What's new
What's new

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

2Slow

Hot Rolled
Joined
Jun 26, 2006
Location
South East Michigan, USA
I have to drill a small (#62) through hole in the center of a 1" long grade 5 bolt. Actually I have a few to do. I need a pair of #63s, a pair of #62s, and a pair of #61s. These are jets for a Stanley Steamer burner.

I tried tonight and things didn't go great.

I held the bolt (1/4-28) in a collet.

I touched the bolt head with a center drill.

I used one of those sliding attachments that for a small chuck and lets you feed it by sliding with your hand to hold the #62 bit & ran the machine at 2,000 RPM

The bit was a 118 degree point, HSS from Irwin Hansen #61 - #80 kit.
https://www.amazon.com/gp/product/B000EB3YL2/ref=oh_aui_search_asin_title?ie=UTF8&psc=1


I started with a #61, but it really didn't want to cut. After going about a 1/4" deep it took a lot of pressure and didn't cut, so I went down to a #62. The # 62 cut well for about 1/2" more, but then I snapped the stupid thing in the bolt...

So I need a couple of new bits. Debating between solid carbide for 10 bucks each, or a dozen 135 degree HSS for $1.38 each from McMaster Carr.

Thoughts?
-Joe
 
Here's your tip - drill and tap the bolt for a 6-32 thread, about a 1/4" deep. Take some 6-32 set screws, drill them for the size hole you need, then secure in the bolt. Stake if needed to prevent loosening, if risk of leakage around thread then seal with ceramic-based gasket compounds.

You can use carbide drills on the set screws, actual depth of hole should only be about 1/8" or so.
 
HSS will do it but cobalt would be better, I like Precision Twist drill but there are lots of good brands. 2000rpm is going to make it slow going, lots of pecks.

Sent from my SM-T560NU using Tapatalk
 
personally I would drill about 800 rpms with lots of oil or thick cutting fluid like emuge. toss the hand feed thing away (thats for plastic and alum)you should be able to feel in a decent handmill in a cnc it wont be a problem.

Whats happening is that the rpms are too fast for the chip evacuating and breaking your bits. while "BOOK" calls for a faster speed and feeds, your out of the books league when it comes to depth, runout in the drill etc etc besides your making a few not a production job
if you have any play/run out in the drill chuck forget it not going to happen.
use a stub drill to drill as deep as you can chucking up just to the flutes then replace it with the longer drill.
lots of pecks and oil and clean that drill off all the time.
 
Jets are rarely the nominal size for the entire length, you could drill 1/8" diameter 7/8" into your bolt and then finish with the number drill. Put the small hole at the business end.

I've made burner jets smaller by soldering up the hole and redrilling to the new size. Not for anything as interesting as a Stanley Steamer, though.
 
I have a Clausing Metosa 14x40 lathe sold as a "South Bend". 2,000 RPM is all she's got so I will have to go slow.

Thanks,
-Joe

oh if your on a lathe. dont use a tail stock. put the drill chuck in the tool post, indicate the drill in. if on a lathe I would go about 500rpms, any run out and your screwed, its actually harder to drill small deep holes with a tail stock in a hand lathe then a hand mill.
 
Jets are rarely the nominal size for the entire length, you could drill 1/8" diameter 7/8" into your bolt and then finish with the number drill. Put the small hole at the business end.

I've made burner jets smaller by soldering up the hole and redrilling to the new size. Not for anything as interesting as a Stanley Steamer, though.

thats the easiest and best bet
 
The business end is the head of the bolt. Unfortunately the stepped hole diameter would not work well for this application. The fuel that passes through the jets is first passed through a "vaporizing coil" that is in the burner to turn the liquid to vapor. Unfortunately the liquid often overheats, cracks and you get carbon flakes. The flakes can clog the nozzle. A stepped hole would basically make a funnel to trap the carbon flakes and it would plug a lot.

The nicer jets actually have multiple feed holes that are slightly smaller then the jet size to act as a filter and reduce the chance of clogging. I would just buy them, but the smallest size I have been able to find are #60, and that I tried them and they are too big. I have been tuning with single hole versions with a hope of finding the right size, than making a multiport version. It looks like #62 is about right, but I want to try a #61 & #63 to see.

These are the multiport jets to reduce clogging:
244 Multi Port Nozzle Jet Sold as pair | Vintage Steam Products

If someone wanted to make multiport jets like you see above, I can provide dimensions and would gladly pay $50 per pair for a set of #61, #62, #63.


This is a tool every Stanley owner has to clean the jets when they get carbon fouled:
206 Nozzle Picker | Vintage Steam Products

Thanks!
-Joe
 
Here is a thought: You might want to try some different bolts from another source. Fasteners are made to mechanical specs rather than chemistry. Result is you can have different machining characteristics between two otherwise identical bolts.

Or make them from scratch from a free machining steel.
 
Why grade #5? I would use softer material. Drill the main hole bigger and then the small jet at working end. loose pack copper wool as filter into big hole or use pipe thread for inline filter. My Ford used a NPT fuel filter directly screwed into carb. I think the other end was hose nipple or flare connection.
Or mount a remote engine oil filter with bracket or diesel filter.
Bil lD.
 
