Project: Frank(enstein)

Making a 23" extended collar timpani with a 25" Slingerland timpani's frame.

Slingerland "Supreme" Frame
(WFL Bowl)

Ludwig "Field" Machine Timpani

Finished 23" Extended Collar

The initial idea is to have a 23" timpani. My current set up includes a 32" Slingerland, 28" and 25" Leedy timpani, and a 25" Slingerland timpani frame with an old 25" WFL bowl. While having 2 25"'s had some advantages, there were a few times in which I could not push the Slingerland 25" to G# or A as often needed in different repertoire. I bought a 23" Ludwig or WFL machine - sometimes known as a "field" - timpani. The 23" copper bowl will be the new 23" extended collar timpani. This web page is a sort of journal of what the project entails. At the time of this writing, I had already completely dissembled both the 25" Slingerland frame and the 23" Ludwig, each from now on labeled by their company names.

Problems the Slingerland timpani had:

With the range pushed up to a 23"'s normal range, the 25" bowl held a decent Eb to a flat G#. However, with the design of the clutch pedal, I believe with a small amount of material being removed from the base, the range can be extended by at least a step. The top of the pedal hits the base near the hinge - by grinding some of this away, the range may be extended.


A few ears on the counterhoop seem to be coming loose - but they never rattle. I am going to look into the different options on how to fix this

Over all, the 25" did not sound too bad, in fact, I liked it's sound the best out of my set of 4. But with major range issues, I figured it was worth it to make a 23" timpani.


Problems with the Ludwig timpani:

Although I did not spend much time with this drum after opening the box, I could tell right away that the bowl had a reversed bottom. I thought about hammering this back into shape, but I figure I will leave it alone for 2 reasons. First, I do not think the sonic differences will be noticeable in a drum of this quality. Second, if I ever want to revert the 23" bowl back to a machine timpani, it will be easy enough to do.


Although the counterhoop looks great (at least the ears are attached!), I believe it to be slightly un level. The bad quality head does not help much either. Neither of these problems should really matter since I will not use the hoop or head.

Minus a few dents, some extra large holes and the weird shape on the bottom of the bowl, this copper kettle will be great for the project. The lip will need some smoothing - maybe teflon tape will do the trick.


Possible issues with the "transplant" project:

My first concern was the alignment of the holes from the Slingerland hardware to the Ludwig bowl. Although it is only about 1/8" of a difference, I think my design for a spacer will work around this problem.

My spacer design may not have enough surface area to safely support the timpani's pressure. Will the spider fit through the current holes? It is my goal to not have to drill ANY holes in the bowl.


Extended collar explained:

My main goal was to get a 23" timpani with the same post-clutch pedal that I have on all my drums. I figured it would be more fun and cheaper to simply transplant a bowl into the frame. The machine timpani offered the best and simplest solution - less hardware to remove, or more importantly, to pay for. It seems that the Ludwig machine timpani is not a popular design therefore the drums sell for cheap. I purchased my 23" from Falls Percussion for $290 with shipping. One advantage to this system is that I can reuse the parts to create a 25" machine timpani in the future.

Most 23" timpani with extended collars actually take a 25" timpani head. A 25" bowl without an extended collar normally takes a 26" head. Therefore, my project will produce a 23" timpani with a 26" head, making a 1.5" collar, which is more common on timpani such as Hinger timpani. I cannot wait to see what this does to the sound. Unfortunately for now, I am planning on using the 26" Remo Hazy Renaissance head that I had mounted on the Slingerland 25" so the head is used, but I will not be reseating any collars. I believe the result should not be too drastically different than from a brand new head.

Spacer design:

While I could have had blocks of aluminum or brass machined to match the face of the Slingerland struts, I decided to take a cheaper (much cheaper) route. And this is where some people who may want to attempt a similar project should tune in. I decided to use 6061 Aluminum Alloy round stock. I could have decided to use square or rounded square, but my preference is round. I believe brass would work just as well if not better, but right now the plan is 6061 alloy. I may have the local machine shop do most of the work, but I could easily do this with a band saw and tap set.

