Werowance attempts Upshur Vertical Single

[Sprocket]

Mid shaft sounds right. There is a section of the needle where the sides are parallel that is going to be soldered into the cap. The eye gets cut off, and the tapered tip is used for adjusting fuel flow, so the midsection is all you can really measure.
Also, looking at A.Wakes plans, are there really any flat bottom holes? It looks like there are always through holes with a smaller drill, which pretty much takes away the tip, so you could measure from the lip, or edge of the flute because the pointy part is going to be drilled away. Maybe I'm not looking at the same places you are.
Doug

 

[werowance]

well, im looking at the jet tube, .040 is the thru hole, but then followed by .052 on one side and then .063 on the other side. which both appear to be depicted with flat bottom holes. and since its such a small part i wanted to make sure that the .052 and the .063 were not flat bottom as well as where on the drill did awake start at. hoping not flat bottom and that he measured from the point of the drill which will make life much easier

 

[Sprocket]

That's what I was looking at too. Truly, they are not flat bottom but what remains of your drill point angle for a distance of half the difference in drill diameters. It is too small to show up in a drawing. It's good to try to hit the dimensions exactly, but the difference between the point and the lip of a .063" drill is only .019"
for a 118 degree point. Less for a 135 degree point. The important thing here is that you don't drill through, and the plans show .100" of .040" hole. The .063" side is gas inlet, and probably not too critical. the .052" side needs to be past the spray bar hole a little, but again, the difference between .052" and ,040" doesn't show up as an angled end to the hole, but it is, slight as that may be. But what the plans show as a measuring point is the intersection of the drill lip (flute) with the side wall, so if you really want to hit the measurement, start when the lip hits the surface. Hope that makes sense.
Doug

 

[werowance]

sprocket, "when the lip hits the surface" is probably the best description I have heard. I appreciate that very much.

 

[awake]

Oops, sorry - I missed the questions until now. No, the only flat bottom is the one I have been sitting on for too long! I blame the person who drew up the CAD plans ... oh, wait, that was me.

In general, I start measuring from where the drill tip ends and the full body diameter begins. But let me hasten to say that 1) we're only talking a few thousands difference - there's not much tip length on a .051" or .040" drill bit; not much even on a .0625" - and 2) there is some wiggle room in the design, especially at the bottom. The .0625 hole in the bottom of the jet is really there just to keep from having to drill the whole length at .040". I confess that the decision on how long the .040" section should be was based on highly sophisticated TLAR engineering - That Looks About Right! Certainly when I made it, I did not attempt to be overly precise with measuring the depth of the holes - I expect I was within .010" to .016" of the designed depth, but that's as much as I can promise when drilling on the lathe.

I also can't promise that the upper section of the jet that I made matches the design as drawn; basically, I bought a pack of needles off of Amazon and picked the one that seemed closest to what I needed, then drilled accordingly.

on edit: Sprocket said it perfectly!

 

[werowance]

i went to hobby lobby yesterday and found some darning needles - an assortent pack that had a #18 as its highest number in the pack. i measured each needle in mid shaft moving up and down a bit to make sure i was on the straight section and not on taper or swelled eye end of the needle. the 2 closest needles were .048 and .055 mid shaft and the largest was .06something which was way to big. so with .048 and .055 as my choices which would be the best to use? or should i just pitch those and try to find one closer to the right size?

 

[awake]

As best I recall, the needle I used was in the range you are talking about ... but I don't remember which. I don't know if it would matter between those two sizes - ?? Just drill the hole the needle goes in accordingly to give an easy sliding fit. Or at least, that was the assumption I made. But keep in mind that I have built a grand total of ONE carburetor. It worked ... but was that sheer luck, or clever TLAR engineering??? I need to move on with my second engine so that I can double my experience.

 

[werowance]

Thanks Awake, one more question, do you remember what your base needle setting was when starting your webster on this carb? might make starting mine a bit easier having a "rough" sarting setting.

 

[werowance]

well, all i can say for tonights work is grrrrrr.
im on jet tube number 6 now. first one was a simple mistake, started from the wrong end before i thought about it but the rest is i keep botching the 8-32 threads on the tube. it just wipes them out like i was just cutting it round with a lathe and not using a die. ive had this before and its usually because im going to big with the stock, not putting enough preasure on the die or not using cutting fluid. but i just cant seem to get it tonight so i quit for tonight and went inside to eat the japanese yakanikanu (beef) my wife brought home for me for supper and now im stuffed and searching for proper outside dia of 8-32 when cutting with a die. may just go measure an 8-32 bolt tomorrow idk.. but tonight its time to quit and pout about it lol.

and for anyone reading this, the carb jet tube should start on the end that the needle sticks in so that all the drills and threads on that side are exact, the opposite side of the jet tube isnt as important as its just the fuel inlet side. ( first failure but only a .250 loss in stock is all)

 

[Sprocket]

Make sure you are starting from the right side of the die.
You may wonder how I know....
Also, make the part 1/8 or so long and file a little taper on it to get started, then trim that later if you need to.

