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Looking for a centering tool for drilling holes in rounds

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Posted · Report post

This has been coming up too much lately and while my eye is sometimes successful, I need a more accurate method to locate the exact center in the end of a round rod or object to drill a hole. There must be some machinist tool or trick for this that doesn't cost $200 and would work on the small diameter round we use at our scales..

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Posted · Report post

If you can draw a perfect X across the face then you can find the center every time. I don't know if they make it on a small scale, but I have something that I use in my shop when working on real race cars that will work. It's simply a metal V with a metal straight edge rule that runs in the center of the V. You put the V on the outer face of the round stock and draw a line and then rotate and draw another line. You can do it as many times as you like, but all lines cross on the center where you want to drill.

Here's a link to a pick of what I am talking about.

http://www.harborfreight.com/cpi/ctaf/disp...Itemnumber=4185

Now, only if they make it on a smaller scale that would be nice.

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Posted · Report post

If you can draw a perfect X across the face then you can find the center every time. I don't know if they make it on a small scale, but I have something that I use in my shop when working on real race cars that will work. It's simply a metal V with a metal straight edge rule that runs in the center of the V. You put the V on the outer face of the round stock and draw a line and then rotate and draw another line. You can do it as many times as you like, but all lines cross on the center where you want to drill.

Now, only if they make it on a smaller scale that would be nice.

I've seen those tools before, even simpler than the one you link too. would be nice to see something like that for smaller objects.

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Posted · Report post

Whenever I've built/modified RC cars, I've always had problems lining up holes and marking hole-location's for perfect drilling. Even with carefull measuring, I still can't get the darn thing's perfect. Marking holes for precision, or near-precision is darn-difficult!

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Posted · Report post

I've got a contest this weekend. I'll have to ask around and see what they say.

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Posted (edited) · Report post

Here is a trick I have used a few times (requires drill press, vise and some patience): Take a piece of angle metal (brass, steel, whatever) and mount it in the vise with the open side up, i.e. like this: V. Chuck something round and pointed (a nail, scratch awl, whatever you got that is straight and has a sharp pointed tip) in the drill press as a center finder and move the vise around until the center of the drill aligns with the bottom of the "V". The chuck is now centered with the channel, so a piece of round rod or tube will also be centered if you place it in the V-channel. It can be a bit tricky if you want to drill metal, as you have to hold it firmly or even clamp it, but it works quite well when drilling softer materials like wood or plastic.

BTW: Here's another nifty little thing you can use, but I'm not sure if it will work on smaller parts: http://www.micromark.com/CENTER-FINDER-FOR...STOCK,7949.html

Edit: I read the question again, and it's obviously about drilling a hole in the end of a rod... Oh well, now you know how to cut a perpendicular hole anyway.

Edited by Olle F

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Posted (edited) · Report post

I'm not sure what you're trying to do, but once I needed a small hole in the end of a tube frame section. The frame was 1/8" tubing, so what I did was insert a small 1/4" long piece of the next smaller size tubing....then insert a size smaller than that.....and so on, until there was a tiny little hole for a wire, perfectly in the center of the tubing.

Does this help any? Does this even make any sense? :)

Edited by roadhawg

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Posted · Report post

Here is a trick I have used a few times (requires drill press, vise and some patience): Take a piece of angle metal (brass, steel, whatever) and mount it in the vise with the open side up, i.e. like this: V. Chuck something round and pointed (a nail, scratch awl, whatever you got that is straight and has a sharp pointed tip) in the drill press as a center finder and move the vise around until the center of the drill aligns with the bottom of the "V". The chuck is now centered with the channel, so a piece of round rod or tube will also be centered if you place it in the V-channel. It can be a bit tricky if you want to drill metal, as you have to hold it firmly or even clamp it, but it works quite well when drilling softer materials like wood or plastic.

BTW: Here's another nifty little thing you can use, but I'm not sure if it will work on smaller parts: http://www.micromark.com/CENTER-FINDER-FOR...STOCK,7949.html

Edit: I read the question again, and it's obviously about drilling a hole in the end of a rod... Oh well, now you know how to cut a perpendicular hole anyway.

That's cool Olle .. that tool is based on the same principle as the centering tool.

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Posted · Report post

I'm not sure what you're trying to do, but once I needed a small hole in the end of a tube frame section. The frame was 1/8" tubing, so what I did was insert a small 1/4" long piece of the next smaller size tubing....then insert a size smaller than that.....and so on, until there was a tiny little hole for a wire, perfectly in the center of the tubing.

