is held this autumn, looking back to, 75 years ago. But this sculpture was not the only thing that still needed to be done. I've been carving away for St. John's Cathedral in Den Bosch, for the the Utrecht cathedral, again for Saint John's Cathedral, and the flying buttress figurines for St. Eusebius' Church itself should be ready in time as well.

Day and Night

This corner sculpture is located at about 15 meters up and was originally carved in tuff by Eduard van Kuilenburg. She's part of a pair: there is a guy with a rooster, breaking his shackles and brandishing a mop (or should it represent a flaming torch?), and yes, this woman with a nest of owls too. The Day and The Night. This lascivious young lady is sitting with the left hand in her hair, on one knee, with a stick in her right hand. The purpose of the stick is not clear to me, or perhaps it should represent an extinguished candle. The owls represent nightlife, the rooster and the broken shackles stand for dawn. I suppose he's about to extinguish the torch and is not going to mop the floor, because he 's not carrying a bucket.


This relief is the biggest block from this church we received in the yard in recent years: almost 1 cubic metre. Due to time constraints we decided to use the copying saw, but the block was so large that it couldn't even turn around on the turntable of the machine. I had to literally cut a number of corners to make it fit. These were however just those corners that ultimately will be embedded inside the masonry, so you won't see anything of it later on. This presawing is saving me days of measuring work, by enabling me to start carving by eye from quite early on. Plus it saves me a lot of rough carving and sawing with an angle grinder, freeing me from a lot of the hard work. I glued two stainless steel threaded rods M16 into the top of the new block, onto which I can screw a eye bolt for lifting, making the block easy to move. It may come in handy on the scaffolds later on as well for the restoration masons.

Little feet

The block of new Muschelkalk limestone of over 1800 kilos was provided by the Stonemasonry Firm, who also carved the profiles on it. Unfortunately, the stonemason in question was somewhat preactieve, which caused that I was short on material for the lady's toes. Added to that was that the original sculpture was a lady with a unique anatomy. Her knee was pointing straight forward, but her left foot was targeted towards the viewers at home. So I made a virtue of necessity and right away took the opportunity to give her left foot a somewhat more logical position. The right foot also missed a lot of stone, but I was still able to carve it nicely by putting it more back and in a bit flatter position. If you don't place the original right next to it, it will not stand out at all. It was an interesting challenge and I'm really pleased with how it turned out (See the slideshow below for pictures).

Nest of owls, finish

Near her right shoulder is an owl mother with her nest with two young. The chicks look endearing, with their surprised look.

I finished the entire sculpture with a wide tooth chisel, and then smoothened the body of the young lady with a coarse grater, leaving the chisel marks still barely visible, for a lively effect. Her hair and the owl's feathers I accented with the tooth chisel.

Sculpture The Night by Eduard Kuilsburg- new copy in Muschelkalk limestoneSculpture The Night by Eduard Kuilsburg- new copy in Muschelkalk limestone

Headless chicken

The sculpture of The Day was in a lot worse condition than The Night. The rooster and the man were both missing their heads , and the hand with the torch had disappeared as well. So I first needed to reconstruct those parts before I could start presawing. I modeled the neck and head of the rooster with plasticine and the hand was remade pretty quickly too. The tricky part was the position of the original hand, because in the only picture I had, the fingers were in an almost impossible position. But the head was more of a challenge. because this young man had quite a big head. I had glued a piece of hard PIR-foam onto his shoulders and from there I started looking for the right size, position and shape of the head.
I tried to see my progress by comparing my pictures with the original image. In the end Stide decided he would carve this one, so he has has been the one to make the finishing touches to the remodelling. See the gallery below for an impression.

Gallery -click on a thumbnail for the entire picture- is the blog of Koen van Velzen, sculptor in stone and bronze. Look up my website as well:

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Flying buttress figurine: A Wise Maiden

flying buttress statue Wise Maiden

After the 26 flying buttress scupltures from the north side of St. Eusebius's Church I (along with team member Jelle) started carving the 27 sculptures from the South Side. The themes of these four flying buttresses are the Trumpeting angels (that I carved in September 2016 already), the Wise Maidens, the Foolish Maidens and the represent the Beatitudes. So the trumpet angels have already been completed, as are two of the Wise Maidens, the Beatitudes are almost done, on the top block to which the Supreme Commander In Chief is after, so we only have a few of these girls to go. This sculpture was a …Read the whole article…

Corbel for the Eusebius Tower: a bird-like beast?

Bird beast: a copy of a tufa stone corbel by John Grosman in new Muschelkalk limestone for the Eusebius Tower in Arnhem
One of the last of the 10 corbels for the South- and North side of the tower of the Eusebius Church at 23 meters high was this winged bird-like beast. It sits somewhat cramped in its corner and there spreads its claws and wings. This piece was originally …Read the whole article…

Corbel: a cat with wings

copy of Corbel for Eusebius Tower: cat with wings after a tufa original, new in muschelkalk limestone
copy of Corbel for Eusebius Tower: cat with wings after a tufa original, new in muschelkalk limestoneThis next corbel for the Eusebius Tower is destined for the north side at 22 meters height, and is part of a group chimeras or a kind of winged cats.
The cat with wings on the corbel holding …Read the whole article…

Pan in porphyry 2: starting with rough carving (video)

Pan in porphyry. The precutand not yet carved piece of stone It is very busy at present, and then it sometimes happens that there is a hitch. After first having a deep cut on my thumb keep me two weeks at home, I am now at home with an tennis elbow that keeps me lying low for a while. Not because of all the sculpting however, neither of those. But that gave me the opportunity to make the video below about the first caving of the sculpture of Pan in porphyry.

Pan will have to wait a little longer anyway, for a coat of arms and seven pinnacles and finials in Irish bluestone for Aachen Cathedral wil have to go first… more on that later. is the blog of Koen van Velzen, sculptor in stone and bronze. Look up my website as well:

Pan in Red Porphyry (1) (video)

block of porphyry for plaster image of Panwooden frame for plaster model. for Pan sculpture in porphyry


I finally continued with my plaster statue of Pan (read here more about it). After much doubt about a beautiful red block of granite it ultimately became a piece of Chinese Porphyry. It is not too expensive, it's easier to carve and looks stunning.

I thought I could take the opportunity to …Read the whole article…

A monkey in a wig (flying buttress figurine)

flying buttress figurine Monkey, Copying from tuffstone into Muschelkalk

copying the Monkey

The old Monkey from tuffstone

One of the nicest flying buttress figurines from the series 'Noah's Ark’ by Theo van Reijn was now ready to be copied: a Monkey. The creature has an endearing belly, skinny legs and a Big Smile on its snout. And a wig.

That my sawing machine after all of the welding- and tinkering can now cut so accurately is also clearly visible in the pre-cut block. It saves quite a bit …Read the whole article…

A Bear with a honeypot (flying buttress figurine)

The bear that didn't look like a bear

flying buttress statuette of bear with honeypot - old original tuff

flying buttress statuette bear with honey -new copy in muschelkalk limestone

And then the bear came with its long snout and blew out… no, he ate all the honey. This 'bear’ was the next flying buttress figurine for St. Eusebius's Church in Arnhem which was to be copied into new stone. Only you have to look very good …Read the whole article…