HDU cutting depth....

[gamisano]

Any of you who have cut HDU in the past....What are you using for a cutting depth per pass? I'm using a Belin 13635b 1/4" CED, 2 1/4" Cut Length spiral O Flute. This is my first HDU cut, and I don't want to be too agressive and break the bit, but at the same time, I've heard it cuts like butter, and at 1/4" depth per pass is going to take a long time. Can I go deeper on HDU with the tool that I listed?

I should add that I searched extensively this evening for info on depth per pass on HDU, but only found feed and speed recommendations.

I'm planning on cutting at 2.5" per second, with the spindle set to 18K.....I just need to know what maximum depth is reasonable. Thanks for any help!

Guido

[den73160]

Guido

I have cut HDU in the past and will again. Right it does cut like butter and I have always gone twice the bit on the cut. Not lost any bits yet that way, but since I am running a PRT have to watch STATIC or I loose position.

[cbradshaw]

I cut a lot of 1 1/2 inch HDU and I cut it in one pass per the recommendation of the tool supplier.

Carroll

[gamisano]

@#%*!!! Against my better judgement, and after hearing from several people that did it successfully, I tried the one pass cut, and broke my bit within 3 inches!! I didn't really want that $50 anyhow.

So, then I tried another bit with only 1/2" depth at 1" per second, and I got a loud squealing noise. I tried some different speeds, but the same sound. WTF? I've read how easy it is to cut, but now I'm out a new $50 bit, and am uncertain if I can even cut it.
Can someone bestow some wisdom upon me? Here are my questions:

What bit? (especially you, Carroll) I need it to cut 2" HDU, 15#
What feedrate, and spindle speed?
What stepdown? (I know, some of you already responded to this one...just curious what others are doing)

Thanks again,

Frustrated Guido

[cbradshaw]

Guido,
I buy my bits form Hartlauer Bits, they have a website. I buy the 1/4 inch spiral upcut bit.
I run the router anywhere from 1.5 to 2 (mostly 1.5) at 18,000 rpm. If I can find an invoice with the bit number I will send it to you. Otherwise, give them a call and they will tell you what bit to use. I thought the same may as you originally that I needed to take 1/4 inch passes, however the supplier told me to cut full depth. Obviously, I don't think you would do that in any material other than HDU.

Carroll

[conceptmachine]

Guido,
I cut some 3/4 hdu a few days ago using a onsrud foam cutter 1/8 dia,did it in one pass at 16k rpm .7 ips.it does make a high pitch sound but it did a great job.
shawn

[gamisano]

Thanks everyone. I figured it out. I used an Onsrud Spiral O and it cut great. There is a very small rpm range where there was no squealing during cutting. I found that at 1 ips, 15,300 - 15,400 rpm was the sweet spot. Very quiet, and as I had heard from others, it cuts like butter. I wound up only going 1/2" per pass, and felt like after I dialed it in, I could've went deeper. However, I needed to finish the job I was doing and didn't want to risk brealing another bit. Anyhow, thanks again for your input!

Guido

[luke]

Guido,
Can you provide the specific Onsrud bit item number.

[gamisano]

64-026