Thanks for the comments guys. I do assume that the forum is hanging on my every word and awaiting the next installment with baited breath
The mixer (although I tend to think of it as the carb). Jerry used a PM Research elbow casting. Not easily available in the UK so first thing is to fabricate an elbow from 3/8" diam. brass. I milled a recess into a bar with a 3/8" endmill to slightly less than half depth. The picture is actually of a test run on a bar end
Then another length of 3/8" brass was reduced to 5 thou less than the diameter and slotted into the recess, fluxed and a ring of silver (hard) solder placed around the upright
Then warmed up until the solder flowed
I'd put centres into both of the components before assembly as an aid to setting up in the small 4 jaw chuck for drilling the holes to match up at the corner (sorry about the focus
)
After some careful filing we have an elbow
The body of the carb is made from 1/2" hex brass. After facing in the lathe I transferred the chuck to the dividing head in the lathe and lined up one side of the hex with a set square
After rotating to bring a face to the horizontal I drilled and reamed 1/8" for the spray bar
The spray bar is held in place by a set screw so I had to mill a starting flat but the ER25 collet was to big to bring the endmill close enough to the job so I resorted to using an ER11 collet holder with a 1/2" shank held in the ER25 collet
Then drilled and tapped
After returning the chuck to the lathe the through hole was drilled and a bit of hand turning finished off the end
Here's the finished body soft soldered with solder paint to the elbow (you'll notice that the elbow is very nearly a right angle!)
The spray bar needs to have some scary small holes in it. I very rarely use the larger drive pulley on my lathe but I went for the highest speed I can get of 2500 rpm. It all went very well. The tailstock feed on a Myford Super 7 is a 3 start square thread which is quite quick to advance and retard when pecking a hole.
The jet is #76 (0.5mm). Transferred to the mill, I had to put a centre dimple first before drilling using the sliding small chuck holder at the mill maximum speed which is also 2500rpm
The finished (well I guess I will polish it) spray bar
The needle was made from an 8BA screw
Don't let anyone tell you that you can't take fine cuts with carbide. This is a CCGT tip with a 0.2mm radius
The needle is finished off with a knurled brass knob, tapped and loctited in place. My knurling tool lives in the Gibraltar tool post - it's too big to fit into a QC holder but is quick to exchange with the top (compound) slide.
The finished mixer
Lets hope it works
