Router Drum Mill

Router mills are the go to shop fixture for stave and segmented drum builders who don't have or choose not to use a lathe. I'm not anti-lathe, but I'd want a precision setup with autofeed and a machine capable of turning 14"+ diameter shells isn't small, nor in the current budget.

A quick search will produce pages of results with varied designs, so I'm not blazing any new trails in that regard. Instead, I'm taking what I deem to be the best parts of multiple existing designs, combining them into a dual purpose machine, and further expanding on my modular drum fixture system.

The risers I made for the Table Saw Drum Mill will fit onto this fixture for the outside milling operation. And the conveyor rollers for this fixture are shorter version of what I used for my Drum Shell Roller Jig, so they're also cross compatible.

A lot of the components were built to fit and measured afterwards, so while I'll drop dimensions here and there, I'll also list them all in the final step for those interested.

3/4" plywood
Screws
Carriage bolts
T-nuts
3/8" acme rod and nuts
5/16" star knobs
1/4" acrylic
1/16" aluminum angle stock
Conveyor rollers
Aluminum angle stock
Fender washers
5/8"top collars
Minimal blood and sweat
No tears

The deck is made from 3/4" plywood - cut to 20" x 36" [Fig. 1-2]. In the dead center of the deck, I drilled a 1 1/2" hole [Fig. 3], which I then rounded over on both sides. I'll probably never use this hole, but I might want to the option of mounting a router on the underside in the future, and it's easier to drill the hole now than later.

Next up were dadoes - around 1/4" in depth. I'm using a dado stack set up for 3/4" plywood.

Fence Dadoes: A central field of 27 1/2" is necessary for the rollers, so I mark 13 3/4" left and right of center to establish the inside cut line. Once that was cut was made on both ends, the fence was moved and successive cuts made until two layers of 3/4" fit into the recess [Fig. 4-6].
T-Track Dado: A centered groove was cut down the length of the deck in one pass [Fig. 7].
Side Gusset Dadoes: Fence was set 1 1/4" from the blade edge and stop blocks used to make the cuts [Fig. 8-9].
Note: I did make two of the cuts from the backside of the saw (reverse). That's like making a climb cut on a router, so don't do it unless you are comfortable with machine and accept the risk.

The fence stock is a 2 layer lamination of 3/4" plywood. It was glued up oversized and once cured, cut to final dimensions of 4 7/8" x 20" [Fig. 1-4]. Dadoes were cut into outer face to accommodate support gussets.
Note: The dadoes were cut at the same time as the deck to ensure accurate alignment.

The gussets are 3/4" plywood. The height of 4 7/8" was known and i just marked the width in place [Fig. 5]. The flat offsets were marked by eye, connected with a line, and then the Rockler crosscut sled used to batch out six identical parts [Fig. 6-8].

The fence slots were cut on the router table with a 1/2" bit, a lot of set up, and some clenched cheeks.

The router fence was tightened to the table and then a few more turns were made for good measure. Stop block on the left ... stop block on the right .. and a larger piece of wood clamped to the front of the table. The large block keeps the work piece tight against the fence.

This type of plunge cut on a router table can be intimidating because the bit can be "grabby" due to the climb cutting forces.

The slots were cut in multiple passes - raising the bit each time. A CNC would be more comfortable, but I don't have one. Another method could be using a template and guide bushing, but you'd probably need to make the cut from both sides for this depth and getting perfect alignment would be tricky.

With all the deck, fence, and gusset parts complete, it was time to drill. Layout, awl punched, drilled with a 1/8" bit, and applicable faces countersunk [Fig. 1-3].

Secondary drilling was done for the risers and those holes were marked using a setup block from when I fabricated the risers. Outside face holes are drilled with a 7/8" Forstner bit to recess the T-nut flange [Fig. 4], then through drilled at 5/16".

The T-nuts have 3 prongs, which I mark and pilot drill to avoid splitting of wood. The T-nut is then hammered into place [Fig. 5]. Bolts on the risers thread into these fence T-Nuts to lock the parts together [Fig. 6-8]

After test fitting the risers, I screwed the fences and gussets in place - no glue in case I want or need to make modifications. Few screws for the fences, clamps and a speed square for alignment ... more screws [Fig. 9-10].

The majority of router mills I've seen use casters for the inside milling operation and my initial designs followed suit, but in the end they added unnecessary complexity in regard to adjustability for varied shell depths and diameters. After building a few roller jigs, I found myself joining the minority and using 26" conveyor rollers [specs at bottom of this step].

The roller brackets are made from 3/4" plywood and I need four of them, which I'm making as connected pairs for two reasons. The larger board is easier to work with and I had no idea of the final dimensions. Board width is 3 5/8" - they need holes and slots.

Holes [Fig. 1]
Hole locations are 1/5/8" up from the bottom and 2 1/4" in from the short edge.
Drilled first with a 3/4 Forstner bit to recess the carriage bolt head and followed up with a 5/16" through hole.

