Thanks all for the kind words, makes it even more worth while I got the head jigged at the next angle to mill the port faces flat and machine them up, The second of 4 skims, All flat, Roughing pass around outside to form the 4 flanges, Casting very near net so a .4mm finish pass got me machined edges on 98% of the edges, Same for the port entries, bit touched off in a lot of places. This is not that critical as the butterflies are not full sealing like a throttle body. Ports all ended up being within .3mm of being round so thats fine, Mounting hole locations spotted off for drilling/tapping later, From below, I have to mill on a few datum points before unbolting this setup but thats pretty much this jig up session done, Because we all love pictures: Later... Brian,
@ Sparrow, ah stop lol Its all very simple if you break it down, patience and a bit of inside out thinking is all it takes Got the faces grooved for O-ring seals, dropped in a cut O ring to give you an idea, Ill get the proper size when I need them, or make them up off the roll. (or screen print silicone in there) Head is now un-jigged again - will be getting re-jigged for the butterfly spindle bushing bores shortly, Ideally, and I probably will, Id like to check for swirl within the head when this is all done. Thats pretty easy measure in basic terms and I want it at the maximum for a more complete air/fuel mix at low rpm. I may or may not extend the splitter into the head to minimize cross talk between both runners(@ Injector) - lets see how it is first, Its probably pretty good as is. Thats a while off yet but Im just letting you guys know the forecast. BG,
Ok, so onto the next bit, Located some butterfly spindle shafting - its 7mm ground En24T(817M40T). The T meaning its been heat treated. This is serious gear and you do need carbide tooling to touch it, or last any length of time during that roughing period at least lol Im not going to slot this but instead mill it down past half way for 1.5mm thick butterflies. Machining 1.5mm slots needs carbide slitting saws which I dont have. Halving them is fine and done a lot on normal throttles for more performance/flow - supposedly. Given that those are under full vacuum pull and last, then these will be fine. They are not under any major vacuum 'pull' like the main TB. Im saying this because Im taking the spindles down to just 2mm thick. Im sure some would be nervous of this but if you are reading Ed theres no need for alarm - homework has been done. So onto machining...A holding jig had to be first made in some scrap alloy, First a shot of the bar - I got the faces tapped too for studs, the throttle shafts are going ''up and down'' and not side to side remember - Chopped bar up into 4 and mounted in jig, Milling, Milled, Had to re-jig all 4 again to bore the holes for the M3 screws holding the butterflies on, This was because I wanted the clamps near the action the first time round - they were too high for the very short 2mm endmill to pocket out the holes, you will notice the thinner plates(and M8 bolt) now holding it down and the clamps backed out of the way, Very short solid carbide bit, Holes milled - they were 2.5mm or so for the M3 tap(cant remember exact size, Managed to bore all 8 holes without killing the endmill, Tapping, Next up, the butterfly plates. I thought I had 1.5mm brass but it turned out it was 2.5mm so I went with CF instead. Have a good bit of 1.5mm lying around. This is prepreg made on a heated platten press so spot on for the job, I always use wood for a base when machining CF. Its fine for doing inner/outer profiles but you cannot use wood for half depth pocketing as it swells a little as the coolant gets into it and will throw your Z readings. It does mean you dont need to tap it for holding bolts though and you can just use screws with a plain shank for location, Clamped at outsides and drilled, 8 of the worst screws in the world now entered - ya need these to hold the circles as they are cut. They are also the fixing holes to locate CF discs onto the spindles, CF HAS to be cut with solid carbide. If you use HSS they will dull rapid and tatter the edges after a few inches. This is not all bad though as you use the sides of the cutters which are still possibly like new. You can plunge right down as far as you have a cutting edge to get a sharp spot. One thing you do need to do is plunge away from the finished edge and side mill up to it. You can see this tangential lead in move in the software below, Doing this means you dont burst out the far side if your cutter face is dull. Machining.... Feed very low - approx 40mm per minute @4krpm Machined, Free'd off the wood, I left .05mm on them - they are a pretty decent fit, All in, they are not going this way as mentioned, but ''up and down'' - vertical, but they 'store' like this easier... Brian,
I almost didn`t click this thread, but boy, am I glad I did. ! Really like reading about this sort of manufacturing / design. Many thanks for the updates on what you are doing
Thanks again gents. @Nige, I think if something is explained it takes all the ''Where would you start'' questions out of the equation. Same goes for materials and machining too, and all the rest. Its all about keeping the ''Thats not possible'' thoughts well out of your head and take on the notion anything is possible. That works for me anyway lol So another bit of an update now that my phone is on charge, Wanted to get the curved section upto the runners pegged down and the mould box done so I made a start on it. Im waiting on bearings for the throttle spindles and Im not going to chance boring an interference fit for them until I have them in my hand. This mould is a little trickier than the first as its curved in both planes and has undercuts. First, I mapped out the curve with some brake pipe. You could spend 3 days drawing all the various parts in Solidworks including the head but I took the easy way out and just mocked it on the bench. A plug is tapped into the port and the pipe inserted and bent up ''nice'' around and onto rocker, A disc is turned to size clearance with everything, There are a few marks cut on the pipe to let me know datum's or points of importance, These marks are then dotted with paint so I can see them, if you look close you can see two blue marks at the left of the disc. The leftmost dot is where a straight line intersects the pipe when taken off the flat face of the flange below it.. The pipe is then removed very carefully and transferred to mill, this all looks a bit flimsy but it actually works very well provided you dont bend the pipe handling it or anything, Before its tacked down its rubbed with a file to give a shiny pipe center datum, It then gets tacked, The mapping can now begin, the mill is zero'd on one of the blue dots, the drawing is also zero'd at this point - basically, everything is set to ZERO here , The mill is now manually walked to the dot at port entry, and 7? other random points along the pipes curve. The co-ordinates of the mill at each location are noted and transferred to the drawing at the same time(manually) Here is where the mill is reading when parked above - Enter these co-ords in drawing, And BOOM circle moves to correct location of mill... If you were really good at joining the dots in school then you wont need many of these points to get what you need...I went with I think 7 on the curve, And you just then join the points on the drawing, You then have the dead center of the runner, the bottom flange angle, and the top end angle. The entire mould is based around these three critical locations. Below you can see a cross-section starting to emerge... Its worth keeping in mind that the runners also have to curve in the other plane heading 44mm to the right as you look at engine. Its possibly a good Idea to transfer this cross-section to Solidworks at this point and add the 3d aspect/features but since Im not communicating this drawing with anyone Im comfortable enough doing the 3d part in my head off the 2d drawings. I have more the reason to do so as the mould will be built, and not cnc'd from a solid block of wood or model board. You could use those and do it that way if you wanted, but that then means 3d drawings for sure and a lot of time wasted in the process on a fairly simple part. I feel this way also gives hope to anyone without a cnc or Solidworks. A lot of folk think that you need a cnc to do anything - you dont...your head is far better than a cnc ever will be so keep the faith! Im glad that terribly boring post is out the way now...but it is important I guess on how you get a curve like that onto a screen without a 3d scanner or other 'stuff'. Brian,
