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Slotting 3/16" 1018 steel on a little CNC bentchtop mill Few newbie questions

ioffe

Plastic
Joined
Oct 21, 2020
I am on the explorative journey of seamlessly endless world of possibilities as CNC hobbies. I am quite new at this so bear with me:

I am trying to make a thin wrench out of 3/16" 1018 steel. Little what I know I picked 3D contouring in Fusion360, selected a face and seems to be a finished project. However I would like to validate the idea with some basic practices.

Q1: Is it even practical to slot the length of 30" with end-mill ? I would gladly use a band saw(if i'd have one) or angle grinder in most crude and uninspiring way.
Q2: Suppose the answer for Q1 is positive, how do I select a proper end-mill size for a task? I supposed the bigger mill would have more millage and take a deeper cuts but require more power and possibly coolant? What is the science behind a right size for end-mill while slotting?

Q3: Should I go in 1 pass at full depth to utilize the max cutting length of the tool (possibly to prolong the life of the tool) albeit slowly, or do it in multiple passes(to reduce temperature and possibly avoid the cooling mess)?

Context: I have .9hp bench-top mill with spindle spinning only clockwise. Also I have my trusty solid carbide 1/4" 4fl GARR end-mill which it would absolutely suck to brake. It handled every task before, but this is more milling that I ever done. Thank you for your help.
 

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30” of 3/16 plate ?

Buy more garr end mills, great price to quality ratio.

Instead of cnc zone try sendcutsend for this part.
 
I am trying to make a thin wrench out of 3/16" 1018 steel.
Got it.

Little what I know I picked 3D contouring in Fusion360, selected a face and seems to be a finished project.
That should have been a 2D contour but, I haven't done a single cutter path in Fusion. Nothing about your picture suggests 3D contouring.

Q1: Is it even practical to slot the length of 30" with end-mill ?
Yes. They do it all the time. They taste terrible and most of them are kind of boring to look at. What else will you do with it?

I would gladly use a band saw(if i'd have one) or angle grinder in most crude and uninspiring way.
I wouldn't. I would use an end mill.

Q2: Suppose the answer for Q1 is positive, how do I select a proper end-mill size for a task? I supposed the bigger mill would have more millage and take a deeper cuts but require more power and possibly coolant? What is the science behind a right size for end-mill while slotting?
2x the diameter of the endmill in depth per pass is a fair starting point. You said the plate is 3/16" thick so your 3/16" end mill should be fine.

Q3: Should I go in 1 pass at full depth to utilize the max cutting length of the tool (possibly to prolong the life of the tool) albeit slowly, or do it in multiple passes(to reduce temperature and possibly avoid the cooling mess)?
Can your machine cut it in one pass? If it can, yes. You have a carbide end mill. Look up the cutter on their website for recommended feeds and speeds and start on the conservative side of those.


The problem is going to be that with a benchtop machine, the cutting forces are probably not going to allow you to get anywhere near 3/16" deep. It will probably start flexing, vibrating like hell and will likely destroy that end mill in the first inch. You may have no choice but to do it in very shallow depths and lots of passes.

Context: I have .9hp bench-top mill with spindle spinning only clockwise. Also I have my trusty solid carbide 1/4" 4fl GARR end-mill which it would absolutely suck to brake. It handled every task before, but this is more milling that I ever done.

From the pricing on their website, that cutter is under $16. You're talking about it like it was an investment you intend to hang on to it. Cutters are complete consumables. This sounds like "I just bought my first house and I have this really awesome roll of toilet paper. I'd really hate to use it." Yeah, you might go through that cutter on this part. You might break it and need another one. You might break two or three. That's part of the cost of machining.

It should go without saying but, you also need to have that piece of steel clamped down securely to the table or in a vise. There will be a lot of cutting forces and you don't want that getting pulled loose and flung at you. I've also seen broken 1/4" end mills tossed hard enough to embed into drywall 15 feet away, still at face level. Protect yourself accordingly.
 
