### Where to buy "Counterbore" tool. ###
 

this is opposite of countersink tool. Used for making socket head cap screws flush....

Where can I buy one that make 2, 3, 4, mm holes?

thanks"thumbsup"

you could try here http://www1.mscdirect.com/CGI/GSDRVS...00000081527442 or here http://www.mcmastercarr.com

A "counterbore" tool is just an endmill. They are not something that can just be thrown in a drill press and used. The part needs to be securely fastened down in a vice or clamped, and them the tool running at a pretty decent speed, usually over 1200rpm for aluminum and fed into the part very slowly.

If you are not careful, it will grab the part and royally damage it.

Actually,they do make counter boring tools.
Only problem I see is that they are not cheap.

:idea:try www.wttool.com

That is correct but also incorrect. With the proper Counter bore tool you can use a hand drill. The have a "guide" that fits in the drilled hole and centers the tool. You can also use a spot face tool. I use a 7/8" daily at work for locating BAVA vibration probes using a Milwaukee cordless drill.

http://www.mcmaster.com/

3mm- $10.64
4mm- $13.92

Well, up to you guys, still had better have that part clamped down solid. I would still be pretty hesitant to try and counter bore the full depth of a 3 or 4mm socket head into aluminum by hand, but for those that want to try, here are the part numbers at www.mcmasters.com-

3mm -
29445A21
4mm
29445A22

Sorry Darksoul, you're correct on having the parts held tight, clamp, vice something. I was more referring to using a hand drill if needed. My bad.

Why don't you just use a standard drill bit? I have used drill bits for countersinking those "square headed" cap screws many times...and it works great. Plus, typically for the price of an end mill, a drill bit set is far cheaper and you have the multiple different sizes available to you.

Sorry.Wasn't trying to flame you.Those tools aren't my preferred method either but,not everyone has access to a mill.And yes,you're correct,it would be a good idea to clamp the part down.It doesn't feel good if it spins.;-)

Step drills work great.

I'm not sure what 5150bronco has in mind for these, but a drill is by no means the same thing or for the same purpose as a counterbore. A drill bit will not leave a flat surface for the bolt to tighten up against. That is the whole purpose of the counterbore, its not to drill a hole , but to ream the holes bottom end to allow the most surface area between the bolts head and the piece being bolted. Also a counterbore shares some of it features with an endmill but it is not the same thing, as stated above a counterbore has a pilot to align the bore/counterbore.

You can get a set from Grizzly too. I don't know about the quality though....we buy ours from MSC.

True these aren't endmills, but true you should firmly clamp your workpiece to use these properly. That being said...........I have used these in a handrill before. Not the best practice, but sometimes you just need to get something done. Many times though if the work is held secure, I'll just use an endmill. I did a lot of that on the chassis I'm working on:

http://www.rccrawler.com/forum/showt...=143170&page=3

Oops.....I just noticed these are for standard SHCS....not Metric. Sorry

I never said it was the same thing, or was for the same purpose. I merely stated that the drill bit works just fine without having to buy a "special" counterbore just to make a squared hole. I have used both brad point and standard twist bit point bits, and they both work great for this purpose. The brad point bits (like in this pic) seem to do a cleaner job though.

http://www.morriswoodtool.com/endgrain.jpg

when i'm doing my flintlock build i bought some countersink bits in 4 sizes from #4, #6, #8, and #10 wood screws....but they have been working for any screw that needs to be countersunk ;-) ..............bob

....

Okay. So, what I am trying to do is similar to countersinking.

I want to make a hole in skid plate so I can use socket head cap screw to mount tranny. circular hole not cone shaped (like countersink).

Thanks for all the reply's. "thumbsup"

Hey Offroader........, where can I get that particular drill bit to fit 3mm cap screw?

this is what i found at rutlandtool.com

Robert Charles 3.4mm Dia. 3-Flute Metric Cap Screw Counterbore
$21.84

part # 11673500

will this work?

this is exactly what I want to accomplish! Thanks for the imput and helping me clarify what I am trying to do.

I got a set off of ebay for $30,I am not sure if I have 2mm in my set but I can check when I get home, I used them with the part in a vise and a hand drill, no problem "thumbsup",
I had mad my own that kinda worked on alum , I took a busted drill bit and my dremel and cut a notch about 1/4" from the tip of the bit, then ground the bottom part of the bit off, like the guide part , it was soso, not nearly as clean as the actual thing, but when your in a bind you find ways to make things work 8)

Not sure on an exact bit like that one. I have a whole drill bit set with the brad point tips on them. The head of a 3mm that I have here is 5.5mm...so a 7/32" drill bit would be perfect. On a 4mm screw the head is 7mm, so a 19/64" bit would work well there. I don't have any 2mm hardware to check, but I assume you could get just as close with a smaller bit.

I can't tell from the description if that cuts a 5mm or 6mm counterbore. If it cuts a 6mm hole, it'll be good for the 3mm hardware...but if it cuts a 5mm, the head of the 3mm won't quite fit.