 

[werowance]

well, i was always told to start the die on the sharp side however i have always had better luck starting the die on the tapered end of the die threads. that said i tried both. on the 1/8 or so longer, yep did that and usually take a ******* file wile lathe running to taper / angle the tip for easy starting but tonight i think im just beat and needed to walk away. that said am i right on the starting a die on the sharp side instead of the tapered side? even though i always have better luck the opposite way?

 

[Sprocket]

They often say “start from this side “ on the die and that’s the tapered side to make starting easier. Then you can turn it around to get more complete threads further up the part. You could also turn a short section to the minor diameter ( tap drill size) and that can ease starting too.

 

[werowance]

Thanks Sprocket, thats how i normally do it. start with the tapered end of the die, run it up, when im as close to the end as i can get then i back it off turn it arround and run up the non tapered end of the die which normally gives me better threads as well as threads all the way to the end with full threads that way.

makes me feel better that my technique is right. its got to be the outside dia i am starting with plus a build up of frustration. i hope i get a chance to try again tonight.

 

[Brian Rupnow]

I do it the same way--start the die on the tapered side, and if I'm threading up to a shoulder then I turn the die around and use the untapered side to get in tight to the shoulder. If the treaded part is screwing into something that the shoulder must bear against, then I will go in with a 1/16" wide parting off tool and undercut the thread a little bit. If you are having trouble getting the die to start, then turn a small 60 degree included angle on the end of the part to be threaded.---Brian

 

[awake]

Thanks Awake, one more question, do you remember what your base needle setting was when starting your webster on this carb? might make starting mine a bit easier having a "rough" sarting setting.

For a cold start, I close it all the way, then open it up about a quarter turn - maybe a bit less. I'm sure the specific shape of the needle used will have some influence on this setting. I open the throttle (air passage) half-way or more. Most of the time I can hand-start it, though sometimes it is recalcitrant and I have to resort to the drill starter. I usually run with a few degrees of advance on the timing.

 

[awake]

Interesting on the use of a die - I almost never use a die to create a thread; instead I virtually always single-point it. Sometimes I may use a die to finish it off, especially if I need to get as close as possible to a shoulder. My practice may reflect the fact that the vast majority of the dies that I have on hand are the cheap carbon steel import specials that I bought at the very beginning ... or maybe the fact that I've never upgraded to better dies reflects the fact that I always single-point. Hmm, chicken or egg ...

 

[Sprocket]

Actually, I always single point to start ,too. I finish with a die just to get it as close as I can. I didn't try single pointing with my old lathe because minimum speed was 150 RPM and I found that scary, but with the South Bend I have now, I can thread in back gear at 50 (?) rpm and it's very controllable. I don't know what Werowance is using, so didn't suggest it. It is definitely a skill worth learning.
Doug

 

[werowance]

well, single point threading is something i suck at. i almost always use a die. but GOOD NEWS. the problem was found. the new die that i had never used in my kit was awefull. inspection under a magnifying glass (my eyes are getting bad at 46 - ugh) shows horriible threads. i pulled out a very old northern tool and equpment tap and die set i bought over a decade ago before i even had my first lathe. they were rusty, hex dies but first attempt on a few test pieces gave nice deep threads. ill try to upload some pics of the bad die and the cheap rusty one. at any rate i still failled on now attempt 8. but this failure was my fault as i was drilling the clearance hole for the needle.(already drlled the .040 hole) i drilled it to the correct depth but then just to check it i put the drill back in and said, hey this isnt the right depth. then as i was drilling deeper i realized i was trying to do a "thru" drill like with the .040 drill. thus i went to deep. in my defense there is a lot going on at my home today and a whole lot of poping in the garage door quietly then realizing i have equipment running and thus yelling my name which i just about jump thru the roof from the startle.... at any rate im happy its just a bad die which is going to the trash and im very(post edit) experienced now after multiple attempts in the cuts leading up to the die and can get to that point pretty darn quick now....

 

[werowance]

first pic, cheap working northern tool die that worked. second pic, my higher end kit that i had never used the die before until this brass jet tube with bad threads on it. last pic is the jet tube threads

 

[Sprocket]

Don't know if it matters, or would make it easier, but I usually drill the largest diameter hole first, then only have a little way to go with smaller drills.
They are going to center on the point of he other drill anyway, and I don't like drilling any deeper than I have to with tiny drills.
Doug