I am on the explorative journey of seamlessly endless world of possibilities as CNC hobbies. I am quite new at this so bear with me:
Are we witnessing the first not so seamless integration of AI and a humanoid robot.
 
Got it.


That should have been a 2D contour but, I haven't done a single cutter path in Fusion. Nothing about your picture suggests 3D contouring.


Yes. They do it all the time. They taste terrible and most of them are kind of boring to look at. What else will you do with it?


I wouldn't. I would use an end mill.




Can your machine cut it in one pass? If it can, yes. You have a carbide end mill. Look up the cutter on their website for recommended feeds and speeds and start on the conservative side of those.


The problem is going to be that with a benchtop machine, the cutting forces are probably not going to allow you to get anywhere near 3/16" deep. It will probably start flexing, vibrating like hell and will likely destroy that end mill in the first inch. You may have no choice but to do it in very shallow depths and lots of passes.



From the pricing on their website, that cutter is under $16. You're talking about it like it was an investment you intend to hang on to it. Cutters are complete consumables. This sounds like "I just bought my first house and I have this really awesome roll of toilet paper. I'd really hate to use it." Yeah, you might go through that cutter on this part. You might break it and need another one. You might break two or three. That's part of the cost of machining.

It should go without saying but, you also need to have that piece of steel clamped down securely to the table or in a vise. There will be a lot of cutting forces and you don't want that getting pulled loose and flung at you. I've also seen broken 1/4" end mills tossed hard enough to embed into drywall 15 feet away, still at face level. Protect yourself accordingly.

You are amazing @Donkey Hotey! You practically restored my faith in humanity :) Thank you very much for taking the time to answer and pointing out the potential dangers. I will double on the safety checks.

You are probably right about it should be 2D contour, 3D generated about the same code as 2D would do.
Good point on consumables. I am myself of a scientific background rather than engineering so I developed a professional deformation of sorts... I measure 10x times before I cut. I have this machine for 2 years now and I have yet to break my first end-mill. Speaks volumes how much machining I do. Just this week I had make a 3/32" slot in 3/16" hardened steel dowel pin. This little mill went through C60 hardened steel like it was made of butter. It the math is right the tools should last.

The work is being held in 3" precision vises. With that much lateral force I doubt it's going anywhere. I will experiment with the depth of cut.

Thank you very much for your guidance.
 

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Are we witnessing the first not so seamless integration of AI and a humanoid robot.
No, not yet. In beautiful world of AI there wouldn't be close to 90% useless and irrelevant comments to this thread created by very worm-blooded and yet lesser humans.
 
@ioffe
Check out onlinecarbide.com for end mills. Their tools are all ground in the USA and priced very well. The shop grinding the tools also runs the site so it's not some middle-man game.
 
Your set up is going to chatter and slap the poor cutter silly. I just finished a run that ate few bits with 2x1/4 angle 3” to 4” away from the vice from chatter. I should have used a corncob then finisher but not what bossmen wanted to buy.

That is a saw or laser part. Sendcutsend. For just over the retail cost of material the part is in your hand by the end of week.

Biggest part of having a hammer is learning everything is not a nail.
 
Happy to report that the end-mill gets to live another day. I followed advice of @Donkey Hotey I went with 3/32" endmill at the snail pace (2500 RPM @ 4ipm) plus occasional sprinkles of cutting fluid in multiple 0.04" steps. And it came out much better than expected. I didn't think about a piece that would fall down on the last pass I would have coded things differently. I had to improvise to catch the damn thing mid-flight. No chatter, no broken tools, tolerance(?) who cares, serene happiness. Feels like my setup can go about 20% harder If need be. Many thanks to those who shared the wisdom.
 

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Good deal! Glad to see it worked out for you. Did you have to do a control retrofit on that machine? I see those little Light Machines come up at auction on occasion but they always claim to need a "software upgrade". They look very well built for a bench top machine. Doesn’t it have an R8 spindle?
 