Slots [Fig. 2-4]
To cut the slots, I used my Multi-Function Router Table Jig and a mess of stop blocks. Blocks on the sled for alignment and blocks on the track for a depth stop.
Slot position: 3 1/4" in from the edge
Slot depth: 1 7/8"
Note: Bolts were removed to cut the slot on the opposite side of the board.

After a quick test fit, I cut the blocks to a final length of 5 1/2" using the small parts crosscut sled on the table saw [Fig. 5].

1/2" PEX, which happens to be 5/16" ID, was used as a bushing to prevent the threads from chewing up the plywood. Length was cut to fit using the crosscut sled on the table saw [Fig. 6-7].

The roller axles were longer than necessary, so I wrapped them in painters tape, marked them at 11/16", and reduced them using an angle grinder with cutoff wheel [Fig. 8].

Assembly
The bracket bolt/bushing go through the slot from the inside. Washer and star knob go on from the outside. Quick and easy adjustability using a combo square for accuracy.

Roller Specifics
Medium duty rollers from Grainger - $19.25 each at time of purchase.
1 15/16" roller diameter
7/16" axle
26" between frame width
Item #: 24K708

The router carriage is made from 1/4" thick acrylic cut to 4 3/4" x 10". The dimensions were determined by the router base casting and I made it as narrow as possible. The width of the router base casting is 4", so I added 3/8" to each side and landed on 4 3/4".

Masking tape and the router base were used to mark the bolt location, which were then drilled and countersunk at the drill press [Fig. 2-3].

To accurately mark the router bit hole location, I used the actual router, a small V bit, and manually turned the collet. The acrylic was then removed and a 1 1/2" hole was drilled using a Forstner bit at the drill press.

The router rail starts with 3/4" plywood. 4 3/4" width to match the carriage x 27 1/2" length, which is the spacing between fences [Fig. 1-2]. 1 1/4" aluminum angle stock was then cut to two lengths of 27 1/2" using the crosscut sled on the table saw and then one side was ripped to a width of 3/8" [Fig. 3-4].

The aluminum stock will be attached to either side of plywood and hook over top of the acrylic, which create a channel/runner for the carriage. I did a test fit before drilling holes [Fig. 5-6].
Note: The aluminum purposely extends past the bottom of the plywood for auto-alignment regarding not yet built rail support.

I arbitrarily opted for seven evenly spaced #8 stainless steel machine screws on each side and those holes were drilled with a brad tip bit at the drill press [Fig. 7].

The router rail needs a slot for the router bit, which I mistakenly placed in the middle and had to redo because the actual router base is offset. The pictures are from the first attempt, but the process is the same.
1. Mark the center of the holes 4 1/2" in from each short end.
2. Drill a 1 1/2" hole using a Forstner bit. My process is to drill most of the way through from one side, flip the board, and use the pin hole as a center guide to finish the hole from the opposite side [Fig. 8]. I find this is more effective at eliminating blow out compared to a backing block.
3. Remove most of the waste material. I used the table saw, but a jigsaw would work [Fig. 9].
4. Remove the remaining material and make a perfect slot using the router table [Fig. 10].

For assembly, I used the router carriage and a second piece of acrylic as spacers to auto align the aluminum stock. Screw location were punched with an awl, pilot drilled, and screws driven [Fig. 11].

Wax was applied to the channels for smooth running [Fig. 12] and then I couldn't resist a test fit [Fig. 13].

The center T-track is from Rocker and it's function will make sense in the next step. It was cut to a length of 12 1/8", spaced away from the fences to accommodate the risers when in place, pilot drilled with a Vix/Vicks bit, and attached with screws [Fig. 1-2].

Interior milling operation test fit was successful [Fig 3].
Exterior milling operation test fit revealed a beneficial modification. If the aluminum was notched in 3/4" from each edges, it would friction fit between the risers and basically auto-square itself to the drum shell [Fig. 4-5].

These parts serve a dual purpose as they support the router rail and keep the shell tracking inline during the interior milling operation. The slide along the T-Track so that they can be adjusted for various shell depths. The measurements for the parts are a bit crazy [listed below], but I was cutting to fit and rabbets are involved. The only imperative dimensions are the width and finished height.
4 3/4" width matches the router rail and friction fits between the aluminum rails.
3 5/8" height matches the roller brackets.

After ripping some 4 3/4" stock, I started with the "bottom panel," which gets a centered 3/4" groove, so that it can register onto and slide along the T-track [Fig. 1-3]. The other side of this "bottom panel," as well as one side of the "front panel," gets 3/4" rabbets on the long edges [Fig. 4].

