How to build a Surdo?

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This is a description how to build a plywood (Sperrholz) surdo.

You may click on all the pictures below to get an enlarged picture. This description is written in SurdoEnglish in order to serve a bigger samba drumming community, but for some technical terms an German explanation is given in parentheses in order to ease understanding for German readers. Before I started building the drums I did not find any description on how to make a plywood shell and surdo. With this step-by-step description I want to fill this gap and to encourage other samba groups to build their own drums. I am neither an an expert in building drums nor in woodworks. I just wanted to report that we (total amateurs) built (up to know) 7 surdos, that they worked out well and that our samba percussion teacher really liked them. This description demonstrates only one possible way to build a surdo and there will be plenty of other ways. For comparison have also a look at the links to other drum building pages below at the end of this site (go to links).

First I want to thank people for helping with the construction and contributing ideas. Foremost I want to thank Brigitte Adamik. We built together most of the surdos and she contributed a lot of ideas who to build the surdos. Furhter I want to thank Mike Vaslod who had the Idea to build the surdos instead of buying them and showed strong confidence that this is doable. In the beginning I was thinking that is really a stupid idea and that we should rather focus in collecting money than building surdos. But than I started to get really excited with building “masses of surdos”. Furhter I want to mention Edison Tadeu (our drumming teacher) who confirmed that he has built homemade plywood surdos before and that it can be done; thank Stefan Eibl for suggesting to use wood to build the frame for the wood bending and my brother Florian Totschnig for contributing the idea how to bend the aluminium counterhoops (see) and how to clamp the ends together (see).

Why build a surdo rather than buy one ?

Building a plywood surdo does not require big woodworking skills, but it does take quite some time (see time budget below) to build them. The time needed to build the surdo also depends on the availabe tools which may ease the construction. Actually a price of 200-300 Euro for a commercial surdo is quite good, compared that the material costs of a homemade surdo was for me about 120 - 150 Euro and considering the time needed to build the surdos. If you have to buy some tools then this will increase the price of the surdo considerably (see costs section below). Since we wanted to have a bateria with at least 10 surdos and since the people were not able to invest a lot of money (e.g. 10x250=2500 Euro only for the surdos) I decided to build the surdos myself. If you build 10 surdos, then also the purchasing costs of tools can be split among 10 surdos. Actually one purpose of this how to do guide is to reduce your costs, through the experience we acquired. So it was fun, but it was also quite laborious to build the surdos and you can not save a lot of money compared to buy a cheap one.

Material selection:

Basically what you need for a surdo is:

  • a big cylindrical tube for the shell of the drum
  • 2 drum heads
  • and some way to tune the drumheads: counterhoops and tuning rods.

After having finished 7 surdos we are now thinking to build a Alfaia type <Alfaia> base drum (see picture ont the side and Brians page or The advantage of this type of drum is that it uses a rope to tune the drum. So you spare the manufacturing of the metal counterhoops and tensioning rods (see picture). We may also want to use a real skin for selfmade drumheads. But in the beginning we were somewhat scared to build the drum heads (see picture) ourselves, so we rather decided to buy them. They are available for 20 to 50 Euros per piece at diameters of 18, 20, 22 and 24 inch (1 inch is 2.54 cm). Since the commercial drumheads have these predefined diameters, the drum shell diameter needs to be chosen accordingly. Before I decided to build plywood surdos, we were thinking about different materials: Plastic pipes, use empty metal barrels and homemade glass-fiber reinforced plastic shells [abbr.: GRP] ( Glasfaser verstärkter Kunststoff [Abk.: GFK]) or homemade aluminum shells. But we did not find plastic pipes or metal barrels with the appropriate diameter and the costs of a homemade GPR was estimated by me to be about 60 Euros per shell if you build 3 surdos (see and see). In the internet we found Marcelo Müller's informative description of how to build a aluminium surdo. But our teacher said that he really likes the sound of wood surdos more than any other and it seems that the wood surdos tend to be more light weight than other materials and also plywood seems to be rather inexpensive compared to aluminium or GRP. So I decided to go for plywood surdos.

