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Tips to drill a 1" deep #62 hole in a Grade 5 bolt?

2slow... I'm a bit confused. When you use that pricking tool are you cleaning out the jet or the cross holes which act as an inlet/filter? I am assuming that you are cleaning the main orifice or you would need to remove the entire nozzle to clean the cross holes. If I am correct then how does carbon get past the cross holes and clog the jet if the cross holes are smaller then the jet orifice? If it is the jet orifice that is getting clogged by say the accumulation of small pieces of carbon that make it past the cross holes, then surface finish of the inside of the jet seems like it would be critical. They must be catching on something like machine marks from when it was drilled. Has anyone ever tried an oil furnace nozzle? They do get carbon on them but it is coming from the business end and not from the fuel itself breaking down. It seems like a 1 gph 80 degree jet may work for a starting point which could be drilled out fairly easily. About 2 bucks. Comes with a sintered filter on the feed end as well. Just a thought.
Its a vehicle??? Cool...

Why did I think this was an industrial carpet cleaner????

Question... On the pics of the orfice/bolts you posted earlier..
Which direction does the fuel move?? From the multi hole end to the
bolt head end??? And when you clean it with your tool, which end do
you have access to?
That huge burner hole the OP is talking about seems as if it would benefit from a mesh filter on the input. Lots better than a few large holes.

The hole is around 0.9mm, not very small. Any mesh filter of the type a lawnmower carburetor used to have would be good enough to stop flakes that would clog a 0.9mm hole. If it is buildup of smaller ones, then OK, but even then, a mesh filter should do a good job, probably last a day's driving without a problem. The mesh can be had far finer than 0.9mm.

it is also possible to cut the orifice so that the inlet counterbore ends in a cone with the point oriented toward the inlet, against the fuel flow, The hole is in the point, so rather than being guided toward the hole, as with a drilled hole that is coned the other way, flakes etc that come in will mostly go off to the side, and cleaning with the "pricker" will knock them out to fall to the side.
Not sure the job needs doing, as per several posts, but I used to do a job drilling .032 either 3/8 or 1/2 deep in pure nickel

center drill
as much rpm as you got
tiny pecks

I used solid carbide,started manually in my Lagun
got maybe 10 or 12 parts on average before you slipped up

struggle was worst on fresh drill a good carbide is sharper than it is strong and you would snap them if you did not keep control of the quill. Once they wore a bit you could feel the drill and that would be fine until you got where the drill was too dull for its strength

Switched to CNC and tiny pecks and got 50+ per drill

so the moral is lots of rpm, lots of lube small pecks and patience and it can be done.

OR take some of the advice and do something different
Have you contacted the Vintage Steam Products people and asked them to make the jets with the sizes you want? Someone has to make the current jets and you probably aren't the only one to want smaller diameters.
Find a shop with a hole popper and save yourself time and money. This is an everyday easy job.

I was considering recommending this, but I think the EDM finish would tend to attract and trap the very same particles that cause the issue here.

On the other hand, I used to work at a place very well suited to this kind of thing. Good ol' George loved helping people modify their fuel injectors (mostly diesel) and he had no problem doing onsey-twosies if it was an interesting project. He would be able to give you an inlet hole pattern of whatever size you wanted, down to about .008" per hole. 8-12 holes at 0.008" - 0.011" each was pretty standard for diesel injectors. Big one could go blind almost to the end with no trouble.

Not sure if I should post the contact info here, but you could PM me for sure. I also don't know if George is still around, but if he's on this side of the turf he'll be in front of an EDM machine!

Edit for phrasing/clarity.
Look at the system used by old Coleman gas stoves and lanterns.

Might even be able to adapt the valve.

The valve has a lever on the side, with a shaft running inside through a packing.

Inside the valve, the shaft is bent into a simple open end crank shaft.

Attached to the crank rod end, is a small wire with a loop end for a rod bearing.

Other end of wire, has a finer wire swaged in center..

Wire runs through the length of the generator/vaporizer tube, to screwed on jet

Rotating lever, pushes fine wire through jet.

Cleans carbon and soot out of jet.
9100 - I will order some Guhring drill bits

Cross thread - The pricking tool only cleans out the center hole. The original Stanley jets only had a singular hole, so the prick would push the carbon out of it. The multiport jets have a through hole as well as several radial holes. The pricker only clears the center holes. The radial holes get cleared before you take off the next day. I don't know for sure how the carbon gets past the smaller holes to get through the orifice, but I suspect it is making its way down the full sized center hole and getting stuck after it passes the radial holes. It could also be accumulation, but there is a lot of 140PSI kerosene vapor passing through that should clean that away. I don't know if anyone has ever tried a boiler furnace nozzle, but I have never seen it done. I think the real issue is the primitive vaporizing system creating a lot of carbon. At the end of the day we take the jets out and flush the system and there is enough carbon to cover the bottom of a bucket.