Does this help any? Does this even make any sense? :)

you understand exactly what I'm trying to do, drill a centered hole in the end of a rod. I've been using you trick quite a lot when the tube-in-tube trick can work. I actually have a carb air cleaner that was created in just this manner. the outside diameter is about 3/8" tube and it was build up solid from progressively smaller tubes ending in a small, solid piece. Here's a pic of the piece before chucking in the Dremel and turning it to shape on the top.

51Plymouth_AirFilter2_DSC0732.jpg

My problem is I have to use a large drill point to create an indentation in the top where the wing nut goes. Due to the slight differences between ID and OD of the tubes, the solid rod in the center is NOT centered .. enough that creating this indentation using that is visually off center.

This is the specific task that prompted this, but it is defiantly a general question that comes up over and over for everyone I'm sure.

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Posted · Report post

maybe put a tube one size bigger than what your using and then use the same size drill bit to find the center then use the desired size drill bit for the hole .

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Posted · Report post

maybe put a tube one size bigger than what your using and then use the same size drill bit to find the center then use the desired size drill bit for the hole .

OH! great idea! ... will have to check the BIG drill set.. :)

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Posted · Report post

maybe put a tube one size bigger than what your using and then use the same size drill bit to find the center then use the desired size drill bit for the hole .

Or even put a piece smaller tube as a guide inside the bigger tube, and use the correct size drill bit right away? Speaking of tube, why not do it the other way around and use tube to begin with, and then fill it to the desired depth with a styrene rod? Styrene tubes and rods usually fit together nicely, so that might be an option as well.

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Posted · Report post

Or even put a piece smaller tube as a guide inside the bigger tube, and use the correct size drill bit right away? Speaking of tube, why not do it the other way around and use tube to begin with, and then fill it to the desired depth with a styrene rod? Styrene tubes and rods usually fit together nicely, so that might be an option as well.

that's how I made the base for the part, one tube inside another. .. see photo above. In the end, the problem was there was enough slop in the tubes that the final solid one in the center wasn't in the exact center. When I drilled the the small center tube it visibly off center. I need a dip in the center, not a hole. The tip of a large drill will give what i need if I can center it.

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Posted (edited) · Report post

maybe put a tube one size bigger than what your using and then use the same size drill bit to find the center then use the desired size drill bit for the hole .

Follow up to randx0's suggestion ... after I used it! I didn't have a larger tube to fit outside but easily rolled the same size together with the air cleaner and slipped a 1/4" drill bit matching the ID down and a few twists by hand .....

AirCleanerDrillSleeve_DSC0911.jpg

a BEAUTIFUL dimple in the top!! :)

AirFilterDimple_DSC0916.jpg

This ends with at least a method for this particular situation that worked well. Don't anyone stop thinking.. thanks for all the suggestions!

Edited by Foxer

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Posted · Report post

Well if all else fails you can log onto either Micro-Mark or Model expo. they both sell a center finder cheap. it similar to a 90 degree square other then it is about 60 degrees. they sell a small one and a large one.

All you do is lay it against the end of your round stock and make a mark rotae it at least 45 degrees and make another mark. Viola perfect center. They are a common tool in a machine shop and other fabricating shops.

Micro-Mark

Model expo hobby tools

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Posted · Report post

Well if all else fails you can log onto either Micro-Mark or Model expo. they both sell a center finder cheap. it similar to a 90 degree square other then it is about 60 degrees. they sell a small one and a large one.

All you do is lay it against the end of your round stock and make a mark rotae it at least 45 degrees and make another mark. Viola perfect center. They are a common tool in a machine shop and other fabricating shops.

Micro-Mark

Model expo hobby tools

Thanks for the leads, :( ... but I'm still unable to find a center finder that is usable on the size of circular objects common in 1/25th modeling. Most I've seen have a notch at the intersection that appears larger than most round objects I'd need to mark. Model expo hobby tools has none in their catalog and a search does turn up a number and price but with a photo of a cardboard box. Possibly a discontinued item. Micro Mark's is on a steel square and appears too large and difficult to tell if the notch on that would hamper use on small items.

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Posted · Report post

Try Harbor freight tools or any other tool supply for machine shops. I have a set that if you could see you could find the center on a >032" rod.

Harbor Freight

J&L industrial tools

McMasterCar

Good luck I have had mine for over 30 years

Ernie

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Posted (edited) · Report post

I really do appreciate you efforts Ernie. Machine shops must be all digital now and no one uses these anymore. I see lots of plastic ones too. All seem to have slots at the apex that would prevent uses on small diameters. B)

Looks like I'll have to make one.

Edited by Foxer

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