The plywood:

The inspection of a commercial Contemorena plywood surdo see picture above, told that the used plywood was about 3 mm thick. So I went to the plywood trading company Frischeis and looked for the available ply woods. Up to know we have tested 4 different types of plywood (3-5 mm thick) and all of them could be bent without any problem to required 18-22 inch diameters. All these plywoods had only 3 ply layers (Sperrholzschichten). A 4 ply plywood would be much harder to bend. No steam bending or soaking of the wood in the water was required. Actually I used a 4 mm birch (Birke) plywood to test if there is any difference between bending the dry plywood or bending the plywood after being soaked in water for 4 days. I could not observe any difference in Plywood Slideshowthe required bending force. For this water test I had of course to a plywood, where the different plies are glued together with a water-resistant glue (sometimes called marine plywood). On it is reported that they showered the plywood with hot water in a bath tub. So maybe hot water helps, but if you use a thin 3 layer plywood you can bend it dry. Click on the picture to the right for a slideshow with a detailed description of the 4 different used plywoods. Basically we used 3 mm beech (Buche), 3 mm poplar (Pappel), 4 mm birch (Birke), and a special 5 mm bending plywood. At the moment I can't comment on which sounds best.

Another thing you have to take care before cutting the plywood is that the 3 layer plywood has a preferred bending direction. Most easily it can be bent perpendicular to the fibres of the top ply layer. So before cutting the ply wood, you should manually test the easiest bending directions.

Making the frame:

We built up to now 7 surdos: 3 x 18 inch, 2 x 20 inch and 2 x 22 inch diameter (1 inch is 2.54 cm). For each diameter (18, Frames Slideshow20 or 22) we built 3 frames made out of a 12 mm construction plywood (see piture slideshow right). So in total it were 9 frames for each diameter. In order to design the 9 frames I bought the 18, 20 and 22 drumheads and used a tape measure to estimate the appropriate diameter for the wooden shell. I tried to make the diameter of the wooden shell be about 4-6 mm less than the inner diameter of the aluminium ring of the drum head. But I am actually not sure if a tighter fit would be better. After determining the desired diameter of the wooden shell, a pen was used to draw a circle of the desired diameter and a jigsaw and drilling machine were used to cut out the hole see (see piture slideshow above). At one corner the frame was cut open and holes for tightening screws were drilled. After cutting the hole into the frame is good to measure again the diameter to ensure that the desired diameter was achieved. If the diameter is a little too big or too small you can use wedges or the tightening screws to change the diameter of the frame a little bit. Maybe you can use even cheaper types of chipboard (Spanplatte), but I am not sure. It could break when you try to tighten the frame.

Construction of the shell:

Now we have to cut the plywood for the shell: First you have to make sure that the plywood is cut and then bend the in its preferred bending direction (see description above). The height is easily determined. All the commercial surdos I inspected were all 60 cm high. But there is also a type of surdos called Bahia Surdos which are 40-50cm high (see). So you have to decide what you want. In order to determine the width of the plywood, we have to take more care. Mathematically the circumference (Umfang) C of a circle is equal to the diameter D multiplied by Pi (=3.14). C=D*3.14. But during the bending process the outward oriented plies are stretched and the inward oriented plies are compressed. So if you cut the plywood to a certain width and then bend it to a tube then the circumference will be larger than the width which you cut. As a rule of thumb you can calculate the width W of plywood you need to cut from the diameter D of the shell you want to achieve by W=D*3,14 - T*3,14 where T is the thickness of the plywood used for the shell. I tested the formula using a 3 mm poplar and it worked out very well.

Example: The inner diameter of the aluminium ring of the 18 inch drummhead I bought is 45,9cm. If you say you want to make the shell with 5 mm less circular sawdiameter than the aluminum ring than that would be 45,4cm (D=454mm). If you want to use 3 mm poplar (T=3mm), then the width W for cutting the plywood calculates to W=454*3,14 - 3*3,14=1416,1 mm. This formula is especially helpful if you do not have circular saw (buzz saw, Kreissäge) available. Because then you can ask the company where you buy the plywood to cut it to the calculated width. If you have a circular saw available you can cut the width of the plywood and shorten it yourself in small steps till it fits into the frame. A circular saw is very helpful since it cuts smooth edges.

