Cutting 1/4" Hardboard Masonite

[mnrite]

I am cutting a lot of 1/4" hardboard (tempered masonite) with an Alpha Shopbot & a PC router. I keep burning up 1/4" bits, both double flute solid carbide straight & double flute solid carbide down spiral. Any sugestions for bits feeds & speeds would be appreciated.

Thanks
Mike

[paco]

Can you slow down the RPM?

Can you use shorter cutting length tool bit? Too long CEL can cause vibration which doesn't help keeping the bit cool... You either end up slowing the feed or get bad cut.
For this application, I would consider 1/2" CEL Straight edges 2 flutes carbide tipped standard router bits. Clean edge and very stiff small diameter tool bit... yet VERY affordable (around 10$).

You sure that's solid carbide? I have yet to burn solid carbide... but burned HSS in such length as 6" of cut in melamine!

[mnrite]

Thanks for the response

I slowed the router to 16,000, at 10,000 or 13,000 the router bogs down even at slow move speeds and shallow cuts.

The Home Depot package says solid carbide, today I bought the carbide tiped, short bit, I'll try it tonight.

Thanks Again
Mike

[paco]

Home Depot doesn't sound "solid" to me... anyway, since you're cutting 1/4" thick material, keep the cutting length as short as possible.

Unfortunately, the PC 7518 doesn't keep a nice steady speed on low RPM... so you have to push the feed and keep the RPM med. to high. That cause problem with long CEL that machine only thin pass/material. Wood solid carbide bit often have lint range of CEL while carbide tipped have more choice (FS tool) and you may want to have a look at plastic bits too. Those late often can be as short as 3/8" which would be very nice in this case.

I just tested 1" vs 3/4" in 5/8" melamine at 3/8" thick pass and the 3/4" CEL produced a much better cut (no chatter) than the 1" from the very same bit model (carbide tipped that is). I have cut acrylics with 1/2" CEL carbide tipped with good success (nice shavings) and I was pushing the feed quite a lot more than I thought... I'm sure I would have snapped the 1" in no time in similar conditions.

[davidp]

Mike,

Try the Onsrud 65-010 (1/8) a single flute spiral. I can not remember the number for the 1/4

My tool of choice and for a hugely better result and a much cleaner finish try the Carbi-Tool TSPL04 again a single flute sprial solid carbide.1/8 bits. CarbiTool also have a TSPL08 that is a 1/4. It is the same geometry as the 1/8 bit and a little bit more robust. It will fly through 6mm (1/4) masonite and you will not need any sanding.

I get around 100 sheets from the carbi tool cutter cutting masonite and MDF before they need replacing.

Regards,

David

[mthomas]

David,

Where do you source the CarbiTool bits from?

Thanks,
mt

[davidp]

Micheal,

Go to
http://www.carbitool.com.au
they accept all major credit cards and will ship overnight or air frieght.

I have tried dozens of different bits for MDF, plywood and Masonite and theses achieve the best results I have tried so far.

Regards,

[john_m5]

Mike

1/4" is a fairly tight slot for your vacuum to suck chips from. If the chips aren't getting out, then the bit is getting very hot, very quickly.

I've done a lot of masonite cutting and I've used 1/4" dual flute upcuts and single "Super 0" upcuts from Onsrud. Down spirals will have less than half the life of up spirals.

But I'd look at your vacuum pickup and make sure the slot is staying clean so the bit only has to cut the material once.

Going to a 5/16" makes a lot of difference as well.

Regards,
John M.