# Adjustable drill.



## 100model (Apr 25, 2022)

This method will be useful if you have a need to drill large holes with a pedestal drill and don't want to buy expensive large drills.


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## 10K Pete (Apr 25, 2022)

That's great! A real slap-yer-forehead idea. Could have used that a half dozen times....
Thank you for posting!
Pete


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## 100model (Apr 27, 2022)

That idea has helped me a lot.


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## timo_gross (Apr 29, 2022)

I wonder, if it would make any sense to use this method for countersinking cap head bolt holes.

Later Edit: Turns out that it all becomes very small, so countersink was a rubbish idea.
But principle seemed to work quite well, until my tool "exploded", half sized in the workpiece, the cutting pin went flying and the shaft still in the drill chuck.


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## timo_gross (Apr 29, 2022)

I do not believe all Youtube videos.

Arbor exploded to big set screw, too small diameter, too big cutting bit
smaller cutting bit, ground too tiny, tool bit grabbed and broke.
Tool ground to 120° like a piece of cake. Then the underside just slightly tilted that I have a little bit clearance under the edge.
In Steel I do not dare to try, in Aluminium it works so fantastic a super clean flat bottom hole.

Thanks for the tip!

Cheers Timo


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## 100model (May 1, 2022)

If you use my tool to drill a flat bottom hole in steel without the pilot hole it will cause problems, with aluminium and plastic it works really well.


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## timo_gross (May 3, 2022)

100model said:


> If you use my tool to drill a flat bottom hole in steel without the pilot hole it will cause problems, with aluminium and plastic it works really well.



My copy of your tool is using a 12 mm pilot hole. I do not think I am able to make the center cut. (or I misunderstood what you mean by "without pilot hole") 
I guess the pilot hole that guides the tool is the secret that kept it without any chatter at all.  
Maybe if a hole all the way through creates problems in the final bit of remaining material, sandwiching a sacrificial guide plate under the actual work will help?


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## homemachinist (May 3, 2022)

100model said:


> This method will be useful if you have a need to drill large holes with a pedestal drill and don't want to buy expensive large drills.




Hello there from Melbourne 

Didn't realise you're from Vic. I enjoy watching your videos, especially ones re. pouring cast iron. Did you end up trying Gotteswinter's flexure design for the boring bar ?


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## 100model (May 4, 2022)

I don't have a slitting saw so it will have to wait until I get one. I probably live not far from you.


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## homemachinist (May 4, 2022)

righto, looking forward to the video when you get it! I've been planning to make one too, might get some time in the shed next week.

Great to know that a few YouTubers I watch are close by, Nigel from smallcnclathes channel is based in eastern suburbs as well.


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## Rains (May 11, 2022)

I think the drill tool must be tough enough to endure the drilling process of any strength and thickness. I personally will be able to provide good quality and inexpensive drilling tools, as well as other milling tools. Feel free to visit our website and browse around.  tianzhaocutter.com


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## homemachinist (May 11, 2022)

Rains said:


> I think the drill tool must be tough enough to endure the drilling process of any strength and thickness. I personally will be able to provide good quality and inexpensive drilling tools, as well as other milling tools. Feel free to visit our website and browse around.  tianzhaocutter.com



Do you have a price list somewhere ? I do this as a hobby so probably not going to be able to spend a lot on drill bits of varying sizes, which is why boring bars for anything more than 10-12mm is attractive.


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## Rains (May 11, 2022)

Yeah, I can surely provide you with a price list. Could you please give me your email address or WhatsApp so I can further discuss this with you?


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## homemachinist (May 11, 2022)

Rains said:


> Yeah, I can surely provide you with a price list. Could you please give me your email address or WhatsApp so I can further discuss this with you?



You can upload / attach files to this thread. I don't have any specific requirements at this stage but it may be useful to others on this forum as well.


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## Rains (May 11, 2022)

deepfryed said:


> You can upload / attach files to this thread. I don't have any specific requirements at this stage but it may be useful to others on this forum as well.


OK, sure, I will do that.


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