I will cut 1" pieces of 1" diameter stock. Since I have 6 struts, I need 12 spacers; one spacer for each bolt coming from the strut. I am using 1" spacers because I need 2" of "missing bowl" space to make up for. (25" - 23" = 2". Or, bigger bowl - smaller bowl = x. Divide x by 2 to get spacer size.) Originally the struts had 2 bolts that attached it to the bowl of the timpani. I am going to use the original bolt holes to attach the spacers via a threaded hole in the aluminum. The other side of the spacer will have a hole drilled in it to align to the holes in the bowl - this is where the misaligned holes should not be an issue. The holes do not (and should not) be centered for 3 reasons: first, the strut has a slight curve in the surface to meet the bowl. By flat mounting the face of the spacer to it, it will continue that curve-angle to the bowl thus making the spacers point inward and making the center to center measurement smaller. Second, a deeper hole can be made if the holes on either side do not line up. Both of these holes need to be threaded using a tap set. I plan on threading the holes with the same size bolt previously used (5/16"?) just to stay as original as possible. Third, if the strut hole spacing is larger or smaller, it won't matter so long as the spacer can be drilled and tapped to meet the holes on both the bowl and strut surface. It may not look the greatest, but if the spacers need to stick out from behind the strut to align, that is better than re drilling or making any holes bigger.

With the spacers threaded onto the struts tightly (much like a nut and bolt assembly), they are then ready to be mounted to the bowl. As I am writing this I am wondering if I should use a rubber gasket of some sort.

Update 3/6:

I had 12 aluminum spacers made, slightly bigger than 1" which will give me room for errors, but I think they will be just fine. I tapped 4 today and they went onto the struts very nicely.
I removed some of the metal from the base as I had thought about doing and it in fact allows the pedal to move up farther on the post now, thus extending the range. The enamel paint I used to repaint the base with looks very nice and I like the color, but not only did I miss a small spot which I'll touch up soon, but it chipped a small amount where paint had previously chipped. (The spot where the metal meets metal on the pedal.) I tapped the bottom of the base and added a rubber foot-stopper. I think there used to be one there because as I was drilling I noticed a different type of metal coming out of the spot I was drilling - a spot where a bolt must have been before. I'm feeling very good about this project up to this point, so as luck will have it, something should go wrong soon, right? All I need to do is continue installing the spacers onto the struts then marking some holes and doing some more drilling and tapping. I plan on getting teflon tape for the bowl's edge. I also decided to get rubber washers to put between the bowl and the spacers - less metal on metal contact and it looks better.
I might cut T-rods that came with the Ludwig into normal key-tuned square rods. I could use them on "Frank" (the new 23") or on my 32" which has hex-bolts at the moment. It would be nice to match throughout the set.

In other news, the 25" bowl is currently serving as a drink holder for the pit orchestra of "Man of La Mancha" here in Denton. Don't worry, I have plans to make it into a timpani again someday.


Update 3/9: I decided to drill the spacers straight through rather than offset each hole. The angle of the strut actually places the screw right where it needs to be in order to line up with the holes in the bowl. This makes it easier to level the bowl and struts evenly. I put everything together and checked out the alignment and for the most part everything was really good. I decided to shorten the spacers to exactly an inch, when they were cut to 1-1/8". I am using the metal lathe to do that. This will allow the tension rods to go straight down rather than out at an awkward angle. Just with low tension tuning with t-rods, the drum didn't sound too bad. I have some teflon tape to put on the bowl that I got from Lone Star Percussion in Dallas. Their teflon tape is larger than most companies carry - 1" in width, giving more adhesive surface to work with.


Well everything went as planned except one thing: the range of the pedal and drum. I increased the range of the pedal as planned, but this had no effect on the severely decreased pitch range of the drum with an extended collar on it. In this experiment I have found the the farther extended a collar becomes, the farther decreased the range becomes. Although the finished project sounded very nice, I had to take it apart in the end and bend the Slingerland framing tubes to fit a 23" bowl. That worked out nicely and that is how I ended up with a 23" timpani (with non-extended collar.) One reason I gave up so easy without trying to figure a way around the range problem: the 23" just better matches the rest of my timpani this way. Another reason is simply the range. With the non-extended collar and the spider system from the 25" Slingerland, the 23" timpani has a working range from C# to B. Below are pictures documenting the project.

Removal of metal to extend pedal range

Closer view of removed metal

Making the aluminum spacers

Spacers attached to struts

Side view of spacers and strut

A closer view

Repainted base (enamel)

Putting things together

Almost done

All put together and done

The actual result of the long project is shown to the left. I'll admit I wasted a good bit of time trying to extend the collar on the 23". However, the lessons and knowledge gained from this experience have been great. If I ever try to extend a collar again, I will certainly use the same system of spacers with only 1/2" rather than the 1" design. I might use hexagonal aluminum to make working with it easier. I used vice grips to hold the spacers while drilling, however a clamping system would have been nicer.


© 2007 DK Percussion

DK Percussion
Daniel Kirkpatrick