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Spraymist

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bogstandard: You are spot on Chuck, D-bits can get you out of those silly situations you tend to end up in where there is no easy way out of. If care is taken, they are a fine replacement for a reamer. The one I have made doesn't have to cut on the nose, so to give you some idea of what it should be like with a cutting nose, say for a blind hole or as a reamer, I have done a C-o-C sketch. I was hoping to get this nozzle finished very soon, but personal issues have taken it's toll, so it might be a couple of days still. John

bogstandard: Lets get this nozzle finished off. I have almost done the inside bit, but before going any further the outside nozzle needs to be made. So a bit of brass bar about 2" long was chucked up. A 3mm hole was drilled to a depth of about 40mm, then it was followed down by a 10.5mm hole to a depth of 12.5mm. Time to break out the D-bit I made the other day, in the hope that it works (not really, if you make them to the basic dimensions I showed, they are almost guaranteed to get the job done) I had marked it up so that it would penetrate to about 35mm. The lathe was set to it's slowest speed of 65 RPM. It is then a matter of pecking into the hole and clearing very often. As you can see, it is doing a lovely job of scraping the shape out of the inside. As I have said before, if you can make a good one, they can be used instead of a reamer. But that 1 or 2 thou thicker than centre and razor sharp edges are critical. To allow me to get super fine adjustment for the nozzle, I threaded the inside bit with 7/16ths by 40 TPI. This is the same pitch as an imperial micrometer uses, so one full turn of the nozzle will move it backwards or forwards by 0.025" (0.62mm). The nozzle was turned around in the chuck, and the end faced away until there was 3mm straight portion left of the previously drilled 3mm hole. After that it started to open out into the taper I had cut with the D-bit. The topslide was then set over by 11 degrees, the same as the internal taper. This shot from the top is when I was cutting the outside taper using the topslide. This is what it ended up like, a 3mm straight bit at the nose and then the taper. This should be the same as the profile on the inside. I did a little more work on the outside, but nothing that really deserves a mention. So now onto the other bit of the nozzle. The end was faced up and an external thread the same as the other was cut onto it. The two mating parts. Now I just need to get the tube into the inside bit. The inside part was tapped out, and to cut a long story short, the bit of brass was drilled thru with the same diameter as the tube and a thread cut to match the small thread just cut was put onto it. After Loctiting the tube into the holder, the assembly was screwed into the inside part. If necessary, different sizes of tube with their holder can be made up and screwed into position. The business end of the nozzle. Do ya feel lucky, punk!! This is how it will fit onto the locline. By doing it this way, I have about 10mm adjustment of the outer nozzle in relation to the inner one. You might think I am going to a lot of trouble making this nozzle. By doing it this way, with adjustments to the critical positions and sizes, I should be able to find the ideal settings that I want, and be able to replicate an easier made nozzle for the four units I require. Plus I should also be able to do a sketch so that people can make their own if they want. So all this work will not be wasted, it is called R&D. The control block will follow soon. Bogs

Russel: Wow, that nozzle looks great! Thank you for posting this...I wouldn't even know where to start. Now I have more great info to file away between the ears, until I need it. Thanks again, Russ

kvom: If I understand it correctly, then the tapered D-bit is cutting only on the left edge, so you needed to offset it a bit on that the right side wouldn't rub.

NickG: Thanks John, I've seen people making d bits before but never tried it. Will definitely give it a go now. I don't have a set of reamers, all mine are ancient and large and just chucked in a box which as you said once means they are probably all damaged. Nick

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