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Proper drill speed question

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Forum topic by hairy posted 06-23-2011 05:49 PM 1474 views 0 times favorited 11 replies Add to Favorites Watch
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hairy

2099 posts in 2256 days


06-23-2011 05:49 PM

I’m attempting to make a thin parting tool. Thanks, Capt. Eddie!

I have encountered my first design change opportunity.

The hole in the handle is my problem. My original plan was to use 3/16” brass rod to pin the handle on, similar to a knife handle. Instead of laminating handle grips to the tool blade, I cut a mortise into the wood to accept the cutting blade. I used a glue that I have had success with to glue the pieces together, and it has held well, in fact I have used this tool as it is.

I was trying to drill through the wood and metal when my troubles began. The blade is a lawn edger blade from Home Depot.

I don’t know what kind of steel it is, but it’s harder than Chinese arithmetic. It did not drill the metal at all, and my immediate reaction was to apply brute force. Really crank down on the drill press handle. I found out that’s a good way to drill a 17/64” hole in walnut with a 3/16” drill bit. That info might come in handy someday, but it ain’t today.

I did look at a drill speed chart to see what speed and bit combination to use, but it only had 1 speed listed (1800rpm??) for steel. I vaguely remember something about stainless needs to be drilled at a slow speed, but this steel is magnetic. I was using a good bit.

Most tools of this style have a short handle to be held in one hand. I like this big handle, I can hold it in one hand if I want, and still get the good control of two hands when needed.

I do have a Plan B, but I still need to drill. Can anyone tell me what speed and bit will do this?

Thanks!!

-- in the confusion, I mighta grabbed the gold ...


11 replies so far

View Dan's profile

Dan

3543 posts in 1604 days


#1 posted 06-23-2011 06:41 PM

I cant really give you a direct answer but I have drilled through cast iron and I know I was drilling at a speed less then 1000rpm. I may have even been as low as 500rpm. I would slow your speed down.

-- Dan - "Collector of Hand Planes"

View ajosephg's profile

ajosephg

1857 posts in 2285 days


#2 posted 06-23-2011 07:14 PM

Besides slowing it down, you probably need a better drill bit (assuming that you may be using a generic high speed steel bit.) Get a titanium coated or a cobalt drill bit.

Also use a peck and release method to allow the bit to cool. Also be a good idea to use cutting oil to help cool things off.

-- Joe

View Dan's profile

Dan

3543 posts in 1604 days


#3 posted 06-23-2011 07:22 PM

Joe – Good point on the peck and release method. I do the same anytime I drill through metal. I get the hold started then pull it back then back in a bit then back. I have only used water but oil is probably better.

-- Dan - "Collector of Hand Planes"

View crank49's profile

crank49

3481 posts in 1695 days


#4 posted 06-23-2011 07:27 PM

Drill diameter as well as material being drilled determine the correct speed.

That metal you’re drilling is probably harder than average, and needs a good quality drill bit. Might even need to be cobalt steel which will outlast HSS by a good margin. You also can’t drill the metal inside the wood unless you are willing to get oil on your wood. To drill in hard metal you have to lubricate the bit while it’s cutting.

Are your bits good HSS steel at least? I have heard that some Chinese drill bit sets only use HSS steel for the 1/8”, 1/4”, 5/16” and 3/8” bits in a set because those are the sizes most likely to be used.

I have drilled 3/16” holes in extremely hard high chrome iron alloy that was at Rc 64, which is a few points harder than most tool steel. That required a speed of 600 rpm and power feed in a very massive geared head drill using a carbide bit and oil lubricant.

You might try annealing the handle portion of your blade. Clamp the working end into a heavy smooth jaw vise, or between two pieces of copper or steel in a searrated jaw vise, and heat the spot where you want to drill with a torch till its bright red, then let it air cool. After the part gets below about 200 degrees you can cool it in water. Now you should be able to drill it with a regular drill bit.

Sorry Joe and Dan, I didn’t mean to write over you. Ya’ll must have posted while I was writing my reply. Well, at least we seem to all be saying about the same thing.