A quick test fit with a star knob to determine required size before cutting the panel into individual parts [Fig. 5-6], then back to the dado stack to cut a rabbet on one more edge [Fig. 7]. The front panel was then cut to the required size and I used offcuts to source the gusset. As with the fences, they were just cut to fit - no measuring before the fabrication [Fig. 8-9].

Hole locations for the 5/16" T-bolts are centered side to side and 1 1/4" from the back edge - the edge without a rabbet. These were punched with an awl and then drilled using the press.

For quick assembly, I used wood glue and pin nail [Fig. 10]. Once the glue was set, I added screws for strength [Fig. 11]. I then cut out a notch for the router bit, which was done using the small crosscut sled on the table saw [Fig. 12].

For 14" and smaller diameter drums, two of these are enough to keep the drum inline and support the center of the router rail because the roller brackets are in close to the shell and support the ends of the rail. Should I want to mill something larger than 16", I might need all four. Better to make them all at once to ensure they match.

Dimensions
Bottoms: 4 3/4" x 3 1/16" x 3/4"
Fronts: 4 3/4" x 3 1/16" x 3/4"
Gussets: 2 11/16" x 3 1/16" 3/4"

I could easily advance the router carriage by just pushing it, but a lead screw is exponentially more fun. I won't get into most of the dimensions of the wooden parts or hole locations, but those are relative to the router being used - specifically the cast base of the router. I'm using 3/8"-8 Acme rod and screws from McMaster-Carr - 0.125 travel distance per turn.

Carriage Screw Block
Solid wood is best for this part and I used Poplar. I want to run the Acme rod through the cut out area at the bottom of the router base, so I sized my block for that area and marked the location for the hole [Fig. 1]. Acme flanged nuts (think T-nut) are available, but too rich for my blood, so I just used a standard Acme nut. A 3/4" hole was drilled deep enough for the nut and then the remaining depth drilled at 3/8" for the rod [Fig. 2]. The nut was persuaded into the hole with a rubber mallet and to keep it from working it's way back out, I secured a 7/8" fender washer to the block with two screws [Fig. 3].
The block is attached to the acrylic carriage with two screws - opposite corners and one on each side of the rod [Fig. 4]. Holes are countersunk so that the screw heads don't bind on the router rail [Fig. 5].
My Block dimensions: 1 1/2" high x 1" wide x 1 3/4" long

End Blocks
These blocks are 3/4" plywood, 1 3/4" high and the width was cut to fit between the aluminum. The rod was
threaded through the carriage block and used to mark hole locations, which were then drilled using a 3/8"
Forstner bit [Fig. 6]. A clamp was used to hold the block in place while pilot holes and countersinks were drilled -
three screws each and no glue in case I needed to modify them in the future [Fig. 7-8].

Rod Assembly
The Acme rod is fed through one end block, threaded through the carriage screw block, and fed through the opposite end block. A fender washer and two nuts go on the outside of each end block, which are jammed together [Fig. 9-10].

Handle
Taking inspiration from my small metal lathe, I made a round handle. It's a 4" diameter 1" thick plywood disc with a 3/8" center hole and an offset hole for a recessed 5/16" T-nut - 7/8" for the flange and 3/8" for the barrel [Fig. 11]. The knob is a 2" length of a 1" diameter poplar dowel with a not so straight 5/16" hole drilled through the center [Fig. 12].

The 3 1/2" long carriage bolt goes through the dowel, through the offset hole, and threads through the T-nut. Once the desired tension is achieved, a 5/16" jam nut is added on the back side against the T-nut flange [Fig. 13]. The disc is secured to the Acme rod with a fender washer and nut on each side, which are tightened towards each other. This locks the disc so that it actually turns the rod instead of just free spinning.

Nothing fancy for finish ... just a seal coat of shellac. That's enough protection to stave off shop dust and human hand oils.

This is a deceptively dense project and while I could try to explain how each configuration works via text, I think video footage of actually milling drum shells is more beneficial.

I don't have a "tour" video of the mill .... yet. However, I do have footage of milling real life customer drums.

Exterior Milling

Interior Milling

Dimensions
Deck: 20" x 36" x 3/4"
Fences: 4 7/8: x 20" x 1 1/2"
Roller Brackets: 3 5/8" x 5 1/2" x 3/4"
Router Carriage [Acrylic]: 4 3/4" x 10" x 1/4"
Router Rail: 4 3/4" x 27 1/2" x 3/4"
Shell Fence/Rail Support Bottoms: 4 3/4" x 3 1/16" x 3/4"
Shell Fence/Rail Support Fronts: 4 3/4" x 3 1/16" x 3/4"
Shell Fence/Rail SupportGussets: 2 11/16" x 3 1/16" 3/4"
Acme Rod: 3/8"-8 x 36" length
Round Handle: 4" Diameter x 1" thick
Handle Knob: 1" diameter x 0" long poplar dowel
Roller Specifics: 1 15/16" roller diameter - 7/16" axle - 26" between frame width | Item #: 24K708