No, I did not. The seller gave me a control box and PCI card. Just popped the PCI card into a computer that I inherited from my wife's grandmother and that was it.

Intelitek has a decent website with all software and drivers for all discontinued hardware. They even respond to my technical inquiries (when they have something material to share) after they sold my machine 24 years ago and not to me. I find it refreshing. Their electronics are quite elegant and simple. Their original software does pretty much everything I need. These machines were made as educational machines and education they do phenomenally well. My understanding they are made to resemble real CNC machines (real quality made ball screws, granite epoxy base, and minimum viable G-Code industry compliance met, etc.. ). They have outstanding manuals that explain how CNC machines work in some depth.

I am fairly new to machining in general so take my opinion with skepticism

Negatives:
  1. They don't support many contemporary G-Code features, specifically fancy canned cycles, Nothing a good post processor wouldn't fix
  2. Slow speed moving, 25 ipm is your rapid
  3. Spindle is limited to 5000rpm. All those NYCNC carbide recipes can't be reproduced because contemporary machines are much faster.
  4. Spindle only turns clockwise (nothing that LH boring bar and gcode witchcraft can't fix)
  5. Spindle is useless below 300 rpm
  6. I wish it'd have a bit bigger working envelop (there is never enough space)
  7. Precision. Mostly it is probably my machine. Repeatability is a bit of an issue. Mine is within 0.002". May be ballscrew bearings have to be adjusted, may be these ancient steppers are not in their prime. It should be 0.0005 but in my case it is 0.002 for X and Y, and 0.001 for Z. That is after I measured and set adjustments for the backlash.
  8. I had to write my own Fusion360 post processor to allow seamless integration with a lathe. Autodesk has some post processors for Light Machines but they are only good as starting points.
Positives
  1. It's a proper CNC machine made in USA with no expense spared.
  2. It sits on a workbench weighting 450 lbs. it is not a puny machine.
  3. It works off a single phase 15a outlet
  4. it mills about anything. I did some micro milling of hardened dowel pins, 4140 in annealed state, 1018 yesterday. It just works.
  5. My mill does have R8 tooling which I find plentiful and reasonably priced. These mills had a BT30 option as well, depends on your luck I guess.
  6. Even if your machine comes with no controller and cards. You can buy those things on eBay under $400 (even LinuxCNC retrofit would realistically be around $1k) and start making chips
  7. Used Light Machines are 1/4th of used Tormach price. Does Tormach have a bigger envelop or more powerful spindle? No.
 
Just FWIW - if I needed a part that was like that, and the only precision bit was the end, I'd CNC mill that out of a smaller piece of metal then weld it to a bit of flat bar or similar.

PDW
 
No, not yet. In beautiful world of AI there wouldn't be close to 90% useless and irrelevant comments to this thread created by very worm-blooded and yet lesser humans.

You, being a robot, are ignoring one of the primary rules of this site - no benchtop poop. I can put it in a language you will understand...it's Stardate 2560 and the Starship Enterprise has just landed on a previously unknown planet. You, in total violation of the Prime Directive, run out and begin having intercourse with the natives while helping overthrow their government. See the prob?
 
No, I did not. The seller gave me a control box and PCI card. Just popped the PCI card into a computer that I inherited from my wife's grandmother and that was it.

Intelitek has a decent website with all software and drivers for all discontinued hardware. They even respond to my technical inquiries (when they have something material to share) after they sold my machine 24 years ago and not to me. I find it refreshing. Their electronics are quite elegant and simple. Their original software does pretty much everything I need. These machines were made as educational machines and education they do phenomenally well. My understanding they are made to resemble real CNC machines (real quality made ball screws, granite epoxy base, and minimum viable G-Code industry compliance met, etc.. ). They have outstanding manuals that explain how CNC machines work in some depth.