Or press a multi-hole plug into the other end of the jet. Lots of easier solutions than hole depth that's 25x it's diameter.

Yup.
Drill that bolt with 1/8" or so, and tap 1/16" npt
Take an "off the shelf" 1/16" npt plug (flush hex socket, or sq. head)
and make your orifice designs there, fill 1/8" dia hole with filter material.
Pipe cleaners comes to mind

Or buy some hex material, and make your own, from scratch.
 
1/4-28 thread on your link..

Just buy some mig welding nozzles and chop them to length.


A customer of mine makes a lot of things with burners, and a lot of
it is trial and error when he's proving out a new design.. I modified
a lot of welding nozzles this past fall, and if you need to open the
hole up a bit, its pretty darn easy since you've already got a pilot.

If you want turbulent flow, use a 1/4-28 grease fitting with the ball
and spring taken out.
 
Pecking pecking pecking is the key to success. And that is far more easily and quickly done if you use a sensitive feed chuck in the tailstock. High RPMs are not needed. Carbide circuit board drills are too stiff/fragile for practical use in this application.

When I did a job making 20 #74 hole jets I used steel bits and pecked about 30 times per minute. Yup 30 times a minute. The reason: if the flutes load up, the swarf heats up, welds and the bit snaps—-every time. The chips clear without pecking for the first 5 diameters or so, but after that it will clog, weld, and snap. A blast of compressed air provided by a fixed nozzle at the hole opening helps rapidly clear out the flutes when you peck. Cutting oil is some help.

Cutting the hole without the sensitive feed chuck will be slow going.

Added: You will need to center your hole to start with a small spotting drill to make a concentric hole—-a long springy drill will dance all over the place.
Denis
 
Lot’s of great ideas here. Some combination of them is likely going to be a solution. Let me provide a little context on the use case, as it is a little more than a simple orifice.


I burn either Kerosene, or a mixture of Gasoline & Diesel at roughly 50/50 proportion. The fuel is under about 140PSI of pressure and passes through a “vaporizer” coil prior to going through the jet / orifice. The vaporizer is a Stainless tube in-between the burner fire and the boiler and it serves to heat the liquid fuel to the point it becomes a vapor. It has a stainless cable inside it which serves to both reduce fuel volume (allowing quicker on / off response) and retains heat for when the fuel comes back on after being shut down when the boiler reaches pressure. The fuel has to be completely vaporized to effectively burn which requires bringing it to about 600º F. Liquid fuel can accumulate in the pan and things get interesting when the vapors above it ignite.


Pan_fire.jpg

Burner_2.jpg


Unfortunately the vaporizer system is not perfectly controlled and in order to always get fully vaporized fuel when needed, (pan fires are no fun) it invariably overheats portions of the fuel and cracks it creating carbon flakes. The little carbon flakes accumulate on the jets and when enough accumulate, flow is restricted. When this happens you notice you are not making pressure in the boiler fast enough. The simple solution is to get out and “prick” the jets by inserting a small steel pin of the pricking tool to clear the obstruction.
206 Nozzle Picker | Vintage Steam Products


Carbon is a very real fact of running a Stanley. If you plan on going more than 50 miles or so you are likely to have to prick the jets at least once. At the end of every day’s drive I remove the stainless cable in the vaporizer, the jets, and flush the system with a burst of kerosene.


The point of all that was to explain that the “filter” is really just a way to prevent the jet from clogging. The flakes of carbon don’t hurt anything as long as they make it through the jet. An oil filter would be impractical as you need to get the hot vapor to the jets quickly or it will condense. The plumbing is very direct and short between the vaporizer & the jet for this reason. I am also not sure an oil filter would be happy with the temperatures associated with vaporized diesel. The idea of the multiport jets is that all of the feed holes are a little smaller than the orifice so anything that made it through the feed hole will make it out the orifice. In practice, they are much better than single hole jets, but they still clog.


Carbon production is very real, and unless a design can handle a long day’s worth of driving without clogging, I need a way to clear obstructions as they happen on the road. The through hole is there to allow me to do a roadside carbon clearing with the pricking tool. The finer filter ideas (steel mesh etc) would not be able to be cleared without disassembly, and it is a pain in the butt to disassemble the jets on the side of the road while they are 600 – 700ºF.


Why a grade 5 bolt? That is a great question, and I don’t know other than that is what the Stanley people I know said to use. The jets are subject to high temperatures and need to be removed and reinstalled every day – but I don’t know that I need a hardened bolt because of that. Maybe making the whole thing may actually be easier than starting with a bolt…


After looking at the jets and the distribution forks they bolt into closer, I don’t think they need to be the full 1” long. I think shortening the overall assemble will only make things easier to machine.
 
A friend who does this sort of drilling every day, making surgical equipment, says the first thing is to get good drills. Trying to do it with Hansen drills is shooting yourself in the foot before you start. He says the best drills are Gurings, HSS rather than carbide because the carbide ones too often break when they break through the other side.

Guhring, Inc. - World-class Drills, End Mills, Taps, Thread Mills, Tool Holders, Tool Management, Coating Services, Tool Reconditiong - Guhring Inc

We both use Albrecht sliding chucks like you describe

Bill
 








 
Back
Top