[ynneb]

I have a 2400W spindle. The maximum power for a single phase power point.

I and driving the spindle at probably 60% of its full speed.

If I increase the spindle speed and also the feed rate, the cut isnt as smooth and can even scorch the MDF.

If I just increase the feed rate the router starts to labour and the cut isnt very smooth.

Is it a case of a different router bit?

I have experimented with lots of bits and have found the one that does the best job at the right speed, but I would like to increase my output.

I wouldnt be able to tell you what speed I am cutting now. ( I havnt worked this out. )

Have I just reached my limits? Will I just have to put up with this?

Because my router has a variable speed electronic dial on it and it is a cheapo Chinese one, I am wondering if when I have the speed turned down that it also reduces the torque? If it reduces the torque could this be why it slows down when I increase the feed rate? If I had a different speed reduction system would this then alow me to increase my feed rate without having to increase the router speed and therefore burn the wood?

[kong]

I found a small amount of info over here that may help. They recommend cutting the MDF at 20-25 cuts per inch, and give a formula to work out the feed speed in ft/min thus:
(RPM x no. of cutting edges) / (100 x cuts / inch)

So if you are cutting at 20K rpm, using 2 flutes, your feed speed should be 192 IPM.

So you could be right that your router is slowing down at low RPM's, since lower RPM and higher feed would be the way to go.
Sorry I can't really help much, I don't do that much MDF work

[Ken_Shea]

Benny since you stated you have tried many cutters this may be a moot point. Is the cutter you are using specifically designed for MDF, if not you may want to look into that. There are material specific cutters for about every material you can imagine.

http://ballewsaw.com/VENDORS/Onsrud/..._MDF_Bits.aspx


Ken

[ger21]

I'm guessing it's a limitation of your spindle. Most tooling manufaturers will tell you to go as fast as possible unless cut quality is an issue. You seem to have reached that point. How fast is your feed rate? If you're getting burning, can you increase the feedrate even more, or are you maxed out? Are you getting a lot of vibration at the higher speeds. Vibration and machine flex will cause bad cuts. Commercial routers use powerful spindles (10HP or so), so you don't have to worry about the spindle being overloaded. You might want to look at a better quality router, like the PC 7518. I can't gaurantee it will work, though. And you probably don't want to spend $5000 on a real spindle. What exact bits are you using? And, are you cutting the MDF with the metal laminates? Let me know what bits you're using and I'll see if there are better options. (They won't be cheap, though.)

[HuFlungDung]

Benny,

You haven't stated whether your tool is in climb milling mode or conventional milling mode.

Conventional milling mode will likely have a greater tendency to burn the work if your feedrate is too low. However, if you are climb milling, and your machine has mechanical backlash, or general flimsiness, this could cause rough cutting. If the spindle is flimsy, or inadequately supported, then this can also cause the rough cutting when you feed it heavily (as per normal cutting)

If you are mixing both modes of cutting together, this would make for the worst of both worlds.

[ger21]

Hu, when cutting MDF, typically you'll get better cuts conventional milling vs climb milling. This is true for most wood and wood products, from my experience. There are some situations where climb is better, usually due to wood tearout, but almost never in MDF.

[seansear]

Do a search on the internet for chip load / or feeds and speeds. These are both important items to learn. Every bit (tool) that cuts has a chip load. Try this link

http://www.woodweb.com/knowledge_bas...nd_speeds.html

[ger21]

Originally posted by seansear
Do a search on the internet for chip load / or feeds and speeds. These are both important items to learn. Every bit (tool) that cuts has a chip load. Try this link

http://www.woodweb.com/knowledge_bas...nd_speeds.html

I think the problem is is that his spindle doesn't have enough power to get a proper chip load.