Not my car, but videos of Burners firing



This guy's pilot goes out when he switches to kerosene, and he floods the burner with wet fuel Things get interesting when he pokes a torch in the flooded burner @ 7:18.

Bobw - The fuel moves from the multihole end to the bolt head end. When pricking, you only have access to the bolt head.

JST - The mesh filter would probably clog pretty quickly and require disassembly to clean which is not really possible on the side of the road. People have tried similar things and you need a mesh coarse enough to pass the little stuff without clogging and fine enough to catch the bigger bits. Not much package space for surface area. I do really like your inverted cone idea. I have never scene it done, but it could only help.

RJT - I am in the Detroit area and there are lots of local shops. I could ask around a bit. I am going to draw something up and add JST's inverted cone idea.

Kenton - I asked Don at Vintage steam about it. He buys these in bulk, and his supplier didn't want to do a small run.

BoxcarPete - I will send you a PM.

Thanks to all so far
This is my current thinking for jet design:


This is the car blowing down at the end of a show:
Crossthread - Looked at furnace nozzle pics online and I am pretty sure that filter on the back would clog in no time. There ends up being a lot of carbon in the fuel flow and you have to let the little stuff pass or you clog up immediately.

Addendum- saw the fellow I mentioned earlier, helping thaw out his water line victim of this miserable weather. Rather than simple HSS, he prefers cobalt steel drills.

The cone idea comes from K. N. Harris, in his model boilers book, where vaporizing, and other, burners are discussed.

Incidentally, he seems to have had Stanley's back in or near their time. He mentions having experience with Stanley and also White, I believe.
If you can see yourself doing this very often, I'd scrounge up a little Electro-Mechano benchtop high speed drill press with a sensitive chuck. Fingertip pressure, good control. And the right drills, of course. Peckity peckity peckity, pretty easy with the right stuff.
I pulled the existing jets out, and there was a big old flake of carbon sitting on one of the holes. The car only had about an hour of driving since I pulled the jets and it was not plugged, but you get the idea of what is floating around in there.



I also took a look and modified the design a little to make it shorter / make the hole a little easier to drill. I think EDM may be the way to go, and then clean up the EDM'd central hole with a drill bit.



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Some of the BF Goodrich fuel-oil heater nozzles that I used building a DIY gas turbine engine out of a turbocharger had a sintered bronze filter on their inlet side.

Odds are the coke is from the paraffins in the fuel. Can you step up to #2 diesel? It will have a lower paraffin content. Jet-A or JP8 will be a very similar fuel and have little to no paraffin content at all.

The set-screw idea seems to have been glossed over, but holds real promise from several perspectives. Allows for a bigger blind hole upstream of the metering orifice. Makes generating the cone feature mentioned by JST rather simple and straight forward to do. Can make the metering orifice from some other material that *might* be easier to drill. FWIW I would not try to drill carbon steel set screws. Due to work-hardening the bottom of the drive socket will be nearly as hard as the drill bit. I found this out drilling #8 set screws with nearly the same size drill for making Leak-down gauges for Infernal Combustion engines. OTOH drilling a SS set screw only suffers from the normal problems of drilling SS, which at all well known and surmountable. Those that I drilled (std 18-8 alloy) were much, much easier to drill than the carbon steel set screws.
As a slight variation on the setscrew idea, drill .094" thru, then press fit 1" length of SS tube (McMaster 6100K452, OD .094, ID .038). This makes the drilling easy and gives you the desired diameter over the full length. I'd start with an 18-8 bolt so that the material is similar to the tubing.
I have a Bridgeport too - If you think the center hole is better done on the mill, I can try that. Back to 1st question HSS or Carbide?

I much prefer the BP on small holes over the lathe. More RPM's to play with, much better feel for what the drill is going through.

Cobalt drills, spot with a center drill. Blast it with a spray mister. Hold'em in a 5C indexer, hex up.
Looking at this from an engineer's perspective - The specs for grade 5 bolts don't say anything about hardness; so one has to assume there is going to be a substantial variation depending on who made them and when. One search I turned up indicated a variation of 25-34 Rockwell C. But since hardness isn't in the bolt specification you can expect a wide variation especially in fasteners from current popular sources. I think the hardness is what is giving you problems. It's likely the thread rolling is done before heat treat and the specified proof loads are what drive the heat treating process. That said I'm mystified as to why the jets have to be so hard other than to resist sharp cleaning tools and not break off if rusted in place. And rusted in place is easily dealt with using modern antisieze coatings. In the worst of all possible worlds you can try to anneal the bolts somewhat before you machine them and heat treat them afterward. Ed Weldon