Drilling Deep Holes in End Grain

      Advice on how to drill three-foot wiring chases into the ends of wooden deck posts, in the field. November 26, 2008

I need some advice please. I am a carpenter in WI and have been asked to bore wire chase holes in the knewel posts of the owner’s deck. The holes are to fish low voltage wire for lighting. This is in the field milling and I do not have access to a lathe or CNC Router. I was anticipating having some bits fabricated to varying lengths by welding an extension to them but how in the world will I ever keep them straight? Or at least straight enough that I do not shoot out the side of the treated 6x6? The bore will need to be at least 36" deep.

Is this even possible? I seem to always find a way to accommodate goofy architects but this one I am having a hard time with.

Forum Responses
(Solid Wood Machining Forum)
From contributor J:
I just bought a 18"x1" drill bit at Home Depot and a 18" extension I can drill a 34" deep hole pretty straight with a holehawg drill you could always add another extension to go deeper and the total cost would be around $50.

From contributor J:
The bit is likely to drift off course drilling a hole that deep in end grain. Some people use an air-cooled bit to help alleviate that problem.

From contributor R:
Ship auger bits are designed to do what you want. They are available in 18" lengths so you will still need an extension or two.

From contributor H:
Dado a groove in the back of the post and fill it with a glued wedge half the depth of the dado. Or put the wire in and then fill with the wedge.

From contributor D:
I have drilled out 7 foot reclaimed columns to be used for lamp bases by running a length of pipe up the hole around an electricians auger bit. The auger tip really pulls the bit, but the pipe seemed to steady it, and I was able to direct it fairly well. I drilled from both directions; not as accurate as the Chunnel but it worked.

From contributor C:
I once saw a man twisted into a knot while using a shipauger bit. That is the tool for the job in my opinion, but you had better be sure to extract it every few inches to clear the chips or it will bind up and if your drill is powerful enough it will twist you in a knot. We welded pencil rod to the end to bore really deep holes.

From contributor A:
This may sound weird, but it actually worked for me when I had to deep drill a precision hole. As the others suggested, we used a deep boring bit with an extension. What we did to ensure that the bore was truly vertical was to station two helpers 90 degrees apart.

Each person eyeballs a sight line ensuring that the drill bit and newel post are parallel. If you drift a little in any direction, your helpers tell you left or right, and you make the slight adjustment as needed.

From contributor S:
I recognize this is an extremely deep hole but you would be surprised at how well a simple jig with a drill bushing clamped to the post can work. Bushings are available in different diameters and different lengths. A longer bushing will obviously help you stay straight on a deeper hole. Bushings help remove any lateral movement of the drill. That is one reason they help keep holes accurate and bits sharp when drilling steel. If you have ever drilled steel on a press and then with a hand drill you will appreciate that drilling with a hand drill and a bushing is closer to drilling on a press than freehand. Also you can start with a smaller diameter hole (if the bit is available) and ream the hole to finished dimension after.

Would you like to add information to this article?
Interested in writing or submitting an article?
Have a question about this article?

Have you reviewed the related Knowledge Base areas below?
  • KnowledgeBase: Knowledge Base

  • KnowledgeBase: Architectural Millwork

  • KnowledgeBase: Architectural Millwork: Millwork Installer

    Would you like to add information to this article? ... Click Here

    If you have a question regarding a Knowledge Base article, your best chance at uncovering an answer is to search the entire Knowledge Base for related articles or to post your question at the appropriate WOODWEB Forum. Before posting your message, be sure to
    review our Forum Guidelines.

    Questions entered in the Knowledge Base Article comment form will not generate responses! A list of WOODWEB Forums can be found at WOODWEB's Site Map.

    When you post your question at the Forum, be sure to include references to the Knowledge Base article that inspired your question. The more information you provide with your question, the better your chances are of receiving responses.

    Return to beginning of article.

    Refer a Friend || Read This Important Information || Site Map || Privacy Policy || Site User Agreement

    Letters, questions or comments? E-Mail us and let us know what you think. Be sure to review our Frequently Asked Questions page.

    Contact us to discuss advertising or to report problems with this site.

    To report a problem, send an e-mail to our Webmaster

    Copyright © 1996-2020 - WOODWEB ® Inc.
    All rights reserved. No part of this publication may be reproduced in any manner without permission of the Editor.
    Review WOODWEB's Copyright Policy.

    The editors, writers, and staff at WOODWEB try to promote safe practices. What is safe for one woodworker under certain conditions may not be safe for others in different circumstances. Readers should undertake the use of materials and methods discussed at WOODWEB after considerate evaluation, and at their own risk.

    WOODWEB, Inc.
    335 Bedell Road
    Montrose, PA 18801

    Contact WOODWEB

  • WOODWEB - the leading resource for professional woodworkers

      Home » Knowledge Base » Knowledge Base Article