-- Michael :-{| “If you tell a big enough lie and tell it frequently enough, it will be believed.” ― A H

View murch's profile

murch

1185 posts in 1348 days


#5 posted 06-23-2011 09:22 PM

Hairy, they gave no worthwhile info about the steel on the H/D page but if it’s as hard as you said it is then the bottom half of what Cranky is telling you is the way to go.
If you don’t soften it it will skin one drill bit after another and screech up at you while it’s doing it.

p.s. keep back a bit from the flame and don’t set your head on fire!!

-- A family man has photos in his wallet where his money used to be.

View richgreer's profile

richgreer

4525 posts in 1798 days


#6 posted 06-23-2011 09:48 PM

Can you securely clamp the handle in place so that it absolutely will not move? If so, this might be worth a try.

Drill a small hole first, change the bit and drill a slightly larger hole and continue until you have the diameter you want. Of course, all the bits need to be of high quality and sharp and you still need cutting oil, but you may get less oil on the wood this way.

FYI – This is what I do when drilling large holes (up to 3”) in really hard wood like Paduck. I start with a 1” Forstner bit and work up from that.

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

View hairy's profile

hairy

2099 posts in 2256 days


#7 posted 06-23-2011 09:57 PM

Thanks fellas!

I went back and checked the speed chart I was using. It recommended 1000 rpm, and that is what I used. The bit I used is high speed steel, USA made.

It’s too late to anneal this one, I would ruin the handle breaking the glue bond . It’s glued in pretty good.

The steel is less than 1/8” thick, 0.113” or 2.86mm.

-- in the confusion, I mighta grabbed the gold ...

View Grandpa's profile

Grandpa

3193 posts in 1399 days


#8 posted 06-23-2011 11:35 PM

OOPS! on timing. Crank is right. Anneal the metal next time. I would wrap a wet rag aroun the part you plane to keep hard and hold it in a vise or some clamping device. The wet rag will keep the end cooler. heat the spot to be drilled to red and let it air cool. Come back in a hour or so and you should be able to drill it. work it like you want and if you need to harden it heat it again and cool it quickly. You can make it so hard it will shatter if dropped. Tempering goes from there.

View Nomad62's profile

Nomad62

726 posts in 1682 days


#9 posted 06-24-2011 05:36 PM

Only thing I could add from my experience drilling hard steel would be to start with a small bit and go up. Using titanium or cobalt coated, new bits is also helpful. The hardset part of the job for the bit is getting the cut going; dipping in and out is hard on it. Watch the shavings; if they stay bright silver you are okay, if they dull or turn blue the bit is too dull. It is almost impossible to turn the bit too slowly, the only difference is the fact you need to “time” the depth of the cut with the drill bit speed. If you have a spare piece of that steel you may try a test hole on it first to get a better feel for it.

-- Power tools put us ahead of the monkeys

View Roger's profile

Roger

15055 posts in 1528 days


#10 posted 06-24-2011 08:54 PM

I agree with Nomad62 about beginning with a smaller bit, and work your way up. That is probable hardened steel, which is a beeee-aaach to drill through. I also agree to the point of a slow speed for that hard steel. I would definately use some sort of cutting oil on the bit, and use the peck, release, then squirt a lil oil, and repeat method. Good luck with it. It is a fine looking parting tool there.

-- Roger from KY. Work/Play/Travel Safe. Kentuk55@bellsouth.net

View bubinga's profile

bubinga

861 posts in 1392 days


#11 posted 06-25-2011 05:12 PM

I agree with Nomad62 .It is almost impossible to turn the bit too slowly,when drilling steel. but to fast will burn up your bit.
You need,either a cobalt, or carbide bit.
Here is a link for some charts you can download (free ) from Wood Magazine
• Drill Press Speed Chart . Wood Screw Chart
• Lumber Sizing Chart
• Decimals conversion chart
The two under here are not PDF, I copied, and pasted them , in word, and saved them, it worked good.
The others are PDF
• Decimal and Millimeter Equivalents
• Glue Chart

http://www.woodmagazine.com/woodworking-tips/techniques/free-woodworking-charts/?sssdmh=dm17.523724&page=5&esrc=nwwood050511&email=3150142140

-- E J ------- Always Keep a Firm Grip on Your Tool

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