Mechanized oxy-fuel cutting of 1/4", 3/8" & 1/2" mild steel

snowman · Oct 16, 2017

The 3/8 and 1/2" are both relatively doable...1/4" gets tough. I have a koike body, and they do make a tip that is stated to cut 1/4", but the only feedback I have is "doesn't work". For other reasons, I don't put much in their experience.

Curious if anyone has done it, and has any tips.

It's a 106D7-0 tip for 1/4 and 3/8, and a 106D7-1 tip for the 1/2"

They even make a tip for cutting 1/8"...and it is koike, so I have a hard time believing that it doesn't work, since I've always found their tips to be install, set the regulator to their settings, and get amazing cut quality...just like that.

https://www.koike.com/documents/Product-Brochures/Accessories/CUTTINGTIPS_PGA_ENG_WEB.pdf

DDoug · Oct 16, 2017

I do 1/8" but it's a bit iffy.

You have to run fast to keep enough iron fuel to burn, but not over run
your preheat.

I usually pick a tip with heavy pre-heat and small blow orfice.

Yes, heavy pre-heat, sounds odd eh ?

But I'm running with a water table, the water up tight underneath the plate, and running fast.

The slag ? With the fast quench, it's tenacious.
I use a 4" masonry chisel to scrape it off, but some holes and such I have to grind.

A question for you, I have seen many oxy cutting machines, including the higher end 5 regulator systems.

Have you ever seen one with flowmeters on the gasses ?

The preheat flame can be easily adjusted over a wide range for any given tip,
and if a flow meter was on both the fuel and the preheat oxy, maybe
a chart could be made up for repeatability in this kind of critical
application.

snowman · Oct 17, 2017

No...I haven't. I have machine torches for Harris, koike, and a couple other brands. I prefer koike just because it's what I'm used to. I've always just used the divergent tip.

The preheat actually makes sense....gets it to a critical point where you can move fast. Don't have the intense heat of plasma to blow through.

I miss plasma, but I haven't worked to develop oxy fuel.

Anything of quantity I just get laser cut...but I need something for prototyping, and don't want the cost of plasma.

Is the 1/4 pretty reasonable in comparison?

Sent from my iPhone using Tapatalk

Mud · Oct 17, 2017

1/4" is easy with O/A. I did down to .090 on occasion, did 1/8" frequently. I started with a Smith torch and had no difficulty. One day it all went south and nothing would fix it, new tips, different tips, different strategies, regulators, bottles, had the torch rebuilt, nothing. I bought a Victor torch and started over, cutting was easy again, no one could explain what changed with the Smith torch.

DDoug · Oct 17, 2017

snowman said:
No...I haven't. I have machine torches for Harris, koike, and a couple other brands. I prefer koike just because it's what I'm used to. I've always just used the divergent tip.

The preheat actually makes sense....gets it to a critical point where you can move fast. Don't have the intense heat of plasma to blow through.

I miss plasma, but I haven't worked to develop oxy fuel.

Anything of quantity I just get laser cut...but I need something for prototyping, and don't want the cost of plasma.

Is the 1/4 pretty reasonable in comparison?

Sent from my iPhone using Tapatalk

Yes & yes.

1/4" is more repeatable and reliable (to keep the cut going)

I have several Airco torches (hand and machine) so I have probably 30 tips,
most all 2 piece (for propane)

I recently bought off E-bay, a miniature 3 hose torch, a copy of a Koike,
and it works great, came with 3 tips. I have been using the middle tip, IIRC marked "2" (Duh)
The Airco tips will fit the Koike torch.

Airco (and now Concoa) has a more complicated numbering system (and larger amount of offerings).
Hence my comment of picking a tip with "Small cut orfice,large pre-heat flames",
you can pick and choose that way with their tips.

I made up a handwritten little chart, for what central orfice, cut's what width, found with
actual test cuts. I only have a few entries so far, have not found the need to use all my tips.

You have probably seen pictures I have posted here before of my little homemade CNC system, I have
been able to get good parts out of it, but it ain't automated like a plasma would be.

I have read a couple of threads over at the "forbidden cnc forum" of posters asking
about using a time sequence in Mach3 for preheat.
I have never seen in industry, anyone using this, there are too many variables, and you need to watch
the preheat, until you see the "sparklies" before initiating a cut.

snowman · Oct 17, 2017

I actually haven't...you've spoke of it often.

I miss the plasma table, but not so much I want a dedicated plasma building or room. Oxy/fuel I can just tarp next to the garage. The smoke from plasma doesn't allow such public spectacles.

Sent from my iPhone using Tapatalk

DDoug · Oct 17, 2017

Here Ya goes...

While it seems to be a point of much contention, a water table
(when run properly) will stop most all smoke and spatter.

Allot of people refer to it (and some build them like this)
as a "Water tray" and keep the water about 3" below the plate bottom.
This will generate much steam, to the detriment of your gantry.
Also, it does nothing to keep the plate from moving/warping,
and hence make a bad part.

