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new member need help on micro-machining design. forces involved.

unime

Plastic
Joined
Feb 28, 2021
Can anyone tell me what kind of forces are involved in micro machining of parts..

how to design a home built cnc mill to machine tool steel, small pieces, titanium and nickel.

I want to make small intricate parts with 1-3mm endmills. (under 1/8 inch) on a 3+ axis machine.

I figure that the tolerances should be considered in percent error with things so small.. and I would like to reach an accuracy in tenths or microns.

Is a dewalt router going to be enough to power an 1/8 or 1/16 inch endmill through d7 tool steel?

will I need to make a gt2 pully reduction drive and mill head for the dewalt 611. (I think it is 1-1/4 hp)

what would be a good design example for planning ahead to upgrade to 4 and 5 axis?
 
That would be great if I could afford to buy a really expensive pre made mill.

I need to make my own I was thinking of using epoxy granite, steel reinforced concrete. nothing fancy just solid and functional and cheap.
 
I need to make my own I was thinking of using epoxy granite, steel reinforced concrete. nothing fancy just solid and functional and cheap.


I figure that the tolerances should be considered in percent error with things so small.. and I would like to reach an accuracy in tenths or microns.

Many ways to skin a cat, no way to make magic.
To build such a machine in 99.99999999% of cases would cost more then a commercially available machine on the market atm.

Good luck


You want it Done ______ and _______ then it won’t be _____.

(Right)
(Fast)
(Cheap)


Fill in the blanks
 
Just like my sign in the shop , good, fast, cheap
Pick 2. Unfortunately your not going to make your 3 a reality imo. Your tolerance on the router spindle probably > than the cutter you want to use.


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oh I don't care if it is slow.

If I can put it in the other room for a week and get the part to the resolution i want it is still better than having to buy a machine from someone else (And eventually I will have one I designed of my own that is faster.)
 
Microlution made mills specifically for micromachining, but they were bought out and ceased production of that type of machine. They were over $100k. They did a lot of research on the matter and had some papers about sharpness of cutting edges (tiny tools aren't that much sharper) and the need for cutting parameters and machine speeds specifically formulated for micromachining. Don't know if those papers are still around. IMO, trying to build a decent 3-axis machine yourself is a fool's errand. None of the cheap Maker stuff will do what you likely want unless you don't need accuracy or good surface finish. Nor will the next level (<$10k) get you there. BTW, you'll also need to be an encoder expert if you go DIY. Don't even get me started on spindles.

See:
The Most Capable Mill in its Class| Vulcan Machining Co (if they ever survive and ship)
Bantam Tools – Bantam Tools Desktop CNC Machines (cheap but good enough? Nobody will quote you accuracy- gee, wonder why?)
Benchtop Milling Machines and small CNC Mills - MDA Precision
CM-1 | 20-Taper Mill | Compact Mill | Compact CNC | Vertical Mills – Haas CNC Machines (you'll spend this much and not do as well)
 
I was looking at the AS5600 for a contactless encoder and using some form of ball screws.

making PCBs myself, something based on GitHub - makerbase-mks/MKS-SERVO57B: MKS SERVO57B is 3d printer closed loop stepper motor NEMA23 MKS SERVO57 developed by Makerbase that prevents losing steps. CPU is STM32F103CBT6 ARM 32-bit Cortex™-M3 CPU Core,72 MHz. Magnetic encoder is Allegro's A1333LLETR-T Contactless 0deg to 360deg angle sensor IC ,12bit .This Project open source hardware and code,support platformio build and upload firmware...

Small parts shorter ball screws, smaller machine easier to make rigid.

maybe 200 x 400 mm travel x,y. 200mm z would work great too.

Edit: I probably want to tie in feedback from the stepper driver encoder and DROs (they have the 5um and 1um optical dro encoders) into a system. (Linux CNC) but I'm not sure how to go about the I/O possibly FPGA but maybe parallel at first or Raspberry Pi 4 with RTOS or Preempt-RT.

My main problem is what kind of forces involved in milling tool steel with 1 or 3mm mill bits. (KG of force on the end mill contacting the metal)
 
the last thing was fast in my assessment.

it wont be fast.

I could use ECM or Jet ECM but that is only accurate in some dimensions.

if you want something flat that's great for $500 you can build an ECM machine that makes things flat to the micron. (joules equate to material removal)

Edit: not to be confused with the more popular EDM.

This is a $50 upgrade for the ender 3 that allows you to etch into any conductive material. (metal) 3D Printer to CNC Conversion for 50 Dollars: Electrochemical Machining and Jet-ECM - YouTube

Anyway what I was thinking is that give that Jet ECM can be used and removes even just a few microns at a time, I can make the parts I need to make a mill. (And I can use CNC to compensate for any inaccuracy in parts that I buy, even rails and ball screws. followed by wet lapping probably with 1 micron diamond lap.

With this it doesn't matter if it is tungsten or aluminum or brass or steel it removes at generally the same rate. (it has this in common with EDM spark erosion)
 


I think that they look nice and am definitely trying to do this DIY.

I saw the Bantam one and it seems to look nice. I guess that accuracy is a problem and I'll remember that. I doubt I will buy one. It seems to be good only for aluminum and is made of aluminum so I imagine it would need at least two or three times the rigidity to work with steel to a good deal of accuracy.

These other machines look fast which is nice but more than I need at this stage in my working on having a CNC at all.

I have access to all types of steel beams and rolled bars. hex square, i beams, plate. there is a giant warehouse used by many local construction and manufacturing places they have a $500 minimum order.

At this point I have ordered a chinese cross slide from ebay and plan to try to break it down and remove the slop and flatten it using Jet ECM on some optical rails.

