• We want to encourage those of you who ENJOY our site and find it USEFUL to DONATE and UPGRADE your membership from active member to donating or premium membership. If you want to know the differences in membership benefits, please visit THIS PAGE:

    https://www.hobby-machinist.com/premium/

    Donating memberships start at just $10 per year. These memberships are in fact donations that help pay our costs, and keep our site running!
    Thank you for your donation, God Bless You

  • As some of you know, I have wanted to stop managing H-M for some time. It's a tremendous strain on my personal life. I want to set up my own shop. In September, September 15, to be exact, it will be 8 years that Hobby-Machinist has been in existence.

    We've seen a lot of changes. In March, 4 moderators left to start their own site. They took some of you with them. So now you have split loyalties. You know who you are. They didn't like my way of managing this place, and thought they could do better without me. They didn't. The only thing holding them together is that they hate me. Their site was down until mid July. That is why I wanted to stay involved on here until they could learn to run this place. But they wanted me to leave right away, without the training part.

    Anyway, I have been training VTCNC to run things here. Dabbler is going to learn too. I feel that they are ready to start taking over the operation. I will be here to help in case they need, but I don't think they will. Tony Wells is and will be here also to consult with. I will be doing backups, upgrades, and installing addons. Other than that, I don't want to know about this place.

    What about the 4 moderators who were disloyal? I don't care. It isn't my call anymore. I would think that, rather than fumble, they ought to come back and do good work. That's up to them. If they want to return to try to lead more members to their site, I am done caring. I suffered too much aggravation worrying about it. I don't plan to spend any more. What they do impacts on them. I have my own opinions including those of you who followed them there. No longer my problem.

    I am leaving this place in good operating condition, and financial condition.
    --Nelson
[4]

Speeds and Feeds

[3]
[10] Like what you see?
Click here to donate to this forum and upgrade your account!

Brento

Registered
Registered
Joined
May 9, 2018
Messages
117
Likes
35
#1
Hi all, so im sure this question is commonly asked by hobby machinist all around. When i started machining i did it by sound and feel (mainly bc i hand fed on a lagun mill). Now as i am getting more and more experince i am understanding the formulas on how to find your speed and your feed. However the one bit of information i am curious about is what is a good sfm and chipload to start out with. This question is also good to know for my job as well. I am cutting Aluminum and steel most of the time but sometimes stainless and titanium. Also same question but for drills and reamers would be great as well!

As a secondary question would you sfm change using carbide vs hss? Ive been told you can double your feed/speed when going from hss and carbide.

Thank you guys for your time in advance.
 

T Bredehoft

Active User
H-M Supporter - Gold Member ($25)
Joined
Dec 27, 2014
Messages
2,587
Likes
1,992
#2
I try to aim at .001 per tooth, any cutting material. Aluminum or steel. (on a mill, lathes are different.) I was 'raised' on HSS, so carbide is a foreign land as far as speed is concerned. Your results may vary.
 

Ianagos

Active User
Registered
Joined
Oct 14, 2014
Messages
115
Likes
88
#3
Depends do you have a cnc? On a 3/8 3fl carbide endmill in aluminum give it .15 stepover up to .625 depth of cut with 6000rpms at around 70ipm or about .004 feed per tooth.

1/4 3fl carbide in aluminum 6000rpm .1 stepover up to .5 depth of cut around 40ipm or .002 feed per tooth.

That’s on an older cnc I would not try those numbers on a manual. Of course also using high quality is made endmills.
 

shooter123456

H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
Joined
Jan 20, 2016
Messages
347
Likes
426
#4
A lot of it will depend on the tool and the machine. There are also other factors such as workholding and tool holding. There a cases where the workholding isn't as secure as it could be and speeds and feeds need to be adjusted. There are also factors such as finishing vs roughing, coolant, etc etc.

You can find a lot of information from the manufacturers of the tools. But carbide will be able to take a lot more SFM than HSS will. In most cases, the SFM for aluminum will not be obtainable on hobby mills, so I usually give it all the RPMs I have, take at least .001 IPT and see where that gets me. Sometimes I need to back it off a little bit on speed, but try to avoid going below .001 IPT. An example from Harvey tool, they recommend 800-1500 SFM for their tools in 6061 aluminum. With a 3/8" end mill, that is 8150 to 15280 RPM. You probably won't get that with most machines. With a 3 flute end mill, the lower SFM and .001 IPT, you need to feed 24.5 IPM. If you don't have CNC, or at least a power feed, that will be tough to get to.

But yes, you will probably want to change SFM between carbide and HSS. I hope everything I said made sense and at least some of it is helpful.
 

ChrisAttebery

Rocket Nerd
Registered
Joined
Jan 11, 2018
Messages
83
Likes
82
#5
General rule I use is D/100 for the feed per tooth. So if I'm using a 3/8" end mill I start with .003-.004" ipt. The speed depends on the tool material and the work material.

I highly recommend that you try FSWizard. (https://fswizard.com/#) You input the material, your cutter properties, cut width and depth. It will tell you what the ideal feeds and speeds for your cut are. On my little G0704 CNC conversion I started out using 50-60% of his feeds. These days I use 80-90% of his recommended feed. On my machine 1.5 cubic inches per minute in aluminum is a the upper limit on MRR. So I try to keep my cuts below that mark.
 

Brento

Registered
Registered
Joined
May 9, 2018
Messages
117
Likes
35
#6
Everything is making sense guys thanks. Does anyone have a suggest standard sfm to start with and then obviously massage it to the conditions in the work area?
 

T Bredehoft

Active User
H-M Supporter - Gold Member ($25)
Joined
Dec 27, 2014
Messages
2,587
Likes
1,992
#7
My little PM25 has variable speed and feed. If I have enough cut to play with, I tweak both until it 'sounds' right. However, this comes with experience, so take it easy.

Edit: fix typos
 

GrayTech

Registered
Registered
Joined
Jan 18, 2018
Messages
34
Likes
9
#11
There are free phone apps that calculate these. Check google play store.

Sent from my H3123 using Tapatalk
 
[6]
[5] [7]
Top