Cutting rate for Porter Cable 3.25hp

[HomeMadeCnc]

Hello All,
I’m in the process of doing the math on my machine. It’s sorta cool when it finally clicks! You can adjust anything but. I don’t have a clue what force my router (3.25 hp) will take using .5 straight endmill. Real world, we’ve all seen the stats but in reality, we all know how it works. What’s my optimum cutting speed? That brings up another question. Is it faster to do multiple passes or one big bite one pass? The machine will be cutting cabinet bodies and doors, so ¾” mdf/melamine/oak and doing relief carvings as well. Screws are 5/8 8tpi acme, motors are 570 in/oz and its geared to whatever will work.
I’ll be putting a coat of paint on “Taz” today, I’ll post the pics soon.
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Thanks for all the support, and ideas,
Tim

[HomeMadeCnc]

If you cut and paste from Office it makes everything lowercase, interesting. . . . .

[GaryCorlew]

I saw a post a couple of months ago that said that as a general rule of thumb at 18000 rpm ipm can be calculated by multiplying 600 times the diameter so .5 x 600 = 300 ipm. I have been using it every since and it works very well. I would not go deeper than the diameter of the bit

[ger21]

Originally Posted by HomeMadeCnc If you cut and paste from Office it makes everything lowercase, interesting. . . . .

No, it doesn't. It's a forum issue.

Optimum speed has more than one answer. Do you want the optimum speed to maximize tool life, or cut quality, or production volume? Manufacturers of good quality tooling will give a recommended chip load, which will give you a feed rate at a given rpm. Your machine may not give an acceptable quality cut at this chip load, so you might have to slow down. Or, your machine may not have enough power to achieve the recommended chip load, so you may have to take multiple shallow cuts, or slow down. If your machine has plenty of power, you may be able to exceed the recommended chip load. Bottom line, is to use recommended chip load as a starting point, and adjust up or down to suit your machine.

Is it faster to make multiple passes? If you're machine can handle one pass, that would probably be fastest. If your cutting particle board and mdf, a good quality compression bit would probably give you the quickest cuts.

Also, tool type plays a big part in how fast you can cut. You mentioned 1/2" straight endmill. Do you mean a metal cutting endmill, a two flute carbide tipped straight bit, a spiral router bit? A spiral bit will cut faster than a two flute straight bit. A three flute spiral even faster. A spiral with chipbreakers even faster still. Tool sharpness plays a part here too, as a dull tool will require more power from your spindle.

This question gets asked a lot, and it's almost impossible to answer, but I use one general rule which covers most situations. Cut as fast as your machine will allow, and still give you an acceptable quality of cut.

[HomeMadeCnc]

Thanks for the help, 300 ipm it is then. Finished painting "Taz" last night. I'll put it together and post pics.

Tim

[turmite]

Tim you really need to go back and read Gerry's post. Let me start by telling you he works in a production facility that uses cnc routers all day long. Let me also re-enforce his statement that an arbitrary ipm # will not work. It might for one type material, but you change material and it will be totally wrong. I use the 3.25 pc routers and in fact have worn out 7 of them with many rebuilds on each router. I can tell you that you will have a hard time pushing the pc through any kind of wood full depth with a .5 bit at 300ipm. When you do that you will see nice blue flaming arc looking things coming off the brushes! You can go ahead and ask me how I know if you want!

I currently use 100ipm carving in axis but that has more to do with my machine's rigidity than the ability of the router.

100ipm with a 1" ballnose making a .500 channel will just about choke the pc.

Mike

[HomeMadeCnc]

Well, I think I'll order a bunch of gear sets and build Taz as beefy as possible. I'll run a 5/8 8 tpi single start dual screw setup and gear to what ever works. If anyone has another point of view , I order on tuesday, I'd love to hear from you. Thanks for all the imput. I guess I'm at the half B.S. stage now.
Tim
p.s. were have all the caps gone?

[zabink]

Tim,

Just curious, do you already have your stepper/servo motors selected? Also, what controller and NC software will you be using?

Keven

[HomeMadeCnc]

Hi Keven, I have 570 in/oz from homeshopcnc.com and a stepmasternc.com 4 axis board with a full version of mach 3. Bobcad or Vcarve pro are in the front runners for software.
Tim