ShopBot Steel Machining

D

davesharps

Plastic

Joined

Mar 4, 2015

• Nov 8, 2017

• #1

Hey There!
So i'm using a 5'x10' shopbot standard with a 18000 rpm 2hp spindle, and someone has requested that I run some 2mm thick steel parts on it. Has anyone done this successfully before? I have found limited information about cutting steel with a shopbot and some folks have said they have done it, others simply say don't do it, but that's about the extent of detail I have found.

If I was to do this, are there any major risks I should be mindful of? Any info on endmill selection? Speeds/feeds?

More detail is always preferred, I just want to know exactly how good/bad an idea this is.

Best,
Dave

 

sfriedberg

Diamond

Joined

Oct 14, 2010

Location

Oregon, USA

• Nov 8, 2017

• #2

Do you normally cut aluminum? If so, as a rough starting point, cut your spindle RPM to 20% of normal and your feeds (in IPR, not IPM) to 50% of normal. Feed in IPM would be 10% of normal.

I don't know how rigid a shopbot is, so don't know how much you can increase back up from there. However, spindle 50% and IPR feed 50% (IPM feed 25%) would be fairly aggressive, just based on unit power requirements for steel versus aluminum.

 

N

nitromarsjipan

Plastic

Joined

Sep 11, 2011

Location

Oslo, Norway

• Nov 8, 2017

• #3

Here's an example with some of the data you might be looking for:

High speed dry machining steel with ShopBot - YouTube

That shop is just up the street from me. Clever people. They usually use their machines for soft woods, but they do some delrin and aluminium now and then.

 

J

JP Machining

Stainless

Joined

Jul 15, 2006

Location

Wisconsin

• Nov 8, 2017

• #4

A shopbot to cut steel.... that'd be like trying to cut down a tree with a wet noodle.

IBTL

 

7

706jim

Titanium

Joined

Jun 14, 2006

Location

Thunder Bay Canada

• Nov 8, 2017

• #5

Don't know what a Shopbot is, but I'm guessing that an 18000rpm 2hp spindle motor is going to have ZERO torque at the rpm needed to cut steel.

That is with any decent sized cutter.

 

N

nitromarsjipan

Plastic

Joined

Sep 11, 2011

Location

Oslo, Norway

• Nov 9, 2017

• #6

JP Machining said:

A shopbot to cut steel.... that'd be like trying to cut down a tree with a wet noodle.

IBTL

Click to expand...

It is, but the noodle wouldn't chatter as bad.

Still it's only a 2mm thick sheet, might work just okay.

 

P

powerglider

Stainless

Joined

Oct 13, 2006

Location

Mediapolis, Iowa

• Nov 9, 2017

• #7

davesharps said:

Hey There!
So i'm using a 5'x10' shopbot standard with a 18000 rpm 2hp spindle, and someone has requested that I run some 2mm thick steel parts on it. Has anyone done this successfully before? I have found limited information about cutting steel with a shopbot and some folks have said they have done it, others simply say don't do it, but that's about the extent of detail I have found.

If I was to do this, are there any major risks I should be mindful of? Any info on endmill selection? Speeds/feeds?

More detail is always preferred, I just want to know exactly how good/bad an idea this is.

Best,
Dave

Click to expand...

if the potential customer is getting quotes elsewhere you are wasting your time. Shopbot is for wood, thin aluminum, some thin plastics, foam as you already know.

If it's a personal project or for family and friend you could try it but will find it's not going to be easy even at 2mm. Plus the grief of working with a large sheet of steel when you aren't used to it.

Bottom line is if you are busy cutting wood and other materials you are used to, don't spend too much time to try and get a quote in that might get accepted and then you have to actually do the work on that steel sheet.

 

M

mjk

Titanium

Joined

Oct 20, 2005

Location

Wilmington DE USA

• Nov 9, 2017

• #8

How much is the machine worth to you if you find a weak link.
One of the few things I learned about cnc's is that the machine will do what you tell it to do.
You program it to cut steel
It will say "Sure you told me", as the tool is turning from red to white and the sparks fly.
Machine didn't care.
If you have a lot of sawdust in the shop, better sweep up first.
If the machine has a vacuum system at tool tip, better not run it, cause a spark may end up in your collection bin
Your not baling on the job by saying no, your being a responsible shop/business owner

 

M

macgyver

Stainless

Joined

Aug 2, 2012

Location

Pittsburg, KS

• Nov 9, 2017

• #9

I have learned the hard way that the vacuum holding the part on the table will keep a fire fed with fresh air until you turn it off. Haven't done it cutting steel as I don't plan on it, but have more than once on wood products.

 

J

JP Machining

Stainless

Joined

Jul 15, 2006

Location

Wisconsin

• Nov 9, 2017

• #10

I guess if you break the spindle, which you probably will, you can just go down to Lowes and pick up a new for what like $60?

Not trying to be mean, but your machine is a hobbyist level designed to cut wood at an ok level, can maybe cut aluminum lightly. On steel if it was all thru cuts like a profile shape in that 2mm steel, my cnc plasma could probably cut more accurate and better finish than a shop bot is going to do without a ton of trial and error and rebuilds. Just have realistic expectations of what your machine was designed to do and what it might be capable of. Unless they've come along way from the one I remember seeing, it had a laminate trim router as its spindle.

 

A

adama

Diamond

Joined

Dec 28, 2004

Location

uk

• Nov 10, 2017

• #11

Small cutters and HSM tool paths can achieve a lot. Just dont be too greedy and follow cutter specs for feeds and speeds.

If this is just cutting out shapes, probaly far easier faster and cheaper to just get them laser cut. 2mm cut on nitrogern will have a near milled edge, be accurate to under +-4 thou and have no sharp edges!