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Forstner bit rotational sped

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Forum topic by lovinmrv posted 03-18-2010 02:40 PM 1626 views 4 times favorited 9 replies Add to Favorites Watch
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lovinmrv

103 posts in 2519 days


03-18-2010 02:40 PM

Topic tags/keywords: forstner bit rpm drill speed resource question

Is there an optimal RPM setting for forstner bits and, if so, what is it?

Apologies if this is already covered…I haven’t been able to find it.

Thanks

-- Life is a sales job.


9 replies so far

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SKFrog16

661 posts in 2660 days


#1 posted 03-18-2010 02:53 PM

http://www.ibiblio.org/twa/info/drillSpeedChart.pdf

lovinmrv, Use this chart. Has all the necessary drill speeds you need.

-- Methods are many,Principles are few.Methods change often,Principles never do.

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Chase

448 posts in 2486 days


#2 posted 03-18-2010 02:59 PM

Fantastic chart UnionLabel, That is getting printed out and possibly laminated for my shop as soon as I get home.

-- Every neighborhood has an eccentric neighbor. I wondered for years "who was ours?" Then I realized it was me.

View DaddyZ's profile

DaddyZ

2475 posts in 2500 days


#3 posted 03-18-2010 03:21 PM

Excellent Chart – done saved to favorites !!

-- Pat - Worker of Wood, Collector of Tools, Father of one

View richgreer's profile

richgreer

4541 posts in 2534 days


#4 posted 03-18-2010 03:31 PM

! agree, the chart is great. I have a similar chart on my wall by my drill press.

The problem is that some drill presses just don’t go slow enough for the big Forstner bits. (I use bits up to 3”).

My advice on drilling large holes is to do it in stages. Clamp the piece securing in place and start with a 1” bit. Then drill again with a 1.5” bit and continue until you have the size you want.

-- Rich, Cedar Rapids, IA - I'm a woodworker. I don't create beauty, I reveal it.

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lovinmrv

103 posts in 2519 days


#5 posted 03-18-2010 03:53 PM

wow…awesome, jocks! Thanks!

-- Life is a sales job.

View PineInTheAsh's profile

PineInTheAsh

404 posts in 2728 days


#6 posted 03-18-2010 04:23 PM

Rich’s “in stages” suggestion (among many eloquent submissions here) is on mark.

Here’s much love to the beautiful gimlet-point bit.

I don’t have a 3” Forstner bit though have played with my 2-1/8” and then jig saw and chisel my way to satisfaction. One day soon am compelled to have a complete Forstner bit of every size they make; the bit design is one of the greatest woodworking inventions ever.

Here’s to the inventive Benjamin Forstner.

—Peter

View SPalm's profile

SPalm

5256 posts in 3342 days


#7 posted 03-18-2010 05:40 PM

Just another thought. Heat will kill these things. So turn it slowly, and lower it slowly. In fact, raise it up and let it cool if you are cutting a deep hole.

There are a lot of really cheap sets of these on the market. They may look alike, but there is a reason that the price differences are there.

Steve

-- -- I'm no rocket surgeon

View Chris Wright's profile

Chris Wright

540 posts in 2941 days


#8 posted 03-18-2010 06:11 PM

My set of bits have the max speed engraved on the shank. None are show a max speed of over 800 RPM. The larger ones say 650 RPM max. The speed I use on my drill press is in the mid 500’s (if the diagram on the inside of the pully cover is correct).

-- "At its best, life is completely unpredictable." - Christopher Walken

View Sawkerf's profile

Sawkerf

1730 posts in 2528 days


#9 posted 03-18-2010 07:11 PM

Drill speed (rpm) is only part of the picture. A lot also depends on the wood you’re working with, the sharpness of the bit, and the feed rate (downward pressure) you’re using.

Use the chart(s) to set your initial speed, but “tweak” it if you need to.

-- Adversity doesn't build character...................it reveals it.

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