[TTalma]

I need to drill 106 holes all the way through 3/4" thick MDF. The hole diameter needs to be 3/32".

I am unable to find a bit small enough to do this. I'd like a center up cut spiral bit. But the only ones I can find only have 1/2" of cutting length.

I bought a couple for testing and even with pecking as soon as the flutes were buried, the flutes got packed and the bit heated up. By the 4th hole the bit was shot, and there are burn marks around the lip.

Normally I would do a spiral cut down, but the trouble is finding a small bit that can do this without breaking.

I was thinking about using a drill bit, but am worried about the heat build up.

Does anyone have any suggestions, or know a source for bits that will work?

[awerby]

Use a drill bit if you're drilling holes; that's what they're for. They're readily available in the size you need, and won't heat up unduly; certainly not as much as endmills with buried flutes.

[dazp1976]

3/32 is the equivalent of 2.381mm.
Maybe a 2.2mm drill bit will be close enough although a tight fitting hole?. That's if you can't find a 3/32.
HSS in that size is crap imo and flexes everywhere.
Generally these days I use cobalt C08 drill bits for everything. I find they're quite strong with little flex.

[Jim Dawson]

I would try this https://www.amazon.com/0938-Solid-Ca.../dp/B006Q4YL3Q

[dazp1976]

I would try this https://www.amazon.com/0938-Solid-Ca.../dp/B006Q4YL3Q

^THIS^
Stubbies are great. I use them often.

Careful with carbide. Pressure can make them break.

[TTalma]

I would try this https://www.amazon.com/0938-Solid-Ca.../dp/B006Q4YL3Q

Thanks, I ordered these. Hopefully they will hold up.

My machine only goes down to 12,000 rpm, so with pecking hopefully they will last. I did see on a site where a guy was doing the same thing, and he put a container of water on the table, and every 5 holes or so he would stop the spindle, dip the bit in water, then dip it between 2 sponges to dry it. repeat.

He said he had no problem with tool life, but it was adding 12 min to to a 20 min job.

[dalrun]

I've been happy w/ 13k rpm, 900mm/min and ~8mm per peck. Slow Z and excessive pecking generate too much heat. That $10+ per bit price is insane, metric is typically a lot cheaper if you're patient, e.g. https://www.aliexpress.com/item/1005002558554925.html @ <$2.

[routalot]

I've put several hundred holes into melamine faced chipboard with a 2mm HSS drill bit at 13000 rpm.Admittedly only 14mm in depth but a peck routine to get the OP's depth wouldn't cause me any anguish at all.