Keep the water up tight to touch the plate (sometimes it comes over
a wee bit) and yes, you'll need more preheat, but it will trap
all the smoke, and not allow the plate to wiggle around.
By having enough "thermal Mass" of a large amount of water available,
it can quench the heat, and not make steam or smoke.

I was repairing a neighbors 5 x 10 Torchmate, and even with plasma,
I use the same water technique, and it kept the machine (and surrounding area)
clean. The only problem I had was splashing of water when cutting within about 3/4"
to the edge. So I kept some sheet metal strips hand to butt against the plate
to add "wings" and keep down any splash. (I have this same problem with my Oxy/propane
setup at home as well, use same sheetmetal pieces)

BTW, first pix is showing how fast the water quenches the flame, it doesn't go at most 2" deep.
2nd pix is the 1/8" part I cut.

hobbyman · Oct 17, 2017

I would suggest a zero or double zero tip for light gauge. The Koike site link does show small sizes for some model tips.
If you do not have a water tray one ploy commonly used years ago was to make a small shower head/ring of small copper tubing with drilled holes. The ring was about 3 inches diameter and surrounded the torch tip with a small stream of water. By immediately quenching the material as it is cut distortion was reduced.

Walter A · Oct 17, 2017

snowman said:
The 3/8 and 1/2" are both relatively doable...1/4" gets tough. I have a koike body, and they do make a tip that is stated to cut 1/4", but the only feedback I have is "doesn't work". For other reasons, I don't put much in their experience.

Curious if anyone has done it, and has any tips.

It's a 106D7-0 tip for 1/4 and 3/8, and a 106D7-1 tip for the 1/2"

They even make a tip for cutting 1/8"...and it is koike, so I have a hard time believing that it doesn't work, since I've always found their tips to be install, set the regulator to their settings, and get amazing cut quality...just like that.

https://www.koike.com/documents/Product-Brochures/Accessories/CUTTINGTIPS_PGA_ENG_WEB.pdf

We do cut down to 1/4" Carbon Steel with Propane/Oxy and our Koike 106-D7 "00" tip. We have a water table but don't worry much about the level when torch cutting. With the cutting flame adjusted just right we have done this with a "0" tip also. You just have to keep the tip set right and the feed quick enough to prevent overheating but slow enough to keep the cut intact. As most we listen for the "putt-putt" cutting noise feedback.

About the thinnest we cut with the torch is 3/16". I just like the cut tolerance better than with our plasma.

Walter

snowman · Oct 17, 2017

digger doug said:
Here Ya goes...

While it seems to be a point of much contention, a water table
(when run properly) will stop most all smoke and spatter.

Allot of people refer to it (and some build them like this)
as a "Water tray" and keep the water about 3" below the plate bottom.
This will generate much steam, to the detriment of your gantry.
Also, it does nothing to keep the plate from moving/warping,
and hence make a bad part.

Keep the water up tight to touch the plate (sometimes it comes over
a wee bit) and yes, you'll need more preheat, but it will trap
all the smoke, and not allow the plate to wiggle around.
By having enough "thermal Mass" of a large amount of water available,
it can quench the heat, and not make steam or smoke.

I was repairing a neighbors 5 x 10 Torchmate, and even with plasma,
I use the same water technique, and it kept the machine (and surrounding area)
clean. The only problem I had was splashing of water when cutting within about 3/4"
to the edge. So I kept some sheet metal strips hand to butt against the plate
to add "wings" and keep down any splash. (I have this same problem with my Oxy/propane
setup at home as well, use same sheetmetal pieces)

BTW, first pix is showing how fast the water quenches the flame, it doesn't go at most 2" deep.
2nd pix is the 1/8" part I cut.

Not too shabby...got a solenoid on your jet so you can automate it?

I know about water tables, and have seen successful ones work...include an air bladder to pump your water and it gets really easy...but then I'd have to worry about freezing too. And when I say next to the garage, it also means that it'll be exposed to the elements. The technology included in a well working plasma table excludes it from that type of torture.

snowman · Oct 17, 2017

Thanks for the other notes...sounds like I need to order a couple tips.

DDoug · Oct 17, 2017

snowman said:
Not too shabby...got a solenoid on your jet so you can automate it?

I know about water tables, and have seen successful ones work...include an air bladder to pump your water and it gets really easy...but then I'd have to worry about freezing too. And when I say next to the garage, it also means that it'll be exposed to the elements. The technology included in a well working plasma table excludes it from that type of torture.

Since i got the 3 hose Koike copy, I have done it, documented it at the "forum that can't be spoken of"
with a solenoid, with feedback to Mach3 to initiate moving. Along with a large rotary switch
to select "plasma", if I should buy a plasma cutter.

So my operation now is as follows. (after setting plate, and setting zero point)
1. light torch
2. start program, it will rapid to first pierce, lower into start height, and wait.
3. watch for sizzle, hit button on remote.
4. oxygen flows, Mach3 starts moving.
5. cut is done, oxy solenoid gets shut off by Mach3, rapids to next pierce.
Lather, rinse, repeat.

As far as the water table, mine is just a pan, I use a bucket to replenish,
and raise the level.

For freezing, try some prestone.

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