Need pass depth & feed rate advise for MDF

[SteveMI]

My experience to date is with solid wood (red oak, soft maple, cedar, cherry), but am being coaxed to make some MFSlab - Work Tables for friends.
http://www.multifunctionslab.com/

The Alpha I use has the spindle speed fixed at 12,000. With solid wood I have found that 1/3 to 1/2 the end mill diameter pass depth increments and 1.5 inch/second feed rate gives me good results and tool life.

So, on to 3/4" MDF. What have people found to work well? Do cutting tools have a different life with MDF? Is a two flute up-cut end mill viable? Since the holes are 20 mm, I intend to use a 1/4" end mill.

Going further, is light weight MDF any different?

Steve.

[adrianm]

How big are the items you're going to be cutting? Any tight curves, sharp angles?

I do a lot of 3/4" MDF running at 4ips at 11k rpm in a single pass with a 1/4" endmill. I could go faster but as what I cut varies in size from 6" to 24" and has some tight curves that's the best compromise.

Tool life is between 5 and 10 sheets depending on how many items are being cut out of each one. That's with a down cut bit though. An up cut would last a lot longer.

There are lots of different grades of MDF so it pays to buy the same brand all the time otherwise you're constantly changing the feed rates.

[SteveMI]

How big are the items you're going to be cutting? Any tight curves, sharp angles?
Smallest radius are 10 mm. Final part perimeter is 60" x 36".


I do a lot of 3/4" MDF running at 4ips at 11k rpm in a single pass with a 1/4" endmill.
My experience is that won't work with solid hardwood.

Seems I need to try some sample sections. I may actually get to like MDF.

Steve.

[adrianm]

Smallest radius are 10 mm. Final part perimeter is 60" x 36".


My experience is that won't work with solid hardwood.

Seems I need to try some sample sections. I may actually get to like MDF.

Steve.
You definitely can't do that with hardwood. I cut at half that speed and would take at least 4 passes on 3/4" hardwood.

MDF is a very different beast, you can cut it quickly and get really nice edges.

[dlcw]

I cut 1/2" and 3/4" MDF in two passes at 6ips 11K rpm with a 1/4" compression bit. First pass is a single climb cut leaving a 1/32" skin. Second pass cuts all the way thru about 1/32". This process gives me a perfect cut perfectly on the line.

I found I had to do this two pass system because there is just too much slop in the CNC for super accurate cutting in one pass.

I've cut circles as small as 4" using this method with no problems. Vacuum holds the parts firmly.

I use the same cutting process with veneer plywood.

[gc3]

buy a couple sheets and learn...

teach yourself...not that hard to do

and yes you will like MDF

especially the dust...

[adrianm]

When you get it dialled in the dust isn't that bad as most of it comes off in chips.

The pile on the left is what a friend of mine used to get and the pile on the right is what I get and what he gets now he has it dialled in.

[dlcw]

As Adrian says, you will need to dial in the feeds and speeds for your system. The pile on the right, in his picture, is what I get with the feeds and speeds specified for MY system. It might be different for your machine. Your mileage will vary. :D:D

[jerry_stanek]

I find the each time I get MDF it cuts just a little different depending on where I get it. Plum Creek cuts totally different than the cheap stuff from Home depot.

[danhamm]

It would be nice, if you said the H.P. of your spindle, it do make a difference.

[ntraub01]

You guys were right...pat yourselves on your backs...

After reading many of your responses I decided to throw caution to the wind and let the dust fly. I'm now cutting 3/4" MDF with a 1/4" Whiteside compression bit at 16000 RPMs at 6 in/sec. IT IS AWESOME!! Just recently cut 30 sheets of 3/4" MDF without a single issue and the bit is still as sharp as it was before we started.

Thank you all!!

[ntraub01]

Oops...

We are running the 2.2HP spindle.