In order to insert the plywood, we laid all three frames (with wedges inserted at the corner slit to expand the diameter) on top of each other on the floor and bend the shell plywood to fit into the frames at one end. One we succeeded, we pusched the top frame up to the top end of the bended plywood. After the bended plywood is inserted, the tightening screws on the The insertion processframe are used to really squeeze the edges of the bent plywood together and to ensure a circular shape. Now we can start to glue it. We used waterproof wood glue. For gluing the ends of the bent shell plywood together we used a 5 cm broad of the same plywood. I also took care that the 5 cm slice is cut also with the same preferred bending direction. The 5 cm slice was cut to be 50 cm long (instead of 60cm as the shell height) so that there is space for the 5 cm reinforcement rings on both ends of the shell. Then a 4 cm beam was placed on top and below the gluing position and 6 clamps were used to clamp the glued woods together see. The purpose of the beam is to apply the pressure of the clamps evenly on the 5 cm slice of plywood. On the glue it was written that it may be strong after 1-2 hours. But I always let the 6 clamps on for at least 6 hours. The commercial wooden surdo shells, have two layers of reinforcement at both edges of the cylindrical shell. Since the drumheads squeeze onto the shell edges with considerable force, we did the same. We cut 5 cm slices of the 4 mm birch plywood according to its preferred bending direction and glued them on both ends of the drums as inner reinforcement rings. We always used the 4 mm birch plywood for the reinforcement rings, since it is rather strong. Even if the rest of the shell was soft poplar, we glued two layer of the 4 mm birch on top of each other. For the reinforcement rings we kept the clamps only for about 1 ½ hours, before gluing the second layer. It turned out to be rather difficult to glue this enforcement ring evenly. We did not glue a ring as one piece but mostly used 2 or 3 shorter slices to make up for a complete layer of the reinforcement ring see. It is not good to clamp first together the two ends of the slice and before clamping the parts between. You should always start at one end and clamp every 5 cm the reinforcement ring to the shell. If you use less clamps gaps between the reinforcement ring and the shell may evolve (see slide show). Really good and cheap are plastic clamps with a spring: They are cheap (90 Eurocents), you can work rally fast and they clamp together but do not fix the ring too tight. With the metal clamps we found it really difficult to be able to glue the reinforcement ring evenly. With the metal clamps, you could start correctly on one end of a piece of reinforcement ring, but then slowly the reinforcement ring bent its direction and then after ending on the other end, the ring was sticking out of the shell. This is actually no big problem since a countersink was used later to make a sharp edge anyways. But it made things a little more complicated. If we were using the plastic clamps we could adjust the direction of the glued reinforcement ring also during the gluing process. In order not to dampen the drumming head, the reinforcement ring should be milled or sanded so that a 45 degree edge is formed just leaving the 3-4 mm of the shell untouched (see slide show). This 3-4mm ridge can then be smoothed to a circular shape using sandpaper by hand. In order to build a 22 inch diameter surdo you need a plywood with a width of about 175cm in the preferred bending direction. Since for some plywoods this was not available at the local plywood trading company. We also made some drums where the shell is glued together from two pieces of plywood. This workes out as well without any bigger problems.

The finish:

All the drums have in the middle of the shell a 1 cm hole. You can cut this easily with a drilling machinePaintedDrums.

Now about the painting: Actually for a samba bateria which wants to go out to the streets it would be best to use plywood, where the plies are glued together with a water resistant glue. So even if the drum would get completely soaked in a rain it would not hurt the shell. But unfortunately the local plywood trading company had only a 4 mm waterproof plywood. But this plywood is rather heavy. All the other ones were not “waterproof”. So I painted the shells of the surdos with a waterproof paint (Holzlasur) and hope that this helps in the case of rain. After the first paint I sanded the surface of the shell to make it smooth, paint it again and finally painted it two times with a finisher (transparenter Klarlack). In order for the paint to dry I used the hole in the shell to let the painted shell hang from some pipe.

