Need to drill a flat bottomed 29/64" hole in wood 1/8" deep.

[SmokeWalker]

Re: Need to drill a flat bottomed 29/64" hole in wood 1/8" deep.

I went out to shop and ground a flat bottomed drill and drilled a piece of metal with it. It would last a long time if all it was cutting was wood. I took a drill and cut it shorter to make it stiffer. But with wood I don;t think you would need to do that. I cut 3 holes .125 deep . I could have drilled the whole plate but 3 holes was enough to show how drill worked. I checked bottom and it is flat within a few thousands. I have been doing this for about 50 years. See pics of drill and steel plate below.
jimsehr




https://lh6.googleusercontent.com/-...kcATkpY/w1112-h695-no/flat+bottomed+drill.jpg

That's exactly what I'd like to do, but so far, every time I've tried flattening and re grinding my bit, I just end up drilling an oversize hole. How do you get the drill sharpened perfectly? You say you've been doing this 50 years, I hope you didn't just master it last month!

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Photobucket isn't working for me now.

Use an adjustable boring head. I took an old 1/2" shank single flute HSS router bit and ground most of it away leaving a cutting spur to pare the wood fibers upon entry, then a flat bottom raker to clean things out.

here's a thread about making a wooden collet rack that used that bit. what you'll have to use will have to be modified to fit the smaller hole.

http://www.owwm.org/viewtopic.php?f=79&t=100587&p=685752&hilit=collet+rack#p685752

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here it is

That looks great, but I'd have to get or make a boring head. I don't know. I'd like a simple technique that is easy to sharpen. That looks good, but the cost of the boring head is eating a bit into the budget right now...

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If you can tolerate a shallow guide hole in the center then consider making a counterbore from drill rod:
http://www.gadgetbuilder.com/CounterBore.html

If you can't tolerate the guide hole then leave the pilot out - but you'll need to hold the part securely and pre-drill then use a drill press or mill etc to hold the counterbore while you finish up. Not appropriate if you're using a hand drill, of course.

Counterbores are fairly quick and easy to make and one made from mild steel - unhardened - should last long enough to see if the concept works for your task. You may need to make a simple jig to aid in accurately sharpening it although even a filed edge should work in wood. Much simpler to sharpen than a twist drill.

John

View attachment 82916

I also like this idea. I'm drilling on the lathe. Shouldn't there be relief on the right side of the tool, so that it's not being rubbed?

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Could you drill at 7/16 and use a chucking reamer? If you have to make lots of parts, a Forster that you can resharpen would be best.

Try as I have, wood doesn't ream. The forstner bit would be fine, except the point ruins my flat bottom. Blast.

 

[Jimsehr]

Re: Need to drill a flat bottomed 29/64" hole in wood 1/8" deep.

That's exactly what I'd like to do, but so far, every time I've tried flattening and re grinding my bit, I just end up drilling an oversize hole. How do you get the drill sharpened perfectly? You say you've been doing this 50 years, I hope you didn't just master it last month!

I have been hand grinding drills for a long time . As I said in post # 8 send me your address and I will make you a drill
that will do the job for 15 bucks .
That is for the drill ,grinding and shipping. I could use a boring head to do the job but the drill is so much faster. I just make things in my shop for fun now. To see if I can do them. I just formed a 3/8 dia ball in the center of a 1 inch cube of aluminum thru 5/16 dia bores to see if I could. The ball is free in the center of cube. I hand ground the tools to form
the ball. If you want go too Photobucket and look at jims_03 and you can see some of my stuff. Or google jimsehr

jimsehr
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[Dr. Duzlittler]

And I want to avoid buying a $40 end mill just for this one task.
Any ideas? I have a 7/16" end mill that seems to cut about .003" (dia.) oversized for 29/64.
I need to make many of these.

Oh, and I had an anger breakdown yesterday trying to sharpen my 29/64 machine screw drill bit. I am no good at sharpening bits. For lack of a better word, I felt like a tool.

I'm thinking I could use a 3/8" end mill to get the right depth, and then fashion my own brad point-ish bit at 29/64 (w/o the point) to get the right diameter.

Thoughts?

I know you said you didn't want to spend $40 for just one bit, I don't at all blame you for that. If I were you I'd get a boring head with a 1/2" shank, then you can run in any drill press with a 1/2" capacity chuck and you can bore ANY SIZE hole that you might would need to in the future. Here's one on EBay for $49.95 that also has a micrometer adjustment which makes it much easier to adjust. If you've never used a boring head before don't let it intimidate you, they're pretty simple to operate and you'll always end up with excellent results. You can bore it to be a press fit or a loose fit. Like I said in my other post, even if you did have the proper size bit you can have run-out in your spindle/chuck and you'll end up with an oversize hole. By using a boring head the run-out won't have any effect on your final hole size per use. Here's the link to the one I saw on EBay, there's a few more on there that come with a set of boring bars also: http://www.ebay.com/itm/ISCAR-Preci...0?pt=BI_Tool_Work_Holding&hash=item51bbab2888

 

[bfd]

ust take a drill that size and grind the end and make a flat bottomed drill. the shipyard I served my apprenticeship at had drawer fulls of them all hand ground tey worked perfectly bill

 

[tq60]

What type of wood and in what machine?

If in a lathe the bit shown above can work and if made smaller it cab be placed in tool holder and hole size dialed in.

If in drill press make your own!

Get a 2 flat end mill for reference and buy some drill bits correct size.

Grind one flat then match end of end mill.

But best bet if doing this for a productiin job is spend the stupid 40 bucks and buy the tool as your labor rate is how much and how long of putzing with making some tool is really costing you?

If yiu take 1 hour to make a tool that is perfect then that hour of work saved you 40 bucks...

If yiu charge more than that as shop rate then you lost the difference.

And 0.003 in wood is very close...wood moves a lot so what is the function?

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