I am fairly new to machining in general so take my opinion with skepticism

Negatives:
  1. They don't support many contemporary G-Code features, specifically fancy canned cycles, Nothing a good post processor wouldn't fix
  2. Slow speed moving, 25 ipm is your rapid
  3. Spindle is limited to 5000rpm. All those NYCNC carbide recipes can't be reproduced because contemporary machines are much faster.
  4. Spindle only turns clockwise (nothing that LH boring bar and gcode witchcraft can't fix)
  5. Spindle is useless below 300 rpm
  6. I wish it'd have a bit bigger working envelop (there is never enough space)
  7. Precision. Mostly it is probably my machine. Repeatability is a bit of an issue. Mine is within 0.002". May be ballscrew bearings have to be adjusted, may be these ancient steppers are not in their prime. It should be 0.0005 but in my case it is 0.002 for X and Y, and 0.001 for Z. That is after I measured and set adjustments for the backlash.
  8. I had to write my own Fusion360 post processor to allow seamless integration with a lathe. Autodesk has some post processors for Light Machines but they are only good as starting points.
Positives
  1. It's a proper CNC machine made in USA with no expense spared.
  2. It sits on a workbench weighting 450 lbs. it is not a puny machine.
  3. It works off a single phase 15a outlet
  4. it mills about anything. I did some micro milling of hardened dowel pins, 4140 in annealed state, 1018 yesterday. It just works.
  5. My mill does have R8 tooling which I find plentiful and reasonably priced. These mills had a BT30 option as well, depends on your luck I guess.
  6. Even if your machine comes with no controller and cards. You can buy those things on eBay under $400 (even LinuxCNC retrofit would realistically be around $1k) and start making chips
  7. Used Light Machines are 1/4th of used Tormach price. Does Tormach have a bigger envelop or more powerful spindle? No.

Thank you for the detailed review. I honestly thought the company was out of business, it is amazing that they still offer some level of support on a 24 year old machine.

It sounds like you're learning a lot through the process, that is half the fun!

Download the FS wizard app for feeds and speeds. It works very well even for lower power machines. The app has a box where you can enter the max spindle speed. It will then give you recommended radial and axial depth of cut along with spindle speed and feed rate.

You, being a robot, are ignoring one of the primary rules of this site - no benchtop poop. I can put it in a language you will understand...it's Stardate 2560 and the Starship Enterprise has just landed on a previously unknown planet. You, in total violation of the Prime Directive, run out and begin having intercourse with the natives while helping overthrow their government. See the prob?

What are you rambling on about? :codger:

He is talking about a decent quality, US built machine. Which rule of this forum places a size requirement on machines that can be discussed? The rules state that cheap, Chinese hobby machines cannot be discussed yet no one complains about Tormach - which by definition are cheaper machines marketed to hobbyists.
 
What is that wrench for? Any nut that needs 30" of leverage will likely cam out of a 1/4" wrench with only 2 sides of grip.
 
What are you rambling on about? :codger:

He is talking about a decent quality, US built machine. Which rule of this forum places a size requirement on machines that can be discussed?
To be fair to us, Free .... that only came out at the very end, and only by accident. When a thread starts out with "the explorative journey of seamlessly endless world of possibilities as CNC hobbies" one can only expect the worst.

Luckily, op came back down to earth a little ... seems like if he brushes off some of that woohoo dust he could be okay. But op, please ? no more "exploratory journeys", okay ? Most people here are not big on Danielle Steele.

The rules state that cheap, Chinese hobby machines cannot be discussed yet no one complains about Tormach - which by definition are cheaper machines marketed to hobbyists.
The ban is literally "we are drawing the line at discussing "home shop grade" Asian machine tools and hand tools." So from his first several posts, there was no way to tell what he had. Could easily have been one of those screwed-together aluminum extrusion things. Sherline, Atlas, Craftsman and those are also banned, but ... it does seem like the attitude of the poster is what counts. A guy who says "I have a piece of junk but need to cut this slot" is okay, while people on journeys of self-exploration, maybe less so :)

Anyway, I think if he'd come off as more practical in the first place, there'd be less backlash.
 








 
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