Feed Rate

This forum is for general discussion regarding VCarve Pro

Feed Rate

Postby auga » Fri Jun 30, 2017 6:51 am

I have up my feed rate on 90 bit when cutting out letter from the default 100 upto 175 IPM with no issues.

But when I using the roughing and final model 3d cut what is safe and good quality feed rate speed? I believe my
taper 1/32 5degree ball nose defaults to 40 IPM on the final cut. Thus takes a very long time to complete the cut. So
with time a concern how fast is safe over quality can I up the IPM feed rate?

Thanks
auga
Vectric Apprentice
 
Posts: 61
Joined: Thu Jun 15, 2017 11:24 pm
Model of CNC Machine: TinyG - Homemade

Re: Feed Rate

Postby dealguy11 » Fri Jun 30, 2017 1:27 pm

There is no single answer to that question. The speed you can run a 1/32" bit will depend on a lot of factors: material, depth of cut, z-axis feedrate, acceleration capability of your machine, amount of relief in the model. In general if you try to push a 1/32 bit too fast in hard material you run a good chance of breaking it, especially if the roughing pass has left a lot of material. If there is lot of relief to the model, then any cut with a vertical component will only go as fast as the slowest feedrate - so even if you set XY to 200 ipm, if your Z is set to 40, then 40 is what you'd get on surfaces where the bit is moving in Z. If there is a lot of movement required for the model then a machine with slower acceleration will never get up to the requested feedrates anyway. I've had a lot of models where I requested 200ipm or more with a 1/8" ballnose and never even approached that speed in reality because of the amount of movement/start/stops required to do the carving.

40 is not a bad place to start. You can try pushing it to 60 or 80. A 1/32 ballnose will always take a long time any any carving of any size, however. Unless something is really tiny, I usually don't see any advantage in going below 1/16", and most of my carvings are with a 1/8" ballnose.
Steve Godding
D&S Artistic Woodworking http://www.dsartisticwood.com
User avatar
dealguy11
Vectric Wizard
 
Posts: 1150
Joined: Tue Sep 22, 2009 9:52 pm
Location: Henryville, PA
Model of CNC Machine: Anderson Selexx 510

Re: Feed Rate

Postby auga » Fri Jun 30, 2017 2:18 pm

Thanks dealguy, Did not think about the Z axis movement. I have ordered some more ball nose from drillman
with 1/8 and 1/16. I agree the 1/32 is a bit small to use. The new one are straight and not taper ball nose.

There a new learning curve cutting the models.

Thanks
auga
Vectric Apprentice
 
Posts: 61
Joined: Thu Jun 15, 2017 11:24 pm
Model of CNC Machine: TinyG - Homemade

Re: Feed Rate

Postby Leo » Fri Jun 30, 2017 5:00 pm

Things about FEED and SPEED

1) Number of flutes - cutting edges
2) Diameter of cutter
3) Depth of cut
4) Material being cut
5) RPM of spindle - Speed

Sooo, there are FIVE things to consider when determining FEED and SPEED.

Each one of those 5 things is dependent on the other and they all work in conjunction with each other.

There is ONE more, but it somewhat separate from the 5 listed about.
The particular machine.

First thing is to figure out HOW the 5 work together to come up with the FEED and SPEED that works.

There is a little bit of math to do this, but is pretty easy math. I'm not going to do the math here, because there are a number of available tools online to help with that, and I can confuse the issue if I get into it. However, it not really hard.

Pretty much the bottom line is that you want to find the "chipload" that fits the criteria above and adjust the Speed or Feed to achieve the chipload that your machine can handle and still make the chip load numbers work.
Imagine the Possibilities of a Creative mind

www.leosworkshop.com
User avatar
Leo
Vectric Wizard
 
Posts: 2418
Joined: Sat Jul 14, 2007 3:02 am
Location: East Freetown, Ma.
Model of CNC Machine: 1300 x 1300 x 254

Re: Feed Rate

Postby Rcnewcomb » Fri Jun 30, 2017 6:06 pm

As Steve (aka dealguy) mentioned, on a 3D finish toolpath chipload isn't really a factor since, with acceleration and deceleration in XY & Z, it is unlikely the machine will ever move fast enough to achieve the target chipload.

For the 3D finish toolpath the better thing to look for is how fast can your machine move and still achieve acceptable results. On my machine I found that setting the feedrate to be the same for XY & Z (3IPS = 180 IPM) and custom tuned my accelerations for 3D work, then I was able to get good results with reasonable machine times. Mind you, some of the designs still took 8 hours for the finish pass.
- Randall Newcomb
10 fingers in, 10 fingers out - another good day in the shop
User avatar
Rcnewcomb
Vectric Wizard
 
Posts: 2691
Joined: Fri Nov 04, 2005 5:54 am
Location: San Jose, California, USA
Model of CNC Machine: Shopbot, CAMaster


Return to VCarve - General

Who is online

Users browsing this forum: dbowlin, jbrown2252 and 12 guests