The metal parts:

For the 18 inch diameter most of the work is done. You can buy two counterhoops (metallene Spannreifen) for 18 inch tom drumheads for 13 Euro each. They have the same 2 cm hight as the counterhoops on the commercial surdos. These counterhoops for tom drumheads only work with tom drumheads: So take care that you do not buy an 18 inch bass drumhead. All what is left is to make the rods to tighten the drumheads (see below). But for 20 inch diameter and more I did not find anymore the 2 cm high counterhoops. So I decided to build my own aliminium counterhoops . Which is not difficult but it just takes a lot of time (1-2 two hole days for one drum). It is really worth to think about to make a more-traditional style Brazilian bass drum called Alfaia (see) instead of an standard surdo. First they look pretty cool and secondly you need not to manufacture the counterhoops. But anyways I wanted to make a Surdo. Since weight is important for a marching samba bateria I decided to make the counterhoops and the tightening rods out of aluminum. There are different types of aluminum. Ask the retailer which can be best machined. The first step is to bend the counterhoop. I bought 2 meter pieces of rectangular 20mm times 3 mm flat aluminum rods. Then I built a bending machine. The basic idea of the bending machine is that 2 wheels hold the aluminum rod and one wheel in between presses the aluminum rod against the other two wheels. Through this pressure it bends the aluminum. An even curvature is archived by pulling and sliding the aluminum rod through these 3 wheels. If the middle wheel presses more then the curvature increases. The hole bending process takes about 5 minutes. If you make the middle wheel adjustable with a screw, then you can obtain any curvature (see slide show). I tested the correct curvature by holding the bent aluminum rod against the drumhead. With a metal saw I cut the bent aluminum to the appropriate size and then used the plastic clams to clamp it on the drumhead. Then a small piece of a bent aluminum rod was cut and holes were drilled in odere to bend togehter the loose ends of the bent aluminum rod (see slide show). With a tape measure then I evenly marked the positions for the 8 holes. I drilled the holes not in the middle bu<Counterhoop>t about 12 mm from one edge and 8 mm from the other edge of the 20 mm high bent aluminum rod. I did so in order that the top nuts are rather low and therefore no danger to be hurt by one of the nuts. The 8 holes were 5 mm in diameter. Inside of the ring I opened the 8 holes with a 45° countersink, so that when using countersinks Allen screws (Senkschrauben mit Innensechskannt) they would merge evenly with the bent aluminum rod see. Next step is to manufacture the aluminum bolts which are attached to the bent aluminum ring and hold the tensioning rods. For the bolts I bought about 1 meter of a 12mm diameter round aluminum rod and cut it into 16 mm long pieces. The cutting was speeded up since I could use the following machine (see above slide show). This machine made a very even cut. If you do it by hand with a metal saw it will take longer and maybe you need to file the cut surface so that it is rather even. After each cut I rounded of the corners of the previous cut with a grindstone (Schleifstein). 9 mm from the end to be attached to the counterhoop I drilled a 6.5 mm hole. This was done with a standing drilling machine and using a holder for the cut aluminum bolts. Similar I drilled the along the axis a 4 mm hole up to the intersection whith the 6.5 mm hole. With a 5 mm tapper (M5 Gewindescheider) I tapped a M5 thread into that 4 mm hole. As screws I used 8 mm long countersink Allen screw. Making the 16 bolts for one drum takes quite some time. Finally I made the aluminum tensioning rods. I bought 3 meter pieces of 6 mm cylindrical aluminum rods and cut them to the appropriate length. 5 of them I cut to a length that is sufficient long to connect both counterhoops through the bolts, but short enough so that one does not get hut when carrying the drum. 3 of them I made longer so that they stick out over the edge of the counterhoop. So then you can play the drum also when it is standing on the floor. The three long rods are spaced rather evenly so that the drum does not wobble around. For each 6 mm aluminum rod I made short taped thread on one side, just sufficient to hold one M6 screw and the other end had a long taped thread. The screw on the short taped thread was fixed to the threaded rod by the use of medium strong Loctite threadlocker (Mittelfeste Schraubensicherung). This is a liquid which holds the screw solid in place after a curing time of some hours. This screw was used to turn the whole rod when tuning the drum. On the other side I used a self fixed screw, which have plastic inserts which prevents that the screw get loose from vibrations, but they are not so strongly fixed as with the medium strong threadlocker liquid.

