Kozo K-27 Rods



Before I get too far with the rods, I need to quarter all of the drivers. This is the start of a jig to perform the quartering. I didn't get too far on this today as the metal shop took forever cutting of a length of stock for the rods. December 31, 2020.


A V-notched plate will be added to each end of the jig to set the 90 degree angle. A clamp will be added to the center plate to strap the axle into position. December 31, 2020.



The V notched end plates have been added which will allow the cranks to be set 90 degrees apart from one another. A pin will be slipped into the left crank and be clamped down to the block at the front left side of the jig. A pin can then be slipped into the right crank and brought up against the V block to set at 90 degrees. The cranks are initially locked into position with Loctite retaining compound. Once dry a pin hole will be drilled through the back flange of the crank and through the axle to insert a locking pin. January 1, 2021.


The jig has been completed with the two brass straps to hold the driver set into position. The left crank has already been pinned and is strapped to the jig to keep it up against the stop. Retaining compound has been spread on the right end of the axle and the crank has been adjusted so that the pin through it is advanced to the 90 degree stop. The assembly will be left in the jig while the retaining compound sets and then a 1/8" pin hole will be drilled through the crank flange and axle to pin it in place. The remaining three driver sets will receive the same treatment. January 3, 2021.


This is about as far as I have been able to get on the main rods since I am waiting on a special bit for fluting them that must be on a slow boat from China. These things are pretty hefty with a width of just over 3/4" x 10 1/4" long and 5/16" thick. They will have bushings added at both pin locations. January 9, 2021.


Work is progressing on the intermediate side rods that will run between drivers 2 and 3. These are about 5 1/4" long and 1" wide at the main crank hole. The lower piece has been heavily machined as compared to the blank at the top. A slot will be cut in the small end for the knuckle joint and then there will to be some radius cuts to finish up both ends. January 10, 2021.


The second intermediate side rod has been machined and a slit cut in the knuckle joint of each rod. This is the stopping point until all of the rods have been completely drilled to match the crank pin spacing. Each rod will then finish shaped with various radius cuts to match the prototype (they still look a bit blocky). January 18, 2021.


The special corner radius key cutter bit finally arrived so I worked on the fluting of the main rods. This requires three different cuts with one straight between the centers of the two holes. The second and third cuts require that the large hole end be dropped down in the vise to angle them away from the center. The small hole end is left at the same height for all of the cuts by pivoting around a rod through the hole. The backsides of the rods will require the same cuts to make them symmetrical. January 24, 2021.


With the fluting work completed attention now turns to shaping the rod. This one has been tapered from the big end down to the small end. Next the small end will get a radius that will taper down to meet with the narrower fluted portion. January 31, 2021.


Both of the main rods have been tapered from the big end down to the small end. The thickness of the I beam portion of the lower rod has been reduced to the final size. The upper rod will need to be thinned and then both rods will be rounded at the small end. February 7, 2021.


One of the main rods has been finished to the final shape. This required a number of cuts on the small end for the radius on the end, the taper and the fillets at the transition from the small part of the rod to the end block. The other rod will receive the same treatment and then there will be some appearance bolts and an oil cup added to the big end. May 16, 2021.


Both of the main rods have now been machined to the final shape. Oil cups have also been machined and added to the big end of the rods. There is still bolt and nut detail to add to the big end and bushings at each end.  May 23, 2021.


The front side-rods are a work in progress with each starting from a 3/8" x 1" x 6" piece of steel. Each end is offset from one another so there is a heavy side cut started on the upper rod. The bottom rod still needs quite a bit of machining. May 30, 2021.


The front side-rods are mirror images of one another so this view provides a look at both sides. This is about as far as the machining can go until all of the rods are fitted on the engine with final holes drilled for the crank pin of driver 1 and the hole in the tab for the intermediate side-rod. May 31, 2021.


This the start of the rear side-rods that will have a knuckle joint at one end and a bushing for the driver 4 cranks. The top one will require some milling on each side for the offset and then the grove for the knuckle joint. June 5, 2021.


This shot provides a view of how the rod set will connect once completed. Final drilling for the joints and the front driver crank pin will be completed with a set of drilling jigs. Once fitted to the engine the final profile of each of the rods will be completed. June 5, 2021.


The sides have now been profiled on the rear side-rods. Next will be the cutting of a slot for the knuckle joint. June 12, 2021.


The slots for the knuckle joint can be seen in this top view of the rear side-rods. June 13, 2021.


Next up are the drilling jigs for the side rods. The holes are spaced at the designed spacing of the drive axles. There will be plugs added at each hole with one visible above. The outer diameter of the plug will fit into the driving box with smaller diameter being the size of the main hole in each of the side rods. The part of the plug that extends into the jig is a slight eccentric that will be used to adjust the two plugs so that they fit into two adjacent driver boxes. Once the eccentric is rotated to where the plugs fit into the driving boxes the location will be fixed and provide the exact spacing for drilling the knuckle joints in two connecting side rods. June 19, 2021.


These are the three jigs that will be used to accurately drill the side rods. Three of the plugs are the same and have an eccentric so that the plugs can be aligned with the driver box holes. The opposite plug on each jig is sized according to the rod that is being drilled. The top jig "A" is used to drill the knuckle joint between the rear side-rod and the intermediate side-rod. Jig B will be used for the knuckle joint between the intermediate and front side-rod. Jig C is used to drill the driver 1 crank pin hole in the front side-rod. June 26, 2021.


This is an example of a rear side-rod and intermediate side-rod set up on the jig. The hole in the knuckle joint can be completed with this jig. A bolt and washer will be used in each of the plugs to hold the rods in place for drilling. June 26, 2021.


After a long break for summer trips it is back to the side rods. The drilling jig for the rear and intermediate side rods has been adjusted for the axle spacing of drivers 3 and 4. With the spacing set the rods are mounted for drilling and reaming of the knuckle joint on the the milling machine. September 6, 2021.


Now that all of the side rods have been drilled on the jigs it is time to start working on the final shape. This is the pair of front side rods with all of the various arcs cut. These will still need to be cleaned up and the lubrication holes drilled in the tops once the bushings have been installed. September 11, 2021.


The arcs at each end of the rear side rods have been cut. There still need to be a transition arc cut from the center of the rods to each end. After that some cleanup and bushings for the large end. September 12, 2021.


The front and rear side rods have been cut to their final shape. They still need oil holes drilled, final clean up and bushings added. September 18, 2021.


Final shaping of the intermediate side rods is progressing. Just some final shaping, oil hole drilling, final cleanup and bushings remaining. September 19, 2021.


These are the two sets off rods after a bit of cleanup. Next will be the machining of the bushings. September 25, 2021.


The bushings for the large end of the main rods have been machined from phosphor bronze stock. September 25, 2021.