Yesterday I designed a 3d printed surface meter that seems to be good to an accuracy of a few microns at this point but only has 0.3mm of travel and seems to be repeatable enough to use on something already relatively flat. (No sudden movements.) The cost was about $0.15. and it works but I haven't made it digital yet.
 
oh I don't care if it is slow.

The "fast" mentioned above is in the time to build the machine. You could make a good machine on the cheap if you spend a lifetime on it, and complete several iterations, with each one better than the previous. If you don't value your time that is.

I and many others here have looked into this extensively. If you value your time at minimum wage or higher, it will be cheaper to buy a machine for $100k or so. The more difficult requirements for such a machine are not obvious at first to someone who hasn't built one or done the research. If you want to do micromachining, and not break your tool every time it touches the work, your precision, rigidity, and advanced, smoothed, motion control must be head and shoulders above what is necessary for normal machining. Programing the motion control software is a career long project on its own.

If you want to play with 5 axis machining, get a Pocket NC for a few $K. If you want to do hobby grade and get some usable parts out if it, get a 5 axis Syil for about $80k. If you want to do it for real, a Haas CM-1 is your bottom of the barrel starting point; you can get one setup for 5 axis for about $110K. Have it setup in metric mode for finer resolution. You can also look at used machines; a 5 axis Haas or Fadal can be had as low as $30k depending on age and condition.

It's like cars; there is no point in the market where you can get a machine of a certain quality and capability cheaper by making it than by buying it.
 
The "fast" mentioned above is in the time to build the machine.

well I understand the mindset of how anything has to be expensive. that has nothing to do with precision and it is entirely dependent upon ones abilities.

This is a thomlinson surface meter I made with a 3d printer using $0.09 in plastic and some 3000 grit sandpaper, ca glue and a #11 guitar wire. the travel is about 90 degrees per 0.3mm and the wire is about 4 inches long.
WIN_20210228_10_28_29_Pro.jpg

Edit: the machine doesn't have to be movable I'm fine with epoxy granite and concrete. If you want to spend so much money then sure go out and buy a steel and aluminum machine it can be moved. This is why people dont still use cast iron that much and bronze. It is heavier and harder to move for the rigidity. But it was possible in the mid 1900s to reach a millionth of an inch, before the transistor.
 
Well if you know better than us, why did you ask?

Yes, it was possible to achieve millionths in the early 1900's. How much time and money do you think they spent to get it done? What do you think a set of Jo blocks cost in 1908?
 
that's what you think.

as soon as anyone starts working, speed is very important.

My son does 3D printing, and speed wasn't important, until it was.
Then he upgraded, and upgraded, and upgraded.

Speed and accuracy/ (rigidity for most cnc) are two of the most common reasons to upgrade.
 
Edit: the machine doesn't have to be movable I'm fine with epoxy granite and concrete. If you want to spend so much money then sure go out and buy a steel and aluminum machine it can be moved. This is why people dont still use cast iron that much and bronze. It is heavier and harder to move for the rigidity. But it was possible in the mid 1900s to reach a millionth of an inch, before the transistor.

WTF are you talking about, most machines are still made from cast iron. Some are made of fancy composites but none that I know of steel or aluminum. Cast iron is used for it's dampening effect.

:ack2:
 
Well if you know better than us, why did you ask?

Yes, it was possible to achieve millionths in the early 1900's. How much time and money do you think they spent to get it done? What do you think a set of Jo blocks cost in 1908?

I am hoping someone would have a ballpark of an idea how thick of standard 2000 psi concrete / how much force is involved in cutting harder to machine materials with smaller bits.

this is a DIY thread not a buy thread.

I also hear people saying to not use Linux as an operating system unless you dont value your time but 85% of the internet runs on linux and it is very DIY (not paying someone else)
 
WTF are you talking about, most machines are still made from cast iron. Some are made of fancy composites but none that I know of steel or aluminum. Cast iron is used for it's dampening effect.

:ack2:

I did not realize this but I think I hear it mentioned before too. They don't use bronze any more but maybe that is just because of the cost of copper and aluminum.

Maybe I should start buying scrap cars and melting them down.
 
well I understand the mindset of how anything has to be expensive. that has nothing to do with precision and it is entirely dependent upon ones abilities.

This is a thomlinson surface meter I made with a 3d printer using $0.09 in plastic and some 3000 grit sandpaper, ca glue and a #11 guitar wire. the travel is about 90 degrees per 0.3mm and the wire is about 4 inches long.
View attachment 315247

Edit: the machine doesn't have to be movable I'm fine with epoxy granite and concrete. If you want to spend so much money then sure go out and buy a steel and aluminum machine it can be moved. This is why people dont still use cast iron that much and bronze. It is heavier and harder to move for the rigidity. But it was possible in the mid 1900s to reach a millionth of an inch, before the transistor.



Well what are you waiting for? Get to work!

Your only going to get the same response to this question here over and over. We’ve reached the end of this discussion.

Good day sir
 
how much force is involved in cutting harder to machine materials with smaller bits.

HSM Advisor will tell you the deflection forces with accuracy for any given cut:

Advanced CNC Speed And Feed Machinist Calculator - HSMAdvisor

What you are probably not understanding, is that we see someone ask this same question every few weeks. "How do I build a 5 axis CNC machine that will hold millionths? I have a budget of $500 / $5000 / $50000."

Every single time, we tell them they'll get a better machine for less money if they just go out and buy one. Every single time, they think they know better, and waste their time and money. One of them also suckered in several Kickstarter investors, and disappeared with the money, leaving the investors with nothing years after the machines were promised. He's since hooked up with a larger company with deep enough pockets to do it right, and is building machines from cast iron like everyone here told him on day one.

Why do you think a Hermle costs what it does?
 








 
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