Drumhead selection:

Generally is the top drumhead choosen to be a thicker material and the bottom drumhead a cheap thin material. The sound of the drum is strongly influenced by the drumhead slection. I do not have jet a prefered choice. For some start see Brians page or take a REMO Emperor white cotated drumhead for the top and an REMO clear Ambasador drumehad for the bottom. This is the favorite choice of our teacher for a dark sounding 20 inch surdo.


The time needed:

The time needed to build a surdo depends on the availabe tools. Using the tools I had it took me the time given below.

Plywood shell: On one weekend (Saturday and Sunday) we could make the frames needed to bend 20 inch and 22 inch surdos and then bend, glue and finish the plywood shells of two 20 inch surdos and two 22 inch surdos. So total 4 plywood shells in 2 days.

The painting of 4 shells took 4 evenings since I repainted them 4 times.

Counterhoops and metal rods: For the 18 inch surdo I bought the counterhoops and 8 threaded rods so that it took just one evening to cut the rods and finish the drum. For the 20 and 22 inch surdos I made the counterhoop and tapped threaded the aluminium rods by myself. To manufacture the aluminium parts of only two drums took me one weekend. So that was much more labourius than the wood bending.

The costs:

The main problem with the costs is that there are the fixed one time costs (e.g. frames and bending machine), that you may need to buy tools and that there is often some minimum quantity you need to buy. For example I used 12 mm construction plywood to make the frames for the plywood bending. This plywood was sold in sheets of 2,5 meter times 1,3 meter and they would cut it for you into smaller pices but you had to buy the whole for 44 Euro. From this pice you could make the frames for two different drum sizes. If you want to make drums with two different diameters anyways than this is perfect. This is also a one time only cost.

Fixed costs or one time only costs: The frames for two different drum diameters 44 Euro (as explained above), for the 20 and 22 inch surdos I had to build the bending machine which had about 30 Euro material costs, I bought 60 plasic clamps for 54 Euro (0,9 Euro per piece), I had to buy tools, paint brushes, ....

Costs for each aditional surdo: The two drumheads may cost about 55 Euro, the two counterhoops and the tensioning rods may cost about 35 Euro (similar price if you buy it or make them yourself), if you make multiple shells the cost for the shell plywood are about 15 Euros and the nuts, paint, sandpaper, wood glue costs around 20 Euro. As mentioned before, the plywood was sold as sheets of a fixed size sufficient for 2-4 shells, depending on the type of plywood. So if you make multiple shells you can use the big sheet of plywood efficiently and divide the costs of the big sheet of plywood and get the costs down to about 15 Euro.

If you have to buy some tools, buy some screw here and some nuts there, try different solutions and make some mistakes it easily sums up to a considerable amount of money. I had to buy some plywood twice, since I did not know that there is something like a preferred bending direction and got the plywood cut wrongly in the plywood store. The costs also increased since I liked to test different plywoods and different metal rods. Actually I spent more than 1300 Euros to build 5 complete surdos and 2 additional shells. If I would do it again it would be cheaper, since I know now how I like to do it.


Some explanation of how to tune a drum can you find on the following sites:

Links to other drum building sites:

These are the links I found on building surdo like bassdrums. Since I was searching for how to make a surdo, Peter Eisenbergers pages on Alfaia and Bombo bass drum construction did not show up in the google search results. I finally found these pages by a link on Bians excellent page. Marcelo Müller's pages I found straight on.

There is Brians huge webpage of the San Diego Drum Community: this page is so big that it is easy to overlook the important drumbuilding subsites:

Peter Eisenberger has two very informative pages on the net:

Marcelo Müller's Music Page:

Mike Cowley:

  • Mike recently buit a very good looking surdo. He is also open to share his experience and tries some inovations. See homepage.



Contact the drum makers:

If you have questions feel free to send me a mail. I would also be happy to hear about your experiences in drum making and learn from your experience. Feel free to link this site or send me your link.

All the best Gerhard TotschnigEmail Adress






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